Health Benefits of Plant Sterols
Raised cholesterol now affects 6 out of 10 UK adults and is becoming a key public health challenge. The good news is that many people can effectively manage their cholesterol levels with a combination of healthy lifestyle and dietary changes.
If you’re conscious about your diet then you’ve probably already heard about the cholesterol-lowering benefits of plant sterols, which are widely available in a range of fortified products including margarine, milk and supplements. Find out why more and more people are choosing to add these intriguing nutrients to their diets.
Why Should I Care About Cholesterol?
As we age, it seems that everywhere we look there are warning signs for high cholesterol and heart disease. But, cholesterol isn’t always the bad guy. This organic fat is essential for the maintenance and renewal of healthy cell membranes and without a sufficient dietary intake, our cells simply wouldn’t survive.
When we eat, cholesterol in food is broken down by the liver and transported in the blood by two different types of protein, also known as lipoproteins. Low-density lipoproteins (LDL) carry cholesterol to the cells that need it, while high-density lipoproteins (HDL) carry excess cholesterol back to the liver.
A diet high in saturated and trans fats, such as processed meats, ready meals and dairy products increases the amount of cholesterol in the blood. If there is insufficient HDL to carry cholesterol back to the liver for disposal, unused cholesterol begins to settle along the inside of artery walls forming fatty plaques. Over time, this causes artery walls to harden and increases the risk of potentially fatal blockages.
What are Plant Sterols?
In their natural state, plant sterols, also called phytosterols, help to form the membranes of plant cells and are structurally similar to cholesterol. When consumed, they work by partially blocking the body’s absorption of cholesterol into the blood and preventing the buildup of excess LDL cholesterol inside artery walls.
Plant sterols are not a new discovery. They were first identified over 50 years ago, however it was not until the turn of the 21st century that a means of adding them to foods (margarine spreads) was achieved. Plants sterols are now widely accepted to be the most effective food to lower cholesterol and reduce the risk of heart disease.
Plant Sterols and Cholesterol
Plant sterols have been well-studied and scrutinised, with over 200 clinical trials to date. Findings show that a daily intake of at least 2000 mg can reduce LDL (“bad”) cholesterol levels by 10% in just 4 weeks when consumed as part of a healthy diet and lifestyle:
- A recent meta-analysis reviewed the findings of 18 controlled clinical trials looking at the effects of plant sterols on cholesterol levels. Findings showed that 2000 mg of plant sterols (fortified margarine) on a daily basis lowered bad cholesterol by between 9% and 14% over a four-week period.
- A separate meta-analysis of 23 controlled clinical trials found that an average intake of 3400 mg per day reduced LDL cholesterol levels by 11% after three weeks.
Other studies have examined the link between cholesterol levels and the risk of heart disease, finding that a 10% reduction in LDL cholesterol reduces the risk of coronary heart disease by over 20%.
What Should My Cholesterol Level Be?
Cholesterol is measured with a simple blood test in units called millimoles per litre. The UK Department of Health recommends cholesterol levels should be:
For healthy adults:
- Total cholesterol below 5mmol/L
- LDL cholesterol below 3mmol/L
- HDL cholesterol above 1mmol/L
For adults at risk of high risk of heart disease:
- Total cholesterol below 4mmol/L
- LDL cholesterol below 2mmol/L
- HDL cholesterol above 1mmol/L
If you are over the age of 40 be sure to get regular check-ups to monitor your numbers.
Sources of Plant Sterols
There are three main sources of plant sterols; natural foods, fortified foods and supplements. Small amounts can be found in plant oils, grains, legumes, nuts and fruits, although the average Western diet only provides around 220 mg to 400 mg per day. You would need to consume around 150 apples to get the amount you need for cholesterol-lowering benefits.
If you wish to add an extra helping of plant sterols to your diet, fortified margarines, cereals and yoghurts are all good options. These are proven to be extremely effective at lowering cholesterol, but their inconsistent serving sizes can make it tricky to consume the exact amount of plant sterols needed.
Plant sterol supplements, sometimes marketed as ß-sitosterol, are another effective option, which has the added benefit of providing a consistent daily dose. It's important to take all forms with food.
How Much Should I Take?
However you choose to consume them, plant sterols need to be taken daily; when consumption stops, the cholesterol-blocking benefits also stop. Adults with raised cholesterol are advised to consume between 1500 mg to 2400 mg of plant sterols per day. Taking super-high doses above 3000 mg appear to offer no additional cholesterol-lowering benefits.
Plant sterols are not recommended for young children or pregnant women. There is evidence to suggest that daily doses over 3000 mg may modestly reduce the body’s absorption of carotenoids, which are required for healthy foetal development during pregnancy. Although this effect is minor, it can be tricky to monitor so pregnant women are advised to exercise caution.
Taking Plant Sterols with Statins
Plant sterols and statins work through different mechanisms so can be taken in combination. In fact, those with very high cholesterol levels are often advised to take both. Many people find plant sterols effective at reducing their dependency on statin drugs, which also lowers the risk of common statin side effects such as muscle weakness and liver damage. However, always consult your GP if you wish to alter your prescription.
Side Effects of Plant Sterols
Plant sterols have been subjected to extensive safety analysis and evaluation and appear to be very well tolerated. On occasion, people have reported looser bowel movements as the body adjusts.
They can also be used effectively alongside statins and fibrates because they all work in different ways. However, do not take them in place of prescribed medications without consulting with your doctor.
Their effect on fat-soluble vitamins has also been studied. Dosages above 3000 mg per day may lower the absorption of beta-carotene and vitamin E, but studies show that this can be prevented by eating the recommended five portions of fruit and vegetables a day, particularly dark green, yellow and orange varieties.