A high-fructose diet impairs basal and stress-mediated lipid metabolism in healthy male subjects

The effects of a 7d high-fructose diet (HFrD) or control diet on lipid metabolism were studied in a group of six healthy lean males. Plasma NEFA and β-hydroxybutyrate concentrations, net lipid oxidation (indirect calorimetry) and exogenous lipid oxidation (13CO2 production) were monitored in basal conditions, after lipid loading (olive oil labelled with [13C]triolein) and during a standardised mental stress. Lactate clearance and the metabolic effects of an exogenous lactate infusion were also monitored. The HFrD lowered plasma concentrations of NEFA and β-hydroxybutyrate as well as lipid oxidation in both basal and after lipid-loading conditions. In addition, the HFrD blunted the increase in plasma NEFA and exogenous lipid oxidation during mental stress. The HFrD also increased basal lactate concentrations by 31·8%, and lactate production by 53·8%, while lactate clearance remained unchanged. Lactate infusion lowered plasma NEFA with the control diet, and net lipid oxidation with both the HFrD and control diet. These results indicate that a 7d HFrD markedly inhibits lipolysis and lipid oxidation. The HFrD also increases lactate production, and the ensuing increased lactate utilisation may contribute to suppress lipid oxidatio

Effects of a short-term overfeeding with fructose or glucose in healthy young males

Consumption of simple carbohydrates has markedly increased over the past decades, and may be involved in the increased prevalence in metabolic diseases. Whether an increased intake of fructose is specifically related to a dysregulation of glucose and lipid metabolism remains controversial. We therefore compared the effects of hypercaloric diets enriched with fructose (HFrD) or glucose (HGlcD) in healthy men. Eleven subjects were studied in a randomised order after 7d of the following diets: (1) weight maintenance, control diet; (2) HFrD (3·5g fructose/kg fat-free mass (ffm) per d, +35% energy intake); (3) HGlcD (3·5g glucose/kg ffm per d, +35% energy intake). Fasting hepatic glucose output (HGO) was measured with 6,6-2H2-glucose. Intrahepatocellular lipids (IHCL) and intramyocellular lipids (IMCL) were measured by 1H magnetic resonance spectroscopy. Both fructose and glucose increased fasting VLDL-TAG (HFrD: +59%, P<0·05; HGlcD: +31%, P=0·11) and IHCL (HFrD: +52%, P<0·05; HGlcD: +58%, P=0·06). HGO increased after both diets (HFrD: +5%, P<0·05; HGlcD: +5%, P=0·05). No change was observed in fasting glycaemia, insulin and alanine aminotransferase concentrations. IMCL increased significantly only after the HGlcD (HFrD: +24%, NS; HGlcD: +59%, P<0·05). IHCL and VLDL-TAG were not different between hypercaloric HFrD and HGlcD, but were increased compared to values observed with a weight maintenance diet. However, glucose led to a higher increase in IMCL than fructos

Balanced carbohydrate ratios are associated with improved diet quality in Australia: A nationally representative cross-sectional study

BACKGROUND: Carbohydrate quality influences major health outcomes; however, the best criteria to assess carbohydrate quality remain unknown. OBJECTIVE: The objectives were to: i) evaluate whether a diet that meets a carbohydrate ratio (simple, modified or dual ratio) is associated with higher nutrient intakes and diet quality, and ii) model the impact of substituting carbohydrate foods that meet the proposed ratios in place of foods that do not, on nutrient intakes. DESIGN: A secondary analysis of cross-sectional data from the 2011–12 Australian National Nutrition and Physical Activity Survey. PARTICIPANTS/SETTING: National data from participants aged 2 years and older (n = 12,153). MAIN OUTCOME MEASURES: Ratios were defined as (i) simple ratio, 10:1 (10g carbohydrate:≥1g dietary fiber); (ii) modified ratio, 10:1:2 (10g carbohydrate:≥1g dietary fiber:≤2g free sugars); and (iii) dual ratio, 10:1 & 1:2 (10g carbohydrate:≥1g dietary fiber & ≤2g free sugars per 1g dietary fiber). Ratios were compared to nutrient intakes obtained via automated multiple-pass 24-hour dietary recall and diet quality calculated using the Australian Healthy Eating Index. STATISTICAL ANALYSES PERFORMED: Substitution dietary modelling was performed. Data were analyzed using paired and independent sample t-tests. RESULTS: Ratio adherence was highest for simple (50.2% adults; 28.6% children), followed by dual (40.6% adults; 21.7% children), then modified (32.7% adults; 18.6% children) ratios. Participants who met any ratio reported higher nutrient intake and diet quality compared to those who failed to meet the respective ratio (P < .001 for all), with the greatest nutrient intakes found for those who met modified or dual ratios. Dietary modelling improved nutrient intakes for all ratios, with the greatest improvement found for the dual ratio. CONCLUSIONS: All carbohydrate ratios were associated with higher diet quality, with a free sugars constraint in the dual ratio providing the greatest improvements

Sex differences in lipid and glucose kinetics after ingestion of an acute oral fructose load

The increase in VLDL TAG concentration after ingestion of a high-fructose diet is more pronounced in men than in pre-menopausal women. We hypothesised that this may be due to a lower fructose-induced stimulation of de novo lipogenesis (DNL) in pre-menopausal women. To evaluate this hypothesis, nine healthy male and nine healthy female subjects were studied after ingestion of oral loads of fructose enriched with 13C6 fructose. Incorporation of 13C into breath CO2, plasma glucose and plasma VLDL palmitate was monitored to evaluate total fructose oxidation, gluconeogenesis and hepatic DNL, respectively. Substrate oxidation was assessed by indirect calorimetry. After 13C fructose ingestion, 44·0 (sd 3·2)% of labelled carbons were recovered in plasma glucose in males v. 41·9 (sd 2·3)% in females (NS), and 42·9 (sd 3·7)% of labelled carbons were recovered in breath CO2 in males v. 43·0 (sd 4·5)% in females (NS), indicating similar gluconeogenesis from fructose and total fructose oxidation in males and females. The area under the curve for 13C VLDL palmitate tracer-to-tracee ratio was four times lower in females (P<0·05), indicating a lower DNL. Furthermore, lipid oxidation was significantly suppressed in males (by 16·4 (sd 5·2), P<0·05), but it was not suppressed in females (−1·3 (sd 4·7)%). These results support the hypothesis that females may be protected against fructose-induced hypertriglyceridaemia because of a lower stimulation of DNL and a lower suppression of lipid oxidatio

A meta-analysis comparing the effectiveness of alternate day fasting, the 5:2 diet, and time-restricted eating for weight loss.

OBJECTIVE The objective of this meta-analysis was to compare the effectiveness of different intermittent fasting (IF) regimens on weight loss, in the general population, and compare these to traditional caloric energy restriction (CER). METHODS Three databases were searched from 2011 to June 2021 for randomized controlled trials (RCTs) that assessed weight loss and IF, including alternate day fasting (ADF), the 5:2 diet, and time-restricted eating (TRE). A random effect network analysis was used to compare the effectiveness between the three regimens. Meta-regression analysis was presented as weighted mean differences of body weight loss. RESULTS The exploratory random effects network analysis of 24 RCTs (n = 1768) ranked ADF as the most effective, followed by CER and TRE. The meta-analysis showed that IF regimens resulted in similar weight loss to CER (mean difference 0.26 kg, 95% CI: -0.31 to 0.84; p = 0.37). Compliance was generally high (>80%) in trials shorter than 3 months. CONCLUSIONS The present meta-analysis concludes that IF is comparable to CER and a promising alternative for weight loss. Among the three regimens, ADF showed the highest effectiveness for weight loss, followed by CER and TRE. Further well-powered RCTs with longer durations of intervention are required to draw solid conclusions

A 4-wk high-fructose diet alters lipid metabolism without affecting insulin sensitivity or ectopic lipids in healthy humans

BACKGROUND: High fructose consumption is suspected to be causally linked to the epidemics of obesity and metabolic disorders. In rodents, fructose leads to insulin resistance and ectopic lipid deposition. In humans, the effects of fructose on insulin sensitivity remain debated, whereas its effect on ectopic lipids has never been investigated. OBJECTIVE: We assessed the effect of moderate fructose supplementation on insulin sensitivity (IS) and ectopic lipids in healthy male volunteers (n = 7). DESIGN: IS, intrahepatocellular lipids (IHCL), and intramyocellular lipids (IMCL) were measured before and after 1 and 4 wk of a high-fructose diet containing 1.5 g fructose . kg body wt(-1) . d(-1). Adipose tissue IS was evaluated from nonesterified fatty acid suppression, hepatic IS from suppression of hepatic glucose output (6,6-2H2-glucose), and muscle IS from the whole-body glucose disposal rate during a 2-step hyperinsulinemic euglycemic clamp. IHCL and IMCL were measured by 1H magnetic resonance spectroscopy. RESULTS: Fructose caused significant (P < 0.05) increases in fasting plasma concentrations of triacylglycerol (36%), VLDL-triacylglycerol (72%), lactate (49%), glucose (5.5%), and leptin (48%) without any significant changes in body weight, IHCL, IMCL, or IS. IHCL were negatively correlated with triacylglycerol after 4 wk of the high-fructose diet (r = -0.78, P < 0.05). CONCLUSION: Moderate fructose supplementation over 4 wk increases plasma triacylglycerol and glucose concentrations without causing ectopic lipid deposition or insulin resistance in healthy humans

Health Effects of Fructose and Fructose-Containing Caloric Sweeteners: Where Do We Stand 10Years After the Initial Whistle Blowings?

Suspicion that fructose-containing caloric sweeteners (FCCS) may play a causal role in the development of metabolic diseases has elicited intense basic and clinical research over the past 10years. Prospective cohort studies converge to indicate that FCCS, and more specifically sugar-sweetened beverages (SSBs), consumption is associated with weight gain over time. Intervention studies in which FCCS or SSB consumption is altered while food intake is otherwise left ad libitum indicate that increased FCCS generally increases total energy intake and body weight, while FCCS reduction decreases body weight gain. Clinical trials assessing the effects of SSB reduction as a sole intervention however fail to observe clinically significant weight loss. Many mechanistic studies indicate that excess FCCS can cause potential adverse metabolic effects. Whether this is associated with a long-term risk remains unknown. Scientific evidence that excess FCCS intake causes more deleterious effects to health than excess of other macronutrients is presently lacking. However, the large consumption of FCCS in the population makes it one out of several targets for the treatment and prevention of metabolic diseases

Importance of Carbohydrate Quality: What does it Mean and How to Measure it?

Dietary carbohydrates are our main source of energy. Traditionally, they are classified based on the polymer length between simple and complex carbohydrates, which does not necessarily reflect their impact on health. Simple sugars, such as fructose, glucose and lactose, despite having a similar energy efficiency and caloric content have very distinct metabolic effects, leading to increased risk for various chronic diseases when consumed in excess. In addition, beyond the absolute amount of carbohydrate consumed, recent data point out that the food form or processing level can modulate both the energy efficiency and the cardiometabolic risk associated with specific carbohydrates. In order to account for both of these aspects - the quality of carbohydrates as well as its food form - several metrics can be proposed to help identifying carbohydrate-rich food sources and distinguish between those that would favor the development of chronic diseases, of those that may contribute to prevent these. This review summarizes the findings presented during the American Society of Nutrition Satellite symposium on 'Carbohydrates Quality', where these different aspects were presented