Comparison of a Daily Steviol Glycoside Beverage compared with a Sucrose Beverage for Four Weeks on Gut Microbiome in Healthy Adults

BACKGROUND

Recent studies suggest that some nonnutritive sweeteners (NNS) have deleterious effects on the human gut microbiome (HGM). The effect of steviol glycosides on the HGM has not been well studied.

OBJECTIVE

We aimed to evaluate the effects of stevia- compared with sucrose-sweetened beverages on the HGM and fecal short-chain fatty acid (SCFA) profiles.

METHODS

Using a randomized, double-blinded, parallel-design study, n = 59 healthy adults [female/male, n = 36/23, aged 31±9 y, body mass index (BMI): 22.6±1.7 kg/m2] consumed 16 oz of a beverage containing either 25% of the acceptable daily intake (ADI) of stevia or 30 g of sucrose daily for 4 weeks followed by a 4-week washout. At weeks 0 (baseline), 4, and 8, the HGM was characterized via shotgun sequencing, fecal SCFA concentrations were measured using ultra-high performance liquid chromatography-tandem mass spectrometry and anthropometric measurements, fasting serum glucose, insulin and lipids, blood pressure, pulse, and 3-d diet records were obtained.

RESULTS

There were no significant differences in the HGM or fecal SCFA between the stevia and sucrose groups at baseline (P > 0.05). At week 4 (after intervention), there were no significant differences in the HGM at the phylum, family, genus, or species level between the stevia and sucrose groups and no significant differences in fecal SCFA. At week 4, BMI had increased by 0.3 kg/m2 (P = 0.013) in sucrose compared with stevia, but all other anthropometric and cardiometabolic measures and food intake did not differ significantly (P > 0.05). At week 8 (after washout), there were no significant differences in the HGM, fecal SFCA, or any anthropometric or cardiometabolic measure between the stevia and sucrose groups (P > 0.05).

CONCLUSIONS

Daily consumption of a beverage sweetened with 25% of the ADI of stevia for 4 weeks had no significant effects on the HGM, fecal SCFA, or fasting cardiometabolic measures, compared with daily consumption of a beverage sweetened with 30 g of sucrose.

TRIAL REGISTRATION

clinicaltrials.gov as NCT05264636.

Important food sources of fructose-containing sugars and adiposity: A systematic review and meta-analysis of controlled feeding trials

BACKGROUND

Sugar-sweetened beverages (SSBs) providing excess energy increase adiposity. The effect of other food sources of sugars at different energy control levels is unclear.

OBJECTIVES

To determine the effect of food sources of fructose-containing sugars by energy control on adiposity.

METHODS

In this systematic review and meta-analysis, MEDLINE, Embase, and Cochrane Library were searched through April 2022 for controlled trials ≥2 wk. We prespecified 4 trial designs by energy control: substitution (energy-matched replacement of sugars), addition (energy from sugars added), subtraction (energy from sugars subtracted), and ad libitum (energy from sugars freely replaced). Independent authors extracted data. The primary outcome was body weight. Secondary outcomes included other adiposity measures. Grading of Recommendations Assessment, Development, and Evaluation (GRADE) was used to assess the certainty of evidence.

RESULTS

We included 169 trials (255 trial comparisons, n = 10,357) assessing 14 food sources at 4 energy control levels over a median 12 wk. Total fructose-containing sugars increased body weight (MD: 0.28 kg; 95% CI: 0.06, 0.50 kg; P_MD = 0.011) in addition trials and decreased body weight (MD: -0.96 kg; 95% CI: -1.78, -0.14 kg; P_MD = 0.022) in subtraction trials with no effect in substitution or ad libitum trials. There was interaction/influence by food sources on body weight: substitution trials [fruits decreased; added nutritive sweeteners and mixed sources (with SSBs) increased]; addition trials [dried fruits, honey, fruits (≤10%E), and 100% fruit juice (≤10%E) decreased; SSBs, fruit drink, and mixed sources (with SSBs) increased]; subtraction trials [removal of mixed sources (with SSBs) decreased]; and ad libitum trials [mixed sources (with/without SSBs) increased]. GRADE scores were generally moderate. Results were similar across secondary outcomes.

CONCLUSIONS

Energy control and food sources mediate the effect of fructose-containing sugars on adiposity. The evidence provides a good indication that excess energy from sugars (particularly SSBs at high doses ≥20%E or 100 g/d) increase adiposity, whereas their removal decrease adiposity. Most other food sources had no effect, with some showing decreases (particularly fruits at lower doses ≤10%E or 50 g/d). This trial was registered at clinicaltrials.gov as NCT02558920 (https://clinicaltrials.gov/ct2/show/NCT02558920).

An Oat β-Glucan Beverage Reduces LDL Cholesterol and Cardiovascular Disease Risk in Men and Women with Borderline High Cholesterol: A Double-Blind, Randomized, Controlled Clinical Trial

BACKGROUND

High-molecular-weight (MW) oat β-glucan (OBG), consumed at 3-4 g/d, in solid foods reduces LDL cholesterol by a median of ∼6.5%.

OBJECTIVES

We evaluated the effect of a beverage providing 3 g/d high-MW OBG on reduction of LDL cholesterol (primary endpoint) when compared with placebo.

METHODS

We performed a parallel-design, randomized clinical trial at a contract research organization; participants, caregivers, and outcome assessors were blinded to treatment allocation. Participants with LDL cholesterol between 3.0 and 5.0 mmol/L, inclusive [n = 538 screened, n = 260 ineligible, n = 23 lost, n = 48 withdrawn (product safety); n = 207 randomly assigned, n = 7 dropped out, n = 9 withdrawn (protocol violation); n = 191 analyzed; n = 72 (37.7%) male, mean ± SD age: 43.3 ± 14.3 y, BMI: 29.7 ± 5.2 kg/m2], were randomly assigned to consume, 3 times daily for 4 wk, 1 g OBG (n = 104, n = 96 analyzed) or rice powder (Control, n = 103, n = 95 analyzed) mixed into 250 mL water. Treatment effects were assessed as change from baseline and differences analyzed using a 2-sided t test via ANOVA with baseline characteristics as covariates.

RESULTS

After 4 wk, change from baseline least-squares-mean LDL cholesterol on OBG (-0.195 mmol/L) was less than on Control (0.012 mmol/L) by mean: 0.207 mmol/L (95% CI: 0.318, 0.096 mmol/L; P = 0.0003); the following secondary endpoints were also reduced as follows: total cholesterol (TC) (0.226 mmol/L; 95% CI: 0.361, 0.091 mmol/L; P = 0.001), TC:HDL cholesterol ratio (0.147; 95% CI: 0.284, 0.010; P = 0.036), non-HDL cholesterol (0.194 mmol/L; 95% CI: 0.314, 0.073 mmol/L; P = 0.002), and Framingham cardiovascular disease (CVD) risk (0.474; 95% CI: 0.900, 0.049, P = 0.029). Changes in HDL cholesterol, triglycerides, glucose, and insulin did not differ between treatment groups (P > 0.05). Lipid treatment effects were not significantly modified by age, sex, BMI, or hypertension treatment. There were no major adverse events, but both treatments transiently increased gastrointestinal symptoms.

CONCLUSIONS

Consuming a beverage containing 1 g high-MW OBG 3 times daily for 4 wk significantly reduced LDL cholesterol by ∼6% and CVD risk by ∼8% in healthy adults with LDL cholesterol between 3 and 5 mmol/L.This trial was registered at clinicaltrials.gov as NCT03911427.

Different Food Sources of Fructose-Containing Sugars and Fasting Blood Uric Acid Levels: A Systematic Review and Meta-Analysis of Controlled Feeding Trials

BACKGROUND

Although fructose as a source of excess calories increases uric acid, the effect of the food matrix is unclear.

OBJECTIVES

To assess the effects of fructose-containing sugars by food source at different levels of energy control on uric acid, we conducted a systematic review and meta-analysis of controlled trials.

METHODS

MEDLINE, Embase, and the Cochrane Library were searched (through 11 January 2021) for trials ≥ 7 days. We prespecified 4 trial designs by energy control: substitution (energy-matched replacement of sugars in diets); addition (excess energy from sugars added to diets); subtraction (energy from sugars subtracted from diets); and ad libitum (energy from sugars freely replaced in diets) designs. Independent reviewers (≥2) extracted data and assessed the risk of bias. Grading of Recommendations, Assessment, Development, and Evaluation was used to assess the certainty of evidence.

RESULTS

We included 47 trials (85 comparisons; N = 2763) assessing 9 food sources [sugar-sweetened beverages (SSBs), sweetened dairy, fruit drinks, 100% fruit juice, fruit, dried fruit, sweets and desserts, added nutritive sweetener, and mixed sources] across 4 energy control levels in predominantly healthy, mixed-weight adults. Total fructose-containing sugars increased uric acid levels in substitution trials (mean difference, 0.16 mg/dL;  95% CI:  0.06-0.27 mg/dL;  P = 0.003), with no effect across the other energy control levels. There was evidence of an interaction by food source: SSBs and sweets and desserts increased uric acid levels in the substitution design, while SSBs increased and 100% fruit juice decreased uric acid levels in addition trials. The certainty of evidence was high for the increasing effect of SSBs in substitution and addition trials and the decreasing effect of 100% fruit juice in addition trials and was moderate to very low for all other comparisons.

CONCLUSIONS

Food source more than energy control appears to mediate the effects of fructose-containing sugars on uric acid. The available evidence provides reliable indications that SSBs increase and 100% fruit juice decreases uric acid levels. More high-quality trials of different food sources are needed. This trial was registered at clinicaltrials.gov as NCT02716870.

Acute glycemic and insulin response of Fossence™ alone, or when substituted or added to a carbohydrate challenge: A three-phase, acute, randomized, cross-over, double blind clinical trial

Short chain fructo-oligosaccharides (scFOS) are well-recognized prebiotic fibers. Fossence™ (FOSS) is a scFOS that has been produced from sucrose via a proprietary fermentation process and has not been tested for its digestibility or glucose/insulin response (GR and IR, respectively). The present randomized, controlled, cross-over study was conducted in 3 phases to explore GR and IR to ingestion of FOSS, when replaced by/added to available-carbohydrates (avCHO) among 25 healthy adults (40 ± 14years). In each phase GR and IR elicited by 3-4 test-meals were measured among the fasted recruited subjects. The interventional test meals were as follows: Phase-1, water alone or 10g FOSS or 10g Dextrose in 250ml water; Phase-2, 250ml water containing Dextrose:FOSS (g:g) in the content as 50:0 or 50:15 or 35:0 or 35:15; Phase-3 portions of white-bread (WB) containing avCHO:FOSS (g:g) in the content as 50:0 or 50:15 or 35:0 or 35:15. Blood samples (finger prick method) were collected at fasting and 15, 30, 45, 60, 90 and 120 min after start of test meal ingestion. Plasma glucose and serum insulin were analyzed utilizing standard methods. The primary endpoint was differences in glucose IAUC. All subjects provided their written consent to participate in the study (ClinicalTrials.gov: NCT03755232). The results demonstrated that FOSS, when consumed alone, showed no raise in glycaemia or insulinemia and was statistically equivalent to response of water alone. GR and IR elicited by dextrose:FOSS and WB:FOSS test-meals of Phase 2 and Phase 3, were statistically equivalent to the respective test-meals without FOSS. Result of the 3 phases support the hypothesis that FOSS is resistant to breakdown and is indigestible in the human small-intestine, and therefore can be classified as an unavailable carbohydrate that does not raise post prandial blood glucose or insulin. FOSS, being sweet to taste, may be an acceptable sugar replacer in beverages without compromising their taste and sensory qualities.

Important food sources of fructose-containing sugars and incident gout: a systematic review and meta-analysis of prospective cohort studies

OBJECTIVE

Sugar-sweetened beverages (SSBs) are associated with hyperuricaemia and gout. Whether other important food sources of fructose-containing sugars share this association is unclear.

DESIGN

To assess the relation of important food sources of fructose-containing sugars with incident gout and hyperuricaemia, we conducted a systematic review and meta-analysis of prospective cohort studies.

METHODS

We searched MEDLINE, Embase and the Cochrane Library (through 13 September 2017). We included prospective cohort studies that investigated the relationship between food sources of sugar and incident gout or hyperuricaemia. Two independent reviewers extracted relevant data and assessed the risk of bias. We pooled natural-log transformed risk ratios (RRs) using the generic inverse variance method with random effects model and expressed as RR with 95% confidence intervals (CIs). The overall certainty of the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation system.

RESULTS

We identified three studies (1 54 289 participants, 1761 cases of gout), comparing the highest with the lowest level of exposure for SSBs, fruit juices and fruits. No reports were found reporting incident hyperuricaemia. Fruit juice and SSB intake showed an adverse association (fruit juice: RR=1.77, 95% CI 1.20 to 2.61; SSB: RR=2.08, 95% CI 1.40 to 3.08), when comparing the highest to lowest intake of the most adjusted models. There was no significant association between fruit intake and gout (RR 0.85, 95% CI 0.63 to 1.14). The strongest evidence was for the adverse association with SSB intake (moderate certainty), and the weakest evidence was for the adverse association with fruit juice intake (very low certainty) and lack of association with fruit intake (very low certainty).

CONCLUSION

There is an adverse association of SSB and fruit juice intake with incident gout, which does not appear to extend to fruit intake. Further research is needed to improve our estimates.

TRIAL REGISTRATION NUMBER

NCT02702375; Results.

Yogurt Is a Low-Glycemic Index Food

High yogurt intake is associated with a reduced risk of type 2 diabetes (T2DM). Although several mechanisms could explain this association, this paper addresses the glycemic and insulinemic impact of yogurt. There is evidence that low-glycemic index (GI) and low-glycemic load (GL) diets are associated with a reduced risk of T2DM. The 93 GI values for yogurt in the University of Sydney's GI database have a mean ± SD of 34 ± 13, and 92% of the yogurts are low-GI (≤55). The 43 plain yogurts in the database have a lower GI than the 50 sweetened yogurts, 27 ± 11 compared with 41 ± 11 (P < 0.0001). This difference is not explained by sugar, per se, but rather by the higher protein-to-carbohydrate ratio in plain yogurt. Although yogurt has a low GI, its insulinemic index (II) is higher than its GI. High insulin responses may be deleterious because hyperinsulinemia is associated with an increased risk of T2DM. Nevertheless, this may not be a concern for yogurt because, although its II is higher than its GI, the II of yogurt is within the range of II values for nondairy low-GI foods. In addition, mixed meals containing dairy protein elicit insulin responses similar to those elicited by mixed meals of similar composition containing nondairy protein. Because the GI of yogurt is lower than that of most other carbohydrate foods, exchanging yogurt for other protein and carbohydrate sources can reduce the GI and GL of the diet, and is in line with recommended dietary patterns, which include whole grains, fruits, vegetables, nuts, legumes, fish, vegetable oils, and yogurt.

Reformulating cereal bars: high resistant starch reduces in vitro digestibility but not in vivo glucose or insulin response; whey protein reduces glucose but disproportionately increases insulin

BACKGROUND

Resistant starch (RS) and whey protein are thought to be effective nutrients for reducing glycemic responses.

OBJECTIVE

We aimed to determine the effect of varying the sucrose, RS, and whey protein content of cereal bars on glucose and insulin responses.

DESIGN

Twelve healthy subjects [mean ± SD age: 36 ± 12 y; mean ± SD body mass index (in kg/m²): 24.9 ± 2.7] consumed 40 g available-carbohydrate (avCHO) portions of 5 whole-grain cereal bars that contained varying amounts of RS and whey protein concentrate [WPC; 70% protein; RS:WPC, %wt:wt: 15:0 (Bar15/0); 15:0, low in sucrose (Bar15/0LS); 15:5 (Bar15/5); 10:5 (Bar10/5); and 10:10 (Bar10/10)] and 2 portion sizes of a control bar low in whole grains, protein, and RS [control 1 contained 40 g avCHO (Control1); control 2 contained total carbohydrate equal to Bar15/0LS (Control2)] on separate days by using a randomized crossover design. Glucose and insulin responses in vivo and carbohydrate digestibility in vitro were measured over 3 h.

RESULTS

Incremental area under the curve (iAUC) over 0-3 h for glucose (min × mmol/L) differed significantly between treatments (P < 0.001) [Bar15/0LS (mean ± SEM), 169 ± 14; Control2, 164 ± 20; Bar15/0, 144 ± 15; Control1, 140 ± 17; Bar10/5, 117 ± 12; Bar15/5, 116 ± 9; and Bar10/10, 100 ± 9; Tukey's least significant difference = 42, P < 0.05], but insulin iAUC did not differ significantly. Higher protein content was associated with a lower glucose iAUC (P = 0.028) and a higher insulin-to-glucose iAUC ratio (P = 0.002) All 5 RS-containing bars were digested in vitro ∼30% more slowly than the control bars (P < 0.05); however, in vivo responses were not related to digestibility in vitro. Glucose and insulin responses elicited by high-RS, whey protein-free bars were similar to those elicited from control bars.

CONCLUSIONS

The inclusion of RS in cereal bar formulations did not reduce glycemic responses despite slower starch digestion in vitro. Thus, caution is required when extrapolating in vitro starch digestibility to in vivo glycemic response. The inclusion of whey protein in cereal bar formulations to reduce glycemic response requires caution because this may be associated with a disproportionate increase in insulin as judged by an increased insulin-to-glucose iAUC ratio. This trial was registered at clinicaltrials.gov as NCT02537587.

Whole Soy Flour Incorporated into a Muffin and Consumed at 2 Doses of Soy Protein Does Not Lower LDL Cholesterol in a Randomized, Double-Blind Controlled Trial of Hypercholesterolemic Adults

BACKGROUND

Soy protein may reduce coronary heart disease (CHD) risk by lowering LDL cholesterol, but few studies have assessed whether whole soy flour displays a similar effect.

OBJECTIVE

The aim of this study was to assess the dose effect of whole soy flour incorporated into muffins on plasma LDL cholesterol in hypercholesterolemic adults.

METHODS

Adults aged 30-70 y (n = 243) with elevated LDL cholesterol (≥3.0 and ≤5.0 mmol/L) were stratified by LDL cholesterol and randomly assigned to consume 2 soy muffins containing 25 g soy protein [high-dose soy (HDS)], 1 soy and 1 wheat muffin containing 12.5 g soy protein and 12.5 g whey protein [low-dose soy (LDS)], or 2 wheat muffins containing 25 g whey protein (control) daily for 6 wk while consuming a self-selected diet. Fasting blood samples were collected at weeks 0, 3, and 6 for analysis of plasma lipids [total, LDL, and HDL cholesterol and triglycerides (TGs)], glucose, insulin, C-reactive protein (CRP), and isoflavones. Blood pressures also were measured. Dietary intake was assessed at weeks 0 and 4 with the use of 3 d food records. Treatment effects were assessed with the use of intention-to-treat analysis with multiple imputation and LDL cholesterol as the primary outcome.

RESULTS

In total, 213 (87.6%) participants completed the trial. Participants were primarily Caucasian (83%) and mostly female (63%), with a mean ± SD body mass index (in kg/m2) of 28.0 ± 4.6 and systolic and diastolic blood pressures of 122 ± 16 and 77 ± 11 mm Hg, respectively. Despite a dose-dependent increase in plasma isoflavones (P < 0.001), neither HDS nor LDS had a significant effect on LDL cholesterol compared with control (mean ± SEM changes: control, -0.04 ± 0.05 mmol/L; HDS, 0.01 ± 0.05 mmol/L; and LDS, -0.04 ± 0.06 mmol/L). There were no significant treatment effects on total or HDL cholesterol, TGs, CRP, homeostatic model assessment of insulin resistance, blood pressure, or the Framingham 10-y CHD risk score.

CONCLUSION

Consuming 12.5 or 25 g protein from defatted soy flour incorporated into muffins does not reduce LDL cholesterol or other CHD risk factors in hypercholesterolemic adults. This trial was registered at clinicaltrials.gov as NCT01547585.

Sugar-sweetened beverage consumption and incident hypertension: a systematic review and meta-analysis of prospective cohorts

BACKGROUND

The role of sugar-sweetened beverages (SSBs) that contain free or bound fructose in the pathogenesis of hypertension remains unclear.

OBJECTIVE

We conducted a systematic review and meta-analysis of prospective cohort studies to quantify the association between fructose-containing SSBs and risk of hypertension.

DESIGN

MEDLINE, Embase, Cumulative Index to Nursing and Allied Health Literature, and the Cochrane registry were searched from conception through 11 November 2014. Two independent reviewers extracted data and assessed the quality of studies (with the use of the Newcastle-Ottawa Scale). Risk estimates of extreme quantiles of SSB intake (lowest compared with highest) for hypertension incidence were generated with the use of generic inverse-variance methods with random-effects models and expressed as risk ratios with 95% CIs. Heterogeneity was assessed with the Cochran Q statistic and quantified with the I(2) statistic.

RESULTS

Six prospective cohort studies (n = 240,508) with 79,251 cases of hypertension observed over ≥3,197,528 person-years of follow-up were included. SSB consumption significantly increased the risk of developing hypertension by 12% (risk ratio: 1.12; 95% CI: 1.06, 1.17) with evidence of significant heterogeneity (I(2) = 62%, P = 0.02) when highest [≥1 serving (6.7, 8, or 12 oz)/d] and lowest (none) quantiles of intake were compared. With the use of a dose-response analysis, a significant 8.2% increase in risk of every additional SSB per day from none to ≥1 SSB/d (β = 0.0027, P < 0.001) was identified. Limitations include unexplained heterogeneity and residual confounding. The results may also have been subject to collinearity effects from aspects of a Western dietary pattern.

CONCLUSIONS

SSBs were associated with a modest risk of developing hypertension in 6 cohorts. There is a need for high-quality randomized trials to assess the role of SSBs in the development of hypertension and its complications. This study was registered at clinicaltrials.gov as NCT01608620.

Utility of non-high-density lipoprotein cholesterol in assessing incident type 2 diabetes risk

AIMS

Traditional lipid indices have been associated with type 2 diabetes, but limited data are available regarding non-high-density lipoprotein (non-HDL) cholesterol. In view of recent guidelines for the clinical management of dyslipidemia recommending the monitoring of non-HDL cholesterol as a secondary target after achieving the low-density lipoprotein (LDL) cholesterol goal, we aimed to assess the association of non-HDL cholesterol with incident type 2 diabetes and compare its utility as a risk predictor with traditional lipid variables in Aboriginal Canadians.

METHODS

Of 606 diabetes-free participants at baseline, 540 (89.1%) returned for 10-year follow-up assessments. Baseline anthropometry, blood pressure, fasting insulin and serum lipids were measured. Fasting and 2-h postload glucose were obtained at baseline and follow-up to determine the incidence of type 2 diabetes.

RESULTS

The cumulative incidence of type 2 diabetes was 17.5%. Higher non-HDL cholesterol, total-to-HDL cholesterol ratio, apolipoprotein B, triglyceride and LDL cholesterol and lower HDL cholesterol concentrations were individually associated with incident type 2 diabetes in univariate analyses (all p < 0.05). Non-HDL cholesterol was a superior determinant of incident diabetes compared with LDL cholesterol (comparing C-statistics of univariate models p = 0.01) or HDL cholesterol (p = 0.004). With multivariate adjustment including waist circumference, non-HDL cholesterol remained associated with incident diabetes [odds ratio (OR) 1.42 (95% confidence interval, CI 1.07-1.88)], while LDL cholesterol and HDL cholesterol became non-significant.

CONCLUSIONS

Non-HDL cholesterol was associated with incident type 2 diabetes and was superior to LDL cholesterol as a risk predictor in this population. Further studies are required to establish the utility of non-HDL cholesterol in non-Aboriginal populations.

Informing food choices and health outcomes by use of the dietary glycemic index

Considerable epidemiologic evidence links consuming lower glycemic index (GI) diets with good health, particularly upon aging. The GI is a kinetic parameter that reflects the ability of carbohydrate (CHO) contained in consumed foods to raise blood glucose in vivo. Newer nutritional, clinical, and experimental data link intake of lower dietary GI foods to favorable outcomes of chronic diseases, and compel further examination of the record. Based upon the new information there are two specific questions: 1) should the GI concept be promoted as a way to prolong health, and 2) should food labels contain GI information? Further, what are the remaining concerns about methodological issues and consistency of epidemiological data and clinical trials that need to be resolved in order to exploit the benefits of consuming lower GI diets? These issues are addressed in this review.

Genetic variation in TAS1R2 (Ile191Val) is associated with consumption of sugars in overweight and obese individuals in 2 distinct populations

BACKGROUND

Taste is an important determinant of food consumption, and genetic variations in the sweet taste receptor subunit TAS1R2 may contribute to interindividual variations in sugar consumption.

OBJECTIVE

We determined whether Ser9Cys and Ile191Val variations in TAS1R2 were associated with differences in the consumption of sugars in 2 populations.

DESIGN

Population 1 included 1037 diabetes-free young adults in whom we assessed dietary intake by using a 1-mo, 196-item food-frequency questionnaire. Population 2 consisted of 100 individuals with type 2 diabetes with dietary intakes assessed by using 2 sets of 3-d food records administered 2 wk apart. Dietary counseling was provided between food records 1 and 2. Dietary intakes between genotypes were compared by using analysis of covariance adjusted for potential confounders.

RESULTS

In population 1, a significant Ile191Val × body mass index (BMI; in kg/m²) interaction was detected for the consumption of sugars, and the effect of genotype was significant only in individuals with a BMI ≥ 25 (n = 205). In comparison with individuals homozygous for the Ile allele, Val carriers consumed fewer sugars (122 ± 6 compared with 103 ± 6 g sugar/d, respectively; P = 0.01). Regression estimates that associated BMI with total sugar consumption by Ile/Ile and Val-carrier genotype intersected at a BMI of 23.5. In population 2, Val carriers also consumed less sugar than did individuals with the Ile/Ile genotype (99 ± 6 compared with 83 ± 6 g sugar/d, respectively; P = 0.04) on food record 2, and sugar was the only macronutrient that decreased significantly (-9 ± 4 g sugar/d, P = 0.02) in Val carriers who received dietary counseling.

CONCLUSION

Our findings show that a genetic variation in TAS1R2 affects habitual consumption of sugars and may contribute to interindividual differences in changing behaviors in response to dietary counseling.

Reduction of postprandial glycemia by the novel viscous polysaccharide PGX, in a dose-dependent manner, independent of food form

OBJECTIVE

Health benefits of viscous fiber intake are well established; nevertheless few effective and palatable preparations are available. The objective of the study therefore was to determine palatability and effectiveness of escalating doses of PGX, a novel viscous polysaccharide (NVP), in reducing postprandial glycemia when added to a liquid and a solid meal.

DESIGN

Two open-label, randomized, controlled trials were undertaken.

SETTING

Glycemic Index Laboratories, Inc, Toronto, Ontario, Canada.

SUBJECTS

Two groups of 10 healthy subjects each (group 1: 5 M, 5 F; 35.6 +/- 13.2 y; 24.6 +/- 2.1 kg/m(2); and group 2: 3 M, 7 F; 33.5 +/- 11.1 y; 26.3 +/- 5.2 kg/m(2)) were studied.

INTERVENTIONS

Zero, 2.5, 5, and 7.5 g of NVP were added to a glucose drink (group 1) or to white bread and margarine (WB + Marg) (group 2). Subjects repeated glucose control (group 1) or WB control (group 2) 3 times to allow calculation of the glycemic index (GI). Measures of Outcomes: Palatability of foods and capillary blood glucose concentrations were measured fasting and at 15, 30, 45, 60, 90, and 120 minutes after the start of the meal.

RESULTS

Addition of NVP to the meal reduced blood glucose incremental areas under the curve irrespective of dose, reaching significance at the 7.5 g dose when added to glucose (p < 0.01), and at the 5 and 7.5 g doses when added to WB + Marg (p < 0.001). The GI values of glucose with 0, 2.5, 5, or 7.5 g of NVP were (mean +/- standard error of the mean [SEM]) 100.0 +/- 0.0, 83.7 +/- 9.0, 77.7 +/- 8.2, and 72.5 +/- 5.9, respectively; the GI of the WB alone, or of WB + Marg, with 0, 2.5, 5, or 7.5 g of NVP was 71.0 +/- 0.0, 66.8 +/- 3.0, 47.5 +/- 5.9, 37.3 +/- 5.9, and 33.9 +/- 3.6, respectively.

CONCLUSION

Addition of NVP to different food matrices is highly effective in lowering the glycemic index of a food in a dose-responsive manner.

Dietary protein, carbohydrate, and fat enhance memory performance in the healthy elderly

BACKGROUND

Dietary carbohydrates can improve memory. Whether these effects are related to elevations in blood glucose or to energy ingestion is unknown.

OBJECTIVES

Our objectives were to determine 1) the influence of isoenergetic protein-, carbohydrate-, and fat-containing drinks on cognitive performance and 2) whether the time period after ingestion affects cognition.

DESIGN

After fasting overnight, 11 men and 11 women aged 61-79 y consumed either a 300-mL drink containing 774 kJ as pure protein (whey), carbohydrate (glucose), or fat (safflower oil) or a nonenergy placebo on 4 separate mornings. Cognitive tests were administered 15 and 60 min after ingestion of the drinks. Plasma glucose and serum insulin concentrations were measured.

RESULTS

Only the carbohydrate drink increased blood glucose (P < 0.0001). Compared with the placebo, all 3 macronutrients improved delayed paragraph recall (PR) (P < 0.001) and improved or tended to improve immediate PR (P < 0.04) 15 min after ingestion. Beneficial effects on other cognitive tests were confined to one or more of the macronutrients: carbohydrate improved Trail Making Test (Trails) performance at 60 min (P = 0.02) and tended to improve Trails at 15 min (P = 0.04) and PR at 60 min in men, carbohydrate and fat improved or tended to improve performance on Trails at 15 and 60 min in subjects with poor baseline scores (r > -0.41, P < 0.03), fat tended to improve attention at 60 min (P < 0.05), and protein reduced the rate of forgetting on the PR at 15 min (P = 0.002).

CONCLUSIONS

Energy intake from protein, carbohydrate, or fat can enhance memory independently of elevations in blood glucose. Each macronutrient may also exert unique effects on cognition.

Cross-sectional and prospective associations between proinsulin and cardiovascular disease risk factors in a population experiencing rapid cultural transition

OBJECTIVE

To examine cross-sectional and prospective associations between proinsulin and cardiovascular disease risk factors using data from a population-based study of type 2 diabetes among Native Canadians.

RESEARCH DESIGN AND METHODS

Between 1993 and 1995, 72% of eligible members of a Native Canadian community participated in a baseline diabetes prevalence survey. Fasting samples were collected for glucose, C-peptide, proinsulin, lipids, and apolipoproteins. A 75-g oral glucose tolerance test was administered, and a second sample for glucose was drawn after 120 min. Blood pressure and waist circumference were determined. In the present study, subjects with normal glucose tolerance (NGT) (n = 505) and impaired glucose tolerance (IGT) (n = 74) were included in cross-sectional analyses. In 1998, 95 individuals who had IGT or NGT at baseline with an elevated 2-h glucose concentration (> or = 7.0 mmol/l) participated in a follow-up evaluation using the protocol used at baseline. Cross-sectional and prospective associations between proinsulin and cardiovascular risk factors were assessed using correlation and multiple linear regression analyses.

RESULTS

After adjustment for covariates including age, sex, C-peptide, waist circumference, and glucose tolerance status, fasting proinsulin concentration was significantly associated with concurrently measured lipid and apolipoprotein concentrations (triglycerides: r = 0.18, P < 0.0001; total cholesterol: r = 0.10, P = 0.02; LDL cholesterol: r = 0.11, P = 0.01; HDL cholesterol: r = -0.16, P = 0.0002; apolipoprotein (apo) B: r = 0.17, P < 0.0001; apoAI: r = -0.11, P = 0.008). In the adjusted prospective analysis, baseline triglycerides, HDL cholesterol, and apoB were associated with changes over time in proinsulin (r = 0.23, P = 0.04; r = -0.30, P = 0.01; r = 0.23, P = 0.04; respectively).

CONCLUSIONS

These results confirm previously reported cross-sectional associations between proinsulin and lipid concentrations. In addition, an unexpected association between baseline lipids and proinsulin change was documented.

Mechanisms linking diet and colorectal cancer: the possible role of insulin resistance

Diet is clearly implicated in the origin of colorectal cancer, with risk factors for the disease including reduced consumption of vegetables, fiber, and starch and increased consumption of red meat and animal fat. Several hypotheses have been developed to explain these associations. Most recently, McKeown-Eyssen and Giovannucci noted the similarity of the risk factors for colorectal cancer and those for insulin resistance and suggested that insulin resistance leads to colorectal cancer through the growth-promoting effect of elevated levels of insulin, glucose, or triglycerides. We briefly review the evidence from observational, epidemiological, and experimental animal studies linking diet with insulin resistance and colorectal cancer. The evidence suggests that diets high in energy and saturated fat and with high glycemic index carbohydrate and low levels of fiber and n-3 fatty acids lead to insulin resistance with hyperinsulinemia, hyperglycemia, and hypertriglyceridemia. We then consider how insulin, the related insulin-like growth factors, triglycerides, and nonesterified fatty acids could lead to increased growth of colon cancer precursor lesions and the development of colorectal cancer. Finally, we consider the implications of this scheme on possible future research directions, including studies of satiety and clinical tests of the importance of insulin resistance in the colon carcinogenesis process.

Glycemic response to a food starch esterified by 1-octenyl succinic anhydride in humans

To evaluate the glycemic response to a food starch esterified by 1-octenyl succinic anhydride (OSA), 30 healthy nondiabetic adult subjects were studied in a double-blind crossover design. After an overnight fast, subjects consumed a product containing either 25 g of glucose or 25 g of OSA-substituted starch. Finger-prick capillary blood was obtained at baseline and 15, 30, 45, 60, 90, and 120 min postprandial for glucose measurement. After OSA treatment, the rise in blood glucose was reduced (P < 0.05) at 15 and 30 min and tended (P < 0.08) to be lower at 45 min. Mean peak rise in glucose was reduced 19% (P < 0.01) by OSA (3.30 +/- 0.19 versus 2.66 +/- 0.16 mmol/L) compared to glucose, but time to peak did not differ between treatments. Net incremental area under the curve was also lower (P < 0.05) on OSA compared to glucose. Minimal effects on gastrointestinal symptoms (intensity and frequency of nausea, cramping, distention, and flatulence) were noted for both products, with no clinically significant difference between products. In conclusion, starch substitution with OSA attenuated the postprandial glycemic excursion compared to an equivalent glucose challenge and was well tolerated by fasting healthy adult subjects.

Cognitive performance is associated with glucose regulation in healthy elderly persons and can be enhanced with glucose and dietary carbohydrates

BACKGROUND

A glucose drink has been shown to improve memory in persons with poor glucose regulation and poor cognition.

OBJECTIVE

The objective of this study was to determine 1) whether an association between cognition and glucose regulation is apparent in healthy seniors and 2) the effects of dietary carbohydrates on cognition.

DESIGN

After an overnight fast, 10 men and 10 women (aged 60-82 y) consumed 50 g carbohydrate as glucose, potatoes, or barley or a placebo on 4 separate mornings. Cognitive tests were administered 15, 60, and 105 min after ingestion of the carbohydrate. Plasma glucose and serum insulin were measured.

RESULTS

In a multiple regression analysis, poor baseline (placebo) verbal declarative memory (immediate and 20-min delayed paragraph recall and word list recall) and visuomotor task performance were predicted by poor beta cell function, high incremental area under the glucose curve, low insulin resistance, and low body mass index. The difference in plasma glucose after food consumption [glucose > potatoes > barley > placebo (P: < 0.03)] did not predict performance. Although overall performance did not differ with consumption of the different test foods, baseline score and beta cell function correlated with improvements in immediate and delayed paragraph recall for all 3 carbohydrates (compared with placebo); the poorer the baseline memory or beta cell function, the greater the improvement (correlation between beta cell function and improvement in delayed paragraph recall: r > -0.50, P: < 0.03). Poor beta cell function correlated with improvement for all carbohydrates in visuomotor task performance but not on an attention task.

CONCLUSIONS

Glucose regulation was associated with cognitive performance in elderly subjects with normal glucose tolerance. Dietary carbohydrates (potatoes and barley) enhanced cognition in subjects with poor memories or beta cell function independently of plasma glucose.

Different substrates and methane producing status affect short-chain fatty acid profiles produced by In vitro fermentation of human feces

Five different substrates, i.e., lactulose, rhamnose, cornstarch, guar and ileostomy effluent, were used to determine whether methane producing status alters the production of short-chain fatty acids (SCFA) in methane producers (MP; n = 6) and nonproducers (MNP; n = 5). Fecal samples from MP and MNP were fermented with the five substrates using an in vitro fermentation method. Subjects with a mean breath methane concentration > 0.045 micromol/L above ambient air were classified as MP. Fermentation was stopped and samples were obtained at 3, 5 and 24 h. An HPLC method was used to measure the SCFA, acetate, propionate, isobutyrate, butyrate, valerate and isocaproate. A significant interaction between methane producing status and time for acetate production from lactulose was observed. There were no differences in fermentation of the four remaining substrates between MP and MNP, but there were significant differences among substrates in the two groups combined. Acetate production from lactulose was significantly greater than from the four other substrates, whereas that from ileostomy effluent was significantly less than the four other substrates. The amount of propionate produced from rhamnose was significantly higher than from the other substrates. The amount of butyrate produced from lactulose and cornstarch was significantly higher than from the other substrates. We conclude that differences exist in the fermentation patterns of lactulose, rhamnose, cornstarch, guar and ileostomy effluent. Methane producing status may influence fermentation patterns only of substrates that are largely fermented to acetate and not others.

Comparison of high- and low-glycemic-index breakfast cereals with monounsaturated fat in the long-term dietary management of type 2 diabetes

BACKGROUND

Results of 6-wk studies suggest that high-carbohydrate diets are deleterious for people with type 2 diabetes.

OBJECTIVE

Our objective was to see whether long-term replacement of dietary monounsaturated fatty acids (MUFAs) with carbohydrate from breakfast cereals with either a high or a low glycemic index (GI) affected blood glucose and lipids in subjects with type 2 diabetes.

DESIGN

Subjects with type 2 diabetes (n = 91) were randomly assigned to receive approximately 10% of energy from a low-GI breakfast cereal, a high-GI cereal, or oil or margarine containing MUFA for 6 mo. Eating breakfast cereal was prohibited for subjects in the MUFA group.

RESULTS

Seventy-two subjects completed the trial. The subjects who received cereals consumed approximately 10% more energy from carbohydrate than did the subjects in the MUFA group. Changes in glycated hemoglobin, body weight, and fasting cholesterol and triacylglycerol did not differ significantly among groups. HDL cholesterol increased by approximately 10% in the MUFA group compared with subjects who consumed either high- or low-GI cereals (P = 0.002). The ratio of total to HDL cholesterol was higher in the subjects who consumed the high-GI cereal than in the MUFA group at 3 mo but not at 6 mo (diet x time interaction, P = 0.041). During 8-h metabolic profiles, mean plasma insulin was higher and mean free fatty acids were lower in the 2 cereal groups than in the MUFA group (P < 0.05).

CONCLUSIONS

A 10% increase in carbohydrate intake associated with breakfast cereal consumption had no deleterious effects on glycemic control or blood lipids over 6 mo in subjects with type 2 diabetes. The increase in plasma insulin and the reduction in free fatty acids associated with higher carbohydrate intake may reduce the rate of progression of diabetes.

Acarbose raises serum butyrate in human subjects with impaired glucose tolerance

The fermentation of starch in vitro produces a higher proportion of butyrate than the fermentation of most other substrates. The alpha-glucosidase inhibitor acarbose increases the amount of starch entering the colon, and has been shown to increase faecal butyrate in humans. It is generally considered that colonic butyrate is quantitatively removed by the colonic mucosa and liver and does not appear in peripheral blood. However, studies in animals suggest that a small proportion of colonic butyrate reaches peripheral blood. Thus, we hypothesised that an increase in colonic butyrate production would result in a rise in serum butyrate in human subjects. To test this, subjects with impaired glucose tolerance were randomly treated in a double-blind fashion with placebo (n 11) or acarbose (n 11) (100 mg three times per day). Serum short-chain fatty acid concentrations were measured twelve times over 12 h with subjects eating a standard diet before randomization and after 4 months of therapy. At baseline, 12 h mean serum butyrate concentrations were similar in the placebo and acarbose groups (2.8 (SE 0.7) and 3.3 (SE 0.6) microM, respectively). After 4 months on placebo, mean serum butyrate (2.6 (SE 0.5) microM) was no different from baseline. However, after 4 months on acarbose, serum butyrate had increased to 4.2 (SE 1.0) microM, a value which differed significantly from both the baseline value in the acarbose group and the treatment value in the placebo group. We conclude that acarbose increased serum butyrate in subjects with impaired glucose tolerance. These results support the hypothesis that increased colonic butyrate production in human subjects can be detected by an increase in serum butyrate.

Dietary carbohydrates and insulin action in humans

The metabolic syndrome represents a vicious cycle whereby insulin resistance leads to compensatory hyperinsulinaemia, which maintains normal plasma glucose but may exacerbate insulin resistance. Excess insulin secretion may eventually reduce beta-cell function due to amyloid deposition, leading to raised blood glucose and further deterioration of beta-cell function and insulin sensitivity via glucose toxicity. Reducing postprandial glucose and insulin responses may be a way to interrupt this process, but there is disagreement about the dietary approach to achieve this. Glucose and insulin responses are determined primarily by the amount of carbohydrate consumed and its rate of absorption. Slowly absorbed, low glycaemic-index (GI) foods are associated with increased HDL cholesterol and reduced risk of type 2 diabetes. There is some evidence that low-GI foods improve insulin sensitivity in humans, although studies using established techniques (glucose clamp or frequently sampled intravenous glucose tolerance test) have not been done. Low carbohydrate diets have been suggested to be beneficial in the treatment of the metabolic syndrome because of reduced postprandial insulin. However, they may increase fasting glucose and impair oral glucose tolerance--effects which define carbohydrate intolerance. The effects of low carbohydrate diets on insulin sensitivity depend on what is used to replace the dietary carbohydrate, and the nature of the subjects studied. Dietary carbohydrates may affect insulin action, at least in part, via alterations in plasma free fatty acids. In normal subjects a high-carbohydrate/low-GI breakfast meal reduced free fatty acids by reducing the undershoot of plasma glucose, whereas low-carbohydrate breakfasts increased postprandial free fatty acids. It is unknown if these effects occur in insulin-resistant or diabetic subjects. Thus further work needs to be done before a firm conclusion can be drawn as to the optimal amount and type of dietary carbohydrate for the treatment of the metabolic syndrome.

Overweight among children and adolescents in a Native Canadian community: prevalence and associated factors

BACKGROUND

The prevalence of pediatric obesity in North America is increasing. Native American children are at especially high risk.

OBJECTIVES

The objective was to evaluate the prevalence of pediatric overweight and associated behavioral factors in a Native Canadian community with high rates of adult obesity and type 2 diabetes mellitus.

DESIGN

Height and weight were measured in 445 children and adolescents aged 2-19 y. Fitness level, television viewing, body image concepts, and dietary intake were assessed in 242 subjects aged 10-19 y. Overweight was defined as a body mass index > or =85th percentile value for age- and sex-specific reference data from the third National Health and Nutrition Examination Survey (NHANES III). Multiple logistic regression was used to examine factors associated with overweight, with adjustment for age and sex.

RESULTS

The overall prevalence of overweight in subjects aged 2-19 y was significantly higher than NHANES III reference data [boys: 27. 7% (95% CI: 21.8, 34.5); girls: 33.7% (95% CI: 27.9, 40.1)]. In the subset aged 10-19 y, > or =5 h television viewing/d was associated with a significantly higher risk of overweight than was < or =2 h/d [odds ratio (OR) = 2.52; 95% CI: 1.06, 5.98]. Subjects in the third and fourth quartiles of fitness had a substantially lower risk of overweight than did those in the first quartile [third quartile compared with first quartile: OR = 0.24 (95% CI: 0.09, 0.66); fourth quartile compared with first quartile: OR = 0.13 (95% CI: 0.03, 0. 48)]. Fiber consumption on the previous day was associated with a decreased risk of overweight (OR = 0.69; 95% CI: 0.47, 0.99 for each 0.77 g/MJ increase in fiber intake).

CONCLUSIONS

Pediatric overweight is a harbinger of future diabetes risk and indicates a need for programs targeting primary prevention of obesity in children and adolescents.

Effects of calcium concentration, acetate, and propionate on calcium absorption in the human distal colon

Previous studies have shown that the short-chain fatty acids acetate (Ac) and propionate (Pr) enhance the absorption of calcium (Ca) in the rectum and distal colon of humans, with Pr being more effective than Ac. To investigate the effect of Ac and Pr on the kinetics of Ca absorption from the human rectum and distal colon, six healthy subjects were studied. Solutions containing various concentrations of CaCl2.H2O with 56.3 mmol/L Ac, Pr, or NaCl were rectally infused to each subject. Rectal fluid was sampled at the end of the infusion (0 min), and 30 min later colonic contents were collected. Ca absorption for all treatments increased linearly with Ca concentration. For Ca + NaCl, the slope of regression line was 62 mumol.mmol-1.L Ca. With Ac + Ca, the slope of Ca absorption increased significantly to 113 mumol.mmol-1.L Ca, and with Pr + Ca, the slope increased to 159 mumol.mmol-1.L (P = 0.043 versus Ac + Ca) Ac and Pr absorption were increased by Ca. The data suggest that, over a physiologic range of Ca concentration, in the absence or presence of Ac and Pr, Ca is absorbed in the human rectum and distal colon by a non-saturable diffusion process, and that Ca absorption is enhanced by Ac and Pr. The data also suggest that both Ac and Pr absorption is stimulated by Ca.

Day-to-day consistency in amount and source of carbohydrate intake associated with improved blood glucose control in type 1 diabetes

OBJECTIVE

To determine if a relationship exists between blood glucose control and variability in nutrient intake from day-to-day in subjects with type 1 diabetes.

METHODS

Two three-day diet records and one measurement of glycated hemoglobin (HbA1c) were obtained from 272 subjects with type 1 diabetes treated with a mixture of regular and NPH insulins before breakfast and supper and using a standardized algorithm to adjust insulin dose according to the results of self-monitoring of blood glucose two to four times daily. Day-to-day variation in nutrient intake was expressed as the coefficient of variation (CV = SDx100/mean).

RESULTS

Nutrient intakes in the study population (mean +/- SD) were energy 8.35+/-2.43 MJ, fat 81+/-30 g, protein 94+/-28 g, carbohydrate 227+/-68 g, starch 126+/-38 g and dietary fiber 20+/-6 g with diet glycemic index being 84.2+/-7.4. Neither energy, nutrient intakes nor insulin dose was significantly related to HbA1c. Day-to-day variation of carbohydrate (p = 0.0097) and starch (p = 0.0016) intakes and diet glycemic index (p = 0.033) was positively related to HbA1c, and the associations remained significant when adjusted for age, sex, duration of diabetes and BMI. Day-to-day variation in energy, protein or fat intakes was not related to HbA1c.

CONCLUSIONS

Consistency in the amount and source of carbohydrate intake from day-to-day is associated with improved blood glucose control in people with type 1 diabetes, a result which supports continued educational efforts to achieve adherence to a diabetes diet plan. This conclusion may not apply to people on intensified insulin therapy who adjust their insulin dose based on their actual carbohydrate intake at each meal.

Effect of glucose, sucrose and fructose on plasma glucose and insulin responses in normal humans: comparison with white bread

OBJECTIVE

To determine the plasma glucose and insulin responses of various doses of glucose, sucrose, fructose and white bread in normal human subjects.

DESIGN

Plasma glucose and insulin were measured before and at various times after 8 subjects ate 13 different test meals in randomized order on separate days after an overnight fast. Test meals consisted of 500 ml of tea or water to which was added either nothing, 25, 50, or 100 g of glucose or sucrose, 25 or 50 g fructose, 50 g glucose plus 50 g fructose, or a 25, 50 or 100 g carbohydrate portion of white bread. The glycaemic (GI) and insulinaemic index (II) values of the sugars were calculated by expressing the incremental areas under the plasma glucose and insulin curves (AUC) after glucose, sucrose and fructose as a percentage of the respective AUC after white bread containing the same amount of carbohydrate.

SETTING

University teaching hospital clinical nutrition centre.

SUBJECTS

Lean, normal subjects (4 male, 4 female) 21-33 y of age.

RESULTS

Plasma insulin responses increased nearly linearly as carbohydrate intake increased from 0 to 100 g, but glycaemic responses increased by only 68% and 38% as carbohydrate intake increased from 25 to 50 g and 50 to 100g, respectively. The GI and II values of glucose, 149+/-16 and 147+/-18, respectively, were significantly greater than those of bread (100; P<0.05), while the values for fructose, 16+/-4 and 22+/-3 were significantly less than those of bread (P<0.001). GI values did not differ significantly from II values.

CONCLUSIONS

It is concluded that, in normal subjects, as carbohydrate intake is increased from 0 to 100 g, plasma insulin responses increase at a greater rate than plasma glucose responses. The insulinaemic responses elicited by glucose, sucrose or fructose are similar to those that would be expected from a starchy food with the same glycaemic index.

No relationship between carbohydrate intake and effect of acarbose on HbA1c or gastrointestinal symptoms in type 2 diabetic subjects consuming 30-60% of energy from carbohydrate

OBJECTIVE

To determine the relationship between carbohydrate intake and the effect of acarbose on HbA1c in subjects with type 2 diabetes treated with acarbose alone, acarbose plus sulfonylurea, acarbose plus metformin, or acarbose plus insulin.

RESEARCH DESIGN AND METHODS

We conducted a double-blind randomized placebo-controlled study in which subjects with diabetes in four treatment strata (77 on diet alone, 83 treated with metformin, 103 treated with sulfonylurea, and 91 treated with insulin) were randomized to treatment with placebo or acarbose for 12 months. Before randomization, and 3, 6, 9, and 12 months after randomization, fasting blood was obtained for HbA1c, and 3-day diet records were collected. Subjects who completed at least 6 months of acarbose therapy and provided at least three 3-day diet records were included.

RESULTS

In the 114 subjects included in this analysis, carbohydrate intake varied from approximately 30-60% of energy There was no significant relationship between carbohydrate intake and change in HbA1c in any of the four treatment strata (diet: n=26, r=0.35, P=0.076; metformin: n=27, r=0.26, P=0.19; sulfonylurea: n=35, r=0.24, P=0.16; insulin: n=25, r=-0.27, P=0.19). In the 80 subjects consuming <50% of energy from carbohydrate, the fall in HbA1c (7.83 +/-0.17% at baseline to 6.72+/-0.13% on acarbose, P < 0.001) was no different from that of the 34 subjects consuming >50% of energy from carbohydrate (7.55+/-0.25% at baseline to 6.66+/-0.23% on acarbose, P < 0.001). There was no difference in carbohydrate intake between those who dropped out of the study because of gastrointestinal side effects and those who did not, and there was no relationship between severity of symptoms and the composition of the diet.

CONCLUSIONS

In subjects with type 2 diabetes consuming 30-60% of energy from carbohydrate, the effect of acarbose on HbA1c and gastrointestinal symptoms was not related to carbohydrate intake. Because most people consume at least 30% of energy from carbohydrate, we conclude that no special diet is needed for acarbose to be effective in improving blood glucose control in the treatment of type 2 diabetes.

Aberrant crypt focus promotion and glucose intolerance: correlation in the rat across diets differing in fat, n-3 fatty acids and energy

McKeown-Eyssen (Cancer Epidemiol. Biomarkers Prevent., 3, 687-695, 1994) and Giovannucci (Cancer Causes Control, 6, 164-179, 1995), noting the striking similarity in lifestyle risk factors for colorectal cancer and insulin resistance, proposed that the hyperinsulinemia, glycemia and hypertriglyceridemia associated with insulin resistance promotes colon cancer. To compare the effect of diet on colon cancer promotion and insulin resistance in the F344 rat, we assessed the effect of fat, n-3 fatty acids and energy in pairwise comparisons on average size of aberrant crypt foci (ACF) and on glucose intolerance in the same animals in a single experiment. Diets high in fat and energy increased and diets with increased n-3 fatty acids and calorie restriction decreased both ACF growth and glucose intolerance compared with control diets. The measures of promotion of colon cancer and insulin resistance were strongly correlated (n = 98, r = 0.67, P < 0.001). In addition, both were highly correlated with daily energy intake (r = 0.62 and 0.66) and were also correlated with basal (post-prandial) insulin, glucose and triglycerides (r = 0.31-0.53, P < 0.01). We concluded that ACF growth and glucose intolerance are correlated for a wide range of diets and that increased circulating energy (glucose and triglycerides) may lead to both colon cancer promotion and insulin resistance.

Increased serum cholesterol in healthy human methane producers is confounded by age

It has been theorized that colonic production and absorption of short-chain fatty acids (SCFA) is different in methane producers (MP) compared with nonproducers (MNP). Because colonic SCFA may influence systemic lipid metabolism, blood lipids may differ in MP and MNP. To compare serum lipids and SCFA in fasting MP and MNP, we measured breath gases, serum lipids and SCFA in 167 healthy subjects and excluded subjects with abnormal blood lipids. The 66 MP were significantly older than the 63 MNP (49.5 +/- 16.0 vs. 39.6 +/- 17.0 y, P = 0.0009), and breath methane concentrations were weakly correlated with age in MP (r = 0.268, P = 0.03). Mean serum cholesterol was significantly higher in MP compared with MNP, but the differences were not significant after adjusting for age. No significant differences were observed in serum SCFA between the two groups. This study has shown that breath methane increases with age, which may be due to age-related increases in transit time and carbohydrate malabsorption. These results provide no conclusive link between colonic events and serum lipids in MP because, with age, methane production increased as did serum cholesterol. More research is required before any definite conclusions can be drawn.

Variation of postprandial plasma glucose, palatability, and symptoms associated with a standardized mixed test meal versus 75 g oral glucose

OBJECTIVE

To compare within-subject variability of plasma glucose measured 2 h after a glucose tolerance test (GTT) with that of plasma glucose measured 2 h after administration of a standardized test meal (diabetes screening product [DSP], Ceapro, Edmonton, Alberta, Canada) and to determine the relationship between the two sets of plasma glucose measurements.

RESEARCH DESIGN AND METHODS

Plasma glucose and insulin responses of 36 overnight-fasted subjects (10 lean normal, 9 obese normal, 9 with impaired glucose tolerance [IGT], and 8 with mild diabetes) were studied on eight different mornings after they consumed 75 g oral glucose or 50 g carbohydrate from the DSP. Each test meal was repeated four times by each subject. Within-subject coefficients of variation (CVs) (CV = 100 x SD/mean) of plasma glucose concentrations 2 h after administration of the GTT and DSP were compared by repeated measures ANOVA and linear regression analysis.

RESULTS

Mean plasma glucose 2 h after administration of the DSP (D) was linearly related to that 2 h after the GTT (G): G = 1.5 x D - 1.6 (r = 0.97, P < 0.0001). The CV of 2-h plasma glucose was significantly lower after administration of the DSP, 10.5 +/- 1.0%, than after the GTT, 12.7 +/- 1.18% (P = 0.025). The effect of test meal on CV differed in different groups of subjects (P = 0.018), with the largest difference found in IGT subjects, in whom the CV after DSP administration was 47% less than after the GTT (P = 0.0005). The DSP was significantly more palatable and produced fewer adverse symptoms than the GTT.

CONCLUSIONS

Plasma glucose concentrations measured 2 h after DSP administration are closely related to those measured 2 h after the GTT but are more consistent than the 2-h post-GTT concentrations within the critical IGT range. This finding suggests that measurement of plasma glucose 2 h after administration of the DSP may allow more precise discrimination among normal glucose levels, IGT, and diabetes than measurement of plasma glucose 2 h after the GTT.

Specific patterns of food consumption and preparation are associated with diabetes and obesity in a Native Canadian community

We examined the relationship between usual patterns of food intake, fattiness of food preparation and consumption, and diabetes and obesity status in a Native Canadian reserve in northwestern Ontario. Patterns of intake were estimated using a 34-item food frequency instrument. Scales and scores were developed using factor analysis procedures and were tested for reliability using coefficient alpha. Impaired glucose tolerance (IGT) and diabetes status was determined by administering a 75-g glucose tolerance test. A number of the food groups appear to have a protective effect in regard to IGT and diabetes, including vegetables [odds ratio (OR) = 0.41, confidence interval (CI) = 0.18-0.91], breakfast foods (OR = 0.41, CI = 0.18-0. 93) and hot meal foods (OR = 0.29, CI = 0.11-0.78). Most of these foods are relatively high in fiber and low in fat. High consumption of junk foods and the bread and butter group was associated with substantial increases in risk for diabetes (OR = 2.40, CI = 1.13-5. 10; OR = 2.22, CI = 1.22-4.41, respectively). These foods tend to be high in simple sugars, low in fiber and high in fat. More fatty methods of food preparation are also associated with increased risk for diabetes in this population (OR = 2.58, CI = 1.11-6.02). This information has been incorporated into an ongoing community-based diabetes prevention program in the community.

Insulin resistance and promotion of aberrant crypt foci in the colons of rats on a high-fat diet

McKeown-Eyssen and Giovannucci recently proposed that the etiology of insulin resistance (IR) and colorectal cancer (CRC) are related. They suggested that diets high in fat and energy and low in complex carbohydrates and a sedentary life-style lead to IR and that the associated hyperinsulinemia, hypertriglyceridemia, and glycemia lead to increased CRC risk through the growth-promoting effect of insulin or the increased availability of energy. We reasoned that if diet affects colon carcinogenesis through its effect on IR, evidence of colon cancer promotion would be preceded by evidence of IR. To test this expectation, we compared the effects of a high-fat (HF, 59% energy) diet and a low-fat (LF, 11% energy) diet on indirect measures of IR and promotion in azoxymethane-initiated F344 rats. Promotion was assessed as growth of aberrant crypt foci (ACF) at 100 days after initiation. The HF diet increased ACF size 1.4 times (95% confidence interval = 1.30-1.58) that of the LF diet. The HF diet also led to impaired oral glucose tolerance tests measured at 4, 32, 60, and 88 days and characterized by an average increased glucose concentration of 0.78 +/- 0.17 mmol/l (p < 0.001). It also resulted in an impaired intravenous glucose tolerance test and elevated levels of serum insulin after a glucose gavage. We concluded that with this model a high-fat diet leads to evidence of IR before it is possible to demonstrate CRC promotion, thus providing support, necessary but not sufficient, for the causal hypothesis linking IR and CRC. Possible mechanisms linking diet, IR, and promotion are considered.

Low dietary fiber and high protein intakes associated with newly diagnosed diabetes in a remote aboriginal community

The high prevalence of diabetes mellitus in North American aboriginal populations may be due to recent changes in lifestyle, including the adoption of a high-fat, low-fiber diet. To determine whether fat or fiber intakes were associated with new cases of diabetes, we studied 72% (728/1018) of residents aged > 9 y from a remote aboriginal community in northern Ontario using the 75-g oral-glucose-tolerance test and 24-h dietary recall. The mean fat intake of this population (36% of energy) was typical for North America, but fiber intake (1.2 g/MJ) was very low. Logistic-regression analysis, adjusted for age, sex, and body mass index, showed that a 1-SD increase in fiber intake reduced the risk of having diabetes by 39% (P = 0.026) whereas the same increase in protein intake increased the risk by 38% (P = 0.027). There was no significant effect of energy, fat, starch, or simple sugars. These data support Trowell's original dietary-fiber hypothesis that "... dietary fiber depleted starchy foods are conducive to the development of diabetes mellitus in susceptible human genotypes."

What is a high fiber diet?

There is no recognized definition of what constitutes a high fiber diet. Intakes of dietary fiber in different populations internationally vary widely from less than 20 g to more than 80 g per day. The types of foods contributing fiber also vary; in some countries cereals contribute the most fiber, in others leafy or root vegetables predominate. Vegetables have the highest fiber content per Kcal, and in most populations with fiber intakes over 50 g, vegetables contribute over 50% of total fiber intake. In rural Uganda, where the fiber hypothesis was first developed by Burkitt and Trowell, vegetables contribute over 90% of fiber intake. An experimental diet, the "Simian" diet, has been developed to mimic as closely as possible using human foods, the diet consumed by our simian ancestors the great apes. It is also similar to the Ugandan diet in containing large amounts of vegetables and 50 g fiber/1000 Kcal. Though nutritionally adequate, this diet is very bulky and not a suitable model for general recommendations. Dietary guidelines are that fat intake should be < 30% of energy, with a fiber intake of 20-35 g/d. These recommendations are inconsistent with a high fiber diet because, for people consuming more than about 2400 Kcal, low fiber choices for fruits and grains must be selected to keep dietary fiber intake within the range of 20-35 g. In a 30% fat, 1800 Kcal omnivorous diet, selection of wholemeal bread and whole fruit, results in a fiber intake over 35 g/d, and for and 1800 Kcal vegetarian diet, with substitution of modest amounts of peanut butter and beans for meats, dietary fiber intake goes up to 45 g/d. Thus, if it is desirable to promote the use of unrefined foods, the recommended dietary fiber intake should be a minimum of 15-20 g/1000 Kcal.

Psyllium-enriched cereals lower blood total cholesterol and LDL cholesterol, but not HDL cholesterol, in hypercholesterolemic adults: results of a meta-analysis

We conducted a meta-analysis to determine the effect of consumption of psyllium-enriched cereal products on blood total cholesterol (TC), LDL cholesterol (LDL-C) and HDL cholesterol (HDL-C) levels and to estimate the magnitude of the effect among 404 adults with mild to moderate hypercholesterolemia (TC of 5.17-7.8 mmol/L) who consumed a low fat diet. Studies of psyllium cereals were identified by a computerized search of MEDLINE and Current Contents and by contacting United States-based food companies involved in psyllium research. Published and unpublished studies were reviewed by one author and considered eligible for inclusion in the meta-analysis if they were conducted in humans, were randomized, controlled experiments, and included a control group that ate cereal providing </=3 g soluble fiber/d. Eight published and four unpublished studies, conducted in four countries, met the criteria. Analysis of a linear model was performed, controlling for sex and age. Female subjects were divided into two groups to provide a rough estimate of the effect of menopausal status (premenopausal = <50 y, postmenopausal = >/=50 y) on blood lipids. The meta-analysis showed that subjects who consumed a psyllium cereal had lower TC and LDL-C concentrations [differences of 0.31 mmol/L (5%) and 0.35 mmol/L (9%), respectively] than subjects who ate a control cereal; HDL-C concentrations were unaffected in subjects eating psyllium cereal. There was no effect of sex, age or menopausal status on blood lipids. Results indicate that consuming a psyllium-enriched cereal as part of a low fat diet improves the blood lipid profile of hypercholesterolemic adults over that which can be achieved with a low fat diet alone.

Intestinal fatty acid-binding protein variation associated with variation in the response of plasma lipoproteins to dietary fibre

Increased dietary fibre intake is a component of prudent dietary advice, although the mechanism of its beneficial effect is unclear. Furthermore, plasma lipoprotein response to dietary fibre seems to vary both between individuals and according to the type of fibre consumed. Two common genetic variants, A54 and T54, of the intestinal fatty acid-binding protein gene (FABP2) have different in vitro binding affinities for long-chain fatty acids. We have hypothesized that variation in FABP2 would be associated with interindividual variation in the response of plasma lipoproteins to either dietary soluble or insoluble fibre. We studied 43 subjects who participated in a year-long cross-over study of the effect of insoluble and soluble fibre on plasma lipoproteins. We tested for associations between FABP2 genotypes and the response of plasma lipoproteins to dietary fibre. When compared with subjects homozygous for FABP2 A54, we found that subjects with FABP2 T54 had significantly greater decreases in plasma total and low-density lipoprotein (LDL)-cholesterol and apoB during the period when the diet was high in soluble fibre than during the period when the diet was high in insoluble fibre. Furthermore, compared with subjects with the FABP2 A54 allele, subjects with the FABP2 T54 allele had significantly lower secretion of total fecal bile acids, but this did not increase with dietary soluble fibre. Genetic variation in FABP2 may thus contribute to interindividual variation in the response of plasma lipoproteins to different dietary fibres, but the mechanism does not appear to be related to increases in fecal bile acid secretion.

Apolipoprotein E R112; R251G: a carboxy-terminal variant found in patients with hyperlipidemia and coronary heart disease

A 49 year-old hypercholesterolemic male with marked electrocardiographic ST segment depression on exercise testing was found to have an apo E E3/3 phenotype by isoelectric focusing, but an APOE E4/3 genotype using HhaI restriction isotyping. DNA sequence analysis of the proband's APOE gene found a G-->C point mutation at codon 251. This predicted a change in the amino acid encoded by codon 251, from arginine to glycine. The mutation occurred on an allele that encoded arginine at position 112 and this variant was named APOE R112; R251G. The R251G change altered a recognition site for the endonuclease StuI and was the basis for a restriction isotyping method to rapidly screen for this mutation. In relatives of the proband, APOE R112; R251G was consistently found in subjects with both hyperlipidemia and atherosclerosis. Apo E R112; R251G-containing very low density lipoproteins bound normally to macrophages in vitro. However, the proband had an abnormal post-prandial lipoprotein response to a dietary fat challenge. The association of APOE R112; R251G with abnormal phenotypes suggests that the amino acid change in the carboxy-terminal, perhaps in combination with the common amino acid polymorphism at codon 112, has a functional impact upon lipoprotein metabolism in members of this family.

Small weight loss on long-term acarbose therapy with no change in dietary pattern or nutrient intake of individuals with non-insulin-dependent diabetes

OBJECTIVES

To see if the long-term treatment of non-insulin dependent diabetes (NIDDM) with the alpha-glucosidase inhibitor acarbose affects food intake and body weight.

DESIGN

Randomized, double-blind, placebo-controlled, parallel design clinical trial of 12 months duration.

SUBJECTS

Subjects with NIDDM in four treatment strata: 77 on diet alone, 83 also treated with metformin, 103 also treated with sulfonylurea and 91 also treated with insulin.

MEASUREMENTS

Two 3 day diet records were obtained before randomization to acarbose or placebo therapy, and additional 3 day diet records were obtained at 3, 6, 9 and 12 months after randomization. Body weight was also measured at these times.

RESULTS

Of the 354 subjects randomized, 279 (79%) completed at least 9 months of therapy and, of these, 263 (94%) provided at least one diet record during the baseline period and two diet records during the treatment period. After one year, subjects on acarbose had lost 0.46 +/- 0.28 kg, which differed significantly from the 0.33 +/- 0.25 kg weight gain on placebo (P = 0.027). The difference in weight change between acarbose and placebo did not differ significantly in the different treatment strata. Being in the study had significant effects on diet, including a reduction in energy intake from 1760-1700 Kcal/d (P < 0.05), a reduction in simple sugars intake from 18.5-17.4% of energy (P < 0.001), and reductions in the number of different foods consumed (33-30, P < 0.001) and the number of meals eaten per day (4.7-4.3, P < 0.001). However, compared to placebo treatment, acarbose had no effect on energy intake, nutrient intakes, or dietary patterns.

CONCLUSIONS

In subjects with NIDDM on weight-maintaining diets, long-term acarbose therapy results in a small weight loss, but has no effect on energy or nutrient intakes. The weight loss induced by acarbose may be due partly to reduced doses of concomitant oral agents and insulin and partly to energy loss due to increased colonic fermentation.

Long-term effect of soluble-fiber foods on postprandial fat metabolism in dyslipidemic subjects with apo E3 and apo E4 genotypes

To determine the long-term effect of soluble fiber on postprandial fat metabolism, we studied 33 dyslipidemic subjects, 16 with apolipoprotein (apo) E3/3 (E3) and 17 with E3/4 or E4/4 (E4) genotypes. They ate preweighed low-fat (20% of energy), high-fiber (> 5.7 g/MJ) diets for two 4-mo periods separated by a 2-mo washout period according to a randomized, crossover design. One diet contained foods rich in insoluble fiber and the other foods rich in soluble fiber. On 1 d during the last 2 wk of each diet, subjects ingested a standard, fiber-free, fatty liquid meal containing retinyl palmitate as a marker of intestinally derived lipoproteins. Plasma samples were obtained at hourly intervals for 10 h. Compared with the insoluble-fiber diet, soluble fiber reduced fasting plasma total cholesterol in both E3 (6.6 +/- 2.1%, P = 0.007)and E4 subjects (5.6 +/- 2.1%, P = 0.017). Soluble fiber increased fecal total bile acid output in both E3 (76 +/- 18%, P < 0.001) and E4 subjects (85 +/- 19%, P < 0.001). The incremental area under the chylomicron triacylglycerol response curve was significantly greater after soluble fiber than after insoluble fiber in E3 (3.56 +/- 0.56 compared with 2.87 +/- 0.38 mmol x h/L, respectively, P = 0.046) but not in E4 subjects (5.19 +/- 0.78 compared with 4.92 +/- 0.81 mmol x h/L). Kinetic analysis suggested an increase in retinyl palmitate absorption in E3 subjects after soluble fiber, but no difference in E4 subjects. These results suggest that a long-term increase in dietary soluble fiber has no effect on postprandial fat metabolism in subjects with an apo E3/4 or E4/4 genotype. However, soluble fiber enhances apparent fat absorption in E3 subjects, which could be due to an increased bile acid pool and increased micelle formation.

Time of day and glucose tolerance status affect serum short-chain fatty acid concentrations in humans

Short-chain fatty acids (SCFA) are derived from endogenous (metabolism of fat, carbohydrate, and amino acids) and exogenous (colonic fermentation) sources. To see how time of day and glucose tolerance status influenced serum SCFA concentrations, we determined serum SCFA throughout the day in 22 subjects with impaired glucose tolerance (IGT) and 10 young and eight middle-aged normal controls. On 1 day, insulin sensitivity was assessed as the steady-state plasma glucose (SSPG) level achieved during intravenous infusion of glucose insulin, and somatostatin. On another day, plasma glucose and insulin and serum SCFA levels were measured 12 times over 12 hours with subjects eating a standard diet. SSPG in young controls (5.5 +/- 1.1 mmol/L) was less than in middle-aged controls (9.3 +/- 1.6 mmol/L), which in turn was less than in IGT subjects (13.7 +/- 0.6 mmol/L; P < .01). Mean plasma glucose in IGT subjects was greater than in normal controls, and mean plasma insulin in IGT subjects was higher than in young controls but similar to the levels in middle-aged controls. Mean 12-hour serum acetate in young controls (143 +/- 13 mumol/L) was greater than in middle-aged controls (104 +/- 11 mumol/L) and IGT subjects (113 +/- 5 mumol/L; P < .05). Mean 12-hour serum propionate in young controls (3.8 +/- 0.5 mumol/L) was less than in IGT subjects (5.4 +/- 0.3 mumol/L; P < .01), with middle-aged controls being intermediate (4.6 +/- 0.3 mumol/L). Both young (1.6 +/- 0.3 mumol/L) and middle-aged (1.0 +/- 0.2) controls had lower mean butyrate than IGT subjects (3.1 +/- 0.4 mumol/L; P < .05). Levels of all three SCFA varied significantly during the day, tending to decrease after breakfast and increase transiently after lunch and dinner. It is concluded that both time of day and glucose tolerance status affect serum SCFA levels in nondiabetic humans. The results suggest that serum acetate is derived primarily from colonic fermentation, serum butyrate primarily from endogenous fatty acid metabolism, and serum propionate from both exogenous and endogenous sources.

Effect of a diet high in vegetables, fruit, and nuts on serum lipids

We assessed the effect of a diet high in leafy and green vegetables, fruit, and nuts on serum lipid risk factors for cardiovascular disease. Ten healthy volunteers (seven men and three women aged 33 +/- 4 years [mean +/- SEM]; body mass index, 23 +/- 1 kg/m2) consumed their habitual diet (control diet, 29% +/- 2% fat calories) and a diet consisting largely of leafy and other low-calorie vegetables, fruit, and nuts (vegetable diet, 25% +/- 3% fat calories) for two 2-week periods in a randomized crossover design. After 2 weeks on the vegetable diet, lipid risk factors for cardiovascular disease were significantly reduced by comparison with the control diet (low-density lipoprotein [LDL] cholesterol, 33% +/- 4%, P < .001; ratio of total to high-density lipoprotein [HDL] cholesterol, 21% +/- 4%, P < .001; apolipoprotein [apo] B:A-I, 23% +/- 2%, P < .001; and lipoprotein (a) [Lp(a)], 24% +/- 9%, P = .031). The reduction in apo B was related to increased intakes of soluble fiber (r = .84, P = .003) and vegetable protein (r = -.65, P = .041). On the vegetable compared with the control diet, the reduction in total serum cholesterol was 34% to 49% greater than would be predicted by differences in dietary fat and cholesterol. A diet consisting largely of low-calorie vegetables and fruit and nuts markedly reduced lipid risk factors for cardiovascular disease. Several aspects of such diets, which may have been consumed early in human evolution, have implications for cardiovascular disease prevention.

Effect of psyllium in hypercholesterolemia at two monounsaturated fatty acid intakes

We performed two studies to determine whether the lipid-lowering effect of viscous soluble fiber was modified by monounsaturated fatty acid (MUFA). First, psyllium (1.4 g/MJ) was compared with wheat bran (control) in 1-mo metabolic diets by using a randomized crossover design (n = 32 hyperlipidemic subjects). The background diet contained approximately 6% of energy as MUFA (20% of total fat). The second study (n = 27 hyperlipidemic subjects) was similar to the first but the background diet contained approximately 12% MUFA (29% of total fat) because of the addition of canola oil. At both fat intakes, psyllium resulted in significant reductions in total, low-density-lipoprotein (LDL), and high-density-lipoprotein (HDL) cholesterol compared with the wheat bran control. For the psyllium diet at 6% compared with 12% MUFA, the decreases in LDL cholesterol were 12.3 +/- 1.5% (P < 0.001) and 15.3 +/- 2.4% (P < 0.001), respectively. With the higher-MUFA diet triacylglycerol fell significantly over the control phase (16.6 +/- 5.5%, P = 0.006) and the ratio of LDL to HDL cholesterol fell significantly over the psyllium phase (7.3 +/- 2.8%, P = 0.015). Psyllium and MUFA intakes were negatively related to the percentage change in the ratio of LDL to HDL cholesterol (r = -0.34, P = 0.019 and r = -0.44, P = 0.002, respectively). Chenodeoxycholate synthesis rate increased (30 +/- 13%, P = 0.038) with the psyllium diet in the 12 subjects in whom this was assessed. We conclude that psyllium lowered LDL- and HDL-cholesterol concentrations similarly at both MUFA intakes. However, there may be some advantage in combining soluble fiber and MUFA to reduce the ratio of LDL to HDL cholesterol.