(RxWiki News) Saturated fat — bad. Unsaturated fat — good. End of story. That's what medical and nutritional experts have claimed for over five decades. But is it really the case?
A recent commentary by a heart research scientist calls into question whether the evidence supports the idea that saturated fat is worse for us.
Saturated fats are found in greater amounts in foods such as cream, cheese, butter, fatty meats, chocolate and certain oils.
Unsaturated fats are found in greater amounts in vegetable oils, nuts, margarine and certain dressings.
"Discuss the fat in your diet with your family doctor."
This commentary, written by James DiNicolantonio, PharmD, Cardiovascular Research Scientist at Saint Luke's Mid America Heart Institute, reviewed the research leading up to the present on this issue.
He points out that common wisdom among doctors and dietitians has been that saturated fats present a greater risk for heart disease than unsaturated fats.
Current dietary recommendations suggest replacing calories from saturated fat with calories from carbohydrates and omega-6 polyunsaturated fats, found in poultry, eggs, nuts, cereals and many vegetable oils.
However, Dr. DiNicolantonio states that these current recommendations are not supported by the most recent research into nutrition.
Instead, he writes that these recommendations, created in 1977, were based on research done in the 1950s that did not analyze all of the available data at the time.
The idea was that consuming saturated fats increased a person's cholesterol and therefore increases a person's risk of heart disease, but neither of those two associations have been confirmed by later research.
Dr. DiNicolantonio argued that the increase in obesity and type 2 diabetes in the past several decades has actually occurred because people are consuming more carbohydrates.
In describing how the body may respond to fats and carbohydrates, Dr. DiNicolantonio pointed out how little is actually known about replacing fats with carbohydrates, something that could actually worsen a person's lipids number.
"The public fear that saturated fat raises cholesterol is completely unfounded as the low-density lipoprotein particle size distribution is worsened when fat is replaced with carbohydrate," he wrote.
In fact, he noted that several randomized trials have shown a low-carbohydrate diet to reduce weight and improve a person's lipids more than a low-fat diet did.
Dr. DiNicolantonio also noted that research has shown an increased risk of death among those who replace saturated fats with unsaturated fats if a person consumes too many omega-6 fats and not enough omega-3 fats.
Omega-3 fats are found primarily in fish, with a small amount in eggs, broccoli and some fruits.
Overall, the evidence for low-fat diets reducing heart disease risk or cancer risk is weak, he stated.
Dr. DiNicolantonio therefore called for the medical and nutritional community to look at all the evidence related to fat, carbohydrates, diet, heart disease risk and cancer risk and to reconsider official recommendations.
Deborah Gordon, MD, a dailyRx expert who specializes in nutrition said that Dr. DiNicolantonio "mounts a compelling summary of what should be a convincing indictment of conventional nutritional advice, with some impressive and precise details."
She said clinical research insights can be reasonably expected to be at odds with clinical practice standards up until the research becomes more widely known and accepted.
"Misguidedly, physicians have steered patients away from saturated fats to reduce metabolic morbidity, but studies repeatedly confirm that many metabolic markers deteriorate when that advice is followed," Dr. Gordon said.
"The triple whammy plays out when we consider what has replaced saturated fat in our diet over the last few decades: carbohydrates and poly-unsaturated fats," she said. "Abundant carbohydrates cause metabolic derangement of the sort we observe nationwide, such as the new Gallup Poll showing adult obesity has increased yet again."
Dr. Gordon said the view of fats in the medical and nutritional community has become too simplistic.
"On a simple level of efficiency, I have found in my practice that for the vast majority of patients with metabolic problems, particularly those with a long history of dieting or simple overweight, the intervention is relatively simple," she said.
"It doesn't take long to tell someone to eliminate sources of concentrated carbohydrates (sugars, sweetened liquids, and grains) and omega-6 vegetable oils and simultaneously liberate them to enjoy sources of healthy protein and fat - which now include butter, red meat, and eggs," she said.
The commentary was published March 5 in the journal Open Heart. The piece did not require funding, and Dr. DiNicolantonio declared no conflicts of interest.