Vitamins for Hair: What Really Works and Which Tests to Take

"Which vitamins should I take for my hair?" — the industry answers with bright jars of biotin. But the truth is that vitamins work only when there is a real deficiency, and the ones that matter are often not the ones most advertised. Let's break down which vitamins and minerals hair really needs, what is usually useless, and which tests to take before buying anything.

Which Vitamins and Minerals Matter for Hair

Hair growth is an energy-intensive process sensitive to deficiencies. Reviews show that hair condition is genuinely affected by:

• Iron (ferritin) — the most common and significant deficiency, especially in women
• Vitamin D — vitamin D receptors are involved in the hair follicle cycle
• Zinc — needed for keratin synthesis and cell division
• B12 and folate — blood formation and oxygen delivery to the follicle
• Protein — hair is 90% keratin

The key nuance: supplements help when a deficiency exists. In a person with normal stores, "hair vitamins" do nothing — so start not with a purchase but with labs.

Iron and Ferritin — the Main Deficiency

Diffuse shedding most often comes from low ferritin (iron stores), even with normal hemoglobin. For hair, a comfortable ferritin is noticeably above the "lab lower limit". Which iron to choose and how to take it to raise ferritin is in which iron to take for low ferritin.

Vitamin D and Hair

Vitamin D deficiency is associated with increased shedding and patchy alopecia. Repletion in proven deficiency often improves the picture. Which form and dose of vitamin D to choose is a separate topic, but the baseline is the blood 25-OH level.

Zinc, B12 and Folate

• Zinc — deficiency causes brittleness and shedding; but excess zinc is also harmful, so high doses are not needed without a test.
• B12 and folate — especially in vegetarians and with anemia.

Biotin — Is It Really Needed

Biotin (B7) is heavily marketed "for hair and nails", but true biotin deficiency is rare. In people with normal levels, biotin does not speed up hair growth. Moreover, high biotin doses skew lab tests (for example, thyroid hormones and troponin) — the lab should be warned. Bottom line: biotin is justified only with a confirmed deficiency, not "just in case".

What Can Be Harmful

• Excess vitamin A and retinoids — paradoxically worsen shedding
• Excess selenium — toxic to hair
• Excess iron without deficiency — harmful overload

So "more is better" does not apply here: supplements are matched to real deficiencies, not taken blindly.

Which Tests to Take Before Buying Vitamins

Before choosing supplements, it makes sense to see exactly what is lacking:

• Ferritin, serum iron
• Vitamin D (25-OH), B12, zinc
• TSH — the thyroid is a common cause of shedding

A targeted set is convenient — the hair loss panel. Based on the results, supplement matching by your tests suggests specific forms and doses, not a generic multivitamin. If shedding is pronounced, the causes are covered in hair loss: causes and separately in women.

When to See a Doctor

Vitamins do not solve the problem if the cause is androgenetic alopecia, thyroid disease, an autoimmune process, or medications. If hair falls out in clumps, there are bald patches, itching or scalp flaking (possible seborrhea) — an in-person visit to a trichologist or dermatologist is needed.

This information is for educational purposes and does not replace a specialist consultation.