The Protein Question: How Much Do You Really Need for Thicker, Healthier Hair?

Protein and Hair Growth: How Much Do You Really Need for Thicker, Healthier Hair?

Want to grow muscle?  Eat protein.  Want to lose weight?  Eat more protein.  Want to grow thicker hair?  Yep, you guessed it.  Protein.  Over the past 20 years, average protein intake in the UK has slightly increased and remains well above recommended levels. However, the sources of this protein have shifted dramatically, with a notable decline in red meat consumption and a massive surge in plant-based, dairy, and processed high-protein alternatives.  The average daily protein intake is around 85g per day for men and 67g for women. This is well over the UK Reference Nutrient Intake (RNI) of 0.75g per kg of body weight (about 56g for an average man and 45g for an average woman).  

The established adult protein recommendation answers a limited question: how much protein is likely to prevent overt protein deficiency in most healthy adults under relatively stable conditions? It does not define the amount required to optimise every tissue (like the scalp), preserve lean mass during ageing or weight loss, support recovery from illness, or maintain hair growth where inflammation, poor energy intake or nutrient deficiencies are present.

Protein availability can become inadequate through several routes:

Insufficient intake: restrictive dieting, poor appetite, one meal per day, food insecurity, fear of weight gain, vegan diets without planning or replacement of meals with low-protein snacks, over reliance on protein supplements.

Low energy availability: when carbohydrate and fat intake are inadequate, amino acids are increasingly oxidised for energy rather than retained for protein synthesis.

Poor digestion: reduced gastric acid, pancreatic insufficiency, gastrointestinal surgery or severe digestive dysfunction may reduce protein breakdown.

Poor absorption: coeliac disease, inflammatory bowel disease, inflammatory bowel syndrome, infection or shortened bowel can reduce amino-acid absorption.

Increased losses: kidney disease with protein loss in urine, protein escaping the digestive tract, burns, wounds and some inflammatory conditions increase protein loss or turnover.

Increased demand: pregnancy, lactation, ageing, resistance exercise, recovery from illness, trauma and chronic inflammatory activity all raise requirements.

In hair loss, the most common issue is likely to be insufficient total protein and energy intake to support all competing tissues once the body has prioritised immune activity, organ function, tissue repair and maintenance of lean mass.

How much protein is reasonable in practice?

In a study comparing a lean beef meal of roughly 1300 kcal containing about 40 g versus 70 g of protein, the higher-protein meal produced a greater positive whole-body net protein balance over the roughly 4-hour post-meal measurement period, mainly because it suppressed protein breakdown more strongly [1]. 

A 2023 study by Trommelen and colleagues compared the response to 25 g and 100 g of milk protein following resistance exercise. The 100 g dose produced a larger and more prolonged anabolic response that continued for more than 12 hours, with sustained release of dietary amino acids into the circulation, greater incorporation into muscle protein and a more positive whole-body net protein balance. The larger serving increased several forms of protein synthesis, including lean muscle, connective-tissue and blood-protein synthesis [2].

This does not mean that 100 g of protein keeps protein synthesis maximally elevated at the same rate for 12 hours. The response changes over time. Some amino acids support muscle and other tissue protein synthesis, some suppress breakdown, and some are used for enzymes, immune proteins, transport proteins or energy.

For hair, the important point is that a substantial protein meal may support the wider amino-acid pool and reduce the need to break down body protein for several hours. However, the hair follicle grows continuously over months, so one large meal cannot provide lasting protection if total daily intake is repeatedly inadequate. 

There is no single ideal figure for every person, but a clinically useful framework is:

Around 0.8 g/kg/day is the conventional minimum allowance for a healthy, sedentary adult. It may be enough to avoid overt protein deficiency, but it leaves little room for error when intake is irregular, protein quality is poor or the body is already under greater metabolic demand.  Ig hair loss is already occurring, this level of intake will be too low.

Around 1.0 to 1.2 g/kg/day is a realistic target when the aim is to support healthy hair growth rather than simply avoid overt protein deficiency.  This range may also be more appropriate where digestion or absorption is compromised. 

Around 1.2 to 1.6 g/kg/day may be more appropriate when the follicle is growing against a background of higher biological demand or reduced nutritional reserve. This may include later life, menopause, regular resistance training, active weight loss, recovery from illness, prolonged inflammation, anaemia or several micronutrient insufficiencies occurring together.

Around 1.6 to 2.0 g/kg/day may be useful where hair loss sits within a wider picture of unusually high protein demand. This may include intensive resistance training, significant calorie restriction, loss of lean mass, prolonged recovery from illness, persistent inflammation or a long history of under-eating.

Research using larger protein feedings shows that the anabolic response can continue for far longer than the brief window once assumed. An anabolic response is the period in which the body is building and repairing more protein than it is breaking down. A substantial serving supports amino-acid availability, increases protein synthesis and suppresses the breakdown of the body’s existing proteins for many hours. This protein-sparing effect produces a more positive whole-body net protein balance.

For hair, the significance lies in that reduced breakdown. When less of the body’s own protein needs to be dismantled to support muscle, immunity, repair and enzyme production, the wider amino-acid supply becomes more stable. The follicle still competes with more essential tissues, but it is doing so in a better-supported metabolic environment.

The appropriate intake still depends on the person. A higher target should be matched to body weight, activity, age, digestive capacity, protein quality and the wider pattern of hair loss.  The aim is not to push protein intake as high as possible. It is to create a sustained, usable amino-acid supply while inflammation, micronutrient insufficiency, poor glucose regulation, digestive dysfunction and prolonged under-eating are addressed at the same time. This supports tissue preservation and recovery while creating a stronger biological environment for healthy hair growth.

Is 70 g of plant protein equivalent to 70 g of animal protein?

On paper, 70 grams of protein is 70 grams of protein. Biologically, it is not quite that simple. The body responds not only to the total amount consumed, but to the form it arrives in, the amino acids it delivers and how well it can be used within the wider diet.

Protein quality depends on three main issues:

1. Total protein supplied

2. The indispensable amino-acid profile

3. How much of each amino acid is digested and absorbed

Many animal proteins contain all indispensable amino acids in proportions close to human requirements and tend to have high ileal digestibility. Individual plant proteins may contain less lysine, methionine, leucine or another indispensable amino acid, and their digestion may be reduced by intact cell walls, fibre, tannins, phytates, trypsin inhibitors or food processing.  Cooking legumes, fermenting, soaking, sprouting, milling and producing tofu, tempeh or protein isolates can improve digestibility. A diet containing beans, lentils, peas, chickpeas, whole grains, nuts, seeds and appropriately formulated plant-protein products is different from obtaining most protein from one poorly digestible cereal.

Best practice for protein supplementation

How could protein sparing matter for hair growth?

One of the key aims in supplementation is protein sparing: providing enough dietary protein to reduce the need for the body to break down its own tissues to meet demand.  Hair follicles require a continuous supply of amino acids for keratin synthesis, cellular turnover, enzymes, transport proteins, immune mediators and tissue repair. During inadequate energy or protein intake, the body can obtain amino acids by breaking down existing tissue proteins and redirecting amino acid transport away from the hair follicle.

Improving whole-body net protein balance could therefore support the follicular environment in several ways:

• fewer of the body’s own proteins need to be broken down to maintain amino-acid availability

• more amino acids remain available for tissue repair and keratin production

• adequate protein supports immune-cell and antioxidant-enzyme production

• sufficient protein helps preserve lean muscle mass, which supports glucose disposal and wider metabolic health

• improved energy and protein availability reduces the metabolic pressure that can shorten the growth phase

What else would have to be corrected?

Protein alone would not reverse a metabolic system that has adapted to years of undernutrition. A significant growth response also depends on:

• sufficient carbohydrate and fat for energy

• iron, zinc, copper, B12, folate and vitamin D status

• digestive and pancreatic function

• coeliac disease or inflammatory bowel disease where relevant

• resistance exercise to direct amino acids towards lean tissue

• inflammation, glucose regulation and thyroid function

• adequate sleep and recovery

Hair growth depends on more than simply reaching a daily protein target. The follicle needs a steady supply of usable amino acids, supported by enough energy, effective digestion and the micronutrients required to turn those amino acids into keratin, enzymes and new tissue. 

The practical goal is to create a sufficiently nourished, metabolically stable environment that the body no longer needs to conserve, ration or redirect amino acids away from muscle, repair and hair growth.

1. Kim IY, Schutzler S, Schrader A, Spencer HJ, Azhar G, Ferrando AA, Wolfe RR. The anabolic response to a meal containing different amounts of protein is not limited by the maximal stimulation of protein synthesis in healthy young adults. Am J Physiol Endocrinol Metab. 2016;310(1):E73-80. doi:10.1152/ajpendo.00365.2015.
2. Trommelen J, van Lieshout GAA, Nyakayiru J, Holwerda AM, Smeets JSJ, Hendriks FK, et al. The anabolic response to protein ingestion during recovery from exercise has no upper limit in magnitude and duration in vivo in humans. Cell Rep Med. 2023;4(12):101324. doi:10.1016/j.xcrm.2023.101324.