Vitamin D, zinc and collagen

The NHS advises most adults to consider 10 micrograms of vitamin D in autumn and winter for bones, not as a hair treatment. Zinc should come from food: about 9.5 mg a day for men and 7 mg for women, and not more than 25 mg in supplements unless a doctor advises it. Collagen and marine protein are not NHS treatments for pattern hair loss.

See a GP if hair loss is sudden, patchy, or comes with illness, a rash, or other symptoms. The NHS asks for that conversation before a private clinic.

On this page

On this page

1. Vitamin D
2. Zinc
3. Collagen and marine protein
4. Questions
5. Sources

Vitamin D and zinc are real nutrients with NHS pages. Collagen is a protein powder with a beauty claim. They do not belong in one sentence, which is why the adverts put them there.

Vitamin D

The NHS says vitamin D regulates calcium and phosphate, for bones, teeth and muscles. From late March or early April to the end of September, most people make enough from sunlight. In autumn and winter, everyone should consider 10 micrograms (400 IU) a day. Some people, including those who cover their skin or have darker skin, should consider that dose all year. Do not take more than 100 micrograms (4,000 IU) a day unless a doctor has set a different amount. Too much over time causes high calcium, which can harm kidneys, heart and bones.

NICE CKS says a clinician may consider a vitamin D test when male pattern loss looks atypical. That is a test, not a reason to megadose.

Zinc

Zinc helps make new cells and enzymes, and it helps wound healing. Men aged 19 to 64 need about 9.5 mg a day, women about 7 mg, from food: meat, shellfish, dairy, bread, cereals. High-dose supplements reduce copper absorption and can lead to anaemia and weaker bones. Do not take more than 25 mg of zinc supplements a day unless a doctor advises it.

Collagen and marine protein

These are sold as drinks and capsules for hair, skin and nails. The NHS hair-loss page does not list them. There isn’t a UK public-health recommendation to take marine collagen for pattern baldness. Protein from food is the related, duller advice, on foods for hair growth.

If a marine blend also contains a large biotin dose, read biotin before a blood test.

Common questions

Should I take vitamin D for my hair?

Take it if you are following the NHS bone advice: 10 micrograms in autumn and winter, or all year if you get little sun. That page does not say vitamin D regrows hair.

Can I take a high-dose zinc tablet?

The NHS says not more than 25 mg a day of zinc supplements unless a doctor advises it. High doses reduce copper absorption and can cause anaemia and weaken bones.

Does marine collagen grow hair?

There isn’t an NHS recommendation or a trial result for that claim. It is a food supplement.

Related questions

• What hair supplement should I buy in the UK?
• What foods help hair grow?
• Can low iron make your hair fall out?

Sources

1. NHS: Vitamin D
2. NHS: Other minerals, including zinc
3. NHS: Hair loss
4. NICE CKS: Male pattern hair loss

Keep reading

• Best supplements for hair growth in the UK (2026) Iron, vitamin D, biotin and zinc compared with NHS guidance, and with the branded hair supplements sold in the UK.
• Foods for hair growth Protein, iron-rich foods and a normal varied diet support hair. They do not replace treatment for pattern hair loss.
• Iron deficiency and hair loss Hair loss can be a symptom of iron deficiency anaemia. The NHS treats proven deficiency with iron tablets and food, not with a guessed ferritin number.