Fiber and Insulin Resistance

The present study was conducted to determine the association between fibre intake and insulin resistance in 264 women using a cross-sectional design. Insulin resistance was indexed using homeostasis model assessment of insulin resistance (HOMA-IR) (US formula: fasting insulin (μU/ml) × fasting glucose (mg/dl)/405 international formula: fasting glucose (mmol/l) × fasting insulin (μU/l)/22.5). Fibre and energy consumption were assessed using 7 d weighed food records. Fibre was expressed as g/4184 kJ (1000 kcal). Body fat percentage (BF%) was measured using the BOD POD, and physical activity (PA) was ascertained using Actigraph accelerometers (Health One Technology) worn for seven consecutive days. Women with high total fibre intakes (F= 4•58, P= 0•0332) or high soluble fibre intakes (F= 7•97, P= 0•0051) had significantly less insulin resistance than their counterparts. Participants with high insoluble fibre intakes did not differ from their counterparts (F= 0•7, P= 0•6875). Adjusting for either PA or BF% weakened the relationships significantly. Controlling for BF% nullified the total fibre–HOMA-IR link (F= 1•96, P= 0•1631) and attenuated the association between soluble fibre and HOMA-IR by 32 % (F= 6•86, P= 0•0094). To create dichotomous variables, fibre intake and HOMA-IR were each divided into two categories using the median (low and high). In women who had high soluble fibre intake (upper 50 %), the OR of having an elevated HOMA-IR level was 0•58 (95 % CI 0•36, 0•94) times that of women with low soluble fibre intake (lower 50 %). After controlling for all of the potential confounding factors simultaneously, the OR was 0•52 (95 % CI 0•29, 0•93). High fibre intake, particularly soluble fibre, is significantly related to lower levels of insulin resistance in women. Part of this association is a function of differences in PA and BF%.