Barley protein supplementation and oxidative damage

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ObjectiveTo assess the effect of vegetable protein as high protein barley flour, baked into bread, on risk factors for heart disease (i.e. serum lipids and markers of oxidative damage).MethodIn a randomized controlled crossover design, 23 hypercholesterolemic adults (16F, 7M; 57±7y; LDL‐C, 3.90±0.21mmol/L) completed two 4‐week treatments of bread supplementation containing either 30g/d (per 2000 kcal diet) of barley protein (treatment) or dairy protein (calcium caseinate placebo). Outcomes included serum lipids and markers of oxidative damage, measured as serum protein thiols, and MDA and conjugated dienes in the LDL fraction.ResultsAt week 4, supplementation with barley protein did not provide evidence of improved LDL‐C and TC:HDL‐C, expressed as the difference from baseline (‐0.05±0.12 mmol/L, P=0.685 and 0.19±0.15 mmol/L, P=0.216, respectively) compared to control (‐0.02±0.12 mmol/L, P=0.858 and 0.19±0.11 mmol/L, P=0.094, respectively). No effect was seen on serum protein thiols, as an overall marker of oxidative status. In addition, neither MDA nor conjugated dienes in the LDL fraction, as markers of oxidized LDL, were affected differently by barley compared to dairy protein.ConclusionBarley protein appears similar to low fat dairy protein in its effect on blood lipids and markers of oxidative damage.Research Support: NSERC, Loblaw Companies LimitedGrant Funding SourceCanadian Institutes of Health Research