Butter

Butter is a highly protective saturated fat that Ray Peat considered the safest of all oils to consume, despite containing approximately 3% polyunsaturated fatty acids (PUFA). 2 This small PUFA fraction is partially converted by the cow's rumen bacteria into naturally occurring trans fatty acids, which Peat distinguished sharply from industrially produced trans fats; the natural isomers in butter are chemically different and act as protectors against the toxic effects of polyunsaturated fats. 1 Peat argued that butter's combination of minimal toxic oils and abundant protective factors makes it superior even to olive oil, which he limited to minor flavoring use due to its 8–12% PUFA content. 3

Peat identified butter as a primary anti-stress and anti-inflammatory food, whose main function in context is to calm the excitatory stress systems. 4 Mechanistically, butter turns off the release of adrenaline, ACTH, and cortisol, whereas polyunsaturated fats like corn oil activate these stress mediators and the excitotoxic histamine pathways that can kill brain cells. 6 This calming effect is tied to butter's saturated fat content, particularly stearic acid, which Peat noted is protective against the neurological damage promoted by unsaturated fats. 6 He cited the research of Nanji's group, which demonstrated that saturated fats like butter could cure the liver disease, hepatitis, and cirrhosis caused by the interaction of polyunsaturated fats with alcohol, showing that alcohol is relatively harmless on a diet practically free of unsaturated fat. 2 This protective action applies identically to the arteries, which Peat stated are the first tissues injured by oxidized unsaturated fats, not by the saturated fats in butter. 7

Regarding body composition, Peat held that butter is less fattening than unsaturated oils, with the proportion of saturated to polyunsaturated fats in the diet being more critical than the total fat quantity. 2 He pointed to epidemiological observations, such as the lean, healthy populations in Finland where butterfat consumption is high, contrasting them with populations on starch-based, vegetable-oil-rich diets. 3 While acknowledging that one can gain weight on butter, Peat explained that when balanced with adequate calcium, sodium, and anti-stress proteins like casein and gelatin, butter's anti-stress properties become anti-obesity in effect. 4 He also noted that butter naturally contains vitamin A, vitamin D, and beneficial hormones, and contains significantly less cholesterol per calorie than lean chicken breast. 8

The widespread belief that butter clogs arteries and causes heart disease was, in Peat's view, the result of 50 years of propaganda from the seed oil industry. 7 He explained that when the paint industry shifted to petroleum-based oils, the seed oil industry needed a new market and orchestrated a campaign against tropical and animal fats to sell corn and soy oil to humans. 7 In contrast, animal studies showed that high saturated fat diets greatly extended the lives of animals prone to heart disease, while adding polyunsaturated fats shortened their lives, and that saturated fat diets delayed the development of breast cancer. 6 Peat also noted that the saturation index of tissues consistently showed that people with cancer had much higher concentrations of polyunsaturated fats in their tumors and bodies than healthy individuals. 6