Biotin, Collagen and Hair Supplements: What the Evidence Says

For most people who are not deficient in a nutrient, there is little good evidence that biotin, collagen or "hair, skin and nails" supplements make hair grow thicker or faster. Supplements can help when a real deficiency, such as low iron, is contributing to hair loss. The most useful step is finding out whether you actually have a deficiency, rather than taking several products and hoping one works.

Why supplements are so popular

Hair loss is upsetting, and a daily capsule feels simple and low-risk. Supplement labels often feature words like "supports healthy hair" that sound convincing but are not the same as proof. In Canada, natural health products are licensed by Health Canada, but the standard of evidence required for many claims is lower than for prescription medicines, and studies paid for by manufacturers are often small and short.

That does not mean every supplement is useless. It means the question to ask is: is there a reason to believe I am low in this nutrient?

Biotin

Biotin, also called vitamin B7, plays a role in making keratin, the main protein in hair. True biotin deficiency causes hair loss, a rash and other symptoms, but it is rare. It can occur with certain inherited conditions, some anti-seizure medications, long-term use of some antibiotics, heavy consumption of raw egg whites, or significant malabsorption.

In people without a deficiency, studies have not shown that extra biotin improves hair growth. Most of the positive reports come from people who had an underlying deficiency or a separate condition. Biotin is cheap and generally well tolerated, which is part of its appeal, but it has one important downside.

Biotin and blood tests

High doses of biotin, which are common in hair supplements, can interfere with many laboratory tests that use a biotin-based method. Depending on the test, results can come back falsely high or falsely low. This has been reported with thyroid tests, hormone tests, and troponin, a test used to check for heart attacks. Health Canada and other regulators have issued warnings about this.

If you take biotin, tell your doctor and the lab before any blood work. Your doctor may suggest pausing it for a few days before testing. Never stop a prescribed medication for a test without your doctor's advice.

Collagen

Collagen supplements are made from animal or fish connective tissue and are broken down into amino acids and small peptides during digestion. Hair itself is made of keratin, not collagen. Some small studies have looked at collagen for skin, with mixed results, but there is very little quality evidence that collagen supplements improve hair loss. Collagen can be a source of protein, but ordinary foods such as eggs, fish, dairy and legumes do the same job.

Other popular ingredients

Many hair products combine vitamins with ingredients such as saw palmetto, marine extracts, keratin or plant oils. A few have small early studies, but the evidence is generally limited, short-term and hard to compare between products. Saw palmetto, for example, has been studied for pattern hair loss with uncertain results, and it may not be appropriate in pregnancy or with some medications. If a product contains many ingredients, it is also harder to know what is causing any benefit or side effect.

When a deficiency really matters

Several nutrients have a genuine link to hair, and correcting a true shortfall can help shedding settle:

• Iron. Low iron stores, measured as ferritin, are one of the most common contributors to hair shedding in women, particularly with heavy periods or a plant-based diet.
• Vitamin D. Low levels are common in Nova Scotia, especially in winter. Links with hair loss have been reported, though it is less clear that supplements improve hair if levels are only mildly low.
• Zinc. Deficiency can cause hair loss, especially after bariatric surgery or with poor absorption.
• Vitamin B12 and folate. More often low with vegan diets, certain stomach or bowel conditions, or some medications.
• Protein and calories. Very restrictive eating can trigger shedding. See our article on hair shedding after rapid weight loss.

Your family doctor can decide which tests make sense for you. For a broader look, see thyroid, iron and other medical causes of hair loss.

When more is not better

Supplements can cause harm, particularly at high doses or in combination:

• Too much iron can cause stomach upset, constipation and, over time, iron overload in people who are prone to it
• Excess vitamin A and selenium can actually cause hair loss
• High-dose zinc taken for long periods can lower copper levels
• Some herbal hair products contain ingredients that interact with medications or are not safe in pregnancy or breastfeeding

If you are pregnant, breastfeeding, have kidney or liver disease, or take regular medications, check with your doctor or pharmacist before starting any supplement. Bring your supplement bottles to appointments so your physician can see exactly what and how much you are taking.

What does have evidence for hair loss

For pattern hair loss, which is the most common cause overall, the treatments with the strongest evidence are medications such as topical minoxidil and, for some people, prescription options discussed with a physician. Platelet-rich plasma (PRP) may help some people as an add-on, but its evidence is still developing. Our overview of hair loss medications explains how these compare. A supplement is not a substitute for a diagnosis.

Frequently asked questions

My hair improved after I started biotin. Was it the biotin?

It might have been, if you were low. But many types of shedding settle on their own within months, so improvement can be a coincidence of timing.

Are gummies as good as tablets?

The form matters less than whether you need the nutrient. Gummies often contain sugar and may have lower or less consistent doses.

Should my children take hair vitamins?

Not without a reason. Children with hair loss should be assessed by their family doctor, and some adult supplements contain doses unsuitable for children.

If you are taking supplements for your hair and are unsure whether they are helping, HealthPark Medical Aesthetics can review your hair concerns, encourage the right testing with your family doctor, and talk through options that have stronger evidence.