Phytosterols: allies in cardiovascular health

Preparation

Cardiovascular diseases are responsible for about 40% of deaths in Portugal, representing the principal cause of death in our country and a significant cause of disability. They are mainly due to the accumulation of fats on blood vessel walls - atherosclerosis - which starts at an early age, silently progressing for years and when the first symptoms appear this condition is at an advanced stage. Its consequences, such as myocardial infarction, stroke and death, are often sudden and unexpected.

Most cardiovascular disease results from an inappropriate lifestyle and modifiable risk factors, such as: physical inactivity, high blood pressure, smoking, stress, obesity, diabetes and hypercholesterolemia.

Phytosterols are important allies of cardiovascular health. They are bioactive compounds naturally present in small amounts in foods of plant origin. The main food sources are vegetable oils (especially unrefined oils), oil-rich fruits (such as almonds, peanuts, etc.), seeds and cereals (see Table 1). It is estimated that the average daily intake of phytosterols is less than 500mg. The food industry has been supplying foods enriched in these compounds since 1995, in order to facilitate the recommended daily intake of phytosterols - 2000mg to 3000mg. These fortified foods are not recommended during pregnancy, breastfeeding and for children under the age of 5 years. Patients undergoing cholesterol reduction treatment should only consume such products under medical supervision.

Phytosterols have a chemical structure and biological functions similar to cholesterol, which is a substance essential to life that is a component of cell membranes and transported in the blood plasma of all animals. Most cholesterol is produced in the liver and only a small portion is derived from food. However, when blood concentrations become too high cholesterol becomes a risk factor. The excessive consumption of saturated fat contributes to its increase in the blood, while unsaturated fat helps reduce or maintain adequate cholesterol levels.

Scientific evidence indicates that it is possible to reduce LDL cholesterol by around 10% in three weeks, through the daily intake of 2000mg of phytosterols as part of a healthy diet, with no significant effect on HDL cholesterol and triglycerides. Phytosterols inhibit the intestinal absorption of cholesterol and so it is channelled through the intestine and excreted from the body. This action not only interferes with the absorption of dietary cholesterol but also appears to have an effect on the removal of cholesterol from substances endogenously synthesized by the liver, and which are then recycled in the digestive tract.

Hence, ensuring the intake of phytosterols through a diversified diet, coupled with a healthy lifestyle, may be an important way of reducing cholesterol levels in the population, and therefore reducing the risk of developing cardiovascular disease.

Moreover, the role of phytosterols in relation to auto-immune diseases and protection against the development of cancers is recognised.

Food	Food Quantity	Phytosterol Quantity
Vegetable margarine enriched with phytosterols	1 tablespoon	1600mg
Yoghurt enriched with phytosterols	200g	800mg
Milk enriched with phytoestrogens	250ml=1 glass	800mg
Rice bran oil	1 tablespoon	160mg
Cooked vegetables	100g	130mg
Sesame oil	1 tablespoon	120mg
Corn oil	1 tablespoon	100mg
Canola oil	1 tablespoon	90mg
Pistachio nuts	30g	90mg
Sunflower seeds	30g	90mg
Pumpkin seeds	30g	80mg
Almonds	30g	40mg
Peanuts	30g	40mg
Soybean oil	1 tablespoon	40mg
Brussels sprouts	1 tablespoon	30mg
Rye bread	2 slices	30mg
Olive oil	1 tablespoon	20mg
Wheat bran	1 tablespoon	10mg
Other sources: acai berries, soybeans, pumpkin oil…

Source: Kotsirilos, V. et al, A guide to evidence-based integrative and complementary medicine, 2011.

Dr.ª Zélia Santos - Portuguese Association of Dietitians