What is the recommended dosage for Vitamin A?

General: 700-900 mcg RAE/day (2,300-3,000 IU)

What are the side effects of Vitamin A?

Potential side effects include: Hair loss at excessive doses (hypervitaminosis A), Dry skin and lips, Headache and nausea at high doses, Teratogenicity — contraindicated in pregnancy at high doses.

Does vitamin A deficiency contribute to hair loss?

Both vitamin A deficiency and excess can affect hair health. Vitamin A (retinol) is essential for cell growth and differentiation, including hair follicle stem cells. Deficiency may lead to dry, brittle hair. However, excessive vitamin A intake (hypervitaminosis A) is a well-documented cause of hair loss. Maintaining adequate but not excessive levels is important — consult your healthcare provider for testing.

What is the safe upper limit for vitamin A supplementation and why does it matter for hair?

The tolerable upper intake level (UL) for preformed vitamin A (retinol) for adults is 3,000 mcg RAE (10,000 IU) per day, as established by the National Institutes of Health. Exceeding this chronically — even at levels like 25,000–50,000 IU daily, found in some older supplements — can cause hypervitaminosis A, a well-documented cause of diffuse hair loss (telogen effluvium). This makes vitamin A unusual among hair nutrients: both too little and too much negatively affect hair follicle cycling. Most people eating a varied diet receive adequate vitamin A without supplementation. A blood retinol test can help clarify whether deficiency is actually present before starting supplements. Consult your healthcare provider.

Is beta-carotene (provitamin A) safer than preformed vitamin A for hair health?

Beta-carotene, found in orange and yellow vegetables, is a precursor that the body converts to vitamin A only as needed — so excess beta-carotene from food does not cause vitamin A toxicity. This makes food-derived provitamin A a safer way to meet vitamin A needs without risk of overdose. High-dose beta-carotene supplements (above 30 mg/day), however, have been associated with other risks — most notably increased lung cancer risk in smokers in large trials. For hair health, prioritizing dietary sources like carrots, sweet potatoes, and leafy greens is generally preferable to high-dose supplementation. If supplementation is needed, a product providing mixed carotenoids or modest doses of preformed vitamin A within the tolerable upper limit is typically recommended.

Vitamin A

vitamin

Also known as: Retinol, Retinyl palmitate, Beta-carotene (provitamin A)

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About

Vitamin A plays a critical role in cell differentiation and sebum production in hair follicles. Adequate vitamin A supports normal hair cycling, while both deficiency and excess can contribute to hair loss. Retinoids regulate keratinocyte proliferation in the follicular epithelium.

How It Works

Retinoid receptors (RAR/RXR) in dermal papilla cells regulate hair follicle cycling; vitamin A supports sebaceous gland function and epithelial cell differentiation.

Evidence For Conditions

Condition	Grade	Studies	Participants
Nutritional Deficiency Hair Loss	D	4	1	View →
Scalp Inflammation (Folliculitis & Dermatitis)	D	4	1	View →

Side Effects

Hair loss at excessive doses (hypervitaminosis A)
Dry skin and lips
Headache and nausea at high doses
Teratogenicity — contraindicated in pregnancy at high doses

Drug & Supplement Interactions

Retinoid medications (isotretinoin, tretinoin — additive toxicity risk)
Tetracycline antibiotics (increased intracranial pressure risk)
Anticoagulants (high-dose vitamin A may increase bleeding risk)
Hepatotoxic drugs (additive liver stress at high doses)

Always inform your healthcare provider about all supplements you take.

Related Ingredients

Biotin Folate Vitamin B12 Vitamin D Vitamin E

Quick Facts

Dosage: General: 700-900 mcg RAE/day (2,300-3,000 IU)
Forms: softgel capsule liquid
Natural Sources: Liver, Sweet potato, Carrots, Spinach, Eggs
Upper Limit: 3,000 mcg RAE/day (10,000 IU preformed vitamin A)
Best Time: With a fat-containing meal; consult your healthcare provider about appropriate dosage

Evidence Summary

Nutritional Deficiency Hair Loss D

Scalp Inflammation (Folliculitis & Dermatitis) D

FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. The products and information on this website are not intended to diagnose, treat, cure, or prevent any disease. The evidence grades presented are based on our analysis of published peer-reviewed research and do not constitute medical advice. Always consult your healthcare provider before starting any supplement regimen.