Protein for hair: how does it work?

Has dry, brittle hair got you down? Are you struggling with breakage or finding it impossible to grow your strands past your shoulders? If you’re looking for ways to support your hair, here’s the secret: healthy hair starts from within.¹ A balanced diet is one part of the puzzle when it comes to your locks – and that means getting enough of all the nutrients you need, including protein.¹ Whilst there’s no one single food that equals healthy hair – let’s talk about protein for hair and which protein-rich foods may help your hair.

Hair is mostly made up of a protein called keratin, which is why you’ll normally see haircare treatments with keratin in.^1,2 Sounds like you should eat more keratin then, right? If only it were that simple. Your body can’t absorb most keratin from food because it can’t break it down.² Instead, your body builds all the keratin it needs from the amino acids found in the protein you eat.²

From a protein hair mask to a glossy salon treatment with keratin, topical protein products can make hair feel smoother, less frizzy and add temporary shine. But here’s the important distinction: they don’t work in the same way as the protein you eat. Dietary protein is needed for normal hair growth, while topical treatments work on the appearance and feel of the hair you already have.⁴

Treatments that combine keratin and protein, bond-building formulas, conditioners or even a protein spray for hair are designed to coat or temporarily support the hair fibre and appearance. They may help soften the look of split ends, add shine and make strands feel better, but they can’t feed the follicle or directly trigger new growth.

You might also have seen buzzy terms like ‘hair growth peptides’ or ‘hair and collagen’ popping up in the beauty space. These ingredients are often marketed as strengthening or smoothing heroes but in topical haircare, their effects are mostly cosmetic. Think of them as styling support for the outside of the strand, rather than nutrition for the root.

You've probably also seen claims on social media that too much protein can make hair dry or brittle – rather like uncooked spaghetti that snaps instead of bends. Some people report that frequent use of protein-rich hair products leaves their hair feeling stiff or brittle, which is often described as ‘protein overload’. For now, though, the evidence isn't strong enough to confirm whether that's really the case.

Protein provides the amino acids needed to produce keratin, the structural protein that makes up hair, playing a vital role in both growth and strength.¹ So, when you’re not getting enough, your hair may be affected because the body prioritises essential functions over hair growth. A severe protein deficiency can contribute to hair thinning and even hair loss.¹ One type of hair loss, known as telogen effluvium (TE), can happen when the body isn’t getting enough protein, causing more hairs than usual to enter the shedding phase.⁵ Protein-rich foods also provide important nutrients that support healthy hair, including B vitamins – low levels of certain B vitamins have also been associated with hair loss.^5,6

Your hair can reveal a lot about what's going on inside your body. When you're severely lacking protein, your body prioritises essential functions over hair growth, meaning your strands can become thinner, drier and lose some of their natural shine. In some cases, hair may even lose a little of its colour.⁸

Protein is needed to keep your entire body healthy, so it’s important to eat enough.^1-3 The British Nutrition Foundation advises that UK adults should eat 0.75g of protein per kg of body weight a day.¹¹ So, what does that look like? For a 75kg man, that’s about 56g of protein a day, while a 60kg woman should aim for around 45g.¹¹ However, keep in mind that older adults or those with active lifestyles may need even more.¹¹

When it comes to healthy hair, protein is working behind the scenes long before you notice a good hair day. The good news? You don't need a cupboard full of supplements or miracle treatments. For most people, eating a balanced diet that includes protein-rich foods such as lean meat, fish, eggs, dairy, beans, lentils, tofu and nuts is one of the best ways to support healthy hair.^1-3,11

Disclaimer – This article provides informational advice and is not a substitute for medical care. Working with experts for accuracy, we take great care to ensure the information is up-to-date and relevant. However, you should always consult your GP or healthcare professional before using supplements or alternative products, particularly if you have medical conditions or are under supervision.