Moderate amounts of fructose- or glucose-sweetened beverages do not differentially alter metabolic health in male and female adolescents

Maternal fructose intake aggravates the harmful effects of a Western diet in rat male descendants impacting their cholesterol metabolism

Scope: fructose consumption from added sugars correlates with the epidemic rise in MetS and CVD. Maternal fructose intake has been described to program metabolic diseases in progeny. However, consumption of fructose-containing beverages is allowed during gestation. Cholesterol is also a well-known risk factor for CVD. Therefore, it is essential to study Western diets which combine fructose and cholesterol and how maternal fructose can influence the response of progeny to these diets. Methods and results: a high-cholesterol (2%) diet combined with liquid fructose (10%), as a model of an unhealthy Western diet, was administered to descendants from control and fructose-fed mothers. Gene (mRNA and protein) expression and plasma, fecal and tissue parameters of cholesterol metabolism were measured. Interestingly, progeny from fructose-fed dams consumed less liquid fructose and cholesterol-rich chow than males from control mothers. Moreover, descendants of fructose-fed mothers fed a Western diet showed an increased cholesterol elimination through bile and feces than males from control mothers. Despite these mitigating circumstances to develop a proatherogenic profile, the same degree of hypercholesterolemia and severity of steatosis were observed in all descendants fed a Western diet, independently of maternal intake. An increased intestinal absorption of cholesterol, synthesis, esterification, and assembly into lipoprotein found in males from fructose-fed dams consuming a Western diet could be the cause. Moreover, an augmented GLP2 signalling seen in these animals would explain this enhanced lipid absorption. Conclusions: maternal fructose intake, through a fetal programming, makes a Western diet considerably more harmful in their descendants than in the offspring from control mothers.

Regulation of Macronutrients in Insulin Resistance and Glucose Homeostasis during Type 2 Diabetes Mellitus

Insulin resistance is an important feature of metabolic syndrome and a precursor of type 2 diabetes mellitus (T2DM). Overnutrition-induced obesity is a major risk factor for the development of insulin resistance and T2DM. The intake of macronutrients plays a key role in maintaining energy balance. The components of macronutrients distinctly regulate insulin sensitivity and glucose homeostasis. Precisely adjusting the beneficial food compound intake is important for the prevention of insulin resistance and T2DM. Here, we reviewed the effects of different components of macronutrients on insulin sensitivity and their underlying mechanisms, including fructose, dietary fiber, saturated and unsaturated fatty acids, and amino acids. Understanding the diet-gene interaction will help us to better uncover the molecular mechanisms of T2DM and promote the application of precision nutrition in practice by integrating multi-omics analysis.

Effect of fructose instead of glucose or sucrose on cardiometabolic markers: a systematic review and meta-analysis of isoenergetic intervention trials

CONTEXT

Free, or added, sugars are considered important determinants in the pandemics of obesity and associated chronic diseases, and fructose has emerged as the sugar of main concern.

OBJECTIVE

The aim of this review was to assess the evidence of the effects of isoenergetic replacement of fructose or high-fructose corn syrup (HFCS) for glucose or sucrose on cardiometabolic markers in controlled dietary intervention trials.

DATA SOURCES

The electronic databases PubMed/MEDLINE, the Cochrane Library, and Embase were searched from 1980 to May 5, 2020.

STUDY SELECTION

Studies were eligible if they measured at least one of the following outcomes: total cholesterol, low- and high-density lipoprotein cholesterol, triacylglycerols, apolipoprotein A1, apolipoprotein B, systolic blood pressure, diastolic blood pressure, fasting glucose, and body weight.

DATA EXTRACTION

For each outcome, the mean values and the corresponding measure of dispersion were extracted after the intervention or control diet.

DATA ANALYSIS

Fixed-effects and random-effects models were used to pool study-specific estimates. Between-study heterogeneity was assessed by the χ2 test and the I2 statistic and publication bias by the Egger test and funnel plots.

RESULTS

Twenty-five studies involving 1744 volunteers were identified. No significant effects were found when fructose or HFCS was substituted for glucose, except for a slight decrease in diastolic blood pressure when fructose was substituted for glucose. Similarly, no effects were found when fructose or HFCS was substituted for sucrose, except for a small increase, of uncertain clinical significance, of apolipoprotein B when HFCS was substituted for sucrose.

CONCLUSIONS

Isoenergetic substitution of fructose or HFCS for glucose or sucrose has no significant effect on most of the cardiometabolic markers investigated; however, some results were affected by residual between-study heterogeneity and studies with high or unclear risk of bias.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number CRD42016042930.

Chronic Fructose Substitution for Glucose or Sucrose in Food or Beverages and Metabolic Outcomes: An Updated Systematic Review and Meta-Analysis

Despite the publication of several of meta-analyses in recent years, the effects of fructose on human health remains a topic of debate. We previously undertook two meta-analyses on post-prandial and chronic responses to isoenergetic replacement of fructose for sucrose or glucose in food or beverages (Evans et al. 2017, AJCN 106:506–518 & 519–529). Here we report on the results of an updated search with a complete re-extraction of previously identified studies and a new and more detailed subgroup-analysis and meta-regression. We identified two studies that were published after our previous analyses, which slightly altered effect sizes and conclusions. Overall, the isoenergetic substitution of fructose for glucose resulted in a statistically significant but clinically irrelevant reduction in fasting blood glucose, insulin, and triglyceride concentrations. A subgroup analysis by diabetes status revealed much larger reductions in fasting blood glucose in people with impaired glucose tolerance and type 2 diabetes. However, each of these subgroups contained only a single study. In people with a healthy body mass index, fructose consumption was associated with statistically significant, but clinically irrelevant reductions in fasting blood glucose and fasting blood insulin. Meta-regression of the outcomes by a number of pre-identified and post-hoc covariates revealed some sources of heterogeneity, such as year of publication, age of the participants at baseline, and participants' sex. However, the small number of studies and the large number of potential covariates precluded detailed investigations of effect sizes in different subpopulations. For example, well-controlled, high quality studies in people with impaired glucose tolerance and type 2 diabetes are still lacking. Taken together, the available data suggest that chronic consumption of fructose is neither more beneficial, nor more harmful than equivalent doses of sucrose or glucose for glycemic and other metabolic outcomes.

Maternal Fructose Intake Increases Liver H2 S Synthesis but Exarcebates its Fructose-Induced Decrease in Female Progeny

SCOPE

Fructose intake from added sugars correlates with the epidemic rise in metabolic syndrome and cardiovascular diseases (CVD). However, consumption of beverages containing fructose is allowed during gestation. Homocysteine (Hcy) is a well-known risk factor for CVD while hydrogen sulfide (H₂ S), a product of its metabolism, has been proved to exert opposite effects to Hcy.

METHODS AND RESULTS

First, it is investigated whether maternal fructose intake produces subsequent changes in Hcy metabolism and H₂ S synthesis of the progeny. Carbohydrates are supplied to pregnant rats in drinking water (10% wt/vol) throughout gestation. Adult female descendants from fructose-fed, control or glucose-fed mothers are studied. Females from fructose-fed mothers have elevated homocysteinemia, hepatic H₂ S production, cystathionine γ-lyase (CSE) (the key enzyme in H₂ S synthesis) expression and plasma H₂ S, versus the other two groups. Second, it is studied how adult female progeny from control (C/F), fructose- (F/F), and glucose-fed (G/F) mothers responded to liquid fructose and compared them to the control group (C/C). Interestingly, hepatic CSE expression and H₂ S synthesis are diminished by fructose intake, this effect being more pronounced in F/F females.

CONCLUSION

Maternal fructose intake produces a fetal programming that increases hepatic H₂ S production and, in contrast, exacerbates its fructose-induced drop in female progeny.

Post Meal Exercise May Lead to Transient Hypoglycemia Irrespective of Glycemic Status in Humans

During exercise, there is coordination between various hormonal systems to ensure glucoregulation. This study examined if hypoglycemia occurs during moderate-intensity exercise in non-obese and obese individuals with and without type 2 diabetes (T2D). Eighteen non-obese, 18 obese, and 10 obese with T2D completed 2 study days that included a meal at 1,800 h followed by rest (NOEX) or exercise (PMEX; 45 min/55% of VO₂ max 2 h post meal). Glucose, insulin, and glucagon concentrations were measured throughout this 5.5 h period. Subjects with T2D had elevated glucose responses to the meal on both study days, compared to non-obese and obese subjects (P < 0.05). During evening exercise (PMEX), subjects with T2D had a greater drop in glucose concentration (-98.4 ± 13.3 mg/dL) compared to obese (-44.8 ± 7.1 mg/dL) and non-obese (-39.3 ± 6.1 mg/dL; P < 0.01) subjects. Glucose levels decreased more so in females than males in both conditions (P < 0.01). Nadir glucose levels <70 mg/dL were observed in 33 subjects during NOEX and 39 subjects during PMEX. Obese males had a larger exercise-induced insulin drop than obese females (P = 0.01). During PMEX, peak glucagon concentrations were elevated compared to NOEX (P < 0.001). Male participants with T2D had an increased glucagon response during NOEX and PMEX compared to females (P < 0.01). In conclusion, in individuals with varying glucose tolerance, there is a dramatic drop in glucose levels during moderate-intensity exercise, despite appropriate insulin concentrations prior to exercise, and glucagon levels rising during exercise. Moderate-intensity exercise can result in low glucose concentrations (<60 mg/dL), and yet many of these individuals will be asymptomatic.

Dietary Carbohydrates and Insulin Resistance in Adolescents from Marginalized Areas of Chiapas, México

Evidence of the role that dietary carbohydrates (total carbohydrates, dietary fiber, total sugars, dietary glycemic index (GI) and glycemic load (GL)) exerts on insulin levels in adolescents is controversial. Thus, the aim of this study was to assess the association between dietary carbohydrates and insulin resistance in adolescents from Chiapas, México. A cross-sectional study was conducted in 217 adolescents. Sociodemographic, anthropometric, dietary and biochemical data were obtained. Total carbohydrates, dietary fiber, total sugars, dietary GI and GL were calculated from 24 h recalls. Two validated cut-off points for the homeostasis model assessment of insulin resistance (HOMA-IR) were used as surrogates of insulin resistance. Fasting insulin levels ≥ 14.38 μU/mL were considered as abnormal. Multivariate logistic regression models were fitted to assess the association between tertiles of dietary carbohydrates and insulin resistance or hyperinsulinemia. In our study, adolescents with the highest dietary fiber intake had lower odds of HOMA-IR > 2.97 (OR = 0.34; 95% CI: 0.13-0.93) when adjusted for sex, age, body fat percentage and saturated fatty acids intake. No significant associations were found for the rest of the carbohydrate variables. In summary, high-fiber diets reduce the probability of insulin resistance in adolescents from marginalized areas of Chiapas, México.

Metabolic Implications of Diet and Energy Intake during Physical Inactivity

PURPOSE

Physical inactivity is associated with disruptions in glucose metabolism and energy balance, whereas energy restriction may blunt these adverse manifestations. During hypocaloric feeding, higher-protein intake maintains lean mass which is an important component of metabolic health. This study determined whether mild energy restriction preserves glycemic control during physical inactivity and whether this preservation is more effectively achieved with a higher-protein diet.

METHODS

Ten adults (24 ± 1 yr) consumed a control (64% carbohydrate, 20% fat, 16% protein) and higher-protein diet (50% carbohydrate, 20% fat, 30% protein) during two 10-d inactivity periods (>10,000 → ~5000 steps per day) in a randomized crossover design. Energy intake was decreased by ~400 kcal·d to account for reduced energy expenditure associated with inactivity. A subset of subjects (n = 5) completed 10 d of inactivity while consuming 35% excess of their basal energy requirements, which served as a positive control condition (overfeeding+inactivity).

RESULTS

Daily steps were decreased from 12,154 ± 308 to 4275 ± 269 steps per day (P < 0.05) which was accompanied by reduced V˙O2max (-1.8 ± 0.7 mL·kg·min, P < 0.05), independent of diet conditions. No disruptions in fasting or postprandial glucose, insulin, and nonesterified fatty acids in response to 75 g of oral glucose were observed after inactivity for both diet conditions (P > 0.05). Overfeeding+inactivity increased body weight, body fat, homeostasis model assessment of insulin resistance, and 2-h postprandial glucose and insulin concentrations (P < 0.05), despite no changes in lipid concentrations.

CONCLUSIONS

We show that independent of diet (normal vs higher-protein), mild energy restriction preserves metabolic function during short-term inactivity in healthy subjects. That is, metabolic deterioration with inactivity only manifests in the setting of energy surplus.

Food sources of fructose-containing sugars and glycaemic control: systematic review and meta-analysis of controlled intervention studies

OBJECTIVE

To assess the effect of different food sources of fructose-containing sugars on glycaemic control at different levels of energy control.

DESIGN

Systematic review and meta-analysis of controlled intervention studies.

DATA SOURCES

Medine, Embase, and the Cochrane Library up to 25 April 2018.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Controlled intervention studies of at least seven days' duration and assessing the effect of different food sources of fructose-containing sugars on glycaemic control in people with and without diabetes were included. Four study designs were prespecified on the basis of energy control: substitution studies (sugars in energy matched comparisons with other macronutrients), addition studies (excess energy from sugars added to diets), subtraction studies (energy from sugars subtracted from diets), and ad libitum studies (sugars freely replaced by other macronutrients without control for energy). Outcomes were glycated haemoglobin (HbA1c), fasting blood glucose, and fasting blood glucose insulin.

DATA EXTRACTION AND SYNTHESIS

Four independent reviewers extracted relevant data and assessed risk of bias. Data were pooled by random effects models and overall certainty of the evidence assessed by the GRADE approach (grading of recommendations assessment, development, and evaluation).

RESULTS

155 study comparisons (n=5086) were included. Total fructose-containing sugars had no harmful effect on any outcome in substitution or subtraction studies, with a decrease seen in HbA1c in substitution studies (mean difference -0.22% (95% confidence interval to -0.35% to -0.08%), -25.9 mmol/mol (-27.3 to -24.4)), but a harmful effect was seen on fasting insulin in addition studies (4.68 pmol/L (1.40 to 7.96)) and ad libitum studies (7.24 pmol/L (0.47 to 14.00)). There was interaction by food source, with specific food sources showing beneficial effects (fruit and fruit juice) or harmful effects (sweetened milk and mixed sources) in substitution studies and harmful effects (sugars-sweetened beverages and fruit juice) in addition studies on at least one outcome. Most of the evidence was low quality.

CONCLUSIONS

Energy control and food source appear to mediate the effect of fructose-containing sugars on glycaemic control. Although most food sources of these sugars (especially fruit) do not have a harmful effect in energy matched substitutions with other macronutrients, several food sources of fructose-containing sugars (especially sugars-sweetened beverages) adding excess energy to diets have harmful effects. However, certainty in these estimates is low, and more high quality randomised controlled trials are needed.

STUDY REGISTRATION

Clinicaltrials.gov (NCT02716870).

The Effect of Small Doses of Fructose and Its Epimers on Glycemic Control: A Systematic Review and Meta-Analysis of Controlled Feeding Trials

Objective: Contrary to the concerns that fructose may have adverse metabolic effects, an emerging literature has shown that small doses (≤10 g/meal) of fructose and its low-caloric epimers (allulose, tagatose, and sorbose) decrease the glycemic response to high glycemic index meals. Whether these acute reductions manifest as sustainable improvements in glycemic control is unclear. Our objective was to synthesize the evidence from controlled feeding trials that assessed the effect of small doses of fructose and its low-caloric epimers on glycemic control. Methods: We searched MEDLINE, EMBASE, and the Cochrane Library through April 18, 2018. We included controlled feeding trials of ≥1 week that investigated the effect of small doses (≤50 g/day or ≤10% of total energy intake/day) of fructose and its low-caloric epimers on HbA_1c, fasting glucose, and fasting insulin. Two independent reviewers extracted data and assessed risk of bias. Data were pooled using the generic inverse variance method and expressed as mean differences (MDs) with 95% confidence intervals (CIs). Heterogeneity was assessed using the Cochran Q statistic and quantified using the I² statistic. Grading of Recommendations Assessment, Development and Evaluation (GRADE) assessed the certainty of the evidence. Results: We identified 14 trial comparisons (N = 337) of the effect of fructose in individuals with and without diabetes, 3 trial comparisons (N = 138) of the effect of allulose in individuals without diabetes, 3 trial comparisons (N = 376) of the effect of tagatose mainly in individuals with type 2 diabetes, and 0 trial comparisons of the effect of sorbose. Small doses of fructose and tagatose significantly reduced HbA_1c (MD = -0.38% (95% CI: -0.64%, -0.13%); MD = -0.20% (95% CI: -0.34%, -0.06%)) and fasting glucose (MD = -0.13 mmol/L (95% CI: -0.24 mmol/L, -0.03 mmol/L)); MD = -0.30 mmol/L (95% CI: -0.57 mmol/L, -0.04 mmol/L)) without affecting fasting insulin (p > 0.05). Small doses of allulose did not have a significant effect on HbA_1c and fasting insulin (p > 0.05), while the reduction in fasting glucose was of borderline significance (p = 0.05). The certainty of the evidence of the effect of small doses of fructose and allulose on HbA_1c, fasting glucose, and fasting insulin was graded as low. The certainty of the evidence of the effect of tagatose on HbA_1c, fasting glucose, and fasting insulin was graded as moderate. Conclusions: Our results indicate that small doses of fructose and tagatose may improve glycemic control over the long term. There is a need for long-term randomized controlled trials for all four sugars to improve our certainty in the estimates.

Effects of fructose consumption on postprandial TAG: an update on systematic reviews with meta-analysis

The aim of this study was to re-examine the chronic effect (>7 d) of fructose consumption on postprandial TAG, in adolescents and adults. The research was carried out in March 2017 and used different electronic databases, such as Medline ® (Pubmed®), Embase® and Cochrane. The review considered clinical trials (parallel or crossed) that evaluated the effect of fructose consumption for a period longer than 7 d, in humans. Two investigators independently performed data extraction. The outcome was the absolute delta of TAG concentration in a 4-h postprandial period. The results were presented with delta mean difference between treatments with 95 % CI. The calculations were made based on random-effect models. Statistical heterogeneity of treatment effects between studies was assessed by Cochrane's 'Q Test' and 'I 2' inconsistency test. The meta-analysis of the twelve selected interventions (n 318) showed that fructose generated larger variation (δ) of TAG concentrations during the postprandial period, compared with other carbohydrates (mean difference: 8·02 (95 % CI 0·46, 15·58) mg/dl (0·09 (95 % CI 0·01, 0·18) mmol/l); I 2: 74 %). High heterogeneity was generated almost exclusively by one study, and its withdrawal did not alter the result. We concluded that chronic consumption of fructose (>7 d) has a negative role on postprandial TAG in healthy adolescents and adults, as well as in overweight/obese individuals, but not in diabetics.

Soda Intake Is Directly Associated with Serum C-Reactive Protein Concentration in Mexican Women

Background

Soda intake is associated with an increased risk of cardiovascular disease. Consumption of diet sodas, often considered healthy alternatives to sodas, could also increase the likelihood of cardiovascular outcomes.

Objective

This study aims to evaluate the relation between soda and diet soda and biomarkers of cardiovascular risk.

Methods

We conducted a cross-sectional analysis among 825 Mexican women free of diabetes, cardiovascular disease, and cancer, and for whom serum concentrations of C-reactive protein (CRP), C-peptide, adiponectin, and leptin were available. Mean ± SD age was 45.9 ± 6.6 y, the majority of women were premenopausal (60.4%), and the prevalence of obesity was 35%. We estimated the adjusted percentage differences in biomarkers and 95% CIs by performing multiple linear regression models comparing categories of consumption for soda and diet soda adjusting for age, family history of heart disease, menopause, menopausal hormone therapy, socioeconomic status, region, smoking, physical activity, alcohol intake, and dietary patterns.

Results

In the entire study sample we observed a 50% higher serum CRP concentration in women in the highest soda intake quartile (median intake: 202.9 mL/d, IQR: 101.4, 304.3 mL/d) compared to those in the lowest (median intake: 11.8 mL/d, IQR: 0.0, 152.1 mL/d). After stratification by menopausal status, results remained significant only for premenopausal women. Premenopausal women in the highest quartile of soda intake had 56% higher CRP concentration relative to women in the lowest quartile. We observed no significant association with the other biomarkers. After further adjustment for body mass index, a potential mediator, results remained significant only for CRP. Diet soda consumption was not associated with any of the biomarkers.

Conclusions

Consumption of soda was associated with adverse levels in a biomarker of inflammation and cardiovascular risk, serum CRP, in Mexican women. These results add to the accumulating evidence on soda and cardiovascular risk. More research is necessary to understand the potential impact of artificially sweetened sodas.

Frequent Sugar-Sweetened Beverage Consumption and the Onset of Cardiometabolic Diseases: Cause for Concern?

The incidence of noncommunicable diseases is on the rise and poses a major threat to global public health. This is in parallel to a steady increase in worldwide intake of sugar-sweetened beverages (SSBs) among all age groups. As several studies demonstrated a controversial relationship between SSB consumption and the metabolic syndrome (MetS), this mini-review focuses on links between its intake and (1) MetS, (2) prediabetes/type 2 diabetes mellitus (T2DM), and (3) hypertension. A detailed search for clinical and observational studies published during the past 10 years was conducted using key terms that link SSBs to the MetS, T2DM, and hypertension. Here we excluded all meta-analyses and also literature that solely focused on obesity. The analysis revealed that most epidemiological studies strongly show that frequent SSB intake contributes to the onset of the MetS in the longer term. Some of the findings also show that regular SSB intake can alter glucose handling and insulin sensitivity, thereby contributing to the development of the MetS and T2DM. There is also evidence that frequent SSB intake (and particularly fructose) is linked to hypertension and well-known cardiovascular disease risk factors. However, some studies report on the lack of negative effects as a result of SSB consumption. Because of this discrepancy, we propose that well-designed long-term clinical studies should further enhance our understanding regarding the links between SSB consumption and the onset of cardiometabolic diseases.

Chronic fructose substitution for glucose or sucrose in food or beverages has little effect on fasting blood glucose, insulin, or triglycerides: a systematic review and meta-analysis

Background: Conflicting evidence exists on the role of long-term fructose consumption on health. No systematic review has addressed the effect of isoenergetic fructose replacement of other sugars and its effect on glycated hemoglobin (HbA1c), fasting blood glucose, insulin, and triglycerides.Objective: The objective of this study was to review the evidence for a reduction in fasting glycemic and insulinemic markers after chronic, isoenergetic replacement of glucose or sucrose in foods or beverages by fructose. The target populations were persons without diabetes, those with impaired glucose tolerance, and those with type 2 diabetes.Design: We searched the Cochrane Library, MEDLINE, EMBASE, the WHO International Clinical Trials Registry Platform Search Portal, and clinicaltrials.gov The date of the last search was 26 April 2016. We included randomized controlled trials of isoenergetic replacement of glucose, sucrose, or both by fructose in adults or children with or without diabetes of ≥2 wk duration that measured fasting blood glucose. The main outcomes analyzed were fasting blood glucose and insulin as well as fasting triglycerides, blood lipoproteins, HbA1c, and body weight.Results: We included 14 comparison arms from 11 trials, including 277 patients. The studies varied in length from 2 to 10 wk (mean: 28 d) and included doses of fructose between 40 and 150 g/d (mean: 68 g/d). Fructose substitution in some subgroups resulted in significantly but only slightly lowered fasting blood glucose (-0.14 mmol/L; 95% CI: -0.24, -0.036 mmol/L), HbA1c [-10 g/L (95% CI: -12.90, -7.10 g/L; impaired glucose tolerance) and -6 g/L (95% CI: -8.47, -3.53 g/L; normoglycemia)], triglycerides (-0.08 mmol/L; 95% CI: -0.14, -0.02 mmol/L), and body weight (-1.40 kg; 95% CI: -2.07, -0.74 kg). There was no effect on fasting blood insulin or blood lipids.Conclusions: The evidence suggests that the substitution of fructose for glucose or sucrose in food or beverages may be of benefit to individuals, particularly those with impaired glucose tolerance or type 2 diabetes. However, additional high-quality studies in these populations are required.

Exercise timing and blood lactate concentrations in individuals with type 2 diabetes

The purpose of this study was to characterize how resistance exercise prior to or after a meal alters fasting and postprandial blood lactate concentrations in individuals with type 2 diabetes. Obese individuals with type 2 diabetes (N = 12) completed three 2-day trials, including (i) no exercise (NoEx), (ii) resistance exercise prior to dinner (Ex-M), and (iii) resistance exercise beginning at 45 min postdinner (M-Ex). During day 1 of each trial, fasting and postprandial blood lactate concentrations, perceived exertion, and substrate oxidation were measured, and subsequently on day 2 the following morning fasting blood lactate was measured. The premeal lactate incremental area under the curve (iAUC) during Ex-M (109 ± 66 mmol·L−1·1.6 h−1) was over 100-fold greater (P < 0.01) compared with NoEx (−15 ± 24 mmol·L−1·1.6 h−1) and M-Ex (−2 ± 18 mmol·L−1·1.6 h−1). The postprandial lactate iAUC during M-Ex (304 ± 116 mmol·L−1·4 h−1) was over 2-fold greater (P < 0.01) compared with NoEx (149 ± 74 mmol·L−1·4 h−1) and Ex-M (−140 ± 196 mmol·L−1·4 h−1). Average lactate during exercise was ∼45% greater (P = 0.03) during M-Ex (3.2 ± 0.9 mmol/L) compared with Ex-M (2.2 ± 0.9 mmol/L), but the change in lactate during Ex-M (2.4 ± 1.6 mmol/L) or M-Ex (2.3 ± 1.3 mmol/L) was not different (P > 0.05). Perceived exertion, substrate oxidation, or fasting blood lactate concentrations the day after testing were not different between trials. Blood lactate concentrations during acute resistance exercise are greater when exercise is performed in the postprandial period. Acute resistance exercise performed the night prior does not alter fasting blood lactate concentrations the following morning.

Added Sugars and Cardiovascular Disease Risk in Children: A Scientific Statement From the American Heart Association

BACKGROUND

Poor lifestyle behaviors are leading causes of preventable diseases globally. Added sugars contribute to a diet that is energy dense but nutrient poor and increase risk of developing obesity, cardiovascular disease, hypertension, obesity-related cancers, and dental caries.

METHODS AND RESULTS

For this American Heart Association scientific statement, the writing group reviewed and graded the current scientific evidence for studies examining the cardiovascular health effects of added sugars on children. The available literature was subdivided into 5 broad subareas: effects on blood pressure, lipids, insulin resistance and diabetes mellitus, nonalcoholic fatty liver disease, and obesity.

CONCLUSIONS

Associations between added sugars and increased cardiovascular disease risk factors among US children are present at levels far below current consumption levels. Strong evidence supports the association of added sugars with increased cardiovascular disease risk in children through increased energy intake, increased adiposity, and dyslipidemia. The committee found that it is reasonable to recommend that children consume ≤25 g (100 cal or ≈6 teaspoons) of added sugars per day and to avoid added sugars for children <2 years of age. Although added sugars most likely can be safely consumed in low amounts as part of a healthy diet, few children achieve such levels, making this an important public health target.

High Dietary Fructose: Direct or Indirect Dangerous Factors Disturbing Tissue and Organ Functions

High dietary fructose is a major contributor to insulin resistance and metabolic syndrome, disturbing tissue and organ functions. Fructose is mainly absorbed into systemic circulation by glucose transporter 2 (GLUT2) and GLUT5, and metabolized in liver to produce glucose, lactate, triglyceride (TG), free fatty acid (FFA), uric acid (UA) and methylglyoxal (MG). Its extrahepatic absorption and metabolism also take place. High levels of these metabolites are the direct dangerous factors. During fructose metabolism, ATP depletion occurs and induces oxidative stress and inflammatory response, disturbing functions of local tissues and organs to overproduce inflammatory cytokine, adiponectin, leptin and endotoxin, which act as indirect dangerous factors. Fructose and its metabolites directly and/or indirectly cause oxidative stress, chronic inflammation, endothelial dysfunction, autophagy and increased intestinal permeability, and then further aggravate the metabolic syndrome with tissue and organ dysfunctions. Therefore, this review addresses fructose-induced metabolic syndrome, and the disturbance effects of direct and/or indirect dangerous factors on the functions of liver, adipose, pancreas islet, skeletal muscle, kidney, heart, brain and small intestine. It is important to find the potential correlations between direct and/or indirect risk factors and healthy problems under excess dietary fructose consumption.

A review of recent evidence relating to sugars, insulin resistance and diabetes

The potential impact on health of diets rich in free sugars, and particularly fructose, is of major concern. The focus of this review is the impact of these sugars on insulin resistance and obesity, and the associated risk of developing type 2 diabetes. Much of the concern is focussed on specific metabolic effects of fructose, which are argued to lead to increased fat deposition in the liver and skeletal muscle with subsequent insulin resistance and increased risk of diabetes. However, much of the evidence underpinning these arguments is based on animal studies involving very large intakes of the free sugars. Recent human studies, in the past 5 years, provide a rather different picture, with a clear dose response link between fructose intake and metabolic changes. In particular, the most marked effects are observed when a high sugars intake is accompanied by an excess energy intake. This does not mean that a high intake of free sugars does not have any detrimental impact on health, but rather that such an effect seems more likely to be a result of the high sugars intake increasing the chances of an excessive energy intake rather than it leading to a direct detrimental effect on metabolism.

Fructose during pregnancy provokes fetal oxidative stress: The key role of the placental heme oxygenase-1

SCOPE

One of the features of metabolic syndrome caused by liquid fructose intake is an impairment of redox status. We have investigated whether maternal fructose ingestion modifies the redox status in pregnant rats and their fetuses.

METHODS AND RESULTS

Fructose (10% wt/vol) in the drinking water of rats throughout gestation, leads to maternal hepatic oxidative stress. However, this change was also observed in glucose-fed rats and, in fact, both carbohydrates produced a decrease in antioxidant enzyme activity. Surprisingly, mothers fed carbohydrates displayed low plasma lipid oxidation. In contrast, fetuses from fructose-fed mothers showed elevated levels of plasma lipoperoxides versus fetuses from control or glucose-fed mothers. Interestingly, a clearly augmented oxidative stress was observed in placenta of fructose-fed mothers, accompanied by a lower expression of the transcription factor Nuclear factor-erythroid 2-related factor-2 (Nrf2) and its target gene, heme oxygenase-1 (HO-1), a potent antioxidant molecule. Moreover, histone deacetylase 3 (HDAC3) that has been proposed to upregulate HO-1 expression by stabilizing Nrf2, exhibited a diminished expression in placenta of fructose-supplemented mothers.

CONCLUSIONS

Maternal fructose intake provoked an imbalanced redox status in placenta and a clear diminution of HO-1 expression, which could be responsible for the augmented oxidative stress found in their fetuses.

Fructose overfeeding in first-degree relatives of type 2 diabetic patients impacts energy metabolism and mitochondrial functions in skeletal muscle

SCOPE

The aim of the study was to assess the effects of a high-fructose diet (HFrD) on skeletal muscle transcriptomic response in healthy offspring of patients with type 2 diabetes, a subgroup of individuals prone to metabolic disorders.

METHODS AND RESULTS

Ten healthy normal weight first-degree relatives of type 2 diabetic patients were submitted to a HFrD (+3.5 g fructose/kg fat-free mass per day) during 7 days. A global transcriptomic analysis was performed on skeletal muscle biopsies combined with in vitro experiments using primary myotubes. Transcriptomic analysis highlighted profound effects on fatty acid oxidation and mitochondrial pathways supporting the whole-body metabolic shift with the preferential use of carbohydrates instead of lipids. Bioinformatics tools pointed out possible transcription factors orchestrating this genomic regulation, such as PPARα and NR4A2. In vitro experiments in human myotubes suggested an indirect action of fructose in skeletal muscle, which seemed to be independent from lactate, uric acid, or nitric oxide.

CONCLUSION

This study shows therefore that a large cluster of genes related to energy metabolism, mitochondrial function, and lipid oxidation was downregulated after 7 days of HFrD, thus supporting the concept that overconsumption of fructose-containing foods could contribute to metabolic deterioration in humans.

Effect of Fructose on Established Lipid Targets: A Systematic Review and Meta-Analysis of Controlled Feeding Trials

Background

Debate over the role of fructose in mediating cardiovascular risk remains active. To update the evidence on the effect of fructose on established therapeutic lipid targets for cardiovascular disease (low-density lipoprotein cholesterol [LDL]-C, apolipoprotein B, non-high-density lipoprotein cholesterol [HDL-C]), and metabolic syndrome (triglycerides and HDL-C), we conducted a systematic review and meta-analysis of controlled feeding trials.

Methods and Results

MEDLINE, EMBASE, CINHAL, and the Cochrane Library were searched through July 7, 2015 for controlled feeding trials with follow-up ≥7 days, which investigated the effect of oral fructose compared to a control carbohydrate on lipids (LDL-C, apolipoprotein B, non-HDL-C, triglycerides, and HDL-C) in participants of all health backgrounds. Two independent reviewers extracted relevant data. Data were pooled using random effects models and expressed as mean difference with 95% CI. Interstudy heterogeneity was assessed (Cochran Q statistic) and quantified (I² statistic). Eligibility criteria were met by 51 isocaloric trials (n=943), in which fructose was provided in isocaloric exchange for other carbohydrates, and 8 hypercaloric trials (n=125), in which fructose supplemented control diets with excess calories compared to the control diets alone without the excess calories. Fructose had no effect on LDL-C, non-HDL-C, apolipoprotein B, triglycerides, or HDL-C in isocaloric trials. However, in hypercaloric trials, fructose increased apolipoprotein B (n=2 trials; mean difference = 0.18 mmol/L; 95% CI: 0.05, 0.30; P=0.005) and triglycerides (n=8 trials; mean difference = 0.26 mmol/L; 95% CI: 0.11, 0.41; P<0.001). The study is limited by small sample sizes, limited follow-up, and low quality scores of the included trials.

Conclusions

Pooled analyses showed that fructose only had an adverse effect on established lipid targets when added to existing diets so as to provide excess calories (+21% to 35% energy). When isocalorically exchanged for other carbohydrates, fructose had no adverse effects on blood lipids. More trials that are larger, longer, and higher quality are required.

Clinical Trials Registration

URL: https://www.clinicaltrials.gov/. Unique Identifier: NCT01363791.

The ecologic validity of fructose feeding trials: supraphysiological feeding of fructose in human trials requires careful consideration when drawing conclusions on cardiometabolic risk

Background

Select trials of fructose overfeeding have been used to implicate fructose as a driver of cardiometabolic risk.

Objective

We examined temporal trends of fructose dose in human controlled feeding trials of fructose and cardiometabolic risk.

Methods

We combined studies from eight meta-analyses on fructose and cardiometabolic risk to assess the average fructose dose used in these trials. Two types of trials were identified: (1) substitution trials, in which energy from fructose was exchanged with equal energy from other carbohydrates and (2) addition trials, in which energy from fructose supplemented a diet compared to the diet alone.

Results

We included 64 substitution trials and 16 addition trials. The weighted average fructose dose in substitution trials was 101.7 g/day (95% CI: 98.4–105.1 g/day), and the weighted average fructose dose in addition trials was 187.3 g/day (95% CI: 181.4–192.9 g/day).

Conclusion

Average fructose dose in substitution and addition trials greatly exceed national levels of reported fructose intake (49 ± 1.0 g/day) (NHANES 1977–2004). Future trials using fructose doses at real world levels are needed.

Risks of misinterpretation in the evaluation of the effect of fruit-based drinks in postprandial studies

It has been suggested that some fruit-based drinks (FBD) may delay the onset of postprandial stress, which is involved in the pathogenesis of many diseases. The majority of the studies, which have investigated the effects of FBD on postprandial stress, involved a placebo that was a drink with the same content in sugars or carbohydrates of the FBD, but without the bioactive antioxidant compounds. These studies were aimed more at evaluating the effect of the antioxidants rather than the effect of the FBD as a whole. Only 4 studies compared the effect of FBD with water as control and did not support the hypothesis that FBD could inhibit postprandial dysmetabolism, as well as the studies that compared the effect of orange juice and cola. Overall, the results suggest a complex relationship between postprandial dysmetabolism, inflammation, and oxidative stress. Furthermore, the inflammatory and oxidative stress markers need further analytical validation and normal ranges should be established in order to reach a firm conclusion. Finally, caution should be taken in the interpretation of the effect of FBD in postprandial studies and the reviewed results suggest that dietary recommendations should aim to limit rather than increase sugar-sweetened beverages consumption.