Supplements for skin, hair and joints: what's studied and what isn't
This is the most heavily marketed corner of the supplement aisle: big promises, little strong evidence. This page shows where the research is, where it isn't, and when hair loss or joint pain means a GP visit rather than a purchase.
Collagen supplements: what works
Collagen types I, II and III, marine vs bovine collagen, doses used in trials and how to take it. An honest look at the skin and joint evidence and who funds it.
9 min readHair vitamins and biotin
Do hair growth vitamins and biotin work? Common causes of hair loss (iron, thyroid, hormones), tests to ask your GP for, and why biotin can skew blood test results.
9 min readSkin supplements: what works
Supplements for skin compared: hyaluronic acid, collagen, vitamins C and E, omega-3. What trials found, the doses used and why sun protection comes first.
9 min readJoint supplements: the evidence
Do glucosamine and chondroitin, MSM, type II collagen and omega-3 help osteoarthritis? What Cochrane and NICE say, trial doses, shellfish allergy and warfarin.
9 min readEye vitamins and lutein
Who needs eye vitamins with lutein and zeaxanthin: the AREDS2 formula for macular degeneration, beta-carotene and smoking, and the screen and blue light myths.
10 min readVitamins A and E: limits and risks
Vitamin A and vitamin E benefits, retinol vs beta-carotene, upper limits, risks in pregnancy and bleeding, and how to convert IU to mcg and mg on a supplement label.
9 min readGlutathione and liposomal glutathione
Glutathione supplement benefits examined: is oral glutathione absorbed, liposomal glutathione evidence, NAC as a precursor, skin whitening and injection risks.
10 min readTurmeric and curcumin supplements
Turmeric supplements: curcumin benefits for joint pain, why black pepper is added, tablets vs the spice, liver injury reports, blood thinners and who must avoid it.
9 min readAstaxanthin for skin and eyes
Astaxanthin benefits examined: evidence for skin, eyes and exercise recovery, algae-based Haematococcus supplements, EFSA's safe intake of 8 mg a day and safety.
8 min read
How this section works
No “glowing skin” or “thicker hair” promises here. For each supplement we say what the studies showed, at what dose and who it doesn’t suit, and when the evidence is thin, we tell you.
Find your option: skin, hair and joints
Pick what bothers you to see where to start and what not to expect
What bothers you?
Where to start
Find the cause before buying
The NHS lists iron deficiency, stress, illness and weight loss as causes of temporary hair loss. Biotin helps only if you're low in it, which is rare.
Biotin can distort some blood tests, including thyroid and troponin tests.
Where to start
Collagen: limited evidence
Hydrolysed collagen has mostly been tested in small trials, and the results are mixed. If you try it, give it at least 2–3 months before judging.
Collagen is made from fish, beef or pork – check the source if you have an allergy or dietary rules.
Where to start
GP, exercise and weight
NICE advises against offering glucosamine for osteoarthritis because there's no strong evidence of benefit. Exercise and weight loss have the best evidence.
Pain, swelling or morning stiffness lasting more than a few weeks is a reason to see your GP.
Where to start
Lutein and zeaxanthin
They were studied in age-related macular degeneration, so choose a formula with your optician or eye doctor. Smokers should avoid formulas with beta-carotene.
Vitamins for hair growth: start with the cause
Temporary hair loss can follow iron deficiency, stress, illness or rapid weight loss. So the first step is a blood test, not a hair formula: our tests and deficiencies section explains which ones to ask your GP about. Biotin and hair products get a closer look in hair growth vitamins and biotin.
Hair loss: where to start
Four steps before you buy a hair formula. Tap a step
Think about what might be behind it
The NHS lists iron deficiency, stress, illness and rapid weight loss as causes of temporary hair loss.
A ferritin test and your GP
Ferritin shows your iron stores. Our tests section covers which other tests to ask about.
Low iron confirmed? Take iron
Not a hair formula, but iron itself, such as iron bisglycinate, and only after a blood test.
Biotin helps only if you're deficient
And that's rare. Hair products can contain many times the 30 mcg daily need.
- Biotin interferes with some tests: in reported cases, even a single 10 mg dose distorted thyroid results taken within 24 hours
- Tell your GP and the lab if you take it
Supplements for skin, hair and joints: topics in this section
| Topic | What’s known | Guide |
|---|---|---|
| Collagen | small trials, mixed results | best collagen supplement |
| Hair and biotin | biotin helps only if you’re deficient | hair growth vitamins |
| Skin and hyaluronic acid | little evidence | supplements for skin |
| Joints | NICE advises against glucosamine | glucosamine and chondroitin |
| Eyes | lutein studied in macular degeneration | lutein and eye vitamins |
| Vitamins A and E | easy to go over the upper limit | vitamins A and E |
| Turmeric and curcumin | early evidence for knee osteoarthritis; high-absorption forms linked to rare liver injury | turmeric supplements |
| Glutathione | little evidence, especially for skin whitening | glutathione |
| Astaxanthin | small trials; no proven skin benefit | astaxanthin for skin |
Who should take care
- In pregnancy, avoid supplements with retinol (vitamin A). Beauty formulas may contain it.
- If you smoke or used to, steer clear of high-dose beta-carotene: in trials it raised lung cancer risk.
- With a fish or shellfish allergy, check the source: collagen can be marine, and glucosamine is often made from shellfish.
- Before a blood test, tell your GP about biotin, as it distorts several results.
- Joint pain or swelling that lasts more than a few weeks needs a GP, not a new supplement.
What to check before you buy
- How much vitamin A your multivitamin already has: a beauty formula on top can take you over the limit.
- The collagen source: fish, beef or pork.
- The biotin dose: hair products can contain many times the 30 mcg daily need.
- Whether there’s beta-carotene in it, if you smoke or used to.
How to choose on iHerb
- Define your goal and rule out a deficiency that’s better fixed directly.
- Choose a product with a clear dose of one ingredient rather than a ten-ingredient blend.
- Add up vitamin A, biotin and zinc across all your bottles.
- Read the label with our guide to Supplement Facts.
Bottom line: what to choose
If you want to try collagen
Hydrolysed collagen (peptides)
Judge it after 2–3 months
Collagen on iHerbAge-related macular changes
Lutein and zeaxanthin
No beta-carotene if you smoke or used to
Lutein on iHerbButtons lead to selections of the right form on iHerb. These are affiliate links; your price doesn't change.
FAQ
What are the best vitamins for hair growth?
Find the cause first. The NHS lists iron deficiency, stress, illness and weight loss as causes of temporary hair loss. If a test shows low iron, iron is what you need, not a hair formula. Biotin only helps if you’re deficient, and that’s rare.
Do collagen supplements reduce wrinkles?
Trials of hydrolysed collagen are small and the results are mixed. There’s no strong evidence that it noticeably reduces wrinkles. If you want to try it, give it at least 2–3 months before deciding.
Do glucosamine and chondroitin work for joints?
NICE’s 2022 osteoarthritis guideline says glucosamine should not be offered, because there’s no strong evidence of benefit. Exercise, weight loss and pain relief agreed with your GP have the best evidence.
Should I stop biotin before a blood test?
Tell your GP and the lab that you take it. Biotin interferes with some tests: in reported cases, even a single 10 mg dose distorted thyroid test results taken within 24 hours.
Sources
What to choose
Goal and the best-supported option
- Hair loss
- ferritin test and a GP first, then supplements
- Firmer skin
- collagen: limited, modest evidence
- Joint pain
- exercise and weight; NICE advises against glucosamine
- Macular degeneration
- lutein and zeaxanthin with your eye doctor
- Vitamin A
- EFSA limit 3,000 mcg a day
Biotin can distort blood tests: tell your GP if you take it.