Plant stanols and sterols are also known as phytostanols and phytosterols. They form part of the cell structures in plants and have a similar structure to cholesterol in humans.
Sterols occur naturally in small quantities in fruits, vegetables, nuts, seeds and vegetable oils. Stanols also occur in trace quantities in these foods, but sterols are turned into stanols in a process called hydrogenation, so they can be added to food products.
Some research has shown that plant sterols and stanols appear to lower cholesterol levels in our blood. The body makes its own cholesterol so doesn't need extra from the diet. Cholesterol is separated into different categories, but the types which we're particularly interested in are low density lipoproteins (LDL) and high density lipoproteins (HDL). LDL cholesterol - sometimes called ‘bad' cholesterol - carries cholesterol from the liver to the cells, and HDL cholesterol - or ‘good' cholesterol - returns excess cholesterol to the liver.
Excess cholesterol deposits itself in your blood vessels in the form of plaque, which can damage the vessels and increase your risk of developing heart disease. This is why cholesterol levels in the blood, particularly LDL cholesterol, have been linked to the state of our heart health.
Plant sterols and stanols work by reducing the amount of cholesterol from the diet that is absorbed by the body. The sterols and stanols reduce the LDL (bad) cholesterol, but don't affect the HDL (good) cholesterol. Overall total cholesterol levels in the blood are reduced and the good cholesterol isn't affected.
Studies have shown that a reduction in blood cholesterol levels, particularly a 10-20% reduction in LDL levels, can be achieved by consuming 2-3g of sterols and stanols per day. There is evidence that their effect is additional to a diet low in fat and/or in the use of cholesterol-lowering drugs.
Our typical daily intake of stanols and sterols from plant sources is around about 160 to 400mg per day, and vegetarians may have a daily intake of around 600 to 800mg per day. Higher levels of 2-3g can be achieved by consuming supplements or foods with sterols and stanols added to them. Stanols and sterols tend to be fat soluble, so the types of foods which are typically fortified with plant stanols and sterols are margarines, yoghurts and other milk products. They need to be consumed daily to have an effect on blood cholesterol levels.
Sterol and stanol fortified foods may be useful if you do have raised cholesterol levels; however, they can be costly. If you do choose to try plant stanol and sterol fortified foods, it's important to include them as part of a balanced and varied diet.
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