The American Heart Association (AHA) recently issued a “Presidential Advisory” which linked saturated fat with heart disease, and encouraged the increased use of vegetable seed oils. The lead author said, “…coconut oil is a fad right now — but it is actually a saturated fat, which raises your LDL.” He continues, “But the AHA has always taken the stance that saturated fat is bad and that we should be eating more plant oils, and this view is endorsed by the vast majority of nutritionists who are scientifically qualified (Hughes, 2017)”
The abstract of the advisory states: “In summary: randomized controlled trials that lowered intake of dietary saturated fat and replaced it with polyunsaturated vegetable oil reduced CVD by ≈30%” (American Heart Association, 2017).
For another 20 pages, the AHA makes a vicious assault on saturated fat, the main components of coconut oil and butter. Their basic recommendations? Eat more vegetable oil.
There aren’t many studies comparing vegetable oil intake to butter or coconut oil, but it’s fairly easy to do a diet survey and tracking the disease risks of the participants over time. This technique obviously has some flaws, since a lot of other factors contribute to disease. In this AHA study, instead of looking at all the studies comparing saturated to unsaturated fat, the AHA selected only four studies, some of which have serious confounding factors that the studies did not take into account. Here are a few:
The LA Veterans Hospital Study (Dayton, et.al. 1969)
This study compared two groups of 846 older veterans. The men were divided into two groups, and given meals at the VA Center in Los Angeles. The experimental group was given extra polyunsaturated oils, including soybean oil. The soybean oil group had fewer heart attacks and sudden deaths, but the results were not statistically significant. Some other factors might have skewed the results:
- The experimental group had fewer heavy cigarette smokers.
- The experimental group was consuming much more vitamin E (due to soybean oil).
- The experimental group had a SLIGHT decrease in mortality.
- The authors of the study attributed the fewer deaths to the increased vitamin E (α-tocopherol) in the diet of those in the treatment group.
- What about trans-fats???
In the 1960’s, trans-fats were not known to be harmful. The amount of trans-fat (from margarine) was not taken into account, but were likely higher in the control group. The Sidney Heart Study was excluded on the basis that trans fats skewed the results, so why didn’t they exclude this study as well? Perhaps it didn’t produce the results that the AHA was looking for? The AHA concludes that the decreased mortality is a result of polyunsaturated fats, although the authors of the study attributed it to the much higher vitamin E content, which would have protected from the harmful effects of cigarette smoking, which already was lower in the experimental group!
The Oslo Diet-Heart Study (Circulation, 1970)
In this study, 412 men who previously had a heart attack were assigned to either continue their normal diet with no restrictions and no guidance, or to be assigned to a cholesterol lowering diet, which included the following:
- Soybean oil was provided for free (which is high in vitamin E)
- Sardines canned in cod liver oil were provided for free (high in Vitamin A and calcium).
- Fish and shellfish were recommended.
- Meat was to be eaten lean (visible fat removed).
- Encouraged brown bread (wheat and rye).
- Pure sugar was restricted.
- Encouraged the increased consumption of fruits, vegetables, nuts, beans, and peas.
- Margarine use was restricted.
- Only one egg yolk per week.
A multivitamin was provided to both groups (Laatikainen, 2011)
Notes: The conclusion of the AHA: “The low saturated, high polyunsaturated fat group continued to experience reduced cardiovascular mortality compared with the high saturated fat group….” So, the experimental group was was given free sardines, free cod liver oil, got complementary nutrition advice, and the outcome was attributed to the reduction in saturated fat? This is laughable! Perhaps other factors MIGHT be involved in the results?
Other Studies Cited by The American Heart Association
The AHA also cites the British Medical Research Council study, which had no clear conclusion, and the Finnish Mental Hospital Study, which was not randomized. The AHA seems to be grasping at straws to promote vegetable oils, but the results are far from convincing.
What Fat Raises Blood Cholesterol?
Saturated fat does raise blood cholesterol, and polyunsaturated fat lowers it. At least, these are the short-term effects. Why? Because saturated fats require more of certain nutrients for our liver to metabolize. But these short-term effects do not tell us the whole story. A healthy diet contains some of all kinds of fat, both saturated and unsaturated. The category “saturated fat” includes foods that are healthy, like butter or coconut oil, or foods that are unhealthy, like lard or margarine. Our bodies need polyunsaturated fats, but only in small amounts. Vegetable oils are full of polyunsaturated fats, and they can be harmful in excess. Americans are eating more of them than ever, and heart disease is the leading cause of death.
Recent clinical trials are based on questionnaires of people who are eating unhealthy western diets. Healthy-minded Americans are less likely to be eating saturated fat, especially if they’re eating according to the AHA’s recommendations. Observations of people who are eating saturated fat in the context of a healthy diet do not show any harmful effects to the saturated fat.
Unfortunately, many studies are influenced by political forces, and conclusions typically favor food conglomerates.
Dayton, S., M. L. Pearce, S. Hashimoto, W. J. Dixon, and U. Tomiyasu. “A Controlled Clinical Trial of a Diet High in Unsaturated Fat in Preventing Complications of Atherosclerosis.” Circulation 40.1S2 (1969).
Hughes, Sue AHA Issues ‘Presidential Advisory’ on Harms of Saturated Fat http://www.medscape.com/viewarticle/881689 09 July 2017.
Leren, P. “The Oslo Diet-Heart Study: Eleven-Year Report.” Circulation 42.5 (1970): 935-42. Print.
Reijo Laatikainen, Registered Dietitian at Lääkärikeskus Aava Follow. “Oslo Diet Heart Study.” LinkedIn SlideShare. 22 Sept. 2011. Web. 09 July 2017.
Sacks, Frank M., Alice H. Lichtenstein, Jason H.Y. Wu, Lawrence J. Appel, Mark A. Creager, Penny M. Kris-Etherton, Michael Miller, Eric B. Rimm, Lawrence L. Rudel, Jennifer G. Robinson, Neil J. Stone, Linda V. Van Horn, and On Behalf of the American Heart Association. “Dietary Fats and Cardiovascular Disease: A Presidential Advisory From the American Heart Association.” Circulation. American Heart Association, Inc., 01 Jan. 2017. Web. 09 July 2017.
Shilhavy, Brian, and Marianita Jader. Shilhavy. Virgin Coconut Oil: How It Has Changed People’s Lives, and How It Can Change Yours! West Bend, WI: Tropical Traditions, 2004. Print.
Vegetable oil availability image:
India oil producer image: https://upload.wikimedia.org/wikipedia/commons/5/5f/Grinding_Mustard_Seed_for_oil.jpg