Branched chain fatty acids (BCFA) are bioactive food components that constitute about 2% of fatty acids in cow’s milk fat. Little systematic information on the BCFA content of other foods is available to estimate dietary intakes. We report BCFA distribution and content of fresh and processed foods representing the major foods of Americans and estimate BCFA intake. BCFA are primarily components of dairy and ruminant foods, and were absent from chicken, pork, and salmon. Dairy and beef delivered most of the 500 mg per day mean intake; in comparison, intake of the widely studied long chain polyunsaturates eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is estimated to average 100 mg per day. Common adjustments in diet can double BCFA daily intake. The fermented foods sauerkraut and miso had appreciable fractions of BCFA but overall are low fat foods providing very small amounts in the diet, and other fermented foods did not contain BCFA as might have been expected from microbial exposure. These data support the quantitative importance of BCFA delivered primarily from dairy and beef and highlight the need for research into their health effects.

Branched chain fatty acids (BCFA) are primarily saturated fatty acids (FA) with a methyl branch, usually near the terminal methyl group. BCFA are abundant in bacteria, skin, and vernix caseosa but have seldom been studied with respect to human nutrition. They are constituents of the term newborn infant gut lumen, being swallowed as vernix particulate components of amniotic fluid in the last trimester of normal pregnancy. We recently showed that BCFA protect against Necrotizing Enterocolitis (NEC) in the rat pup model. Dietary BCFA at levels similar to those found in human vernix reduced NEC incidence by more than 50%, increased the abundance of BCFA-containing bacteria, and increased the expression of ileal anti-inflammatory IL-10. The few published reports of BCFA in human milk enable an estimate that breast fed infants consume 19 mg BCFA per 100ml milk. Dietary BCFA consumption from milkfat and other ruminant products, the main sources of dietary BCFA, is more than 400 mg BCFA per day in adult Americans. This estimate exceeds by several fold the average dietary intake of bioactive FA, such as docosahexaenoic acid. BCFA are bioactive, abundant but neglected components of the human food supply.

IntroductionBranched chain fatty acids (BCFA) are a class of primarily saturated fatty acids (FA) with a methyl branch on the carbon chain. We recently showed that BCFA are constituents of the term newborn infant's gut, and feeding neonatal rats with a rat formula with BCFA of the type found in US food altered gut microbiota and reduced the incidence of Necrotizing Enterocolitis. Thus, BCFA may have beneficial effects on proper gut development and function.Our aim was to analyze the levels and distribution of BCFA in common foods consumed in the US, and to estimate the amount of BCFA intake from these foods. Because BCFA have been reported in cow's milk and are a major component of bacterial membranes, we were specifically interested in BCFA from dairy‐based and fermented foods.MethodsFood samples were purchased from local stores. FA analysis was carried out using routine methods.ResultsBCFA concentration in ruminant foods ranged from 1.4–2.7%w/w. Intake of BCFA per capita/d from foods was about 400mg/d. If Americans consumed the recommended amount of servings from the dairy food group, daily BCFA intake would increase.ConclusionsThis is the first report of BCFA concentrations in American foods. The consumption of BCFA per capita per day is higher than the consumption of bioactive n‐3 FA. The prominence of BCFA in the US food supply and their bioactivity strongly suggest that BCFA health effects should be studied.