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; similar to 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.