Branched chain fatty acids content of natto

Branched chain fatty acids (BCFA) are a component of dairy products and beef. The bacterial origin of BCFA suggests they may be rich in fermented foods. We previously found BCFA was at 1% of total fatty acids in sauerkraut and in freshwater fishes. However, dairy products are still the major food source of BCFA, with about 2% BCFA in milkfat, supporting a per capita consumption of 500mg/d BCFA in the United States. In Asian countries where dairy consumption is low, BCFA intake is unlikely to parallel U.S. levels insofar as foods sources are concerned. Natto is a popular Japanese food. It is fermented with bacillus subtilis , which is among species inherently rich in BCFA because of de novo biosynthesized BCFA. Our objective was to determine the BCFA of widely available, traditionally produced natto. Methods Two natto products from a Japanese manufacturer were purchased in a local Asian grocery. They were fermented and maintained at refrigerated temperature, and otherwise similar in most ways except being seasoned by different sauces. Total fatty methyl esters were prepared via a modified one‐step hydrolysis procedure and quantified with GC‐FID. BCFA were identified with EIMS/MS. Results Natto has 1.6% ± 0.02% BCFA of totally fatty acids, mean of both products. Natto is about 30% calories as fat. Consuming one serving (90 g) of natto would provide 7 g fat and 112 mg of BCFA. The major BCFA in natto are iso ‐14:0 , iso ‐15:0 , anteiso ‐15:0 , iso ‐16:0 , iso ‐17:0 and anteiso ‐17:0, substantially recapitulating the BCFA profile of fluid milk except anteiso ‐17:0 is lower in natto. Regular consumption of natto in Japan could contribute significant BCFA to overall intake, supplementing Japanese consumption of beef and other known BCFA sources. Conclusion Natto may contribute substantially to BCFA consumption where dairy consumption is low. Support or Funding Information Internal funds