Could so called “healthy” sterols actually be damaging your health ?
You only have to visit any supermarket to realise that cholesterol-reducing foods are big business. Everything from specialised margarines to yoghurts now line the shelves – all promising to lower cholesterol and promote heart health.
However, the impact a food has on cholesterol levels has little, if any, importance, it’s the impact it has on health that’s crucial. I was reminded of this principle recently when I read a disturbing study on the potential health effects of cholesterol-reducing compounds known as ‘phytosterols’.
Phytosterols have the ability to inhibit the absorption of cholesterol from the gut, which results in lower blood cholesterol levels. ‘Sterols’ (as their name is often abbreviated to) are added to the so-called ‘healthy’ foods already mentioned, such as special margarines which claim to lower cholesterol. The majority of us believe that this cholesterol-lowering action equates to good health.
However, the results of a recent animal study, in which rat heart cells were exposed to sterols in the laboratory, call into question their reputation as a health-promoting compound. The cells were exposed to levels of sterols commonly found in the bodies of individuals who regularly consume foods containing them. The researchers found that the cells ended up incorporating the sterols at the expense of cholesterol. Their findings also showed that the metabolic activity of the heart cells decreased, as did their capacity for growth. Exposing heart cells to sterols appears to, in effect, poison them.
After reading this study, I also uncovered a review of the role of sterols in human health . There is a mass of evidence showing that plant sterols can reduce cholesterol levels by up to 15 per cent. This means nothing though. What would be ideal is for us to have data on what happens to disease risk when people supplement their diets with sterols. Unfortunately, we don’t have this evidence.
However, the review cites several studies in which higher levels of sterols were found to be associated with an increased risk of cardiovascular disease. This does not prove that sterols damage the heart and circulation, but the evidence is suspicious.
Perhaps even more worrying, though, is the evidence showing that sterols have the capacity to damage cells. We have the recent study referred to above, but the review cites other evidence which finds that sterols can damage and even kill the cells lining the blood vessels. Sterols have also been found to shorten the lifespan of cardiovascular disease-prone animals. It’s difficult to reconcile sterols’ healthy image with these effects.
It seems not all are blind to the potentially toxic effects of plant sterols. Health Canada, the government department responsible for helping Canadians maintain and improve their health, has previously raised the issue of sterol safety. In fact, these concerns have been big enough to lead the Government to ban the sale of sterol-enriched foods in Canada.