Differential effects of whole and refined grains on abdominal adipose tissue depots in an exploratory subgroup analysis of the GRAIN Study

Abstract

Abdominal obesity is associated with insulin resistance, specifically having a higher amount of adipose tissue (AT) in visceral (VAT) rather than abdominal subcutaneous (ASAT) depots. We explored the relationship between ASAT, VAT and metabolic and anthropometric variables in a subgroup (n =28/50) of participants from a 12‐week, randomized, parallel arm, weight‐loss study in overweight/obese individuals comparing whole (WG) and refined grains (RG). Abdominal MRI was performed at 0 and 12 weeks. Axial scans at lumbar vertebrae L4–5 to L3 were manually traced to separate the AT depots. Baseline ASAT correlated with BMI, waist circumference, total and central AT (from DXA), C‐reactive protein, interleukin 6, and leptin (Rs>;0.55, P<0.05); VAT correlated with central AT, insulin and HOMA‐IR (Rs>;0.35, P<0.05). VAT % change correlated inversely with alkylresorcinol % change, a biomarker of whole grain intake (L3 only, R=−0.51, P<0.01). While the between group changes in ASAT and VAT were not significant, VAT decreased significantly from baseline in only the WG group (RG: −14 ± 20 g, P=0.08; WG: −18 ± 20 g, P=0.001). These findings suggest that VAT and insulin are strongly associated, whereas ASAT is more highly correlated with body fatness and inflammatory markers. Consumption of WG in the place of RG during weight loss may elicit a greater reduction in VAT, but more research is warranted.Grant Funding Source: General Mills Bell Institute of Health and Nutrition