Hair Loss, Nutrition and Metabolic Health: What Your Hair May Be Telling You

Hair loss can be deeply distressing, especially when it seems to appear suddenly or when standard advice does not explain why it is happening.

Many people are told that hair loss is simply genetic, hormonal or age-related. Sometimes that is true, but hair loss can also reflect wider changes in the body. Nutrient status, inflammation, stress, thyroid function, gut health, medication use and immune activity can all influence the hair growth cycle.

Hair is not essential for survival, so when the body is under strain, it may reduce resources going towards hair growth and prioritise more urgent physiological demands.

Common Types of Hair Loss

There are several different patterns of hair loss, and the pattern often gives useful clues.

Telogen effluvium is a form of increased shedding. The hair becomes thinner overall, often after a period of stress, illness, infection, surgery, significant weight loss, childbirth or emotional trauma. It can appear a few months after the original trigger.

Androgenetic hair loss is often described as male or female pattern hair loss. In men, this may involve a receding hairline or thinning at the crown. In women, it may appear as widening of the parting or thinning through the top of the scalp. Hormones, genetics, insulin resistance, inflammation and nutrient status can all influence this pattern.

Alopecia areata is an autoimmune form of hair loss where the immune system attacks the hair follicles. It often appears as smooth, round patches of hair loss. In more extensive cases, hair loss can affect the whole scalp or body.

Understanding the pattern matters because the underlying drivers may be different.

Hair Loss After Stress, Illness or Infection

Many people notice increased shedding several months after a major stressor. This can include viral infections, high fever, surgery, emotional stress, bereavement, trauma, childbirth or a significant inflammatory flare.

This happens because the hair growth cycle is sensitive to physiological stress. More hairs may shift from the growth phase into the shedding phase, which is why hair loss may appear weeks or months after the original event.

Supporting recovery requires patience. Hair growth is slow, and visible improvement can take several months. During that time, the body needs adequate protein, minerals, vitamins, energy intake and recovery.

The Nutrients Needed for Healthy Hair Growth

Hair is made from protein, and poor protein intake is one of the most overlooked contributors to weak, thinning or slow-growing hair.

Protein provides the amino acids needed to build keratin, collagen and other structural proteins. If someone is under-eating, dieting aggressively, eating a low-protein diet, recovering from illness or struggling with digestion, hair growth may suffer.

Key nutrients involved in hair health include:

Protein and amino acids Hair requires amino acids to grow. Low protein intake, poor digestion or chronic inflammation can all reduce the resources available for hair growth.

Collagen support Collagen is important for connective tissue integrity and the skin environment surrounding the hair follicle. The body needs amino acids, vitamin C, zinc and copper to support collagen formation.

Zinc Zinc is involved in tissue repair, immune regulation, hormone metabolism and hair follicle function. Low zinc may contribute to shedding, poor hair quality or slow regrowth

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Vitamin C Vitamin C is required for collagen cross-linking and connective tissue strength. Low vitamin C can affect skin, gums, blood vessels and hair quality.

Biotin and B vitamins Biotin is often associated with hair, skin and nails, but it is only one part of the picture. Folate, B12, B5 and other B vitamins also support energy production, methylation, cell division and tissue growth.

Iron Iron is needed for oxygen transport and energy production. Low ferritin is commonly seen in women with hair shedding, especially where there has been heavy menstruation, low intake, poor absorption or chronic inflammation.

Vitamin D Vitamin D plays a role in immune regulation and hair follicle cycling. Low vitamin D may be relevant in some forms of hair loss, particularly where immune dysregulation is involved.

Omega-3 fats Omega-3 fats support inflammatory balance, cell membranes and scalp health. They may be especially relevant where inflammation, dry skin or poor skin barrier function is part of the picture.

Selenium Selenium supports thyroid function and antioxidant defence. Both low and excessive selenium can be problematic, so supplementation should be approached carefully.

Thyroid Function and Hair Loss

Thyroid hormones help regulate metabolic rate, energy production and tissue turnover. Both low thyroid function and excessive thyroid medication can contribute to hair loss.

This is especially relevant in women with Hashimoto’s, hypothyroidism, post-viral symptoms, chronic stress or unexplained fatigue.

A useful thyroid assessment may include more than TSH alone. Depending on the case, it may be helpful to look at free T4, free T3, thyroid antibodies, iron status, selenium, zinc, vitamin D, B12 and inflammatory markers.

Hormones and Pattern Hair Loss

Hormones can strongly influence hair growth.

In androgenetic hair loss, sensitivity to androgens such as DHT may contribute to thinning around the crown, temples or parting. This does not always mean hormones are dramatically abnormal on standard blood tests. The issue may involve follicle sensitivity, inflammation, insulin resistance, nutrient status or impaired hormone metabolism.

In women, pattern hair thinning may also be associated with perimenopause, menopause, PCOS, insulin resistance, stress physiology and changes in oestrogen, progesterone and androgen balance.

This is one reason hair loss should not be assessed in isolation. It often sits within a wider metabolic and hormonal picture.

Autoimmune Hair Loss

Alopecia areata is an autoimmune condition. In these cases, the immune system targets the hair follicle.

When autoimmune hair loss is present, it is important to consider wider immune triggers. These may include gut permeability, food reactions, chronic infections, nutrient deficiencies, environmental exposures, stress load and microbiome imbalance.

Gluten may be relevant for some individuals, particularly in those with coeliac disease, non-coeliac gluten sensitivity or other autoimmune conditions such as Hashimoto’s. This does not mean gluten is the cause of every case of hair loss, but in the right clinical context it should not be dismissed.

Medication-Related Hair Loss

Some medications may contribute to hair shedding or changes in hair quality. This does not mean medication should be stopped without medical guidance, but it is worth reviewing medication history when hair loss begins.

Medication groups that may be associated with hair loss in some people include:

• Some thyroid medications, particularly if dosing is too high or too low

• Retinoids used for acne

• Some antidepressants

• Some blood pressure medications

• Anticoagulants

• Hormonal contraceptives or hormone therapy changes

• Chemotherapy drugs

• Immunosuppressants

• Steroids

• Some anti-inflammatory medications

• Weight loss medications, particularly where appetite suppression leads to low nutrient intake

  
  

The timing matters. Hair shedding may begin weeks or months after a medication change, illness, dosage adjustment or major physiological stressor.

Gut Health, Absorption and Hair

Hair growth depends on nutrient availability. Even a good diet may not be enough if digestion and absorption are compromised.

Low stomach acid, inflammatory bowel disease, coeliac disease, chronic diarrhoea, constipation, SIBO, long-term antacid use, gallbladder issues or repeated antibiotic use can all affect nutrient status.

This is particularly important where hair loss appears alongside bloating, reflux, loose stools, constipation, food reactions, fatigue, skin issues or autoimmune symptoms.

What to Test When Hair Loss Is Persistent

Testing should be guided by the person’s symptoms, history and pattern of hair loss, but useful areas to investigate may include:

• Full blood count

• Ferritin and full iron studies

• B12 and folate

• Vitamin D

• Thyroid panel, including thyroid antibodies where appropriate

• Zinc and copper balance

• Inflammatory markers

• Blood glucose, insulin and HbA1c where metabolic issues are suspected

• Coeliac screening where relevant

• Hormone assessment where pattern hair loss, PCOS, perimenopause or menopause are involved

• Gut testing where absorption, inflammation or microbiome issues are suspected

Hair loss is often multifactorial, so a single marker may not explain the whole picture.

Supporting Hair Growth Naturally

A good starting point is to make sure the body has the raw materials needed to grow hair.

This means:

• Eating enough protein

• Avoiding aggressive dieting

• Supporting blood sugar balance

• Correcting iron, B12, folate, vitamin D, zinc or other deficiencies where identified

• Addressing thyroid and hormonal imbalances

• Reducing inflammatory food triggers where relevant

• Supporting gut health and absorption

• Managing stress and sleep

• Reviewing medications with a qualified prescriber where appropriate

Hair growth takes time. The scalp may need several months of improved nutrition and reduced stress before visible changes appear.

The Bigger Picture

Hair loss is rarely just a cosmetic issue. It can be a sign that the body is under strain.

For some people, the trigger may be low iron. For others, it may be thyroid imbalance, stress, post-infectious inflammation, poor protein intake, autoimmune activity, gut dysfunction or hormonal change.

The key is to stop looking at hair loss as an isolated symptom and start asking why the body is not prioritising healthy hair growth.

When the underlying drivers are identified and addressed, hair can often improve alongside energy, skin health, hormones, digestion and overall wellbeing.