Saturated fats have been the antichrist of the American diet for at least 50 years, the stuff you do not want to pass between your lips because they lead to heart disease and a whole host of other health complications. Pretty much every mainline diet and fitness plan makes the same recommendation: minimize - possibly eliminate - saturated fat. Except, just maybe, the 40-year-old study known as the Minnesota Coronary Experiment that helped fuel these beliefs actually proved something entirely different.

What if there is no proof saturated fats harm you? What if it’s the substitutes for saturated fats that are the bad actors?

Back up: what are saturated fats? Mainly animals products. Fatty beef. Butter, cream, cheese. Poultry with skin. Pork. Some vegetable products contain saturated fats - coconut oil is a for instance - but they are rare.

That Minnesota study, conducted from 1968 - 1973, involved some 9,000 people, mainly in a nursing home and mental hospitals. The patient diets were easily controlled and one group was fed foods dripping with saturated fats; another ate a diet with little saturated fat and replaced with lots of corn oil, an ingredient common in processed foods today. The researchers expected to find that that the group that ate little saturated fat was healthier, had lower cholesterol, and also had reduced heart disease. But did the study prove that?

A researcher, Christopher Ramsden at the National Institutes of Health, heard about the Minnesota Coronary research and also that it had never been fully analyzed (nobody knows why). A few years ago he tracked down the original data and, when he sifted through it, he realized it showed something remarkable: in patient groups fed low fat diets, cholesterol (as expected) dropped but mortality rose. The more cholesterol dropped, the more mortality rose.

That was not what anybody expected.

Now a reinterpretation of the full set of Minnesota Coronary Experiment data has been published in the professional journal BMJ. The conclusion is a slap in the face to America’s heart disease establishment: “Available evidence from randomized controlled trials shows that replacement of saturated fat in the diet with linoleic acid [corn oil] effectively lowers serum cholesterol but does not support the hypothesis that this translates to a lower risk of death from coronary heart disease or all causes.”

That is essentially saying the following: eat that burger with cheese because there is no proof - in the vast Minnesota Coronary data - that eating a diet low in saturated fat produces better heart health.

Understand: not everybody is applauding this reinterpretation. Walter Willett, chair of the Nutrition Department at Harvard, sniffed: “This is an interesting historical footnote that has no relevance to current dietary recommendations.”

Willet is one of the nation’s most respected nutritionists. His perspective cannot be ignored.

But is he right? Others are saying not so fast, the BMJ reinterpretation is exactly what they had been waiting to see.

"For years now, we have been recommended to cut out animal fats and replace it with plant sources of fats," said dietician John Rickards in Pennsylvania. "But when you swap out bacon for a bagel in the morning - you essentially cut out fat and replaced it with refined carbs - you run the risk for raising your triglycerides and lowering your HDL cholesterol - increasing your risk for heart disease.”

“Personally, as a dietitian, I recommend that we focus on fat sources from good quality foods like nuts, seeds, avocados and coconut oil if you get some saturated fat in there, but the rest of your diet is in check with veggies, fruits, and whole grains, you're in good shape," Rikards added. 

Michigan chiropractor R. J. Burr threw more fuel on this fire. “Low-fat diets are bad for us," he said. "Fat tastes good, so artificial flavors, sugar, and excess sodium are used in order to make low-fat food palatable. Many key nutrients required for optimal metabolic function are fat-soluble, meaning they need fat in order to be absorbed.”

Burr added: “Fat does not make you fat.”

The reinterpreted Minnesota Coronary data may lead us to reassess the labeling of saturated fats as the dietary devil - but that does not mean we should wallow in the stuff.

Barry Sears, best selling author Enter the Zone, stressed this important point: the reinterpreted research does not claim saturated fats are good for you. It claims instead that eliminating them is not necessarily good for heart health. And that’s a crucial distinction - that is, this is no encouragement to race out to lunch on New Jersey-style ripped hot dogs.

This article is commentary by an independent contributor. At the time of publication, the author held TK positions in the stocks mentioned.