Studies examining the effect of
soy protein on
cardiovascular disease (CVD) risk factors have not taken advantage of the postprandial state as an adjunct to the fasting
lipid profile. The American Heart Association has acknowledged the efficacy of
soy protein in reducing CVD risk factors to be limited. We hypothesized that the postprandial state would be more sensitive to any favorable changes associated with consuming
soy protein compared with the fasting
lipid profile. Furthermore, the presence of
isoflavones in soy would enhance this effect. Thirty sedentary males aged 18-30 years were randomly assigned to
milk protein (Milk),
isoflavone-poor soy (Soy-), or
isoflavone-rich soy (Soy+). Usual diets were supplemented with 25 g/day of
protein for 28 days. Serum samples were collected before and after supplementation in a fasted state and postprandially at 30, 60, 120, 240, and 360 min after a high-fat, 1,000 kcal shake.
Triacylglycerol (TAG), total
cholesterol, non-
esterified fatty acids,
apolipoproteins B-100 and A-I and
glucose concentrations were quantified. Fasting concentrations were not different after any
protein supplementation. Postprandial TAG and TAG AUC increased after Soy-consumption supporting the postprandial state as a more sensitive
indicator of soy ingestion effects on CVD risk factors compared with the fasting
lipid profile. Furthermore, the absence of
isoflavones in
soy protein may have deleterious consequences on purported cardio-protective effects.