The ingredients may work via the traditional route of reducing cholesterol, particularly in the membrane of cancer cells, and by activating an enzyme called caspase which is known to play an essential role in programmed cell death (apoptosis).
“This combined evidence strongly supports an anticarcinogenic action of phytosterols and hence advocates their dietary inclusion as an important strategy in prevention and treatment of cancer,” wrote the reviewers from the Department of Animal Science and the Richardson Centre for Functional Foods and Nutraceuticals, at the University of Manitoba.
The reviews findings are published in the European Journal of Clinical Nutrition.
Phytosterols, cholesterol-like molecules derived from plants, are increasingly well known to consumers due to their scientifically proven ability to reduce cholesterol levels. As consumer awareness has increased, the number of products containing plant sterols or plant stanols and their esters has increased.
Numerous clinical trials in controlled settings have reported that daily consumption of 1.5 to 3 grams of phytosterols/-stanols from foods can reduce total cholesterol levels by eight to 17 per cent, representing a significant reduction in the risk of cardiovascular disease.
The Manitoba-based researchers “critically examine results from recent research regarding the potential effects and mechanisms of action of phytosterols on forms of cancer”.
According to emerging evidence, the phytosterols have shown potential in inhibiting cancers of the stomach, lung, ovaries, and breasts.
Commenting on the mechanism, Peter Jones and his colleagues stated that phytosterols may be linked to increased activity of caspase enzymes. This is achieved by the sterols being incorporated into the cell membranes, resulting in changes to the structure and function of the membranes. These changes ultimately result in an activation of caspase enzymes, said the researchers.
A second potential mechanism could also involve the sterols ‘traditional’ modus operandi of reducing blood cholesterol. “High blood cholesterol level and hence the concentration of cholesterol in lipid rafts of cell membranes are associated with reduced apoptosis of cancer cells,” they said.
Saftey concerns at a recommended daily intake level of two grams appear unfounded, added the researchers, noting that such a dose “does not cause any major health risks”.
“Mounting evidence supports a role for phytosterols in protecting against cancer development,” wrote the researchers.
“Hence, phytosterols could be incorporated in diet not only to lower the cardiovascular disease risk, but also to potentially prevent cancer development,” they concluded.
Healthy heart market
According to a recent market research conducted by Frost & Sullivan, the heart health market is dominated by four ingredients: phytosterols; omega-3s; beta-glucans and soy protein. Phytosterols are the most heart health targeted, said the market analysts, and benefited from approved health claims in many markets (as well as recently approval from the European Food Safety Authority).
The European market was valued at €421m in 2007 and growing at 20 per cent.
Cardiovascular disease (CVD), which cost €192 billion in health care costs across the 27-member state EU in 2007 according to the European Heart Network, can be sub-classified into categories such as hypercholesterolemia, hypertension, heart attack and stroke.
Source: European Journal of Clinical Nutrition
Volume 63, Pages 813-820, doi:10.1038/ejcn.2009.29
“Anticancer effects of phytosterols”
Authors: T.A. Woyengo, V.R. Ramprasath, P.J.H. Jones