An elevation of triglycerides reflecting decreased triglyceride clearance may not be pathogenic – relevance to high-carbohydrate diets

Investigating the Effectiveness of Very Low-Calorie Diets and Low-Fat Vegan Diets on Weight and Glycemic Markers in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis

Caloric restriction and vegan diets have demonstrated protective effects for diabetes, however their role in improving clinically relevant outcomes has not been summarized. Our aim was to evaluate the evidence for low-calorie diets (VLCD) and vegan diets on weight and glycemic control in the management of patients with Type 2 Diabetes. Database searches were conducted using Cochrane Library, MEDLINE (Ovid) and Embase. Systematic Review Registration: CRD42022310299. Methodological quality of studies was assessed using Cochrane RoB Tool for RCTs, Cochrane ROBINS-I RoB Tool for non-RCTs and NIH Quality Assessment tool for other studies. Sixteen studies with a total of 834 individuals were included and assessed to have a moderate to high risk of bias. Statistically significant changes in weight, BMI, and HbA1c were not observed in vegan diet cohorts. However, LDL cholesterol was significantly decreased by vegan diet. VLCDs significantly improved glycaemic control, with reductions in fasting glucose, pooled mean difference (MD) -1.51 mmol/L (95% CI -2.89, -0.13; p = 0.03; 2 studies) and HbA1c, pooled MD -0.66% (95% CI -1.28, -0.03; p = 0.04; 3 studies) compared to non-dietary therapy. Both diets suggested a trend towards improved weight loss and anthropometric markers vs. control. VLCD diet intervention is associated with improvement in glycaemia control in patients with Type 2 Diabetes.

Manipulation of starch bioaccessibility in wheat endosperm to regulate starch digestion, postprandial glycemia, insulinemia, and gut hormone responses: a randomized controlled trial in healthy ileostomy participants

BACKGROUND

Cereal crops, particularly wheat, are a major dietary source of starch, and the bioaccessibility of starch has implications for postprandial glycemia. The structure and properties of plant foods have been identified as critical factors in influencing nutrient bioaccessibility; however, the physical and biochemical disassembly of cereal food during digestion has not been widely studied.

OBJECTIVES

The aims of this study were to compare the effects of 2 porridge meals prepared from wheat endosperm with different degrees of starch bioaccessibility on postprandial metabolism (e.g., glycemia) and to gain insight into the structural and biochemical breakdown of the test meals during gastroileal transit.

DESIGN

A randomized crossover trial in 9 healthy ileostomy participants was designed to compare the effects of 55 g starch, provided as coarse (2-mm particles) or smooth (<0.2-mm particles) wheat porridge, on postprandial changes in blood glucose, insulin, C-peptide, lipids, and gut hormones and on the resistant starch (RS) content of ileal effluent. Undigested food in the ileal output was examined microscopically to identify cell walls and encapsulated starch.

RESULTS

Blood glucose, insulin, C-peptide, and glucose-dependent insulinotropic polypeptide concentrations were significantly lower (i.e., 33%, 43%, 40%, and 50% lower 120-min incremental AUC, respectively) after consumption of the coarse porridge than after the smooth porridge (P < 0.01). In vitro, starch digestion was slower in the coarse porridge than in the smooth porridge (33% less starch digested at 90 min, P < 0.05, paired t test). In vivo, the structural integrity of coarse particles (∼2 mm) of wheat endosperm was retained during gastroileal transit. Microscopic examination revealed a progressive loss of starch from the periphery toward the particle core. The structure of the test meal had no effect on the amount or pattern of RS output.

CONCLUSION

The structural integrity of wheat endosperm is largely retained during gastroileal digestion and has a primary role in influencing the rate of starch amylolysis and, consequently, postprandial metabolism. This trial was registered at isrctn.org as ISRCTN40517475.

A combination of glucosyl hesperidin and caffeine exhibits an anti-obesity effect by inhibition of hepatic lipogenesis in mice

To develop an anti-obesity agent, we examined the combination effect of glucosyl hesperidin (G-hesperidin) and caffeine on obesity in mice. High-fat diet-induced obese KK mice were fed a low-fat diet with or without G-hesperidin, caffeine, or their combination for 2 weeks. Decreases in body weight and significantly lower adipose tissue weight were observed in the combination-fed mice but not in the G-hesperidin-fed or caffeine-fed mice. DNA microarray analysis of mouse liver suggested that the feeding of G-hesperidin + caffeine was associated with lower lipogenesis. Therefore, we examined the anti-lipogenic effect of G-hesperidin + caffeine in fasted-refed KK mice. Hepatic triglyceride levels were significantly lower in the mice fed G-hesperidin + caffeine during the refeeding period but not in the mice fed each alone. In addition, hepatic expressions of genes related to lipogenesis, such as sterol regulatory element-binding protein-1c or fatty acid synthase, were significantly lower in the mice fed G-hesperidin + caffeine compared with that in the control mice. These results suggested that G-hesperidin + caffeine is effective for controlling obesity partly by the inhibition of hepatic lipogenesis.

Lipid profile, apolipoprotein A-I and oxidative stress in professional footballers, sedentary individuals, and their relatives

OBJECTIVE

To evaluate whether lipid profile (LP), apolipoprotein A-1 (apo A-I) and malondialdehyde (MDA) have any relationship with physical exercise by comparing the groups of footballers (FG) with sedentary individuals (CG) and their relatives (RFG and RCG).

SUBJECTS AND METHODS

Twenty individuals from FG and CG, 60 from RFG, and 57 from RCG were studied.

RESULTS

FG showed lower levels of total cholesterol (119.5 ± 37.9 mg/dL), LDL-cholesterol fraction (53.6 ± 30.3), apo A-I (116.7 ± 11.9), and higher level of HDL-cholesterol fraction (HDLc) (49.7 ± 8.5) compared to RFG (148.3 ± 36.9, P = 0.02; 82.4 ± 37.7, P < 0.01; 124.6 ± 10.2, P = 0.03; and 42.7 ± 7.7, P < 0.01; respectively). Moreover, FG had reduced levels of MDA (101.0 ± 77.0 ng/mL) compared to CG (290.0 ± 341.0, P = 0.03) and RFG (209.9 ± 197.5, P = 0.04).

CONCLUSIONS

These results suggest an association between physical exercise and lower levels of MDA in FG. Physical activity seems to promote beneficial effects on the LP regardless of the genetic influence considering HDLc levels.

Combined effects of saturated fat and cholesterol intakes on serum lipids: Tehran Lipid and Glucose Study

OBJECTIVE

This study investigated the combined effect of saturated fat and cholesterol intake on serum lipids among Tehranian adults.

METHODS

In 443 subjects >or=18 y, dietary intake was assessed. Height and weight were measured and body mass index was calculated. Serum cholesterol, triacylglycerol, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol levels were calculated. Cholesterol intakes >or=300 mg/d and saturated fat intakes >or=7% of total energy were defined as high intakes. Individuals were categorized into four groups based on cholesterol and saturated fat intakes.

RESULTS

Subjects' mean age was 40.1 +/- 14.6 y; those in whom cholesterol and saturated fat intake was normal had significantly less energy and fat intake than those with high cholesterol and saturated fat intakes (P < 0.01). Saturated fat intake had a significant effect on serum total and HDL-C levels. Subjects with a normal saturated fat intake had significantly less serum total and HDL-C than those who had high saturated fat intake (P < 0.01 and P < 0.05, respectively). Adjusting for age, sex, and body mass index, the main effect of cholesterol intake on HDL-C was significant (P = 0.05). Mean serum HDL-C was lower in subjects who had normal cholesterol intake than in those with high cholesterol intake.

CONCLUSION

These results show that cholesterol and saturated fat intakes have no combined effect on serum low-density lipoprotein cholesterol level, whereas cholesterol intake per se affects serum HDL-C level.

A combination of caffeine, arginine, soy isoflavones, and L-carnitine enhances both lipolysis and fatty acid oxidation in 3T3-L1 and HepG2 cells in vitro and in KK mice in vivo

To develop an anti-obesity agent containing dietary components, we focused on the mechanisms that enhance both lipolysis and fatty acid oxidation. Caffeine and arginine (CA), a nonselective adenosine-receptor antagonist and an inducer of lipolytic hormone, respectively, were used to stimulate lipolysis. Soy isoflavones and L-carnitine (SL), stimulators of carnitine palmitoyl transferase 1A and a cofactor for beta-oxidation of fatty acids, respectively, were used to enhance fatty acid oxidation. Effects of a combination of CA and SL (CASL) on lipid metabolism were studied in vitro and in vivo. During 3T3-L1 differentiation, lipid accumulation was significantly lower in cells treated with CASL (50 micromol/L, 1 mmol/L, 1 micromol/L, and 1 mmol/L, respectively) compared with each alone. Lipolysis was also significantly greater in 3T3-L1 adipocytes treated with CASL (50 micromol/L, 1 mmol/L, 10 micromol/L and 0.5 mmol/L, respectively) compared with each alone. In addition, treatment with higher concentrations of CASL (2 mmol/L, 1 mmol/L, 10 micromol/L, and 1 mmol/L, respectively) significantly enhanced beta-oxidation in HepG2 cells. The effects of CASL-containing diets (250 mg, 6 g, 200 mg, and 1.5 g/kg diet, respectively) were studied in vivo. When KK mice were food deprived for 48 h and subsequently refed a fat-free diet for 72 h, hepatic triglyceride (TG) accumulation was significantly lower in mice fed CASL compared with the control mice. In addition, after obese KK mice were fed a low-fat diet for 2 wk, adipose tissue weights were significantly lower in those fed CASL, but not CA or SL alone, compared with the control mice. Plasma and liver TG levels were also lower in mice fed CASL than in the control mice. These results suggest that CASL is effective for controlling obesity.

Very low-carbohydrate versus isocaloric high-carbohydrate diet in dietary obese rats

OBJECTIVE

The effects of a very low-carbohydrate (VLC), high-fat (HF) dietary regimen on metabolic syndrome were compared with those of an isocaloric high-carbohydrate (HC), low-fat (LF) regimen in dietary obese rats.

RESEARCH METHODS AND PROCEDURES

Male Sprague-Dawley rats, made obese by 8 weeks ad libitum consumption of an HF diet, developed features of the metabolic syndrome vs. lean control (C) rats, including greater visceral, subcutaneous, and hepatic fat masses, elevated plasma cholesterol levels, impaired glucose tolerance, and fasting and post-load insulin resistance. Half of the obese rats (VLC) were then fed a popular VLC-HF diet (Weeks 9 and 10 at 5% and Weeks 11 to 14 at 15% carbohydrate), and one-half (HC) were pair-fed an HC-LF diet (Weeks 9 to 14 at 60% carbohydrate).

RESULTS

Energy intakes of pair-fed VLC and HC rats were less than C rats throughout Weeks 9 to 14. Compared with HC rats, VLC rats exhibited impaired insulin and glycemic responses to an intraperitoneal glucose load at Week 10 and lower plasma triacylglycerol levels but retarded loss of hepatic, retroperitoneal, and total body fat at Week 14. VLC, HC, and C rats no longer differed in body weight, plasma cholesterol, glucose tolerance, or fasting insulin resistance at Week 14. Progressive decreases in fasting insulin resistance in obese groups paralleled concomitant reductions in hepatic, retroperitoneal, and total body fat.

DISCUSSION

When energy intake was matched, the VLC-HF diet provided no advantage in weight loss or in improving those components of the metabolic syndrome induced by dietary obesity and may delay loss of hepatic and visceral fat as compared with an HC-LF diet.

Combination diet and exercise interventions for the treatment of dyslipidemia: an effective preliminary strategy to lower cholesterol levels?

At present, dyslipidemia is most commonly treated with drug therapy. However, because safety concerns regarding the use of pharmaceutical agents have arisen, a need for alternative nonpharmacological therapies has become increasingly apparent. The National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III) recommends lifestyle therapies, which include a combination of diet and exercise modifications, in place of drug treatment for patients who fall into an intermediate range of coronary heart disease (CHD) risk. This review examined the cholesterol lowering efficacy of the following 2 NCEP-recommended combination therapies: 1) low saturated fat diets combined with exercise, and 2) nutritional supplementation, i.e., fish oil, oat bran, or plant sterol supplementation, combined with exercise, in the treatment of dyslipidemia. Combination therapies are particularly advantageous because diet and exercise elicit complementary effects on lipid profiles. More specifically, diet therapies, with some exceptions, lower total (TC) and LDL cholesterol (LDL-C) concentrations, whereas exercise interventions increase HDL cholesterol (HDL-C) while decreasing triglyceride (TG) levels. With respect to specific interventions, low saturated fat diets combined with exercise lowered TC, LDL-C, and TG concentrations by 7-18, 7-15, and 4-18%, respectively, while increasing HDL-C levels by 5-14%. Alternatively, nutritional supplements combined with exercise, decreased TC, LDL-C, and TG concentrations by 8-26, 8-30, and 12-39%, respectively, while increasing HDL-C levels by 2-8%. These findings suggest that combination lifestyle therapies are an efficacious, preliminary means of improving cholesterol levels in those diagnosed with dyslipidemia, and should be implemented in place of drug therapy when cholesterol levels fall just above the normal range.