Plant Sterols May Help Prevent Alzheimers Disease

SAARBRÜCKEN, GermanyConsuming a diet rich in phytosterols, found naturally in nuts, seeds and plant oils, may help prevent the onset of Alzheimers disease, according to new research published in the Journal of Neuroscience. The findings suggest that a particular sterol, stigmasterol, inhibits the production of proteins that play an important role in the development of the disease.

"Plant sterols are present in various combinations in nuts, seeds and plant oils. As plant sterols are the equivalents of animal cholesterol, they can in principal influence metabolic processes, where cholesterol is involved," said Dr. Marcus Grimm, head of the Experimental Neurology Laboratory at Saarland University. "Because they also lower cholesterol levels, they are extensively used in the food industry and as dietary supplements."

Studies have shown that cholesterol promotes the formation of so-called senile plaques that are composed of proteins, particularly beta-amyloid proteins, that deposit at nerve cells within the brain and are regarded as one of the main causes of Alzheimer's disease.

The researchers collaborated with scientists from Bonn, Finland and the Netherlands to examine how dietary sterols influence the formation of the plaque proteins. It was found that one sterol in particular, stigmasterol, actually inhibited protein formation. The team was been able to confirm the positive effect of stigmasterol in tests on mice.

"Stigmasterol has an effect on a variety of molecular processesit lowers enzyme activity, it inhibits the formation of proteins implicated in the development of Alzheimer's disease, and it alters the structure of the cell membrane," Grimm said "Together, these effects synergistically reduce the production of beta-amyloid proteins."

Overall, the researchers were able to demonstrate that the various plant sterols influence different cellular mechanisms and therefore have to be assessed individually.

"Particularly in the case of Alzheimer's disease, it seems expedient to focus on the dietary intake of specific plant sterols rather than a mixture of sterols," Grimm said.

In 2009, the European Food Safety Authority (EFSA) concluded that foods containing certain levels of plant stanols and sterols can reduce blood cholesterol levels by an average of 7% to 10.5% if a person consumes 1.5 to 2.4 grams of the phytosterols daily. The NDA Panel also concluded that foods such as yogurts and milk, including low-fat yogurts and cheese, margarine-type spreads, mayonnaise, salad dressing and other dairy products, were the most suitable for delivering the cholesterol-lowering effects from plant stanols and sterols to the body. For other foods, information either was lacking or appeared to be less effective in reducing blood cholesterol levels.