Soy Protein and Reduced LDL Cholesterol

Based on 3 studies, 2 showed beneficial effects of soy protein on reducing LDL cholesterol, with effect sizes ranging from small to moderate. The evidence shows moderate beneficial effects in patients with type 2 diabetic nephropathy at doses of approximately 35% soy protein in the diet, though one study found no effect at 40 g/day over 90 days. The median study duration is 90 days, but only 1 of 3 studies reported duration.

• Effective dose range: 35% of diet as soy protein (approx. 40 g/day)
• Studied populations: patients with type 2 diabetic nephropathy

Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. One of the beneficial studies is a systematic review that included soy protein as part of a diet, not as a standalone supplement, and the other beneficial study compared whey protein (not soy) to control while analyzing soy as part of a larger meta-analysis—so the direct evidence for soy protein alone is limited. The only RCT specifically testing soy protein (40 g/day for 90 days) found no significant effect on LDL cholesterol, which contradicts the beneficial findings from the higher-level analyses.