Effect of Soy Protein on TC and LDL-cholesterol

Clinical studies have shown a modest LDL-cholesterol lowering effect of soy protein in the magnitude of 3-4%2, 4 for intakes of at least 25 g of soy protein per day*. As this amount approximately covers 50% of the recommended daily protein intake5 it is difficult to achieve within an everyday Western type diet.

*To get the required intake of 25 g of soy protein you need to combine several soybean-based foods (see Table 13):

Table 13: Soy protein content in soybean products
Soybean source Approximate soy protein amount (g/100 g of edible portion)*
Tofu
16
Soy drink
2.9
Soy yoghurt
5
Soy bean sprouts
6.2
Soy sauce
8.7
Soy burger (soy meat alternative)
15.7

Sources: Composition of food dataset INRAN, http://nut.entecra.it/646/tabelle_di_composizione_degli_alimenti.html; McCance and Widdowson’s The Composition of Foods: Seventh Summary Edition: Edition 7; USDA National Nutrient Database for Standard Reference Release and release 27.

Although achieving the suggested soy protein intake (25 g) in the daily diet can be demanding, a regular consumption of soy food products along with those foods containing plant components is able to lower blood cholesterol and can help to maximize total- and LDL-cholesterol reduction.

The components in soy protein responsible for the LDL-cholesterol lowering effect are not fully clear. It is likely that soy isoflavones, a non-nutrient component of soy protein, might be partially responsible for the LDL-cholesterol reduction6, but the evidence is not conclusive4, 7.

Other evidence suggests that the protein per se and specific soy peptides may be responsible for the cholesterol-lowering effect2.

Scientific studies2,4 suggest that, regardless of the source of soy protein, soy protein-containing foods when replacing animal protein foods may contribute to a modest LDL-cholesterol lowering effect.