Branched chain fatty acids (BCFA) are major components of the western food supply, constituting 500 mg per day mean intake in Americans mainly from dairy, beef, and other ruminant products, and a major component of the first solid meal of human fetuses. We sought to establish the degree to which fish and fermented foods may contain BCFA, and to investigate anecdotal reports of BCFA-rich vernix caseosa in sea lions. Twenty-seven wild fishes collected from fresh waters in the northeastern United States were analyzed. BCFA was only 1% ± 0.5% (mean ± SD) of total fatty acids, contributing only a small amount of BCFA per serving to the diet. Surprisingly, one serving of these fishes contributes much higher amounts of EPA + DHA than generally appreciated (107 mg to 558 mg). This study also revealed that odd chain fatty acids are associated with fish and that the ratio of high 15:0 to 17:0 is indicative of a fish origin whereas the reverse is known for dairy, suggesting a possible biomarker. Though dairy is much less commonly consumed in Asian than in Western countries, a recent study reported similar BCFA in breast milk collected from Asian and American mothers. Numerous well known fermented Asian foods were acquired and tested to determine if they accumulate BCFA during fermentation. Fermented soy known as nātto and fermented shrimp paste had high BCFA as a percent of fatty acids, 1.71±0.17% and 3.18 ± 0.14% BCFA, respectively. The major BCFA in nātto 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. Consuming one typical serving (90 g) of nātto provides 117 mg of BCFA while the shrimp paste, used more as a flavoring agent, had 8.8 mg BCFA per serving (16g). Nātto and shrimp paste are the first fermented foods identified with BCFA approaching or exceeding that of milkfat (2.0% BCFA). Vernix caseosa, rich in BCFA, is the richest BCFA source known to be a nutritional source for humans, but is unknown in any other species. Analysis of GI tract contents of newborn California sea lions (CSL) show high levels of BCFA and squalene. CSL are thus the second species apart from humans now known to biosynthesize vernix in late gestation, delivering BCFA and squalene to the fetal GI tract. These data are further evidence for the importance of BCFA as likely modifiers of microbiota and GI metabolism.