The story of saturated fats and their proposed association with coronary heart disease is bewildering. Although it illustrates the great power of public health authorities and the food industry, it tragically exposes the frailty of governmental handling of health issues.
When dietary and lifestyle recommendations don’t rely on solid scientific evidence, the outcome may be disastrous. Further damage may result from the fact that as soon as contradictory evidence becomes available, authorities will tend to sweep it under the carpet. That’s human nature. You will want to defend your position for as long as you can.
Although most public health authorities still stick with their recommendations about saturated fat, recently an important clinical support resource called UpToDate changed their stands regarding the issue.
UpToDate is an evidence-based clinical decision support system authored by physicians to help clinicians make the right decisions at the point of care. It is highly respected and used by medical professionals and universities worldwide. UpToDate is probably the most trusted clinical decision support resource in the world.
Saturated Fats and Coronary Heart Disease
For decades, doctors, dietitians and other medical professionals have recommended that we limit the intake of saturated fats in order to reduce the risk of coronary heart disease.
When it comes to dietary advice, avoiding animal and dairy fats has frequently been top of the list among the experts. Red meat, whole-fat milk, cheese, cream, butter and eggs should be avoided as much as possible.
Slowly but securely this has become ingrained into our way of thinking. Having eggs and bacon for breakfast is associated with a feeling of guilt. We can almost vision the fat plugging our arteries. So strong is the power of education.
Health officials have urged us to avoid saturated fats as much as possible, saying it should be replaced with polyunsaturated fats like that found in nuts, fish, seeds and vegetable oils.
In an article updated September 24, 2014 the recommendations of the American Heart Association are very clear:
Eating foods that contain saturated fats raises the level of cholesterol in your blood. High levels of LDL cholesterol in your blood increase your risk of heart disease and stroke.
Eating foods that contain saturated fats raises the level of cholesterol in your blood. Be aware, too, that many foods high in saturated fats can be high in calories too.
The American Heart Association recommends aiming for a dietary pattern that achieves 5% to 6% of calories from saturated fat. That means, for example, if you need about 2,000 calories a day, no more than 120 of them should come from saturated fats. That’s about 13 grams of saturated fats a day.
One of the main reasons saturated fats have a bad reputation is that they increase LDL-cholesterol, a type of cholesterol associated with risk of heart attacks.
However, the effects of saturated fats on blood lipids are much more complex than that.
For example saturated fats also increase HDL-cholesterol, the so-called good cholesterol. Furthermore, intake of saturated fats appears to increase the size of LDL-particles. In theory, this could help reduce risk.
So the association with blood lipids is hardly reason enough to advise against the intake of saturated fats. Then, what is?
During the last ten years, a substantial amount of evidence has emerged suggesting that the association between saturated fats and coronary heart disease is either very weak or may not exist at all. Nonetheless, public health authorities have stood firmly by their earlier recommendations.
Recently a large meta-analysis of observational studies found no relationship between the intake of saturated fats and coronary artery disease.
Although many experts did criticize this paper, it certainly doesn’t add any support to the conclusion that eating saturated fats is associated with increased risk.
UpToDate’s recent revision indicates their experts have taken these recent data very seriously:
Although it is known that there is a continuous graded relationship between serum cholesterol concentration and coronary heart disease (CHD), and that dietary intake of saturated fats raises total serum cholesterol, a 2014 meta-analysis of prospective observational studies found no association between intake of saturated fat and risk for CHD.
The meta-analysis also found no relationship between monounsaturated fat intake and CHD, but suggested a reduction in CHD with higher intake of omega-3 polyunsaturated fats; a benefit with omega-6 polyunsaturated fats remains uncertain.
Given these results, we no longer suggest avoiding saturated fats per se, although many foods high in saturated fats are less healthy than foods containing lower levels.
In particular, we no longer feel there is substantial evidence for choosing dairy products based on low-fat content (such as choosing skim milk in preference to higher fat milk). We continue to advise reducing intake of trans fatty acids.
The Bottom Line
In 1977 senator George McGovern’s Select Committee on Nutrition and Human Needs published its famous report, “Dietary goals for the United States”, highlighting the importance of limiting the intake of saturated fats.
Following the publication, Doctor D.M. Hegsted, professor of nutrition at Harvard School of Public Health, who assisted in the preparation of the report said:
The question to be asked, therefore, is not why should we change our diet but why not. What are the risks associated with eating less meat, less fat, less saturated fat, less cholesterol, less sugar, less salt and more fruits, vegetables, unsaturated fat and cereal products – especially whole grain cereals? There are none that can be identified, and important benefits can be expected.
In my opinion, these words reflect the unscientific approach of the committee.
Certainly Hegsted had developed the so-called “Hegsted equation” showing that cholesterol and saturated fats raised blood levels of LDL-cholesterol while monounsaturated fats had little effect and polyunsaturated fats appeared to lower the levels.
However, at that time there was no evidence that the effect on LDL-cholesterol was a measure of a heart healthy diet. It was only a hypothesis, yet to be tested.
Today, blaming the rising incidence of coronary heart disease 40-50 years ago on the intake of red meat, whole-fat milk, cheese, cream, butter and eggs appears naive at best.
To condemn one macronutrient and suggest it be replaced with another, without having any scientific evidence that such and intervention is helpful, would today be considered careless and irresponsible.
Sticking with the same conclusion for 40 years, despite abundant contradictory evidence is shocking and hard to understand. Hopefully, UpToDate’s recent reconsideration of the issue is a sign that the tide is turning.
Of course, there’s no reason to promote high consumption of saturated fats and surely there will often be healthier options. However, it’s time we stop telling people that avoiding saturated fats may protect them from heart disease. Why should we say such a thing if it’s not supported by evidence?
It will be interesting to see how public authorities such as the American Heart Association will react to recent scientific evidence on the proposed link between saturated fats and coronary artery disease. Will we see a change in the forthcoming 2015 version of The Dietary Guidelines for Americans?
Will their approach be evidence-based or not? Will they accept that red meat, whole-fat milk, cheese, cream, butter and eggs can be a part of a healthy diet? Will they reconsider their recommendations like UpToDate now has officially done? Only time will tell.
If you want to dig deeper into the story of saturated fats, the guidelines and the science, I can recommend Nina Teicholz’ great book, The Big Fat Surprise: Why Butter, Meat, and Cheese Belong in a Healthy Diet. It’s a good read for everyone interested in the science of nutrition, public health and the politics.