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Sweeping nutritional guidelines were based on insufficient evidence — dietary advice on fats “should never have been introduced,” study says

By Erin Golden

The advice to keep your heart healthy by avoiding meat, eggs and other fats and stocking up on low-fat options was based on faulty science — and has misled the public and health professionals for decades, according to findings of a study published yesterday in Open Heart, an online cardiovascular medical journal.

In a re-examination of the initial research, scientists say the “evidence did not support the introduction of dietary fat guidelines” rolled out in the late 1970s in the US and early 1980s in the UK. Evidence used to develop the guidelines was based on a handful of small studies, all involving only men — and none that proved conclusively that eating fats led to higher rates of heart disease. 

“It seems incomprehensible that dietary advice was introduced for 220 million Americans and 56 million UK citizens, given the contrary results from a small number of unhealthy men,” the researchers wrote.

James J. DiNicolantonio, PharmD, a cardiac research scientist at Saint Luke’s Mid America Heart Institute in Kansas City, MO, and one of the authors of the new study, says most of the studies used to develop the dietary guidelines didn’t consider specific recommendations on eating fats or saturated fats. Regardless, these studies were used to mount a campaign to strip fats from people’s plates.

“Reducing saturated fat and focusing on and demonizing one specific type of fat — there was no evidence for it, and still is not now,” he says. “Most people think saturated fat coming from an animal is harmful, but there’s no evidence for that.”

DiNicolantonio and his colleagues found that the studies that prompted both the government recommendations and a decades long low-fat food trend didn’t follow guidelines usually required for serious scientific research. Typically, scientists rely on randomized control trials, in which they study people who follow one course of action, and another who don’t. These studies did not include randomized comparisons. 

Steven Nissen, MD, chairman of the department of cardiovascular medicine at Cleveland Clinic, says the study echoes several others that have been released in recent years. All have concluded that fat is an important part of a heart-healthy diet.

“They all have the same message: we really got this wrong,” he says. “All the advice that’s been given over many decades to limit saturated fat was not based upon solid scientific evidence and, in many ways, that’s very unfortunate and persists to this day.”

DiNicolantonio and Nissen both say the recommendations on avoiding fat ignored a major culprit behind obesity and a long list of other health problems: added sugars. In the battle against fats, they say, food producers and consumers opted to swap in sugar and other carbohydrates — and the public has ended up in poorer health as a result.

“Americans need to reduce simple sugars and they need to exercise more; that’s the best antidote to obesity,” Nissen says. “These ultra low-fat diets seem to promote diabetes and obesity because people are often hungry after a large carbohydrate-rich meal.”

Animal-based fats, including meat, eggs and dairy, can be a key part of a healthy diet, DiNicolantonio says. He suggests people focus primarily on eating whole foods, rather than trying to zero in on any one type of food for their grocery lists.

“What they should be looking for in the supermarket is something that’s not processed,” he says. “If it’s an undamaged fat, it’s likely going to be beneficial. Avocado, nuts, whole milk — those are whole foods. Don’t worry about those types of natural foods. Worry about things that are processed, and that includes processed meat.”

Nissen suggests people research the Mediterranean diet, which includes a mixture of fats with fish, some meat and produce. 

Both experts say it could take time before people are willing to shake long-held beliefs about fats.

“We got it wrong, and now we’re going to have to do a lot of re-educating,” Nissen says. 

Published February 10, 2015.

Erin Golden is a journalist based in Minnesota.