Sterols

Sterols are waxy, fat-like molecules with a ring-shaped structure. Cholesterol is the sterol of animals, including people; plant sterols (phytosterols) occur in plants, and ergosterol in fungi. They have important roles in the body, and eating plant sterols can help lower cholesterol.

What is it?

Cholesterol is made by the liver and other cells and is also found in animal foods. Phytosterols and phytostanols are structurally similar plant compounds. Ergosterol in mushrooms and yeast turns into vitamin D2 when exposed to ultraviolet light. See Cholesterol and Phytosterols.

What it does

1. Cholesterol is part of cell membranes and is used to make steroid hormones, bile acids and vitamin D
2. Plant sterols compete with cholesterol for absorption in the gut, lowering LDL
3. Ergosterol is converted to vitamin D2

Food sources

Cholesterol: egg yolks, organ meats, shellfish, meat, poultry and dairy. Plant sterols: vegetable oils, nuts, seeds, wholegrains and legumes, and fortified spreads and yoghurt drinks. Ergosterol: mushrooms and yeast.

Singapore food examples

1. Eggs, prawns and squid for cholesterol
2. Nuts, seeds and plant oils for plant sterols
3. Mushrooms, especially UV-exposed ones, for ergosterol and vitamin D
4. Plant-sterol-fortified yoghurt drinks and spreads — check the label

How much do I need?

There is no recommended intake for sterols. Singapore's dietary guidelines focus on limiting saturated and trans fat, which affects blood cholesterol far more than dietary cholesterol does — see Singapore's dietary guidelines for adults (HealthHub).

Low intake and deficiency

The body makes the cholesterol it needs, so there is no dietary deficiency.

Too much and safety

High blood cholesterol is a major risk factor for heart disease, but it is influenced more by saturated and trans fat, genes and weight than by cholesterol in food. Some people respond more to dietary cholesterol. Rare inherited conditions (familial hypercholesterolaemia, sitosterolaemia) need medical care.

Absorption and bioavailability

Cholesterol is absorbed at about 50 percent. Plant sterols are absorbed at less than 5 percent and block part of cholesterol absorption. Soluble fibre, plant sterols and healthy fats can lower LDL cholesterol.

Connection to daily life

1. Heart health: eat more plant foods and less saturated fat to lower LDL
2. Healthy ageing: regular blood cholesterol checks help guide treatment

Sources: 1. National Academies of Sciences, Engineering, and Medicine — Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (2005) 2. HealthHub Singapore — Recommended Dietary Allowances: https://www.healthhub.sg/well-being-and-lifestyle/food-diet-and-nutrition/recommended_dietary_allowances 3. Health Promotion Board — Singapore Food Insights Database (SG FoodID): https://www.hpb.gov.sg/healthy-living/food-and-beverage/sgfoodid/ 4. FAO/INFOODS — Food composition tables and databases: https://www.fao.org/food-composition/tables-and-databases/en/