Effect of soy-based breakfast cereal on blood lipids and oxidized low-density lipoprotein

Consumption of soy protein may reduce the risk of cardiovascular disease bo th through reduction in serum lipids and by the antioxidant properties of p rotein-associated soy isoflavones. However, the effect that processing requ ired for the manufacture of breakfast cereals may have on the lipid lowerin g and antioxidant activities of soy has not been studied. We have therefore assessed the health benefits of soy incorporation into breakfast cereals. Twenty-five hyperlipidemic men and women took soy (providing 36 g/d soy pro tein and 168 mg/d isoflavones) and control breakfast cereals, each for 3 we eks in a randomized crossover study with a a-week washout period between tr eatments, pasting blood samples were obtained pretreatment and at weeks 2 a nd 3 of each treatment. No significant difference was seen in serum lipids between treatments at week 3 apart from a 3.8% +/- 1.5% higher apolipoprote in A-1 level on control versus soy (P = .021). However, oxidized low-densit y lipoprotein (LDL) was reduced on the test compared with the control both as total dienes in LDL and as the ratio of conjugated dienes to cholesterol in the LDL fraction by 9.2% +/- 4.3% (P = .042) and 8.7% +/- 4.2% (P = .05 0), respectively. High isoflavone intakes in soy breakfast cereals may decr ease the risk of cardiovascular disease by reducing oxidized LDL, while hav ing no significant effect on the absolute concentration of LDL cholesterol. Copyright (C) 2000 by W.B. Saunders Company.