Beta-carotene
Snapshot
Beta-carotene is a provitamin A carotenoid found in orange and dark-green plants; supports vision, skin, and immune health, but high-dose supplements raise lung-cancer risk in smokers.
What It Is
Beta-carotene is a fat-soluble carotenoid pigment and antioxidant. As a provitamin A, it can be enzymatically converted into retinal (vitamin A) in the body, helping maintain normal vision, epithelial integrity, and immune function.
Where It Comes From
Naturally abundant in carrots, sweet potatoes, pumpkin, winter squash, mango, apricots, and leafy greens like spinach and kale. Commercially, it’s produced from algae (Dunaliella salina), palm oil sources, or synthesized, and sold as standalone or mixed-carotenoid supplements.
Key Nutrients & Compounds
The primary compound is beta-carotene (mostly all-trans with some 9-cis/13-cis isomers). It is cleaved by beta-carotene 15,15′-monooxygenase (BCMO1) to retinal; conversion varies with genetics, thyroid status, zinc status, alcohol intake, and overall vitamin A stores.
Health Benefits
Adequate beta-carotene intake from foods contributes to healthy vitamin A status, which supports night vision, skin and mucosal barriers, and immune function. Observational data tie higher carotenoid-rich diets to reduced risk of several chronic diseases, but large trials of supplements have not shown overall cancer benefit—and in certain groups, showed harm (see Cautions).
Recommended Dosage
From foods: aim for several servings of colorful fruits/vegetables daily.
For supplements: common amounts are 3–6 mg/day (sometimes up to 10–12 mg/day) when used to support intake. Remember the conversion: 12 μg dietary beta-carotene ≈ 1 μg retinol activity equivalent (RAE); 2 μg beta-carotene in oil ≈ 1 μg RAE. Avoid high doses if you smoke or were asbestos-exposed.
How To Use It
Take supplements with meals that contain fat to enhance absorption. Consistency beats megadoses. Many eye-health products now use lutein + zeaxanthin instead of beta-carotene for smokers or former smokers.
Who Should Use It
People with low intake of colorful produce who want provitamin A support from diet or modest supplementation. For macular health, smokers or ex-smokers should prefer AREDS2-style formulas (lutein/zeaxanthin) that exclude beta-carotene.
Possible Interactions or Cautions
High-dose beta-carotene (20–30 mg/day) increased lung-cancer risk and overall mortality in male smokers and in smokers/asbestos-exposed populations. Avoid high-dose beta-carotene if you smoke or have significant past asbestos exposure.
Benign yellowing of skin (carotenodermia) can occur with high intakes.
Absorption can be reduced by fat-absorption inhibitors (orlistat), mineral oil, and bile-acid sequestrants; separate dosing and discuss with a clinician. Retinoid medications (e.g., isotretinoin) warrant caution with any vitamin A–related supplements.
Final Thoughts
Prioritize beta-carotene from whole foods. If supplementing, keep doses modest and context-specific. For eye formulas in smokers or former smokers, choose beta-carotene–free (AREDS2-type) products.
Scientific Studies
The Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) trial: beta-carotene increased lung cancer and mortality in male smokers. http://pubmed.ncbi.nlm.nih.gov/8127329/
The CARET trial: beta-carotene + vitamin A increased lung cancer and mortality in smokers/asbestos-exposed. http://pubmed.ncbi.nlm.nih.gov/8663883/
Physicians’ Health Study: no overall cancer/CVD benefit from long-term beta-carotene in mostly non-smoking male physicians. http://pubmed.ncbi.nlm.nih.gov/8948560/
AREDS2: replacing beta-carotene with lutein/zeaxanthin maintained AMD benefits and reduced lung-cancer risk in smokers. http://pubmed.ncbi.nlm.nih.gov/23644932/