False and dangerous advertisements from Unilever
Recently David Jenkins and 16 colleagues published the results from a dietary trial in JAMA (The Journal of the American Medical Association). They had compared the usual low−saturated fat diet with a diet that included plant sterols, soy protein, fibers, and nuts. They succeeded in lowering LDK-cholesterol by about 13% with the plant sterol diet, but only by 3% with the usual low-fat diet.
What is a plant sterol, you may ask.
Cholesterol is an important constituent of plants as well, although the molecule looks a little different. There are several types of plant cholesterol; together they are named plant sterols. A typical Western diet contains 400-500 mg plant sterols, but little is taken up in the gut. Human and plant cholesterol compete for uptake in the gut. If you eat much plant sterol, your intake of normal cholesterol goes down. This fact got Unilever the idea to add plant sterols to their food products; in the first hand to margarine. The product is named Promise Active in the US, and Flora Pro.active or Becel Pro.active in other countries. And this was also the product that was given to the participants in the plant sterol group.
It is correct that cholesterol goes down if we eat much plant sterol, but that doesn’t mean that it is able to prevent heart disease, because no one has ever tested that in a scientific experiment. What happens is that our own cholesterol is exchanged with a foreign type of cholesterol, not only in the blood, but also in our cells and cell membranes.
Is it really a good idea? Isn’t it likely that the molecular differences between animal and plant sterols have a meaning? I think so, and science is in support of my view.
Several studies have shown that even a mild elevation of plant sterols in the blood is a risk factor for heart disease, and the findings in people with a rare inborn disease named sitosterolemia are in accord. These people absorb much more plant sterols than normally and they also become atherosclerotic much earlier in life than normal people.
Statin treatment lowers blood cholesterol, but at the same time it raises the level of plant sterols. In the 4S-trial about 25 % of the patients had a mildly elevated level of plant sterols before treatment. In this group statin treatment resulted in a further increase of plant sterols and the number of heart attacks was twice as high compared with the patients with the lowest plant sterol levels. This means that for about 25% of the many millions of people on statin treatment, their risk of heart disease may increase, not decrease.
In spite of that, Unilever still advertise their margarine and other food products with high contents of plant sterols: Enjoy heart healthy buttery spread with Promise!
I became upset when I read that paper and I therefore sent a letter to the editor of JAMA with the following text:
Questionable conclusions from a dietary trial
It is well known that an addition of plant sterols and soybean products to the diet may lower cholesterol by 10-15%. The findings in the dietary trial performed by Jenkins et al.(1) are therefore no surprise. It is questionable, however, if a lowering of cholesterol by dietary means is equivalent with a lowering of the risk of coronary heart disease (CHD) because hitherto no unifactorial dietary trial has succeeded in lowering cardiovascular or total mortality (2,3). What the authors also ignore is that an increased intake of plant sterols is associated with an increased cardiovascular risk. In at least four cohort studies a high intake or a high plasma level of plant sterols were independently associated with a higher risk of CHD, and in experiments on mice a dietary supplementation with plant sterol esters equivalent to a commercial spread induced endothelial dysfunction (4).
1. Jenkins DJ, Jones PJ, Lamarche B et al. Effect of a Dietary Portfolio of Cholesterol-Lowering Foods Given at 2 Levels of Intensity of Dietary Advice on Serum Lipids in Hyperlipidemia: A Randomized Controlled Trial. JAMA. 2011:306(8),831-839.
2. Ravnskov U. The questionable role of saturated and polyunsaturated fatty acids in cardiovascular disease. J Clin Epidemiol. 1998;51(6):443-460.
3. Hooper L, Summerbell CD, Higgins JP et al. Dietary fat intake and prevention of cardiovascular disease: systematic review. BMJ. 2001;322(7289):757-763.
4. Weingärtner O, Böhm M, Laufs U. Controversial role of plant sterol esters in the management of hypercholesterolaemia. Eur Heart J. 2009;30(4):404-409.
A month later I got the following answer from the Editor:
Dear Dr. Ravnskov:
Thank you for your recent letter to the editor. Unfortunately, because of the many submissions we receive and our space limitations in the Letters section, we are unable to publish your letter in JAMA.
After considering the opinions of our editorial staff, we determined your letter did not receive a high enough priority rating for publication in JAMA. We are able to publish only a small fraction of the letters submitted to us each year, which means that published letters must have an extremely high rating.
We encourage you to contact the corresponding author of the article, although we cannot guarantee a response. We do appreciate you taking time to write to us and thank you for the opportunity to look at your letter.
Jody W. Zylke, MD
Senior Editor, JAMA
Letters Section Editor
I haven´t contacted the corresponding author of the paper, as suggested by Dr. Zylke, by the simple reason that nothing would happen. According to the Conflict of Interest Disclosures ten of the authors were supported financially by Unilever and several other producers of the food types used in the trial. Here is for instance Dr. Jenkins´ list:
“Dr Jenkins reported serving on the Scientific Advisory Board of Unilever, Sanitarium Company, California Strawberry Commission, Loblaw Supermarket,Herbal Life International, Nutritional Fundamental for Health, Pacific Health Laboratories, Metagenics, Bayer Consumer Care, Orafti, Dean Foods, Kellogg’s, Quaker Oats, Procter & Gamble, Coca-Cola, NuVal Griffin Hospital, Abbott, Pulse Canada, Saskatchewan Pulse Growers, and Canola Council of Canada; receiving honoraria for scientific advice from the Almond Board of California, International Tree Nut Council Nutrition Research and Education Foundation, Barilla, Unilever Canada, Solae, Oldways, Kellogg’s, Quaker Oats, Procter & Gamble, Coca-Cola, NuVal Griffin Hospital, Abbott, Canola Council of Canada, Dean Foods, California Strawberry Commission, Haine Celestial, and Alpro Foundation; being on the speakers panel for the Almond Board of California; receiving research grants from Loblaw Brands Ltd, Unilever, Barilla, Almond Board of California, Solae, Haine Celestial, Sanitarium Company, Orafti, International Tree Nut Council, and Peanut Institute; and receiving travel support to meetings from the Almond Board of California, Unilever, Alpro Foundation, and International Tree Nut Council.”
In addition Unilever Research and Development provided the donation of margarines used in the study.