Plant sterols are naturally present in vegetable oils and grains, and have been shown to be vitally important for maintaining healthy cholesterol levels. In structure, plant sterols are similar to cholesterol and they have been shown to benefit health by partially blocking cholesterol from being re-absorbed from the gut. Cholesterol is naturally secreted in bile to aid digestion and then re-absorbed further down the gut. By blocking this re-absorption of cholesterol, plant sterols can have a positive effect on blood cholesterol levels, even if a low cholesterol diet is being consumed.
Modern diets tend to be low in plant sterols, and so increasingly foods such as margarine are being fortified with sterols. These fortified foods can make a contribution to the daily intake of sterols but achieving an optimum intake by this means may not suit everyone.