Nutritional Hair Loss: Identifying the Cause Matters

Hair loss can be frustrating and emotional, but successful treatment starts with understanding why it is happening. Hair loss is not one-size-fits-all. Genetics, inflammation, stress, hormonal changes, medications, illness, and nutritional deficiencies can all disrupt the hair cycle. Unless the underlying cause is identified, treatments are often disappointing.

Understanding the Different Types of Hair Loss

Genetic Hair Loss

Androgenetic alopecia is influenced by genetics and sensitivity to dihydrotestosterone (DHT). This gradually shortens the growth phase of the hair cycle, causing follicles to miniaturise and produce finer, shorter hairs over time.

Inflammatory Hair Loss

Inflammation caused by scalp disorders, chronic stress, illness, autoimmune conditions, or environmental factors can push hairs into premature shedding and impair healthy follicle function. Reducing inflammation and supporting scalp health are essential components of treatment.

Nutritional Hair Loss

One of the most common and overlooked causes of hair loss is nutrient deficiency or poor nutrient absorption. Hair is considered non-essential tissue. When nutrients are limited, your body prioritises vital organs and survival over hair growth.

The follicle is one of the most metabolically active structures in the body, requiring a constant supply of amino acids, vitamins, minerals, fatty acids, oxygen and energy to maintain healthy growth. Even mild deficiencies can affect the quantity, quality, strength and diameter of new hairs.

Why Blood Work Matters

Blood testing helps remove the guesswork and allows treatment to be tailored to your individual needs.

Ferritin (Iron Stores)

Ferritin reflects your body's iron reserves. Iron is essential for DNA synthesis, cellular energy production and oxygen delivery to rapidly dividing matrix cells in the follicle.

Low ferritin is one of the most common causes of chronic telogen effluvium.

Optimal ferritin levels for healthy hair growth are generally considered to be:

• 70–100 ng/mL (μg/L)

• Levels below 40 ng/mL are commonly associated with increased shedding.

• Levels below 30 ng/mL are considered deficient.

Iron deficiency can occur due to:

• Heavy menstrual bleeding

• Pregnancy and postpartum recovery

• Vegetarian and vegan diets

• Low stomach acid

• Gut disorders such as coeliac disease

• Frequent blood donation

• Chronic inflammation

Vitamin D

Vitamin D functions more like a hormone than a vitamin. Hair follicles contain vitamin D receptors, which play an important role in regulating the hair cycle and supporting follicular stem cells.

Optimal levels:

• 50–80 ng/mL (125–200 nmol/L)

• Levels below 30 ng/mL (75 nmol/L) are often associated with hair shedding.

Risk factors include:

• Limited sun exposure

• Darker skin tones

• Sunscreen use

• Indoor occupations

• Obesity

• Malabsorption disorders

Vitamin B12

Vitamin B12 supports DNA synthesis, red blood cell production and oxygen delivery.

Optimal levels:

• Above 500 pg/mL

• Levels below 300 pg/mL may contribute to fatigue and poor hair quality.

Risk factors include:

• Vegan diets

• Low stomach acid

• Metformin use

• Long-term antacid medications

• Pernicious anaemia

Folate

Folate works alongside vitamin B12 in cell division and DNA synthesis.

Optimal levels:

• 10 ng/mL

Zinc

Zinc is involved in hundreds of enzymatic reactions and is essential for protein synthesis, tissue repair and regulating inflammation.

Optimal serum zinc:

• 80–120 μg/dL

Deficiency can contribute to:

• Excessive shedding

• Brittle hair

• Slow growth

• Dandruff and scalp inflammation

Food sources include:

• Oysters

• Beef

• Pumpkin seeds

• Chickpeas

• Cashews

Selenium

Selenium supports thyroid hormone metabolism and antioxidant defence.

Food sources:

• Brazil nuts

• Seafood

• Eggs

Both deficiency and excess selenium can cause hair loss, so supplementation should only be guided by testing.

Copper

Copper assists iron metabolism, collagen formation and melanin production.

Food sources include:

• Shellfish

• Nuts

• Seeds

• Organ meats

Long-term zinc supplementation without adequate copper intake can create imbalance.

Protein: The Foundation of Hair

Hair is made primarily of keratin, a structural protein composed of amino acids.

Without adequate protein intake, the body conserves amino acids for essential organs and hair growth slows.

Aim for approximately:

• 1.0–1.5 g protein per kilogram of body weight daily.

• Higher intakes may be beneficial during recovery from telogen effluvium, postpartum shedding or illness.

Important amino acids include:

Cysteine

Provides sulphur bonds that give hair strength.

Sources:

• Eggs

• Poultry

• Fish

• Lentils

• Sunflower seeds

Methionine

Required to form cysteine and keratin.

Sources:

• Eggs

• Meat

• Fish

• Brazil nuts

• Sesame seeds

Lysine

Enhances iron absorption and collagen production.

Sources:

• Beef

• Poultry

• Dairy

• Legumes

Essential Fatty Acids

Omega-3 fats support cell membranes, reduce inflammation and help maintain scalp barrier function.

Sources include:

• Salmon

• Sardines

• Chia seeds

• Flaxseed

• Walnuts

Antioxidants and Collagen Support

Hair follicles generate significant oxidative stress during growth.

Vitamin C is essential for:

• Iron absorption

• Collagen synthesis

• Antioxidant protection

Sources include:

• Kiwifruit

• Berries

• Citrus fruits

• Capsicum

Vitamin E helps protect cell membranes from oxidative damage.

Sources include:

• Almonds

• Sunflower seeds

• Avocado

Supporting Nutrient Absorption

Having nutrients in the diet doesn't guarantee they are being absorbed.

Hair loss can be linked to:

• Low stomach acid

• Coeliac disease

• IBS and inflammatory bowel conditions

• Chronic stress

• Long-term antacid use

• Bariatric surgery

• Heavy menstrual bleeding

• Vegan diets

Supporting digestive health and identifying absorption issues is often just as important as increasing nutrient intake.

Building Hair from the Inside Out

Healthy hair requires:

Protein

The building blocks for keratin.

Iron

Oxygen delivery and cellular energy.

Vitamin D

Hair cycle regulation.

Zinc

Protein synthesis and tissue repair.

Vitamin B12 and Folate

DNA synthesis and rapidly dividing cells.

Essential Fatty Acids

Healthy scalp barrier and anti-inflammatory support.

Antioxidants

Protection against oxidative stress.

Once internal health is optimised, topical products and scalp treatments can support the environment in which hair grows.

Low-level laser therapy (LLLT), microneedling, scalp massage, peptides and targeted topical ingredients can complement internal treatment, but no topical product can overcome an unresolved nutrient deficiency.

The Bottom Line

Hair is one of the first tissues to suffer when the body lacks the nutrients needed for growth. Identifying deficiencies through blood testing, addressing absorption issues, and supplying the follicle with the raw materials it needs provides the foundation for healthy, resilient hair.

Treating hair loss isn't simply about stimulating growth. It's about giving the follicle everything it needs to produce healthy hair in the first place.