Synopsis

Source of validity: Scientific
Rating (out of 5): 2

Vitamin A is involved in numerous biological processes, including cell growth and differentiation, sebum production, and immune function—all of which have some relevance to hair health. Scientifically, Vitamin A deficiency is known to cause hair problems, including thinning and hair loss (alopecia). Several case reports and studies have shown that individuals with low Vitamin A intake may experience hair loss that can be reversed with supplementation. However, there is also clear evidence that excessive Vitamin A intake can actually trigger or worsen hair loss, making its use for hair health a double-edged sword.

Despite the mechanistic rationale—Vitamin A supports epithelial cell growth and normal follicle function—there are few robust, placebo-controlled clinical trials demonstrating that supplementation in people with normal Vitamin A levels improves hair growth or prevents hair loss. Most evidence supporting its use is from deficiency states or animal models. Therefore, while Vitamin A is an essential nutrient for normal hair growth, supplementation is only justified in cases of deficiency, and routine use for hair thinning or loss in otherwise healthy individuals is not supported by strong scientific evidence. Caution is also advised because of the risk of toxicity and paradoxical hair loss with excessive intake.

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