A review of diet-heart hypothesis going back to the late 1950s has claimed misinformation around the impacts of saturated fats on cardiovascular health.
“Recent findings include shortcomings in the scientific review process on saturated fats,” claims journalist Nina Teicholz, writing in the National Library of Medicine.
An advocate of the consumption of saturated fats from dairy and meat, American journalist Teicholz has argued consistently for a narrative and theory change on the health impacts of saturated fats.
“For decades, following the introduction of the diet-heart hypothesis, many scientists were unaware of the lack of evidence for this theory,” she says.
“However, the rediscovery of rigorous clinical trials testing this hypothesis and the subsequent publication of multiple review papers on these data have provided a new awareness of the fundamental inadequacy of the evidence to support the idea that saturated fats cause heart disease,” Teicholz argues.
Clinical argument against saturated fats
However, clinical advice from many government health authorities worldwide consistently state eating too much saturated fat can raise ‘bad’ low-density lipoprotein cholesterol and increase the risk of heart disease and stroke.
In her article, Teicholz dissects a series of contrasting studies to argue against the ‘known’ heart health impacts of saturated fats.
The hypothesis, first proposed in the 1950s by University of Minnesota physiologist Ancel Keys, was flawed at its core.
“Keys based his idea on a handful of small feeding experiments conducted on humans together with some animal data suggesting that high blood cholesterol caused fatty deposits of the type thought to clog arteries and cause heart attacks,” says Teicholz.
Keys' made an association while travelling through Europe that diets low in saturated fats – such as those consumed in Sardinia, Naples and Spain – were healthier for the heart as populations in those countries suffered lower rates of heart disease.
“Keys postulated that saturated fat and cholesterol caused heart disease – his diet-heart hypothesis – whose claims he asserted in no fewer than 20 papers in 1957 and 1958,” argues Teicholz.
Keys went on to conduct and publish other major research, including the Seven Countries Study, launched in 1957, which is considered the foundation of the diet-heart hypothesis.
Why saturated fat might not be bad for heart health
The study focused on Italy, Greece, Yugoslavia, Finland, the Netherlands, the United States and Japan, but not places like Germany, Switzerland, and France, where people ate a great deal of saturated fat yet experienced rates of heart disease similarly low to the focus countries.
“Keys’ selection of nations has given rise to the critique that he ‘cherry picked’ countries to ‘prove’ his hypothesis,” claims Teicholz.
She also believes and highlights countries worldwide had since recognised the need for more research and data around the impact of saturated fat on heart health.
Studies published since Keys' initial narrative-forming research had been overlooked as the acceptance of the hypothesis had become widespread among consumers at a quick pace, making it difficult to alter.
“Despite these extensive findings disproving a relationship between saturated fats and heart disease, speculation about the diet-heart hypothesis continues. For instance, the AHA journal Circulation published findings of an association between linoleic fatty acid, a prominent component of vegetable oils, and a lower incidence of cardiovascular events and mortality,” says Teicholz.
“However, this finding is based on non-standardised, country-level (ecological) data, which is generally regarded to be among the lowest-quality type of evidence.”
Source: A short history of saturated fat: the making and unmaking of a scientific consensus
Published online: 8 December 2024
DOI: 10.1097/MED.0000000000000791
Author: Nina Teicholz