Resistant starch from high-amylose maize increases insulin sensitivity in overweight and obese men.

This study evaluated the effects of 2 levels of intake of high-amylose maize type 2 resistant starch (HAM-RS2) on insulin sensitivity (S(I)) in participants with waist circumference ≥89 (women) or ≥102 cm (men). Participants received 0 (control starch), 15, or 30 g/d (double-blind) of HAM-RS2 in random order for 4-wk periods separated by 3-wk washouts. Minimal model S(I) was assessed at the end of each period using the insulin-modified i.v. glucose tolerance test. The efficacy evaluable sample included 11 men and 22 women (mean ± SEM) age 49.5 ± 1.6 y, with a BMI of 30.6 ± 0.5 kg/m2 and waist circumference 105.3 ± 1.3 cm. A treatment main effect (P = 0.018) and a treatment × sex interaction (P = 0.033) were present. In men, least squares geometric mean analysis for S(I) did not differ after intake of 15 g/d HAM-RS2 (6.90 × 10⁻5 pmol⁻¹ · L⁻¹ × min⁻¹) and 30 g/d HAM-RS2 (7.13 × 10⁻5 pmol⁻¹ · L⁻¹ × min⁻¹), but both were higher than after the control treatment (4.66 × 10⁻5 pmol⁻¹ · L⁻¹ × min⁻¹) (P < 0.05). In women, there was no difference among the treatments (overall least squares ln-transformed mean ± pooled SEM = 1.80 ± 0.08; geometric mean = 6.05 × 10⁻5 pmol⁻¹ · L⁻¹ × min⁻¹). These results suggest that consumption of 15-30 g/d of HAM-RS2 improves S(I) in men. Additional research is needed to understand the mechanisms that might account for the treatment × sex interaction observed.

Relation between estimates of cornstarch digestibility by the Englyst in vitro method and glycemic response, subjective appetite, and short-term food intake in young men.

BACKGROUND: Starch composition and rate of digestion are determinants of blood glucose concentrations and food intake (FI). OBJECTIVE: Our objective was to describe relations between estimates of digestibility of starches by the in vitro Englyst method and their effect on blood glucose concentrations, subjective appetite, and FI in young men. DESIGN: Subjects consumed 5 soups containing 50 g maltodextrin, whole-grain, high-amylose, regular cornstarch, or no added starch at 1-wk intervals. Ad libitum FI was measured at 30 min (experiment 1) or 120 min (experiment 2) later, which were the estimated times of digestion of a rapidly digestible starch (RDS) and slowly digestible starch, respectively. Blood glucose concentrations and appetite were measured pre- and postmeal. RESULTS: At 30 min, FI was reduced by maltodextrin only [86% RDS, 12% resistant starch (RS); P < 0.05], but at 120 min FI was reduced by whole-grain (24% RDS, 66% RS), high-amylose corn (40% RDS, 48% RS), and regular corn (27% RDS, 39% RS) (P < 0.0001). The premeal blood glucose concentration at 30 and 120 min was highest and lowest after maltodextrin treatment, respectively (P < 0.0001). After the meal, the blood glucose area under the curve at 30 min was lower after all starch treatments (P < 0.05), but at 120 min the blood glucose area under the curve was lower only after the regular cornstarch treatment (P < 0.05). Premeal appetite decreased by all treatments (P < 0.05). CONCLUSION: The in vitro estimates of starch digestibility by the Englyst method predicted the effects of starch composition on blood glucose concentrations and FI in young men 30 and 120 min after consumption. This trial was registered at clinicaltrials.gov as NCT00980941 for experiment 1 and NCT00988689 for experiment 2.

Sterol Oxides in Foodstuffs: A Review.

The toxicological significance of oxidized cholesterol has been well documented in numerous studies. This review focuses on the analysis of dietary sterol oxides in the foodstuffs examined to date with particular emphasis on isolation and characterization techniques. Eight common oxidation products of cholesterol have been identified in certain cholesterol-rich foods subjected to oxidative stress during food processing and/or storage. These products include 25-hydroxycholesterol, α or ß 5,6-epoxycholesterol, α or ß 7-hydroxycholesterol, 7-ketocholesterol, cholesta-3,5-dien-7-one and cholestane-3ß, 5α, 6ß-triol. A limited number of studies on the biological effects of dietary phytosterol oxides indicate these products may also be of nutritional concern. Four common autoxidation products of ß-sitosterol have been identified in edible oils; these include α or ß 7-hydroxysitosterol, 7-ketositosterol and setosta-3,5-dien-7-one. Few quantitative data are available on the sterol oxide content of foods. Moreover, studies without apparent precautions against the artifactual formation of sterol oxides may be flawed. Additional research is necessary to adequately identify and quantify the sterol oxides which most likely exist in certain foods.