Comparison of the effects of dried peas with those of potatoes in mixed meals on postprandial glucose and insulin concentrations in patients with type 2 diabetes

Unveiling the Evidence for the Use of Pulses in Managing Type 2 Diabetes Mellitus: A Scoping Review

Management of type 2 diabetes mellitus (T2DM) is a pressing global healthcare challenge. Innovative strategies that integrate superior medical and nutritional practices are essential for holistic care. As such, pulse consumption is encouraged for its potential benefit in reducing hypercholesterolaemia, dyslipidaemia, and triglyceride levels, as well as enhancing glycaemic control. This scoping review aims to assess the depth of evidence supporting the recommendation for pulse consumption in T2DM management and to identify gaps in the existing literature. We conducted a comprehensive search across the databases MEDLINE, Global Health, EMBASE, CINAHL, Web of Science, and the Cochrane Library (up to July 2023). We included population-based studies of any design, and excluded review-style articles. Articles published in languages other than English were also excluded. From the 2449 studies initially identified, 28 met our inclusion criteria. Acute postprandial trials demonstrated improved glucose responses and enhanced insulin responses to pulse-based intervention. Meanwhile, long-term trials reported meaningful improvements in T2DM indicators such as haemoglobin A1C (HbA1c), fasting glucose, fasting insulin, C-peptide, and markers of insulin resistance like homeostatic model assessment (HOMA). Integrating more pulses into the diets of diabetic individuals might offer an efficient and cost-effective strategy in the global initiative to combat T2DM.

Acute Effects of Split Pea-Enriched White Pan Bread on Postprandial Glycemic and Satiety Responses in Healthy Volunteers—A Randomized Crossover Trial

Pulse consumption has been associated with reduced postprandial glucose response (PPGR) and improved satiety. The objective of this study was (i) to investigate the effects of fortifying white pan bread with split yellow pea (Pisum sativum L.) flour on PPGR and appetite-related sensations, and (ii) to determine whether Revtech heat processing of pea flour alters the postprandial effects. A randomized controlled crossover trial was performed with 24 healthy adults. Participants consumed 50 g available carbohydrate from bread containing 20% pea flour that was untreated (USYP), Revtech processed at 140 °C with no steam (RT0%), Revtech processed at 140 °C with 10% steam (RT10%), or a control bread with 100% white wheat flour (100%W). Blood samples were analyzed for glucose and plasma insulin at 0, 15, 30, 45, 60, 90, and 120 min post-meal. Appetite sensations and product acceptability were measured using visual analogue and 9-point hedonic scales. Results showed no significant difference in the postprandial glucose and insulin responses of different bread treatments. However, pea-containing variants resulted in 18% higher fullness and 16–18% lower hunger, desire to eat, and prospective food consumption ratings compared to 100% W. No differences in the aroma, flavor, color, and overall acceptability of different bread products were observed. This trial supports using pea flour as a value-added ingredient to improve the short-term appetite-related sensations of white pan bread without affecting the overall acceptability.

Pulse consumption improves indices of glycemic control in adults with and without type 2 diabetes: a systematic review and meta-analysis of acute and long-term randomized controlled trials

PURPOSE

Findings from randomized controlled trials (RCTs) evaluating the effect of pulse intake on glycemic control are inconsistent and conclusive evidence is lacking. The aim of this study was to systematically review the impact of pulse consumption on post-prandial and long-term glycemic control in adults with and without type 2 diabetes (T2D).

METHODS

Databases were searched for RCTs, reporting outcomes of post-prandial and long-term interventions with different pulse types on parameters of glycemic control in normoglycemic and T2D adults. Effect size (ES) was calculated using random effect model and meta-regression was conducted to assess the impact of various moderator variables such as pulse type, form, dose, and study duration on ES.

RESULTS

From 3334 RCTs identified, 65 studies were eligible for inclusion involving 2102 individuals. In acute RCTs, pulse intake significantly reduced peak post-prandial glucose concentration in participants with T2D (ES  - 2.90; 95%CI  - 4.60,  - 1.21; p ≤ 0.001; I2 = 93%) and without T2D (ES  - 1.38; 95%CI  - 1.78,  - 0.99; p ≤ 0.001; I2 = 86%). Incorporating pulse consumption into long-term eating patterns significantly attenuated fasting glucose in normoglycemic adults (ES  - 0.06; 95%CI  - 0.12, 0.00; p ≤ 0.05; I2 = 30%). Whereas, in T2D participants, pulse intake significantly lowered fasting glucose (ES  - 0.54; 95%CI  - 0.83,  - 0.24; p ≤ 0.001; I2 = 78%), glycated hemoglobin A1c (HbA1c) (ES  - 0.17; 95%CI  - 0.33, 0.00; p ≤ 0.05; I2 = 78) and homeostatic model assessment of insulin resistance (HOMA-IR) (ES  - 0.47; 95%CI  - 1.25,  - 0.31; p ≤ 0.05; I2 = 79%).

CONCLUSION

Pulse consumption significantly reduced acute post-prandial glucose concentration > 1 mmol/L in normoglycemic adults and > 2.5 mmol/L in those with T2D, and improved a range of long-term glycemic control parameters in adults with and without T2D. PROSPERO REGISTRY NUMBER: (CRD42019162322).

Knowledge, Attitudes, and Barriers towards Dietary Pulse Consumption in Women with Polycystic Ovary Syndrome Participating in a Multi-Disciplinary Lifestyle Intervention to Improve Women’s Health

Pulse (beans, lentils, chickpeas, peas) consumption is low in developed countries. Pulses have the potential to benefit the management of polycystic ovary syndrome (PCOS) because they improve aspects of metabolic derangements (dyslipidaemia, insulin resistance), which contribute to reproductive disturbances (oligo-amenorrhea, hyperandrogenism). We compared changes in knowledge, attitudes, and barriers towards pulse consumption in PCOS cohorts who participated in a pulse-based or a Therapeutic Lifestyle Changes (TLC) dietary intervention. Thirty women (18–35 years old) randomised to a pulse-based diet (supplied with pulse-based meals) and 31 women in a TLC group completed pulse consumption questionnaires before and after a 16-week intervention. The pulse-diet group demonstrated increased knowledge of pulses per Canada’s Food Guide recommendations versus the TLC group post-intervention (p < 0.05). In both groups, increased scores were evident in the domain of attitude about pulses (p < 0.01). The top-ranked barrier to pulse consumption in no-/low-consumers was lack of knowledge about cooking pulses pre- and post-intervention. We attributed increased knowledge about pulse consumption in the pulse group to greater awareness through education and consuming pulse foods during the intervention. Our observations highlight the importance of multi-dimensional behavioural counselling and education to integrate healthy dietary practices for improving reproductive and sexual health in this under-studied high-risk population (ClinicalTrials.gov identifier: NCT01288638).

The Role of Pulses in Cardiovascular Disease Risk for Adults With Diabetes

Cardiovascular disease (CVD) is a leading cause of death among adults while associated comorbidities like diabetes further increase risks of CVD-related complications and mortality. Strategies to prevent and manage CVD risk, such as dietary change, are a key component for CVD and diabetes prevention and management. Pulses, defined as the dried edible seeds of plants in the legume family, have received attention for their superior nutritional composition as high-fiber, low-glycemic index foods and have been studied for their potential to reduce CVD and diabetes risk. Both observational and experimental studies conducted among adults with and without diabetes have provided support for pulses in their ability to improve lipid profiles, glycemic control, and blood pressure, all of which are major modifiable risk factors of CVD. These capabilities have been attributed to various mechanisms associated with the nutrient and phytochemical composition of pulses. Overall, this evidence provides support for the consumption of pulses as an important dietary strategy to reduce risk of CVD for those living with and without diabetes.

Development, structure and in vitro digestibility of type 3 resistant starch from acid-thinned and debranched pea and normal maize starches

Type 3 resistant starch (RS3) was developed from native pea starch through acid thinning, debranching and recrystallization, and the resultant pea RS3 was then characterized and compared with that generated from native normal maize starch. Starting from the respective native starches, the modification method yielded 68.1% of RS3 from pea and 59.6% from normal maize. The particles of pea and normal maize RS3 showed a coarse surface and irregular shapes and sizes. Both pea and normal maize RS3 displayed the B-type X-ray diffraction pattern, with 41.0% and 37.7% relative crystallinity, respectively. In vitro starch digestibility assay revealed that pea RS3 - in both uncooked and cooked states - was less digestible by amylolytic enzymes than normal maize RS3 because the former possessed double-helical crystallites of a more compact structure. The information presented in the study is valuable for the development of RS ingredient from pea starch for food applications.

Effect of a pulse-based diet and aerobic exercise on bone measures and body composition in women with polycystic ovary syndrome: A randomized controlled trial

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age, with clinical symptoms including menstrual dysfunction and hyperandrogenemia, as well as insulin resistance which is thought to be a key contributing factor to symptoms. Insulin is also thought to positively affect bone while oligo- and amenorrhea are known to negatively affect bone. Lifestyle modification is the first recommendation to treat symptoms of PCOS; however, little is known about the effect of lifestyle interventions on bone measures in this population. Pulses (e.g., chickpeas, beans, split peas, lentils) have been shown to lower fasting insulin, and the objective of this study was to determine the effect of a pulse-based diet compared to the therapeutic lifestyle changes (TLC) diet on bone measures and body composition in women with PCOS. Women aged 18-35 years with PCOS were randomized to either a pulse-based diet or the TLC diet for 16-weeks while following an aerobic exercise program. Thirty-one in the TLC group and 29 in the pulse group completed dual-energy X-ray absorptiometry analysis following the intervention. After 16-weeks, both groups had a lower BMI, whole body fat mass, and % fat (p < 0.005), with no difference in lean mass. In both groups, lumbar spine bone mineral content (BMC) and density were higher following the intervention (p < 0.05) while femoral neck bone mineral density (BMD) was lower (p < 0.05). Intertrochanteric section modulus improved in both groups while there was a group x time interaction in femoral shaft subperiosteal width which was more favorable in the pulse group (p < 0.05). This study demonstrates that the femoral neck may be compromised during a lifestyle intervention in women with PCOS. Research is warranted to preserve bone health during lifestyle change in women with PCOS.

Pea polyphenolics and hydrolysis processing alter microbial community structure and early pathogen colonization in mice

Health benefits associated with pea consumption have been attributed to the fiber and polyphenolic content concentrated within the pea seed coat. However, the amount of pea polyphenols can vary between cultivars, and it has yet to be studied whether pea polyphenols impact the intestinal microbiota. We hypothesized that pea polyphenols promote a healthy microbiome that supports intestinal integrity and pathogen colonization resistance. To investigate the effects of pea polyphenols, pea cultivars rich and poor in proanthocyanidins were supplemented in raw or acid hydrolyzed form to an isocaloric diet in mice. Acid hydrolysis increases the absorption of pea polyphenols by cleaving polymeric proanthocyanidins to their readily absorbable anthocyanidin monomers. After 3 weeks of diet, mice were challenged with Citrobacter rodentium and pathogen colonization and inflammation were assessed. Counter to our hypothesis, pea seed coat fraction supplementation, especially the non-hydrolyzed proanthocyanidin-rich fraction diet adversely increased C. rodentium pathogen load and inflammation. Ileal, cecal and colon microbial communities were notably distinct between pea seed cultivar and hydrolysis processing. The consumption of intact proanthocyanidins decreased microbial diversity indicating that proanthocyanidins have antimicrobial properties. Together our results indicate supplementation of raw pea seed coat rich in proanthocyanidins adversely affect intestinal integrity. However, acid hydrolysis processing restored community structure and colonization resistance, and the anthocyanidin-rich fractions reduced weight gain on a high fat diet. Establishing a clear understanding of the effects of pea fiber and polyphenolic form on health will help to develop research-based pea products and dietary recommendations.

A Comparison of a Pulse-Based Diet and the Therapeutic Lifestyle Changes Diet in Combination with Exercise and Health Counselling on the Cardio-Metabolic Risk Profile in Women with Polycystic Ovary Syndrome: A Randomized Controlled Trial

We compared the effects of a low-glycemic index pulse-based diet, containing lentils, beans, split peas, and chickpeas, to the Therapeutic Lifestyle Changes (TLC) diet on cardio-metabolic measures in women with polycystic ovary syndrome (PCOS). Ninety-five women (18⁻35 years) enrolled in a 16-week intervention; 30 women in the pulse-based and 31 in the TLC groups completed the study. Women participated in aerobic exercise training (minimum 5 days/week for 45 min/day) and were counselled (monthly) about PCOS and lifestyle modification. Women underwent longitudinal follow-up post-intervention. The pulse-based group had a greater reduction in total area under the curve for insulin response to a 75-g oral glucose tolerance test (mean change ± SD: -121.0 ± 229.9 vs. -27.4 ± 110.2 µIU/mL × min; p = 0.05); diastolic blood pressure (-3.6 ± 6.7 vs. -0.2 ± 6.7 mmHg, p = 0.05); triglyceride (-0.2 ± 0.6 vs. 0.0 ± 0.5 mmol/L, p = 0.04); low-density lipoprotein cholesterol (-0.2 ± 0.4 vs. -0.1 ± 0.4 mmol/L, p = 0.05); total cholesterol/high-density lipoprotein cholesterol (TC/HDL-C; -0.4 ± 0.4 vs. 0.1 ± 0.4, p < 0.001); and a greater increase in HDL-C (0.1 ± 0.2 vs. -0.1 ± 0.2 mmol/L, p < 0.01) than the TLC group. Decreased TC/HDL-C (p = 0.02) at six-month and increased HDL-C and decreased TC/HDL-C (p ≤ 0.02) at 12-month post-intervention were maintained in the pulse-based group. A pulse-based diet may be more effective than the TLC diet at improving cardio-metabolic disease risk factors in women with PCOS.

TRIAL REGISTRATION

CinicalTrials.gov identifier, NCT01288638.

The role of a pulse-based diet on infertility measures and metabolic syndrome risk: protocol of a randomized clinical trial in women with polycystic ovary syndrome

Background

Polycystic Ovary Syndrome (PCOS) is an endocrine disorder in women of reproductive age with an estimated prevalence of 5–20% of premenopausal women. The clinical symptoms common to PCOS include menstrual dysfunction, hyperandrogenemia, hirsutism, polycystic ovaries, insulin resistance, and hyperinsulinemia. Women with PCOS are at an increased risk of infertility, obesity and type 2 diabetes mellitus. Insulin resistance and hyperinsulinemia are believed to be key contributing factors to the pathogenesis of PCOS; excessive amounts of insulin are directly associated with the increased ovarian production of androgens and metabolic features of PCOS. Pulse-based diets (e.g., beans, chickpeas) are associated with improved glycemic control and have insulin lowering effects. The purpose of this study is to determine whether a pulse-based diet is more effective than the diet recommended by the National Cholesterol Education Program. The primary outcomes of this study are disease measures related to PCOS, with secondary outcomes including measures related to metabolic syndrome.

Methods

Women with symptoms of PCOS will be recruited for the study and a diagnosis of PCOS will be determined by an obstetrician-gynecologist. Women with PCOS will be randomly assigned to receive either a pulse-based diet or the National Cholesterol Education Program therapeutic lifestyle changes (TLC) diet for 16 weeks while participating in an aerobic exercise program. One hundred participants will be required (drop-out rate of 32%) for recruitment to provide 80% power for detecting a significant difference in fasting glucose (p < 0.05). Measures related to infertility, metabolic syndrome, quality of life, dietary intake and physical activity will be assessed pre- and post-intervention with follow up assessment at 6- and 12-months post-intervention.

Discussion

Polycystic ovary syndrome is the most common endocrine disorder in women of reproductive age and there is currently no recommended diet for this population of women. The multidisciplinary nature of this study, including determination of measures related to metabolic syndrome, infertility and physical activity provide a comprehensive assessment of any benefits associated with a pulse-based diet in women with PCOS. The results of this study will help in providing evidence-based recommendations for the optimum diet to reduce symptoms associated with PCOS.

Trial registration

NCT01288638. Trial registered January 13, 2011.

Postprandial glucose and insulin levels in type 2 diabetes mellitus patients after consumption of ready-to-eat mixed meals

PURPOSE

To compare the effects of three ready-to-eat mixed meals, with a high fiber content and low glycemic index, on postprandial glycemic and insulinemic response in patients with Type 2 diabetes mellitus (T2DM).

METHODS

The current study followed a prospective, three-way, cross-over design. Twenty-four patients with T2DM consumed three ready-to-eat mixed meals, i.e., "wild greens pie" (meal 1), "chicken burgers with boiled vegetables" (meal 2) and "vegetable moussaka" (meal 3) and an oral glucose load, all providing 50 g of carbohydrates. Venous blood was collected at 0, 30, 60, 90 and 120 min postprandial. Statistical analyses included repeated measures analysis of variance and calculations of the area under the glucose and insulin curves (AUC) for each one of the test meals and the oral glucose load.

RESULTS

Patients consuming each one of the three mixed meals showed better postprandial glycemic responses compared to the oral glucose load (P < 0.001). Furthermore, patients consuming meal 3 showed a better insulinemic response compared to the oral glucose load and meal 1, after 60 and 120 min postprandial, respectively (P < 0.05). In addition, the increase observed in HOMA-IR values from T0 to T120 was significantly lower for meal 3, compared to the oral glucose load (P < 0.001).

CONCLUSIONS

The three ready-to-eat mixed meals examined in the present study were found to elicit significantly lower glycemic responses compared to the oral glucose load in diabetic patients. The mixed meals examined in the present study could be proposed as effective, palatable and practical solutions for diabetics for glucose control.

Reduction of postprandial blood glucose in healthy subjects by buns and flatbreads incorporated with fenugreek seed powder

PURPOSE

This study aimed to determine whether fenugreek seed powder could reduce the glycemic response and glycemic index (GI) when added to buns and flatbreads.

METHODS

In a randomised, controlled crossover trial, ten healthy human subjects (five men, five women) were given 50 g glucose (reference food, twice); buns (0 and 10 % fenugreek seed powder); and flatbreads (0 and 10 % fenugreek seed powder) on six different occasions. Finger prick capillary blood samples were collected at 0, 15, 30, 45, 60, 90 and 120 min after the start of the meal. The palatability of the test meals was scored using Likert scales.

RESULTS

The incremental areas under the glucose curve value of buns and flatbreads with 10 % fenugreek (138 ± 17 mmol × min/L; 121 ± 16 mmol × min/L) were significantly lower than those of 0 % fenugreek bun and flatbreads (227 ± 15 mmol × min/L; 174 ± 14 mmol × min/L, P = <0.01). Adding 10 % fenugreek seed powder reduced the GI of buns from 82 ± 5 to 51 ± 7 (P < 0.01) and to the GI of flatbread from 63 ± 4 to 43 ± 5 (P < 0.01).

CONCLUSIONS

These results suggest that replacing 10 % of refined wheat flour with fenugreek seed powder significantly reduces the glycemic response and the GI of buns and flatbreads. Thus, fenugreek powder may be a useful functional ingredient to reduce postprandial glycemia.

Cooking enhances beneficial effects of pea seed coat consumption on glucose tolerance, incretin, and pancreatic hormones in high-fat-diet-fed rats

Pulses, including dried peas, are nutrient- and fibre-rich foods that improve glucose control in diabetic subjects compared with other fibre sources. We hypothesized feeding cooked pea seed coats to insulin-resistant rats would improve glucose tolerance by modifying gut responses to glucose and reducing stress on pancreatic islets. Glucose intolerance induced in male Sprague-Dawley rats with high-fat diet (HFD; 10% cellulose as fibre) was followed by 3 weeks of HFD with fibre (10%) provided by cellulose, raw-pea seed coat (RP), or cooked-pea seed coat (CP). A fourth group consumed low-fat diet with 10% cellulose. Oral and intraperitoneal glucose tolerance tests (oGTT, ipGTT) were done. CP rats had 30% and 50% lower glucose and insulin responses in oGTT, respectively, compared with the HFD group (P < 0.05) but ipGTT was not different. Plasma islet and incretin hormone concentrations were measured. α- and β-cell areas in the pancreas and density of K- and L-cells in jejunum and ileum were quantified. Jejunal expression of hexose transporters was measured. CP feeding increased fasting glucagon-like peptide 1 and glucose-stimulated gastric inhibitory polypeptide responses (P < 0.05), but K- and L-cells densities were comparable to HFD, as was abundance of SGLT1 and GLUT2 mRNA. No significant difference in β-cell area between diet groups was observed. α-cell area was significantly smaller in CP compared with RP rats (P < 0.05). Overall, our results demonstrate that CP feeding can reverse adverse effects of HFD on glucose homeostasis and is associated with enhanced incretin secretion and reduced α-cell abundance.

Antidiabetic potential of commonly consumed legumes: a review

Over the last few decades, lifestyle changes have resulted in a drastic increase in the incidence of diabetes all over the world, especially in the developing countries. Oral hypoglycemic agents and insulin form the mainstay in controlling diabetes, but they have prominent side effects and fail to significantly alter the course of diabetic complications. Appropriate diet and exercise programs that form a part of lifestyle modifications have proven to be greatly effective in the management of this disease. Dietary therapy is showing a bright future in the prevention and treatment of diabetes. Legumes, owing to their high nutritive value, are increasingly being used in dietetic formulations in the treatment and prevention of diabetes on account of their antidiabetic potential. Given this background, this paper reviews the glucose- and lipid-lowering action possessed by various commonly consumed legumes through several animal and human studies. It is concluded that the various legumes not only have varying degrees of antidiabetic potential but are also beneficial in decreasing the risk factors for cardiovascular and renal disease.

Assessment of the mechanisms exerting glucose-lowering effects of dried peas in glucose-intolerant rats

The present study compared the effects of feeding uncooked pea fractions (embryo v. seed coat) on glucose homeostasis in glucose-intolerant rats and examined potential mechanisms influencing glucose homeostasis. Rats were made glucose intolerant by high-fat feeding, after which diets containing both high-fat and pea fractions were fed for 4 weeks. Rats fed diets containing uncooked pea seed coats low (non-coloured seed coat; NSC) or high (coloured seed coat; CSC) in proanthocyanidins but not embryos had improved oral glucose tolerance (P < 0·05). NSC also lowered fasting and glucose-stimulated insulin secretion (P < 0·05), decreased β-cell mass by 50 % (P < 0·05) and lowered levels of malondialdehyde, a marker of oxidative stress. Furthermore, NSC decreased the mucosal thickness of the colon by 25 % (P < 0·05), which might affect fibre fermentation and other gut functions. Small but statistically significant (P < 0·05) effects consistent with enhanced glucose transport or metabolism were observed in the skeletal muscle of rats fed NSC or CSC, for example, increased levels of AMP-dependent kinase or akt. We conclude that pea seed coats are the fraction exerting beneficial effects on glucose tolerance. Most of the changes were small in amplitude, suggesting that additive effects on multiple tissues may be important. NSC content appeared to have the most beneficial effects in improving glucose homeostasis but our ability to detect the effect of flavonoids may have been limited by their low concentration in the diet.

Impact of glycated pea proteins on the activity of free-swimming and immobilised bacteria

BACKGROUND

Glycation (non-enzymatic glycosylation), a spontaneously occurring process, is responsible for alteration of the structures and biological activities of proteins, making them highly active. Regrettably, information regarding the impact of glycated food proteins on intestinal bacteria still remains sparse. Pea seeds are considered to be a biological material of a high nutritional value, low content of anti-nutritional substances and proven health-promoting action and therefore they were used in this study. Since glycated pea proteins are proven to display a lowered susceptibility to the enzymatic digestion, their impact on the activity of both free-swimming and immobilised bacteria was studied.

RESULTS

In vitro model systems were used to prove the stimulatory impact of glycated pea proteins on the proliferation rate and survival, as well as on the metabolic activity of free-swimming and immobilised bacteria.

CONCLUSIONS

This phenomenon is of great importance because glycated food proteins are not only a source of nutrients and energy but also display new properties and increased biological activities. Additionally, they are able to modify the bacterial intestinal ecosystem, thus affecting the general health status of a consumer.

Facile fingerstick insulin analysis: Application to monitoring postprandial insulin responses to snack foods

BACKGROUND

Energy intake from snacks has been increasing in the American diet, but insulin and glucose responses to foods are generally reported for meal-sized portions (800-1200 kJ). Established methods for insulin determination routinely use indwelling catheters and radioimmunoassay (RIA). The aim of the present study was to develop a more facile method, collecting fingerstick blood samples and measuring insulin with precise ELISA, and then applying this method to determine responses to snack-sized food portions.

METHODS

Six healthy, fasting adult volunteers consumed seven different snack foods on separate days, containing approximately 400 kJ/portion. Insulin was measured by ELISA and glucose was measured with the hexokinase procedure in samples collected by fingerstick at 0, 30, and 60 min after consumption of the snack food.

RESULTS

A portion of doughnut (half a glazed doughnut) led to marked changes in insulin and glucose; skim milk, an apple, and oatmeal changed insulin significantly; wrinkled peas resulted in a lower glucose response than smooth peas; and walnuts led to non-significant changes in both insulin and glucose over a 60-min period.

CONCLUSIONS

The fingerstick sampling and insulin measurement procedure is simple, economical, and more precise than established RIA. The method can be applied to children and adults to monitor insulin responses following food consumption, as well as during therapeutic assessments or intervention trials. Public health advisories regarding snacks that minimize increases in insulin are desirable for individuals trying to reduce or maintain their weight, because elevated insulin stimulates carbohydrate conversion to fat and suppresses the mobilization of stored triglycerides for energy generation.

Validation of an FFQ to assess dietary protein intake in type 2 diabetic subjects attending primary health-care services in Mali

OBJECTIVE

To validate a 53-item quantitative FFQ (QFFQ) for the assessment of dietary protein intake in type 2 diabetic outpatients in Bamako, Mali.

DESIGN

Consumption of protein-containing foods over the week preceding the interview was measured with a 7d QFFQ and compared with intakes measured with 48-h recalls.

SETTING

Centre National de Lutte contre le Diabète.

SUBJECTS

Seventeen male and forty female adults with type 2 diabetes.

RESULTS

Correlation between protein intakes estimated using the QFFQ and 48h recalls was 0.63 (P < 0.0001). There was no significant difference between the two methods concerning the total protein daily intakes and intakes per kilogram of body weight. The QFFQ indicated that foods of animal origin were a lesser source of protein. Animal protein intake did not differ between men and women but sources did. In men, the main sources were beef (54 % of total animal protein), fish (15 %) and milk powder (8 %). In women, the principal sources were fish (28 %), beef (20 %) and birds (13 %). In contrast, plant protein intake was significantly higher in men than in women (P = 0.01), but the same plant foods contributed in similar proportions for both genders, rice being by far the greatest source (47 % of plant protein in men, 53 % in women).

CONCLUSION

The QFFQ developed in this study is a valid tool to evaluate dietary protein intakes in Malian diabetic subjects. While the total protein intakes were low in both men and women, differences in choices and amounts of protein food sources were shown.

Nutritional correlates of dietary glycaemic index: new aspects from a population perspective

The role of dietary glycaemic index (GI) and glycaemic load (GL) in disease aetiology is of increasing interest. However, nutritional factors related to dietary GI and GL are not well understood from a population perspective. We aimed to investigate the relation ship between GI and GL and dietary intake at the food and nutrient level. Study subjects were 1071 non-diabetic adults from the Insulin Resistance Atherosclerosis Study, Exam I, 1992–4. Usual dietary intake was assessed with a 114-item modified Block food frequency questionnaire. Published GI values were assigned to food line items. Correlation and regression analyses were conducted. Intake of white bread, beer, meats and fries/fried potatoes was positively associated with average GI, as was fat, starch and alcohol intake (before and after energy adjustment). Intake of fruits and low-fat milk was inversely associated with GI, as were intakes of mono- and disaccharides, and fibre. GL was positively correlated with carbohydrate foods and inversely with non-carbohydrate foods. Gender-specific regression models identified eight food groups explaining 63 % (men) and 55 % (women) total GI variation after adjusting for demographics; 70 % of variation in GL was explained by eleven (men) and nine (women) food groups, respectively. Although the GI of a food is an indicator of the ability of carbohydrates to raise blood glucose, dietary GI, unlike GL, appears to reflect more dimensions of diet than just carbohydrates, such as the combination of foods consumed. This may have implications for the interpretation of dietary GI in epidemiologic studies.

Effects of meals with high soluble fibre, high amylose barley variant on glucose, insulin, satiety and thermic effect of food in healthy lean women

OBJECTIVE

To examine the effect of barley flour (barley cultivar, Hordeum Vulgare var Himalaya 292) incorporated into breakfast and lunch compared with otherwise identical meals containing white wheat flour on the thermic effect of food (TEF), subsequent food intake and metabolic parameters.

DESIGN

Randomized single blinded crossover study.

SETTING

Outpatient setting.

SUBJECTS AND METHODS

Fourteen healthy women consumed a test breakfast at 0700 h. Energy expenditure, respiratory quotient (RQ), appetite ratings using a visual analogue scale (VAS), insulin and glucose levels were measured before and after a test lunch at 1330 h. Food intake was recorded for the remainder of the day.

RESULTS

The TEF was 5% for both test lunches and meal type did not affect any variable measured by the VAS. There was an increase in post-prandial RQ above baseline (0.80) independent of treatment (0.88 and 0.90 for barley and wheat-containing meals, respectively, P<0.001). Mean area under the glycaemic response curve (AUC) for wheat-containing meals was 4.68+/-1.67 mmol/l/h, 22% higher than for the barley-containing meals (3.67+/-1.91 mmol/l/h), P=0.05. AUC of insulin in response to wheat-containing meals (78.1+/-35.3 mIU/l/h) was 32% greater than barley-containing meals (52.8+/-24.7 mU/l/h), P<0.02. Ad libitum food intake over the next 10 h was reduced by 23% (9.6 vs 11.0 MJ, P<0.05) after the wheat-containing meals compared to the barley-containing glycaemic index meals.

CONCLUSION

Inclusion of an ingredient containing increased soluble fibre and amylose did not reduce spontaneous food intake but rather was associated with higher subsequent energy intakes despite its reduced glycaemic and insulinemic effects.

SPONSORSHIP

CSIRO, Human Nutrition, Adelaide, Australia.

Targeting postprandial hyperglycemia

In healthy individuals, blood glucose levels in the fasting state are maintained by the continuous basal-level insulin secretion. After a meal, the rise in postprandial glucose (PPG) is controlled by the rapid pancreatic release of insulin, stimulated by both glucose and the intestinal production of the incretins glucose-dependent insulinotropic polypeptide and glucagon-like peptide 1. In diabetic individuals, postprandial insulin secretion is insufficient to suppress an excessive rise in PPG. There is increasing evidence that elevated PPG exerts a more deleterious effect on the vascular system than elevation of fasting plasma glucose. In particular, individuals with normal fasting plasma glucose but impaired glucose tolerance have significantly increased risk of cardiovascular events. With the recognition of the importance of PPG and the availability of new pharmacologic options, management of diabetes will shift to greater attention to PPG levels. The prototype for such an approach is in the treatment of gestational diabetes and diabetic pregnancies where PPG is the primary target of efforts at glycemic control. These efforts have been extremely successful in improving the outlook for diabetic pregnant women. There are many approaches to reduction of PPG; dietary management and promotion of exercise are very effective. Sulfonylureas, meglitinides, metformin, thiazolidinediones, and disaccharidase inhibitors all counteract PPG elevation. The development of glucagon-like peptide 1 agonists such as exendin and dipeptidyl peptidase IV inhibitors such as vildagliptin offers a new approach to suppression of PPG elevation. New semisynthetic insulin analogues permit a more aggressive response to postprandial glucose elevation, with lower risk of hypoglycemia, than with regular insulin. Inhaled insulin also has a rapid onset of action and offers benefits in PPG control. It is proposed that an aggressive treatment approach focusing on PPG, similar to the current standards for diabetic pregancies, be directed at individuals with diabetes and impaired glucose tolerance.

Glycemic index and load-dynamic dietary guidelines in the context of diseases

The concepts of glycemic index (GI) and glycemic load (GL) are among a new generation of so-called dynamic dietary guidelines. In contrast to classical static guidelines, these new guidelines do not primarily consider the absolute amount of energy or nutrient to be ingested within 24 h, but rather are focused on the postprandial response. It is claimed that low-GI and -GL diets favorably affect many noncommunicable diseases that are prevalent in developed countries, including type II diabetes, insulin resistance, obesity, cardiovascular disease (CVD), and cancer. During the past 20 years, considerable evidence has accumulated suggesting that low-GI or -GL diets indeed positively influence some but not all diseases. Because virtually no deleterious effects of low-GI and -GL diets have been documented thus far or are to be expected, the promotion of these diets should be considered in the management of noncommunicable diseases.

Food factors and gastrointestinal function: a critical interface

The gastrointestinal tract (GIT) is an interface between the external environment and the body and functions to extract nutrients from foods as well as handle the various non-nutrient compounds found in foods. Thus factors in foods that affect health and disease may mediate their effects either through a direct effect on the GIT or indirectly by the pattern of absorption and subsequent metabolism through the GIT. To explore this relationship one must consider both the physiological responses of the GIT induced by factors in foods as well as the implications of GIT adaptation for metabolism. Metabolic adaptations to dietary factors such as cholesterol levels, glucose and insulin response, and immune function appear to be modulated by the manner in which food factors are metabolized in the GIT. New research is needed to understand the inter-relationship between food factors that stimulate GIT response and the subsequent influence on metabolism that influences risk factors for disease and health promotion.