Articles
Plant Sterols
Plant sterols are found in very small amounts in the foods we eat everyday, such as fruits, vegetables, nuts and seeds. When eaten in sufficient amounts, they have the ability to decrease the LDL, or ‘bad’, cholesterol level in our blood. Manufacturers have the ability to extract concentrated sources of plant sterols, and are now legally allowed to incorporate these into a small range of foods, including margarines, low fat milk and yoghurt and even some breakfast cereals. Food Standards Australia and New Zealand (FSANZ) are also currently considering whether to allow manufacturers to include plant sterols in cheeses and low fat cheese products.
How do plant sterols reduce cholesterol?
Plant sterols are part of the structure of cell walls of plants and animals. Cholesterol is a sterol found in the cell walls of animals. Plants produce sterols called phytosterols which have a similar structure to cholesterol. Cholesterol is absorbed from the intestine by first binding to the intestinal cell walls. Because of their similar structure, phytosterols can fill up the binding sites and prevent cholesterol from being absorbed. The overall effect is a reduction in blood cholesterol levels.
Is it safe to eat plant sterols added to foods?
After rigorous investigation, FSANZ have concluded that plant sterols added to foods are safe for most people to consume.
It is not seen as being unsafe for children or pregnant women to eat plant sterol enriched foods, but it is not recommended unless advised by a doctor. Generally speaking, these groups do not need to be concerned about cholesterol, and therefore do not need to actively consume plant sterol enriched foods. Manufacturers must include information about added plant sterols on the food label, and if nutrition claims are made, the amount of plant sterol must be indicated on the nutrition information panel.
How much plant sterol is needed?
It is shown that 2-3g of plant sterols per day is most effective to have a cholesterol lowering effect. To get this amount, you would need to consume about 2-3 serves of plant sterol containing foods each day. Eating more than this will not increase the effect, and eating less than this will simply have less of an effect. High levels of plant sterols may also reduce absorption of fat soluble vitamins such as beta-carotene. You can combat this by making sure you include fruits and vegetables rich in beta-carotene in your diet. These include carrot, spinach, pumpkin, rock melon and apricots.
The inclusion of plant sterols in foods such as spreads has provided a palatable way to increase intake of plant sterols. Controlled trials have shown that as little as 25 grams (about one tablespoon) of spread per day is enough to lower serum total cholesterol by 10 per cent and LDL (bad) cholesterol by 10 to 15 per cent. There is minimum change in HDL (good) cholesterol and results have been achieved after only three weeks.
Plant sterols also provide benefits for people already taking cholesterol lowering medications, such as statins. Plant sterols reduce cholesterol absorption whereas statins reduce LDL cholesterol production from saturated fats. However, plant sterols can not replace your current medications, and it is wise to talk to your doctor or dietitian about how plant sterol enriched foods can provide added benefits.
Do other Countries allow plant sterols in foods?
Yes. In Europe, plant sterols are permitted in table spreads, milk, yoghurt and cheese products, some cereal products and spicy sauces, and rye bread (pumpernickel). In the US, plant sterols are also permitted in orange juice.
The number of foods enriched with plant sterols in Europe is slightly larger than that in Australia. The list currently comprises of table spreads, milk, yoghurt, cheese, some cereals, spicy sauces and rye bread. The United States also allow the addition of plant sterols to orange juice. In June of this year, Health Canada authorities issued a ruling to allow plant sterols to be added to foods. As well as those allowed in Australia, Canadian manufacturers are also able to enrich mayonnaises, vegetable and fruit juices and salad dressings.
Quick Plant Sterol Facts
Effects on intestinal and blood cholesterol
Cholesterol in the intestines comes not only from the diet but also from the bile that is released into the intestines to help digest fat. Cholesterol in bile is produced from saturated fat in the diet. Some of this cholesterol is normally reabsorbed. Plant sterols in the diet inhibit absorption of both dietary and biliary cholesterol from the digestive system. With low absorption, liver cholesterol levels fall. This stimulates increased liver uptake of LDL-cholesterol from the blood causing blood total and LDL-cholesterol to fall.
Vitamin insurance
Whilst sterol enriched foods appear to be beneficial, some studies show that they may reduce blood levels of vitamin E and carotenoids. Eating plenty of leafy green vegetables and yellow and orange fruits such as rock melon and vegetables such as carrots will help to maintain higher levels of carotenoids.
Cost of sterol enriched spreads
Sterol enriched spreads cost two to three times more than other margarines but if used in the amounts recommended the cost is only 40 cents a day.
Added to site on : Monday, 29 November 2010