Beta-carotene (standalone supplement)

Tier 3 — weak evidence · Antioxidant · Vision · Immune

A provitamin A that your body converts to retinol as needed. However, the ATBC and CARET trials found beta-carotene supplements INCREASED lung cancer risk by 18 to 28 percent in smokers. This is one of the most important cautionary examples in supplement research. Non-smokers may benefit modestly for immune function. Getting beta-carotene from food (carrots, sweet potatoes) is safe and preferred.

Dose: Do NOT supplement isolated beta-carotene if you smoke or have ever smoked — increased lung cancer risk in CARET and ATBC trials. For non-smokers seeking carotenoids: 5–15 mg/day mixed carotenoids with food, but food sources (orange vegetables, dark leafy greens) are preferred.