Also known as: Phytosterols, Beta-sitosterol, Campesterol, Stigmasterol, Sterol esters
FoundationalStrong evidence
Plant compounds structurally similar to cholesterol that block its absorption by competing for the same route. One of a small number of ingredients with an authorised health claim behind it.
Typical dose
1.5–3.0 g per day
With fat-containing meals, split across two or three
What it is
Plant sterols and stanols are the plant equivalents of cholesterol, present in small amounts in vegetable oils, nuts, seeds and grains. Stanols are the saturated versions of sterols and behave similarly.
Ordinary diets supply only a few hundred milligrams a day, well below the amount needed for an effect, which is why fortified foods and supplements exist.
They are usually supplied as esters, which improves solubility in fat and makes them easier to incorporate into spreads, yoghurts and drinks. This is one of the few areas where the fortified food format has a genuine advantage over a capsule, because the compounds need to be present in the gut at the same time as dietary fat.
How it works
Sterols and stanols are close enough in structure to cholesterol to compete with it for space in the mixed micelles that carry fat through the intestinal wall. Displaced cholesterol passes through rather than being absorbed.
This affects both dietary cholesterol and the larger quantity the body secretes in bile, which is why the effect is meaningful even for people eating little cholesterol.
They are themselves poorly absorbed, so they do their work in the gut and largely leave. That local action explains both their good safety record and why timing with meals matters so much.
What the evidence shows
The cholesterol-lowering effect is well established across a large body of controlled trials, with consistent reductions in LDL at intakes of 1.5 to 3 g daily.
The evidence was considered sufficient for a health claim to be formally authorised, which very few supplement ingredients achieve.
What has been demonstrated is the effect on the marker. Trials showing that lowering cholesterol this particular way changes long-term outcomes are lacking, which is a fair caveat to state rather than skip.
Dosing
The effective range is 1.5 to 3 g daily. Below about 1.5 g the effect becomes marginal, and above 3 g there is little additional benefit.
Take with meals containing fat, and split across two or three meals rather than taking it all at once. The mechanism depends on being present in the gut alongside dietary fat, so timing matters more here than for most supplements.
One genuine trade-off: because they interfere with fat-soluble absorption generally, sterols modestly reduce uptake of carotenoids. Eating plenty of coloured vegetables alongside offsets this.
At a glance
Common forms
Sterol esters, Stanol esters, Beta-sitosterol, Fortified spreads and drinks, Capsules
Half-life / duration
Acts locally in the gut with each meal; lipid changes accrue over 3-4 weeks
Timing
With fat-containing meals, split across two or three
Competition status
Permitted — not on the WADA Prohibited List
Category
Foundational
Safety and side effects
Plant sterols and stanols are well tolerated, with a long record of use in fortified foods. Digestive effects are uncommon and mild.
The reduction in carotenoid absorption is the main practical consideration and is easily offset by eating fruit and vegetables alongside.
Fortified products are not intended for young children or during pregnancy, since cholesterol is needed for development. Speak to your doctor before use if you take regular medication or your lipids are being managed.
Who should avoid it
Not intended for young children or during pregnancy and breastfeeding, since cholesterol is required for development. Speak to your doctor before use if your lipid levels are being managed or you take regular medication. Eat plenty of coloured vegetables alongside to offset reduced carotenoid absorption.
This entry is provided for information only. Food supplements should not be used as a substitute for a varied and balanced diet and a healthy lifestyle. Consult a qualified healthcare professional before use if you are pregnant, breastfeeding, taking medication or under medical supervision.
