Effects of potato resistant starch intake on insulin sensitivity, related metabolic markers and appetite ratings in men and women at risk for type 2 diabetes: a pilot cross-over randomised controlled trial.

BACKGROUND: The intake of certain types of resistant starch (RS) has been associated in some studies with increased whole-body insulin sensitivity. This randomised, cross-over pilot trial evaluated the effect of consuming cooked, then chilled potatoes, a source of RS, compared to isoenergetic, carbohydrate (CHO)-containing control foods, on insulin sensitivity and related markers. METHODS: Nineteen adults with body mass index 27.0-39.9 kg m-2 consumed 300 g day-1 RS-enriched potatoes (approximately two potatoes; ~18 g RS) or CHO-based control foods, as part of lunch, evening and snack meals, over a 24-h period. After an overnight fast, insulin sensitivity, CHO metabolism markers, free fatty acids, breath hydrogen levels and appetite were assessed for up to 5 h after the intake of a standard breakfast. The primary endpoint was insulin sensitivity, assessed with the Matsuda index. P < 0.05 (one-sided) was considered statistically significant. RESULTS: Insulin sensitivity was not significantly different between the potato and control conditions. The potato intervention resulted in higher postprandial breath hydrogen (P = 0.037), lower postprandial free fatty acid concentrations (P = 0.039) and lower fasting plasma glucose (P = 0.043) compared to the control condition. Fullness ratings were significantly lower after potato versus control (P = 0.002). No other significant effects were observed; however, there was a trend toward lower fasting insulin (P = 0.077) in the potato versus the control condition. CONCLUSIONS: The results of this pilot study suggest RS-enriched potatoes may have a favourable impact on carbohydrate metabolism and support the view that additional research in a larger study sample is warranted.

Corn oil intake favorably impacts lipoprotein cholesterol, apolipoprotein and lipoprotein particle levels compared with extra-virgin olive oil.

BACKGROUND: Corn oil (CO) and extra-virgin olive oil (EVOO) are rich sources of unsaturated fatty acids (UFA), but UFA profiles differ among oils, which may affect lipoprotein levels. OBJECTIVES: The objective of this study was to assess the effects of CO versus EVOO intake on fasting lipoprotein and subfraction cholesterol levels, apolipoprotein (apo) A1, apo B, and low-density lipoprotein particle concentrations in men and women. SUBJECTS/METHODS: As part of a weight maintenance diet, men and women were provided with food items prepared with 54 g per day of CO or EVOO (21-day treatment, 21-day washout) in a randomized, double-blind, controlled-feeding, crossover trial. Fasting lipoprotein cholesterol and related variables were determined with density gradient ultracentrifugation. RESULTS: Among the 54 completers, CO reduced total cholesterol, low-density lipoprotein cholesterol (LDL-C), very low-density lipoprotein cholesterol (VLDL-C), non-high-density lipoprotein cholesterol (non-HDL-C), apo B and LDL particle concentration to a greater extent compared with EVOO intake. Changes in LDL-C and VLDL-C contributed to the larger reduction in non-HDL-C with CO compared with EVOO intake (-0.39 mmol/l vs -0.04 mmol/l; P<0.001). The larger reduction in LDL-C by CO intake was attributable to changes (P<0.05) caused by CO vs EVOO in large LDL1+2-C (-0.22 mmol/l) and intermediate-density lipoprotein cholesterol (-0.12 mmol/l). HDL-C responses did not differ between treatments, but apo A1 increased more with EVOO compared with CO intake (4.6 versus 0.7 mg/dl, respectively, P=0.016). CONCLUSIONS: CO intake reduced atherogenic lipoprotein cholesterol and particle concentrations to a larger extent than did EVOO, which may have implications for cardiovascular disease risk.