Antioxidative Functions of Natto: Effect on LDL Oxidation and Lipid Metabolism in Cholesterol-Fed Rats

This animal study examined whether natto’s antioxidant components affect cholesterol and the oxidation of LDL — a process implicated in atherosclerosis — in rats fed a high-cholesterol diet.

Natto-derived fractions lowered plasma triglycerides and total cholesterol, inhibited LDL oxidation in the test tube, and reduced lipid peroxidation in the liver and aorta. The authors concluded natto exerts direct antioxidant effects that improve lipid metabolism in this model.

As with the other natto antioxidant work in this library, the findings are preclinical and in rodents. Antioxidant effects in cholesterol-fed rats have a poor track record of predicting human cardiovascular benefit, and the well-designed human nattokinase trial (Hodis 2021) found no effect on atherosclerosis.

We rate the evidence limited. It is exploratory animal research with no demonstrated relevance to human outcomes; it belongs to the large body of preliminary natto studies that randomized human trials have not borne out.