Effects of Canola and Vegetable Oil Blends on Reactive Hyperemia Index (RHI) in Adults at Risk for Metabolic Syndrome (MetS)

We evaluated the effects of 5 dietary oils on RHI: corn/safflower oil (69.3% LA, 17.6% MUFA), canola oil (62.8% MUFA, 29.3% PUFA: 19.5% LA, 10% ALA), high‐oleic canola oil (72% MUFA, 17% PUFA: 15% LA, 2% ALA), high‐oleic canola oil with DHA (63.8% MUFA, 13% LA, 6% DHA), and flax/safflower oil (69.4% PUFA: 37.5% LA, 32% ALA, 17.9% MUFA). We conducted a multi‐center, randomized, 5‐period crossover, controlled feeding study. RHI was measured after isocaloric, heart‐healthy diets containing one of 5 oils for 4 weeks, followed by >2 week break. In adults at risk of MetS, there was no significant treatment effect for RHI, an index of endothelial function. There was a treatment x period interaction (p=0.03). Because of known menstrual changes in RHI, we made an a priori decision to separately analyze effects excluding premenopausal women. In this subsample (n = 85), there was a significant treatment effect (P=0.048). RHI on the corn/safflower diet was significantly greater than on the flax/safflower diet (mean RHI=2.2±0.1 vs. 1.9 ±0.1 P=0.038). No other differences were significant.