Ignore the noise, here are the four nutrients that actually grow your hair – based on science. Spoiler: biotin is not one of them.
Type the phrase ‘supplements for hair growth” in google, and I guarantee that every result will contain biotin.
While people (especially haircare influencers) portray biotin as a hair-growth aid, the TRUTH is that no scientific evidence backs that claim.
You can get biotin easily from food, and your gut bacteria make it.
Biotin may be effective for hair growth if you have a diagnosed deficiency. Deficiencies are rare, but they can arise if you have a malabsorption disorder, eat raw eggs or take antibiotics frequently.
If none of those applies, taking biotin supplements for hair growth is, in fact, POINTLESS.
Scientific evidence exists for the role of other nutrients in hair growth. Note, however, that these nutrients promote hair growth only if a deficiency exists.
Before we explore the nutrients that actually grow your hair, let’s recap the hair cycle.
The Hair Cycle
Hair is primarily made up of keratin protein – the same protein in your skin and nails. Each hair shaft consists of three layers :
- Cuticle – the protective outer layer
- Cortex – the middle layer, which contains melanin and determines your hair colour
- Medulla – the innermost layer which reflects light
Each hair is attached to the scalp via a follicle. On average, healthy humans have 80,000-120,000 follicles on their scalp .
Hair follicles cycle through three phases, including anagen, catagen and telogen [1, 2].
The anagen (growth) phase lasts between two and six years, and at any given time, 85-90% of hair follicles are in this phase. Some hairs begin to regress and enter the catagen (transition) phase, lasting between two and four weeks. After the transition phase, hairs enter the telogen (resting) phase, which lasts around three months.
Hair is shed after the telogen phase, new hair begins to grow, and the whole cycle repeats itself.
This cycle of growth followed by resting and shedding varies significantly between people. And it is dependent on a variety of factors, including your age, genetics, health status, hormonal imbalances and diet.
Healthy adults shed 70-100 hairs naturally daily . But because new hairs constantly grow and replace them, this natural hair loss isn’t noticeable, and hair volume remains constant.
However, when hair shedding exceeds the usual rate, your hair becomes noticeably thin. If no new hair grows and replaces the hair, that part of the skin becomes bald.
This phenomenon is called alopecia. There are different types of alopecia, but a comprehensive review of alopecia is beyond the scope of this article.
You can’t do anything about your age and genetics, but you can do a lot about your health, hormonal imbalances and diet.
Now let’s explore the components in your diet that actually affect hair growth.
1 | Protein
Protein is made up of amino acids; you need 20 amino acids to function .
Your body can make eleven of them, and these amino acids are known as non-essential amino acids. The other nine are known as essential amino acids because your body can only get them from the food you eat .
Cysteine, methionine and lysine are the three key amino acids that control hair health and growth .
Cysteine and methionine (essential amino acid) are the main building blocks of keratin protein. Cysteine also maintains hair diameter and growth rate .
Lysine, an essential amino acid, maintains hair volume and shape. Lysine deficiencies can cause brittle, thin and limp hair .
Lysine is also vital for zinc and iron absorption, minerals that play critical roles in hair health .
If your diet lacks sufficient quality proteins, your hair can become fragile, brittle and weak, and may eventually fall out. Your hair may also appear lighter or exhibit a banded pattern, known as the flag sign . The darker areas represent those with higher melanin content from improved nutrition
Good sources of the amino acids you need for healthy hair include fish, poultry, legumes, seeds, nuts, grains and eggs.
2 | Fat
Your body needs fat to make steroid hormones, sebum and other fat-containing molecules like ceramides, sterols, cholesterol and phospholipids .
Without sufficient fat in your diet, especially essential fats, your hydration levels decrease, compromising your scalp and hair bulb’s health. You may lose hair on your scalp and eyebrows, and your remaining hair will appear lighter.
Good sources of the essential omega-3 fats include fatty fish, flaxseeds, walnuts and chia seeds. Vegetable oils and nuts are good sources of omega-6 fats, which are also necessary to maintain healthy hair.
Our diets are often heavy in omega 6 fats from consuming vegetable oils, so it’s essential to focus on getting more omega-3s in your diet.
3 | Zinc
Over 300 enzymes in your body require zinc to function correctly . Zinc is essential for growth, development, wound healing, collagen synthesis and immunity.
Your body can’t produce zinc. You can only get it through diet, making it an essential mineral. If your intake of animal proteins, such as poultry, meats and fish, are low, your risk of zinc deficiency increases, especially if you eat plenty of phytate-rich cereal grains .
Phytates bind to zinc and prevent zinc absorption .
People with bowel disease and cystic fibrosis may also be at risk of zinc deficiency due to poor absorption .
People with conditions such as renal disease, sickle cell disease, anorexia, alcoholism who excrete zinc rapidly also have a higher risk of zinc deficiency .
Finally, medications like diuretics, penicillamine and valproic acid lower zinc levels.
Hair dryness, brittleness and alopecia are common and well-established symptoms of zinc deficiency. Studies show hair regrowth with zinc supplementation when deficiencies are present [7,8].
It is worth noting that blood serum levels of zinc are not a good indicator of the body’s zinc stores. However, if you need to supplement with zinc, a professional must monitor your zinc levels because an overdose can lead to copper or calcium deficiencies, drowsiness, and headaches .
4 | Iron
According to the World Health Organisation, iron deficiency is a widespread deficiency that affects up to 80% worldwide [7,9-10].
Iron has many functions . It
- transports oxygen around the body,
- acts as a co-factor for an enzyme vital for DNA synthesis,
- supports a healthy immune system
- promotes collagen synthesis
- acts as a catalyst for many reactions in the body.
Premenopausal women (due to menstrual blood loss), vegans, vegetarians, people with malabsorption disorders (such as celiac disease), and those who use H2 blockers have a higher risk of iron deficiency .
Vegans and vegetarians have a higher risk of iron deficiency because plant foods contain non-heme iron, which humans don’t absorb as efficiently as heme iron found in animal foods. As a result, vegans and vegetarians may have iron requirements that are 1.8 times higher than meat-eaters .
Vegans and vegetarians can improve iron absorption by eating foods rich in vitamin C alongside plant-based iron-rich foods and avoiding excessive tea and coffee consumption .
If you need iron supplements, your doctor must monitor your iron levels because iron overload can cause toxicity. Toxicity can occur even at low levels if you take supplements for prolonged periods .
Much of what we know about micronutrients and hair growth comes from studies in people with diseases or deficiencies. Taking supplements without a diagnosed deficiency is unlikely to have an impact on your hair health and growth.
Food is always the best source of nutrients for your hair and overall health, and now you know the food sources of the four nutrients that actually grow your hair.
If you want to learn how to eat a healthy, balanced diet that’s personalised to your food preferences and unique needs and promotes hair growth and overall health, schedule a 15-minute discovery call to get yourself on the path to wellness.
- Hoover, E., Alhajj, M., Flores, J.L. (2020) Physiology, Hair. Available from: https://www.ncbi.nlm.nih.gov/books/NBK499948/
- Murphrey, M.B., Agarwal, S., and Zito, P.M. (2021) Anatomy, Hair. Available from: https://www.ncbi.nlm.gov/books/NBK513312/
- org [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. What is the structure of hair, and how does it grow? 2019 Aug 29.Available from: https://www.ncbi.nlm.nih.gov/books/NBK546248/
- Wu G (2016) Dietary Protein Intake and Human Health. Food & Function(7): 1251
- Goluch-Koniuszy, Z.S. (2016) Nutrition of women with hair loss problem during the period of menopause. Menopause Reviews, 15, 1.
- Goldberg, L.J., and Lenzy, L. (2010) Nutrition and hair. Clinics in Dermatology, 28, 412–419.
- Almohanna, H.M., Ahmed, A.A., Tsatalis, J.P., Tosti, A. (2019) The role of vitamins and minerals in hair loss: a review. Dermatology and Therapy. 9(1), 51–70.
- Alhaj, E., Alhaj, N., Alhaj, N.E. (2007) Diffuse alopecia in a child due to dietary zinc deficiency. Skinmed, 6(4), 199–200
- Finner, A.M. (2013) Nutrition and hair. Deficiencies and supplements. Dermatology clinics, 31, 167–172.
- Guo, E.L., and Katta, R. (2017) Diet and hair loss: effects of nutrient deficiency and supplement use. Dermatology Practical & Conceptual, 7(1), 1.
- Daniells, S and Hardy, G. (2010) Hair loss in long-term or home parenteral nutrition: are micronutrient deficiencies to blame? Current Opinion in Clinical Nutrition and Metabolic Care, 13, 690-697.