Our hair is more than just an aesthetic feature – it reflects our overall health. To understand how diet and lifestyle affect hair health, we first need to understand the growth cycle and the basics of hair biology.

Each hair goes through a cycle of three phases: The anagen phase is the active growth phase, which can last from 2 to 7 years. During this time, the hair grows about one centimeter per month. The length of this phase determines how long a hair can eventually grow. The catagen phase is a short transition phase of about two weeks, during which the hair follicle regresses. The telogen phase is the resting phase, which lasts about three months before the hair falls out and a new cycle begins.

Approximately 85 to 90 percent of hairs are in the anagen phase at any given time. Losing 50 to 100 hairs per day is normal and part of the natural cycle. It becomes problematic when more hairs than usual fall out or when the regrowing hairs are thinner.

Hair follicles are among the most metabolically active tissues in the body. They divide faster than almost all other cells. This high rate of division makes them sensitive to nutrient deficiencies and metabolic stress – changes in diet or health often become apparent early on in the hair.

Hair health is influenced by genetics, hormones, diet, stress, and external factors. While genetics cannot be changed, the other factors can be positively influenced through lifestyle changes.

Not all hair loss is the same. Distinguishing between different types helps to identify the underlying cause and take appropriate action.

Androgenetic alopecia – hereditary hair loss – is the most common form. In men, it typically manifests as a receding hairline and thinning at the crown. In women, the thinning is more diffuse, often starting at the crown. The cause lies in the genetic sensitivity of the hair follicles to dihydrotestosterone (DHT). This form cannot be cured through diet, but its progression can be slowed.

Telogen effluvium is diffuse hair loss that typically begins 2 to 4 months after a trigger. Triggers can include: crash diets or malnutrition, pregnancy and childbirth, serious illness or surgery, severe psychological stress, medications, and hormonal changes. This form is usually reversible once the trigger is eliminated.

Nutrient deficiency-related hair loss can occur with a lack of iron, zinc, biotin, vitamin D, protein, and other nutrients. It often manifests as diffuse thinning and can overlap with telogen effluvium.

Alopecia areata is an autoimmune disease in which the immune system attacks the hair follicles. It manifests as circular bald patches. Diet plays a minor role in this condition.

Traction alopecia is caused by chronic pulling on the hair – tight hairstyles, extensions, certain styling practices. The solution lies in changing these practices.

Iron is the nutrient most commonly associated with hair loss. Iron deficiency is particularly prevalent among menstruating women, vegetarians, and active female athletes, and can lead to diffuse hair loss – often before other symptoms appear.

The link between iron and hair health is well documented. Hair follicle cells divide rapidly and have a high iron requirement. In case of deficiency, iron is prioritized for more vital functions, and hair growth is restricted.

Interestingly, hair loss can occur even at low ferritin levels, which are still considered 'normal'. Many experts recommend ferritin levels of at least 70 ng/ml for optimal hair health – higher than the lower limit of the normal range.

Supplementation for a proven deficiency typically shows improvement after 3 to 6 months – the time the body needs to replenish its stores and start new, healthy hair cycles.

Dietary iron absorption can be optimized by: combining it with vitamin C, avoiding coffee and tea with meals, and including heme iron from meat whenever possible. If a deficiency persists despite dietary adjustments, supplementation is advisable.

But be careful: Supplementation without a proven deficiency is not recommended. Too much iron is also harmful. A blood test before supplementation is mandatory.

Besides iron, other nutrients play an important role in hair health. Understanding these connections enables targeted nutritional strategies.

Zinc is essential for protein synthesis and cell division – both critical for hair growth. Zinc deficiency can lead to hair loss, thinning hair, and slower growth. Good sources include oysters, beef, pumpkin seeds, and chickpeas. Absorption is inhibited by phytates from whole grains and legumes – a factor in vegetarian diets.

Biotin – vitamin B7 – is the best-known 'hair vitamin', but the evidence is mixed. Biotin deficiency is rare with a normal diet, but can occur with certain genetic disorders, antibiotic use, or excessive consumption of raw eggs. Supplementation helps in cases of proven deficiency; its benefit is questionable in cases of normal levels.

Vitamin D receptors are located in the hair follicles, and vitamin D plays a role in the hair growth cycle. Low vitamin D levels have been associated with various forms of hair loss. Given the high prevalence of vitamin D deficiency, checking and, if necessary, supplementing is advisable.

B vitamins in general – B12, folic acid, and niacin – support cell health and energy production. A B12 deficiency is particularly relevant for vegans and can contribute to hair loss.

Selenium is important for thyroid function and as an antioxidant. Both deficiency and excess can cause hair loss – an argument against indiscriminate supplementation.

Hair consists of approximately 95 percent keratin, a protein. Adequate protein intake is therefore fundamental for hair health – an often overlooked aspect.

When protein is deficient, the body prioritizes vital functions over hair growth. Hair may enter the telogen phase, become thinner, or grow more slowly. Extremely low-protein diets or general malnutrition often manifest in the hair.

The amino acid cysteine ​​is particularly important – it contains sulfur and forms the disulfide bridges that give keratin its structure. Methionine is the precursor of cysteine. Both are found in animal protein, but also in beans, nuts, and seeds.

Lysine plays a role in iron absorption and collagen production. Studies have shown that supplementation with L-lysine, in combination with iron supplementation, yields better results than iron alone.

The recommended protein intake is approximately 0.8 to 1 gram per kilogram of body weight for the general population – active people need more. For hair health, consistent and sufficient intake is more important than the absolute amount.

A balanced diet with various protein sources usually provides all the necessary amino acids. However, with strictly restrictive or very one-sided diets, amino acid intake can become problematic.

Hormones play a central role in many forms of hair loss. Understanding these connections helps to treat the underlying cause rather than just managing the symptoms.

The thyroid gland influences the entire metabolism, including hair growth. Both hypothyroidism and hyperthyroidism can lead to hair loss. In cases of diffuse hair loss, thyroid function should always be checked. The good news is that hair typically recovers when the thyroid problem is treated.

Estrogen generally has positive effects on hair. The drop in estrogen levels after pregnancy explains postpartum hair loss, which often occurs 3 to 6 months after childbirth. Estrogen deficiency during perimenopause and menopause can also contribute to hair thinning.

Androgens – male hormones – are the drivers of androgenetic alopecia. In individuals with a genetic predisposition, the hair follicles are sensitive to DHT and miniaturize over time. In women with PCOS, elevated androgen levels can contribute to this pattern.

Cortisol – the stress hormone – can affect the hair cycle and trigger telogen effluvium when chronically elevated. Stress management is therefore also relevant for hair health.

Regular monitoring of relevant hormones – thyroid, estrogen, testosterone, cortisol – can identify the cause of hair loss.

Certain eating patterns and diets can have a positive or negative impact on hair health. Understanding these connections helps in making informed choices.

Crash diets and extreme calorie restriction are common triggers of telogen effluvium. The body interprets the energy deficit as a crisis signal and reduces non-essential functions – including hair growth. Typically, hair loss begins 2 to 4 months after starting the diet.

Vegetarian and vegan diets require more attention to critical nutrients: iron, zinc, vitamin B12, and protein. With careful planning, a plant-based diet is compatible with good hair health, but the risk of deficiencies is increased.

Low-carb and ketogenic diets can temporarily cause hair loss. This is often due to rapid weight loss, reduced calorie intake, or nutrient deficiencies, not the carbohydrate restriction itself. Hair usually recovers once the diet is stabilized.

The Mediterranean diet – rich in vegetables, fruit, olive oil, fish and moderate meat consumption – typically provides all the nutrients essential for hair health and is associated with good overall health.

The general principle: Extreme and unbalanced diets increase the risk of nutrient deficiencies and therefore hair problems. A balanced, nutrient-rich diet best supports hair health.

Besides diet, other lifestyle factors significantly influence hair health. A holistic approach takes all these aspects into account.

Chronic stress is a known trigger of telogen effluvium. Stress hormones can disrupt the hair growth cycle, causing more follicles to enter the resting phase. Acute stress—for example, from traumatic events—can trigger intense hair loss, which usually recovers over time. Chronic, persistent stress is more problematic.

Lack of sleep impairs the body's regeneration, including that of the hair follicles. Growth hormones are primarily released during sleep and support cell renewal. Chronic sleep deprivation can negatively affect hair health.

Smoking damages microcirculation and thus the supply of nutrients to the hair follicles. Female smokers have an increased risk of premature graying and thinning hair. Quitting is also beneficial for your hair.

Excessive alcohol consumption can impair the absorption of important nutrients and promote inflammation – both of which are bad for hair health.

Environmental factors such as UV radiation, air pollution, and chlorine can damage hair from the outside. While these factors do not primarily cause hair loss, they can affect hair quality.

Physical stress on the hair – tight hairstyles, hot styling, chemical treatments – can lead to traction alopecia or breakage. Gentler handling protects the hair structure.

If hair loss is persistent or severe, a medical evaluation is advisable. A correct diagnosis is the basis for effective treatment.

The first step is typically a consultation with a general practitioner or dermatologist. The medical history – duration and pattern of hair loss, dietary habits, medications, stress levels, hormonal changes – provides important clues.

Blood tests should examine relevant nutrients and hormones: ferritin and iron, zinc, vitamin D, vitamin B12, thyroid hormones – TSH, fT3, fT4 –, and, if hormonal causes are suspected, also testosterone, DHEA, prolactin.

Trichoscopy – a magnified examination of the scalp – can help dermatologists determine the type of hair loss. Miniaturized hairs suggest androgenetic alopecia, while exclamation mark-shaped hairs are typical of alopecia areata.

In some cases, a scalp biopsy may be necessary to confirm the diagnosis – especially in unclear cases or suspected scarring alopecia.

The trichogram – the microscopic examination of plucked hairs – can determine the ratio of anagen to telogen hairs and objectify increased hair loss.

The diagnosis determines the treatment. Nutrient deficiencies are supplemented, hormonal disorders are treated, and specific therapies are available for androgenetic alopecia.

The treatment for hair loss depends on the cause. Realistic expectations are important – recovery takes time, and not all forms of hair loss are completely reversible.

When nutrient deficiencies are present, correcting the deficiency is the first step. Improvement typically becomes apparent after 3 to 6 months – the time the body needs to start new hair growth cycles. Patience is required.

In cases of telogen effluvium, the hair usually recovers spontaneously once the trigger is eliminated. Regeneration can take 6 to 12 months. Supportive measures such as good nutrition and stress reduction can promote the process.

Specific medications are available for androgenetic alopecia: Minoxidil – available without a prescription as a solution or foam – can stimulate hair growth. Finasteride – prescription only, primarily for men – inhibits DHT production. In women, anti-androgens such as spironolactone can be used.

Complementary therapies such as PRP – platelet-rich plasma – mesotherapy or low-level laser therapy have growing evidence, but are not suitable for everyone and are often expensive.

Hair transplantation is a surgical option for advanced hair loss, which can deliver good results when indicated correctly.

Regardless of the specific treatment, a good basic supply of nutrients, stress management and a healthy lifestyle supports hair health and the effectiveness of other therapies.