America’s fear of animal fats started in the early 1950s with the work of scientist Ancel Keys. Using epidemiological data from just six countries, he published a paper showing an association between dietary fat intake and heart disease. With that, the diet-heart hypothesis (alleging that dietary fat causes heart disease) was born. There were many problems with the study and it was only powered only to show correlation (not causation). Nevertheless, Keys promoted his hypothesis strongly. Keys had a strong and persuasive personality, and he responded to critics with vigor. Despite many scientists’ disagreements, Keys’ hypothesis persisted. Despite twenty-two countries showing an at-best nebulous link between fat intake and heart disease, Keys’ hypothesis persisted. Despite ample evidence of healthy populations (Inuit, Masai, and Navajo) eating high-fat diets, Keys’ hypothesis persisted.
The American Heart Association (AHA) got its first big infusion of finances in 1948, so it saw a great deal of growth in the 1950s. This coincided with the timing of Keys’ popularization of his fat-fearing hypothesis. Keys was close to leaders in the AHA and the organization adopted this diet-heart hypothesis as a guiding truth. Over time, the hypothesis evolved to include concern about serum cholesterol levels, which are often elevated by saturated fat consumption. By 1961, the AHA recommended polyunsaturated fats (PUFAs) from industrially processed seed oils as part of its otherwise-low-fat “prudent diet” because of their cholesterol-lowering tendencies. Despite evidence that high triglycerides were more indicative of cardiovascular issues than high cholesterol, the AHA promoted the prudent diet. Despite evidence that high HDL cholesterol (raised by saturated fat) was actually protective, the AHA promoted the prudent diet. Despite a 1967 Indian study showing Southern Indians getting heart disease at 7 times the rate of Northern Indians while Northerners ate 8-19 times more fat, the AHA promoted the prudent diet.
The diet-heart hypothesis remained entrenched in the AHA’s recommendations and in the minds of the American public. In 1977, a small government committee led by Senator George McGovern met to investigate the link between diet and heart disease. McGovern’s team issued Dietary Goals for America that were in line with the AHA’s prudent diet. The central diet-heart hypothesis remained unproven, but the well-intentioned report stated that its authors “cannot afford to await the ultimate proof”. Three years later, those goals were built into the Dietary Guidelines for Americans. Similar logic (“What are the risks associated with eating less meat, less fat, less cholesterol?”) was used to dismiss criticism from a nutrition task force prior to issuance. The idea that saturated fat could be replaced by something worse was not considered realistic. The low-fat diet was assumed right (for everybody) until proven wrong. By 1980, this assumption suddenly had the backing of the AHA, the processed food industry, and the American government. Despite a growing chronic disease epidemic, these same groups continue to promote a similar diet today.
On top of going into detail on the history of America’s dietary guidelines, Teicholz covers many interesting topics, including:
- the history of American red meat consumption
- a fascinating comparison of animal-food-eating Masai vs. geographically similar plant-based Akikuyu
- the dangers of PUFA consumption
- cases of the AHA historically supporting and promoting foods now known to be harmful
- trans fats
- hard candy, sugar, syrup
- breakfast cereals getting stamped with AHA "heart-healthy" sticker (for a fee)
- PUFA-laden industrial seed oils (the AHA still recommends these)
- potential impacts of low-fat diets for children
- the misleadingly-defined Mediterranean Diet
- a history of trans fats
- science and history showing the healthfulness of low-carbohydrate, high-fat diets
Readers of The Big Fat Surprise will learn a great deal about the history, the personalities, and the organizations that shaped America’s dietary guidelines. By spending a decade of her life investigating the issue from every angle, Teicholz masterfully shows that the diet-heart hypothesis emperor has no clothes. Her passionate work demonstrates that saturated fat has been wrongly vilified for the last fifty years. Above all, The Big Fat Surprise teaches that an idea can become widely accepted for a diverse set of reasons that does not include truth.