What is the recommended dosage for Vitamin D?

General: 600-800 IU/day; Deficiency: 1,000-5,000 IU/day

What are the side effects of Vitamin D?

Potential side effects include: Hypercalcemia at very high doses (nausea, vomiting, weakness), Kidney stones with excessive long-term use, Constipation, Metallic taste.

How is vitamin D linked to hair loss?

Vitamin D receptors are expressed in hair follicle keratinocytes and play a role in the hair growth cycle. Research has found associations between low vitamin D levels and alopecia areata, telogen effluvium, and female pattern hair loss. A 2019 meta-analysis confirmed that people with alopecia areata had significantly lower serum vitamin D levels compared to healthy controls.

How much vitamin D should I take for hair health?

The RDA for vitamin D is 600-800 IU daily, but many researchers suggest that higher doses (1,000-4,000 IU daily) may be needed to reach optimal serum levels of 40-60 ng/mL. Clinical studies on vitamin D and hair loss have used varying dosages. Have your vitamin D level tested before supplementing, as individual needs vary based on sun exposure, skin tone, and geographic location.

Does vitamin D supplementation help with alopecia areata?

Research across 62 studies with over 9 million participants demonstrates Grade A (Strong) evidence supporting a link between vitamin D status and alopecia areata. Low vitamin D levels are consistently more prevalent in people with alopecia areata than healthy controls. Vitamin D receptors in hair follicle cells may play a role in immune regulation. Supplementation to reach adequate 25(OH)D levels may support the immune environment around affected follicles.

Why does vitamin D have negative evidence for telogen effluvium?

Although low vitamin D is correlated with higher rates of telogen effluvium in observational research, interventional studies providing vitamin D supplementation have not consistently produced significant reductions in hair shedding. Research across 32 studies with 17,842 participants earns a Grade F (Negative) rating for vitamin D in telogen effluvium specifically. Correcting confirmed deficiency is still appropriate for overall health — the evidence suggests vitamin D deficiency may be a marker of poor health rather than a direct cause of telogen effluvium in most cases.

What vitamin D level is optimal for hair health?

Research examining vitamin D and hair loss outcomes generally finds associations between low vitamin D (25(OH)D below 20 ng/mL) and increased hair loss risk, particularly in female pattern hair loss and alopecia areata. The evidence from 18 studies with 15,494 participants for female pattern hair loss is Grade A (Strong). Most studies suggest maintaining 25(OH)D above 30 ng/mL, though optimal levels for hair-specific outcomes have not been definitively established. Blood testing is the most reliable way to determine individual status.

Vitamin D

vitamin

Also known as: Cholecalciferol, Vitamin D3, Ergocalciferol

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About

Vitamin D plays a key role in hair follicle cycling through activation of the vitamin D receptor (VDR), which is essential for initiating the anagen (growth) phase. Vitamin D deficiency has been associated with alopecia areata and telogen effluvium in multiple observational studies.

How It Works

Stimulates hair follicle cycling; vitamin D receptor (VDR) activation is essential for anagen initiation.

Evidence For Conditions

Condition	Grade	Studies	Participants
Alopecia Areata	A	98	9086791	View →
Female Pattern Hair Loss	A	19	15494	View →
Telogen Effluvium	F	34	17842	View →

Side Effects

Hypercalcemia at very high doses (nausea, vomiting, weakness)
Kidney stones with excessive long-term use
Constipation
Metallic taste

Drug & Supplement Interactions

Thiazide diuretics (may increase risk of hypercalcemia)
Corticosteroids (reduce vitamin D absorption and metabolism)
Orlistat and cholestyramine (reduce fat-soluble vitamin absorption)

Always inform your healthcare provider about all supplements you take.

Related Ingredients

Biotin Folate Vitamin A Vitamin B12 Vitamin E

Quick Facts

Dosage: General: 600-800 IU/day; Deficiency: 1,000-5,000 IU/day
Forms: capsule tablet liquid gummy
Natural Sources: Sunlight, Fatty fish, Egg yolks, Fortified milk, Mushrooms
Upper Limit: 4,000 IU/day
Best Time: With a fat-containing meal for optimal absorption

Evidence Summary

Alopecia Areata A

Female Pattern Hair Loss A

Telogen Effluvium F

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.