FOOD & DRINK
PLANT STEROLS AND STANOLS: AN OVERVIEW Junee Sangani Senior Specialist Diabetes Dietitian Junee is currently a Specialist Diabetes Dietitian at Central Middlesex Hospital, London North West Healthcare NHS Trust. She also works as a Freelance Dietitian. Her specialist areas of interest are chronic diseases, adolescent care and women's health.
From as far back as the 1950s, it has been known that increasing dietary intake of plant sterols and stanols can lower serum total and LDL cholesterol.1 Plant sterols and stanols provide an important role in building plant membranes. They naturally occur in all foods of plant origin such as fruits, vegetables, grain products, seeds and nuts and are especially high in vegetable oils. The dietary intake of naturally occurring plant sterols and stanols is thought to be approximately 200400mg/d and in vegetarian diets it can be double the amount.2 Functional food products enriched with plant sterols and stanols have been marketed since 1995, with margarines being the pioneers. Today, there is a large variety of products including drinks, yoghurts and supplements.1,3 PLANT STEROL AND STANOL FUNCTION
Sterols and stanols have a similar function in plants as cholesterol has in humans; they chemically resemble the structure of cholesterol. There are very slight differences in the structure of sterols, stanols and cholesterol which make them profoundly different in metabolic function. They work by competing with and inhibiting cholesterol absorption in the small intestine, leading to excretion of cholesterol. It is also thought that they regulate hepatic expression of LDL receptors and decrease production of LDL cholesterol. Commonly found plant sterol and stanols are campesterol, campestanol, sitosterol and sitostanol.1,4,5 Plant sterols and stanols have the same mechanism for cholesterol lowering as Ezetimibe, a drug that lowers plasma cholesterol levels, so taking them together doesn’t provide any additional benefit and they both appear to reduce cholesterol levels equally.1
Statins work in a different way by inhibiting HMG-CoA reductase, which is an enzyme that plays an important role in cholesterol production, leading to reduced cholesterol synthesis. The cholesterol lowering effect of statins has been proven to reduce the incidence of heart attack and stroke; however, no such effect has been documented with plant sterol and stanol enriched foods and supplements.1,3 However, combining plant sterols and stanols with 2g/d of statins has been shown in clinical trials to reduce LDL cholesterol by 7-10% above the reduction effect of the statin. It is thought that a similar or better than effect is achieved by doubling the statin dose.6,7 RECOMMENDATIONS
It has been well documented that an intake of 2g per day of plant sterol and stanols can lower LDL cholesterol by 8-10%.1 Certain products claim that an intake of 1.5-2.4g per day can lower cholesterol by 7-10% and an intake of 2.5-3g per day can lower by 10-12.5% in two to three weeks.8 It is recommended that these products are eaten with meals to be effective and, if intake of the product is stopped, the cholesterol lowering effect will also stop.5 Overleaf is a guideline to show what is needed to be consumed to get 1.5-3g plant sterol and stanol per day and a table of some of the products available. www.NHDmag.com July 2017 - Issue 126
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