For the Curious
Plant foods don’t contain cholesterol.
But plants make plant sterols that are remarkably similar in structure to cholesterol.
Because of that similarity, plant sterols can compete with cholesterol in the intestine, reducing how much cholesterol is absorbed. Plant sterols themselves are absorbed only in very small amounts.
The result: less cholesterol is absorbed, and LDL cholesterol can fall.
Plant sterols, also called phytosterols, include beta-sitosterol, campesterol and stigmasterol.
And the Effect Is Real
A meta-analysis of 124 randomized controlled studies found a clear dose-response relationship: roughly 0.6–3.3 grams of plant sterols or stanols per day lowered LDL cholesterol by about 6–12%.
So yes, plant sterols really can affect cholesterol.
There is just one catch.
We Normally Eat Milligrams. The Studies Use Grams.
Plant sterols occur naturally in foods such as:
- vegetable oils
- nuts and seeds
- whole grains and bran
- legumes
- avocados
A typical Western diet provides only about 200–300 mg per day.
Even people eating very plant-rich diets usually consume much less than the amounts used in cholesterol-lowering studies. In one North American study, vegans had the highest intake of any dietary group and averaged about 428 mg per day.
Compare that with roughly 1,500–3,000 mg per day commonly studied for lowering LDL.
That is a very different dose.
Avocado is one of the richer fruit sources. USDA data put several major phytosterols in Hass avocado at roughly 83 mg per 100 grams.
To get 2 grams of plant sterols from avocado alone, you would need roughly 2.4 kilograms—more than 5 pounds—of avocado flesh.
Please don’t take that as a serving suggestion.
Then How Do People Get 2 Grams?
Usually through foods fortified with concentrated plant sterols or supplements.
In clinical studies, about 25 grams of plant-sterol-enriched margarine or spread—roughly 1½ to 2 tablespoons—has provided around 2 grams of plant sterols.
At these higher intakes, the LDL-lowering effect is well established.
There Is More to Plants Than the Nutrition Facts Label
In addition to the well-known vitamins, minerals and fiber, plants contain many other potentially beneficial compounds, including plant sterols.
And we are still learning more about these compounds and what they may do for our health.
Another reason a varied, plant-rich diet has more going for it than the nutrients listed on a Nutrition Facts label.
References
- Ras RT, Geleijnse JM, Trautwein EA. 2014. LDL-cholesterol-lowering effect of plant sterols and stanols across different dose ranges: a meta-analysis of randomised controlled studies. British Journal of Nutrition.
This is the key reference: 124 studies, with 0.6–3.3 g/day associated with about 6–12% LDL reduction.
PubMed record - Jaceldo-Siegl K, et al. 2017. Variations in dietary intake and plasma concentrations of plant sterols across plant-based diets among North American adults. Molecular Nutrition & Food Research.
This supports the dietary-intake comparison: 263 mg/day in nonvegetarians versus 428 mg/day in vegans.
PubMed record - Nutritional Composition of Hass Avocado Pulp. 2023. This review tabulates USDA FoodData Central data: approximately 76 mg beta-sitosterol + 5 mg campesterol + 2 mg stigmasterol per 100 g, which supports our ~83 mg/100 g and >5-lb calculation.
Full text at PubMed Central - For the margarine example, there is an especially clean RCT: participants consumed 25 g/day of spread containing 2 g of plant sterols, producing about a 10% LDL reduction versus control.
PubMed record