Wellness & Education

Low-fat Heart Health Diets Challenged

What if heart healthy eating isn’t what we think it is? What if we can eat whole fat cheeses and yogurt, moderate amounts of unprocessed red meat and other foods high in saturated fat without putting our heart health at risk? If this sounds too good to be true, it could be because it is. Then again, it could simply be that the link between saturated fats and heart health is not as strong as we think. So, which is it?

The conversation needed to settle this question has just gotten started. However, cheese and meat lovers will be happy to hear that it is taking place.

Research Has Yielded Conflicting Results

In the 1950’s, physiologist Ancel Keys first declared that eating foods high in saturated fats caused heart disease. Keys based his belief the Seven Countries Study, which began in 1957. Since then, many studies have been done, involving hundreds of thousands of people. Unfortunately, scientific evidence seems to point in both directions. Some studies seem to confirm the saturated fats/heart disease link. Other studies show that this link doesn’t always apply. The reason for conflicting results isn’t clear. It is clear, however, that the effect of diet on heart disease is not as simple as Ancel Keys believed.

Saturated Fats Don’t Act Alone

Foods are complex, particularly when found in nature (as opposed to being created in a lab). In the 1950’s, this complexity was not fully appreciated. Scientists believed (and some still do) that saturated fats had the same effect on the body regardless of what food contained them. Saturated fat in whole milk yogurt equaled saturated fat in bologna equaled saturated fat in a candy bar.

In reality saturated fats don’t act alone. The way that saturated fat is digested and used can change depending on other nutrients and chemicals that are found alongside it. For this reason, many researchers now believe that saturated fat found in aged cheese, for example, may not have the same effect as saturated fat found in a hot dog. Nutrient and chemical interactions could partially explain the conflicting results among studies.

Gut Microbia Alter the Effect of Foods, and Vice Versa

Research into the field of gut microorganisms didn’t really get started until the late 1990’s. The many, complex, feedback loops that exist among food, gut Microbia and health are only beginning to be understood today. This may be another cause for disagreement.

Researchers have found that some gut bacteria are more or less likely to be present in patients with certain diseases, such as diabetes, that affect the risk of heart disease. It could be that some bacteria help cause diabetes and others help prevent it. It’s also possible that diabetes itself changes the balance of bacterial types found in the gut. In any case, what we eat can affect the bacteria in our gut. The bacteria in our gut also interact in some way with different disease states.

Recent research shows that not all foods with saturated fats have the same effect on our gut bacteria. Fermented whole fat dairy, in particular, seems to help reduce the risk of heart disease, possibly as the result of its effect on our gut microbia. Effects of Full-Fat and Fermented Dairy Products on Cardiometabolic Disease: Food Is More Than the Sum of Its Parts – ScienceDirect

The P.U.R.E. Study

The PURE study is a decades long study that began in 2002 and is expected to complete its first phase in 2030. The study looks at certain disease states and the behaviors that affect them, including diet, in upper, lower and middle income countries.

The study has collected diet and disease data from over 244,597 participants in 80 countries. Using this data, researchers have identified the “PURE Diet”, which is associated with lower numbers of heart disease and premature death. This diet is significantly less strict than traditionally accepted “heart-friendly” diets. Diet, cardiovascular disease, and mortality in 80 countries | European Heart Journal | Oxford Academic (oup.com)

Specific guidelines of the PURE diet are as follows:

  • 2 to 3 servings of fruit per day
  • 2 to 3 servings of vegetables per day
  • 3 to 4 servings of beans and legumes per week
  • 7 servings of nuts per week
  • 2 to 3 servings of fish per week
  • 14 servings of mainly whole-fat dairy per week, excluding butter and whipping cream.

Note: Whole grains and unprocessed red meat are not either recommended or rejected. They are given a take it or leave it” status since they didn’t seem to be either harmful or beneficial.


Support for the PURE diet isn’t universal. Dietary Guidelines from both the American Heart Association and the US government are still strictly low-fat. However, the PURE study has shown that, at the very least, the conversation about heart healthy diets is a hotter topic now than it has been for decades.