Antioxidative Effect of Crude Antioxidant Preparation From Soybean Fermented by Bacillus natto

This early food-science study examined whether fermented soybean (natto) contains antioxidant compounds, testing a crude extract in the laboratory.

The extract showed antioxidative activity comparable to or greater than alpha-tocopherol (vitamin E) in preventing lipid oxidation and protecting cells in assay conditions. The authors suggested natto might confer antioxidant health benefits akin to established antioxidants.

This is purely in vitro chemistry. Antioxidant activity in a test tube has, across decades of nutrition research, repeatedly failed to translate into cardiovascular benefit in people — the broad disappointment of antioxidant supplement trials is a cautionary backdrop. The study tells us nothing about whether eating natto protects arteries.

We rate the evidence limited. It is a basic laboratory observation of historical interest in the natto literature, with no demonstrated relevance to human cardiovascular outcomes.