North Americans can stop cutting out butter, cheese and marbled meats in the name of heart health, according to an editorial published Wednesday in the BMJ-affiliated journal Open Heart.
Diets low in saturated fats do not protect against heart disease or increase life expectancy, said lead author Dr. James DiNicolantonio, a clinical pharmacist at Wegmans Pharmacy in Ithaca, N.Y. He pointed out that study after study has failed to show that a low-fat diet reduces the risk of coronary heart disease, stroke or cardiovascular disease.
But recent trials, including a 2013 study, suggest that replacing saturated fats with polyunsaturated fats, in the form of corn and safflower oils, increases rates of coronary heart and cardiovascular diseases, as well as deaths from all causes.
The harms associated with replacing saturated fats with polyunsaturated fats are irrefutable, DiNicolantonio said. "We're talking about actual deaths in humans in clinical trials."
According to DiNicolantonio, this advice is based on misleading data from the 1950s, when pioneering researcher Ancel Keys theorized that saturated fats caused heart disease.
Keys had access to data on fat consumption and heart disease rates from 22 countries, but excluded data from 16 countries that did not fit his hypothesis, DiNicolantonio said.
A subsequent analysis of all 22 countries' data disproved Keys's theory. Nevertheless, the notion that saturated fats cause heart disease has persisted, DiNicolantonio said.
He cautioned that guidelines urging people to replace saturated fats with polyunsaturated fats do more harm than good.
"We need a public health campaign as strong as the one we had in the seventies and eighties demonizing saturated fats, to say that we got it wrong," he said in a related podcast.
In recent decades, the public health message to reduce total fat intake has resulted in increased consumption of carbohydrates, he added.
But data from numerous studies "provide a strong argument that the increase of consumption in refined carbohydrates was the causative dietary factor of the diabetes and obesity epidemic in the USA," DiNicolantonio wrote in the editorial.
Other researchers, including pediatric endocrinologist Robert Lustig, have sounded the alarm about overconsumption of refined carbohydrates, particularly in the form of high-fructose corn syrup.
"It's very hard to avoid this high intake of sugar," DiNicolantonio said, noting that of 600,000 food items sold in the United States, 80 per cent contain hidden sugar – including tomato sauce and burger buns.
But to reduce the risk of heart disease, he said, "I would recommend a low-carbohydrate, low-sugar diet and I would not recommend replacing saturated fats with those two particular oils – corn oil and safflower oil."