Supplements for Hair Growth: Science-Backed Nutrient Guide

Many people view their hair as a key part of their identity and confidence, making the experience of thinning or dullness deeply personal. While local treatments like scalp oils and targeted shampoos are incredibly popular, true hair vitality starts from within our cells. Scientific evidence suggests that targeted nutritional support may help encourage healthy hair growth by nourishing the scalp from the inside out.

How it works

Hair is produced within tiny structures under the skin called hair follicles. These follicles are highly active, containing some of the fastest-growing cells in the human body. To maintain this rapid rate of cellular division, the follicles require a steady supply of energy, oxygen, and micronutrients delivered directly through the bloodstream.

The hair growth cycle goes through three main phases: active growth (anagen), transition (catagen), and resting (telogen). When the body undergoes physical stress, illness, or nutritional deficiencies, it naturally prioritises survival by sending nutrients to vital organs like the heart and brain first. This shift can starve the hair follicles, pushing them prematurely into the resting phase and leading to increased shedding. Optimising your nutrient intake supports the growth phase and keeps follicles functioning efficiently.

Evidence-based benefits

• Biotin (Vitamin B7) may support keratin production: Biotin is a key coenzyme involved in forming keratin, the fibrous protein that makes up the main structure of your hair shafts. However, biotin supplementation is generally only beneficial if you have a true clinical deficiency, and there is little evidence that extra biotin helps healthy people grow hair.
• Iron may promote oxygen delivery to cells: Iron is essential for the production of haemoglobin, a protein in red blood cells that transports oxygen to your hair follicles to support recovery and growth. Nevertheless, taking iron supplements when your levels are already normal can lead to toxicity, so you should only use them after a clear medical diagnosis.
• Zinc may assist with follicle repair and growth: Zinc is a crucial mineral that helps regulate cellular division and supports the oil glands surrounding each hair follicle. Be aware, however, that excessive zinc supplementation can actually trigger hair loss and interfere with your body's absorption of other key minerals like copper.
• Vitamin D may help stimulate new hair follicles: This hormone-like vitamin plays an important role in follicle differentiation, helping to awaken dormant follicles and maintain the active growth phase. Still, most data connecting vitamin D to hair health is based on observational studies, and clinical trials are ongoing to prove its direct effectiveness.
• Selenium may protect follicles from oxidative stress: As a potent antioxidant, selenium helps neutralise free radicals that can cause premature aging and weakening of the hair structure. However, you must be cautious with dosing, as consuming too much selenium can be toxic and may actually cause hair loss rather than prevent it.

How to take it / typical dose

Finding the right supplement involves identifying which specific nutrients your body is lacking. Rather than guessing, it is best to ask your GP for a simple blood test to check your levels. If you decide to add a supplement to your daily routine, choose high-quality products that contain scientific dosages. A standard daily multivitamin designed for hair often includes recommended daily allowances of biotin, zinc, and selenium. Because the hair growth cycle is a slow, natural process, consistency is vital. You should expect to take a supplement regularly for at least three to six months before expecting to see visible changes in hair density or texture.

Safety and who should avoid it

Although dietary supplements are accessible over the counter, they are not universally safe for everyone. Pregnant or breastfeeding women should avoid taking high doses of pre-formulated hair vitamins, as ingredients like vitamin A can cause cellular issues in developing babies. Biotin is another ingredient to watch closely, as list-topping doses can interfere with vital laboratory tests, including those used to check thyroid and heart health. If you are scheduled to have blood tests or surgery, or if you are currently taking prescription blood thinners, you must discuss your supplement plan with your doctor first.

The bottom line

While nutritional supplements may support the health of your scalp and hair follicles, they work best alongside a balanced diet, proper stress management, and a gentle hair care routine. Nourishing your body from the inside is a great first step, but it is always wise to consult a healthcare professional for personal advice.