‘Phytosterols’ are compounds that can impair the absorption of cholesterol from the gut. In this way, ‘sterols’ (as their name is often abbreviated to) can reduce cholesterol levels in the bloodstream, which conventional wisdom dictates is always a good thing. Sterols are added to ‘functional foods’ including special margarines that promise cholesterol-reducing and, therefore, health-enhancing properties.
However, the reality is that the impact a drug or foodstuff has on cholesterol levels is quite irrelevant – it’s its impact on health that is important. This distinction is critically important: Arsenic and cyanide might reduce cholesterol levels, but that does not make them healthy things to consume.
I was interested to read about a recent study in which the effect of sterols on rat heart cells was assessed . The cells were exposed to levels of sterols commonly found in the bodies of individuals ingesting sterols. The cells ended up incorporating the sterols at the expense of cholesterol. However, at the same time, the metabolic activity of the heart cells decreased, as did their capacity for growth. In short, exposing heart cells to sterols appears to, err, poison them.
The authors point out, that the results of this study cannot necessarily be translated into conclusions about the effect of these compounds on heart health, but add that the findings “raise[s] concerns about the safety of long-term exposure to physiologically relevant PS [phytosterol] concentrations.”
1. Danesi F, et al. Phytosterol supplementation reduces metabolic activity and slows cell growth in cultured rat cardiomyocytes. British Journal of Nutrition 20 April 2011 [epub]