The Function of Hair
The physiological function of hair is primarily to protect the head. In winter, it prevents heat loss, while in summer, it protects against the harmful effects of ultraviolet rays. The main protein that makes up hair is keratin. Healthy hair is a symbol of health and beauty, and like any other part of the body, hair requires various nutrients to regulate its growth cycle. Many nutritional deficiencies are associated with hair loss, and the following are key nutrients closely related to hair health.
How is Abnormal Hair Loss Defined?
In a normal scalp, there are approximately 100,000 to 150,000 hair follicles. Losing fewer than 100 hairs per day is considered normal, but if the daily hair loss exceeds 100 hairs, it may be due to some abnormal factors. The growth and shedding cycle of each hair follicle is determined by genetics, but external factors such as diet, chronic stress, lack of sleep, hair dyeing, hair straightening, postpartum hair loss, etc., can affect the rate of hair loss.
Healthy hair is a symbol of health and beauty, and like any other part of the body, hair requires various nutrients to regulate its growth cycle. In fact, many nutritional deficiencies are associated with hair loss. The following are key nutrients highly relevant to hair.
If daily life is too busy to maintain a balanced diet, it is recommended to supplement with a comprehensive multivitamin to provide these essential nutrients.
Recommendations for Supplementing These 9 Nutrients for Abnormal Hair Loss
Among the B vitamins, biotin (Vitamin B7) is most closely related to hair growth. Biotin is a fundamental vitamin for the basic structure of hair protein. It is often used as an alternative therapy for hair loss, and supplementation in individuals with deficiency can lead to optimal improvement in hair loss. However, biotin is commonly found in various foods, and deficiency is not common unless there is a highly unbalanced diet. Other B vitamins contribute to the production of red blood cells, which carry oxygen and nutrients to the scalp and hair follicles, playing a crucial role in hair growth    .
Hair is primarily composed of proteins, and collagen protein is an essential component of hair structure. Adequate protein strengthens the circulatory system, helping hair follicles receive sufficient nutrients for healthy, moisturized, and shiny hair. Conversely, protein deficiency can lead to hair thinning and loss   .
Iron helps red blood cells carry oxygen to cells, and it is essential for various bodily functions, including hair growth. Iron deficiency is a common nutritional deficiency worldwide, especially in women due to menstrual bleeding and inadequate intake. Some studies found that low serum ferritin (a measure of iron stores) can lead to hair shedding or thinning during the resting phase, and supplementation can improve hair growth and thickness     .
Vitamin A helps hair cell growth and aids sebaceous glands in producing the oily substance called sebum, which moisturizes the scalp and contributes to maintaining healthy hair. Vitamin A deficiency can lead to dry, dull, and easily breakable hair. However, excess intake of vitamin A can also cause hair loss   
Also known as ascorbic acid, vitamin C is a water-soluble vitamin derived from glucose metabolism. It is a powerful antioxidant that helps prevent oxidative stress caused by free radicals. Vitamin C reduces damage from free radicals and prevents hair aging due to oxidative stress. Additionally, vitamin C aids in the absorption of iron in the intestines, a mineral essential for hair growth. Deficiency in vitamin C can lead to abnormal hair conditions     .
Similar to vitamin C, vitamin E is an antioxidant that helps prevent oxidative stress. In a study, individuals with hair loss who supplemented with vitamin E for 8 months experienced a 34.5% increase in hair growth, compared to a minimal increase of 0.1% in the placebo group. Several clinical studies found that individuals with androgenetic alopecia (common baldness) had significantly lower levels of vitamin E on average, suggesting that vitamin E is involved in maintaining the balance of oxidative stress/antioxidants in the body and helps prevent hair loss due to free radical damage. However, like other fat-soluble vitamins, care should be taken not to overdose, leading to toxicity     .
Current research suggests that individuals with hair loss often have low levels of vitamin D. While the specific role of vitamin D in hair growth is not fully understood, it is believed that vitamin D aids in the formation of new hair follicles, contributing to the growth of new hair    .
Zinc plays a crucial role in the growth and repair of hair tissue and helps maintain the normal functioning of oil glands around follicles. Hair loss is a common symptom of zinc deficiency, and supplementation can reduce hair loss caused by zinc deficiency. Some studies found that in 312 patients with alopecia areata, male and female pattern baldness, and telogen effluvium (hair loss during resting phase), zinc concentrations were statistically lower than in 30 healthy control subjects, and zinc supplementation was therapeutically effective     .
Rats deficient in selenium exhibit sparse hair growth, and mice lacking specific selenium protein genes show gradual hair loss after birth. Supplementing selenium can reduce hair thinning caused by selenium deficiency     .