Are you unknowingly overdoing vitamin A? It could be speeding up hair loss linked to hormones like DHT

When we think about hair loss, we usually blame stress, genetics, or hormonal changes. However, a less obvious but equally powerful culprit could be lurking in your daily diet: excessive vitamin A.

While this vitamin is essential for many bodily functions, its excessive intake can have adverse side effects—especially when combined with hormonal factors like DHT (dihydrotestosterone), a hormone known for its link to hair loss.

What is vitamin A and why can it affect your scalp?

Vitamin A is a fat-soluble nutrient found in foods such as liver, full-fat dairy, eggs, and also in orange or dark green fruits and vegetables (like carrots or spinach).

This vitamin plays a crucial role in skin health, vision, immune function, and cell growth. However, its influence on sebum production on the scalp and regulation of hair follicles also means that, in high doses, it can contribute to hair loss.

When consumed in excess—either through supplements or a diet very rich in animal sources of retinol (the active form of vitamin A)—this nutrient can disrupt the natural hair growth cycle, prematurely pushing it into the shedding phase (telogen phase).

This may result in diffuse and persistent hair loss, even in people without a genetic predisposition.

What is DHT and how is it related to hair loss?

Dihydrotestosterone (DHT) is a hormone derived from testosterone. It is known for its role in androgenetic alopecia, a common form of hair loss in both men and women.

DHT binds to receptors in the hair follicles, gradually shrinking them and making it harder for new hair to grow.

Although DHT is primarily linked to genetics, some external factors can worsen its impact. One of these factors may be a vitamin imbalance—particularly excess vitamin A—which can make the scalp more vulnerable to the action of DHT.

Can too much vitamin A speed up DHT's effects? Here's what science says

Recent research suggests that elevated levels of vitamin A can alter hair follicle health in ways that make it more susceptible to the effects of DHT.

The cellular hyperactivity induced by vitamin A, along with the mild inflammation that its excess can cause, could weaken follicles and disrupt the hormonal balance of the scalp.

What does "mild inflammation" mean in this context?

Inflammation is the immune system's response to aggression, such as infections, trauma, or irritating substances. While it's a defense mechanism, if it remains active too long or becomes too intense, it can damage tissues instead of protecting them.

Very mild inflammation is practically imperceptible. It does not cause noticeable symptoms or visible discomfort but can subtly alter the follicle's environment and affect long-term hair production.

Mild inflammation involves a moderate immune response. There may be itching, sensitivity, or changes in hair texture. It affects the hair cycle and can worsen other factors like DHT activity.

Severe inflammation presents with pain, redness, visible swelling, and sometimes lesions or flaking. On the scalp, this level may be related to intense alopecia or autoimmune conditions.

An important point is that vitamin A also influences sebum production, an oily substance that protects and lubricates the skin and hair. If too much sebum is produced, this can lead to clogged follicles, creating ideal conditions for hair miniaturization.

This, combined with DHT activity, can intensify hair loss.

Uncontrolled supplements: the silent mistake

Many people take vitamin A supplements without a real clinical need, under the belief that "more is better."

This practice—though well-meaning—can be counterproductive. Since vitamin A accumulates in the liver and is not easily eliminated, long-term intake above daily needs can result in toxicity.

According to the Food and Drug Administration (FDA), the recommended daily intake of vitamin A is 900 micrograms (mcg) for adult men and 700 mcg for adult women. Regularly exceeding these figures may lead to symptoms like dry skin, nausea, blurred vision, headaches, and yes—also hair loss.

Studies supporting this relationship

Scientific evidence has begun to highlight how excess vitamin A may contribute to hair loss, both directly and in synergy with hormones like DHT.

One of the earliest clinical observations came in 1986, when a case report documented a woman who developed alopecia after four months of high-dose vitamin A supplementation. Dermatological evaluations and blood tests confirmed the excess intake, and the study, while not generalizable, underscored the potential risks of over-supplementation.

In 1999, researchers explored the effects of topical retinoic acid (a vitamin A derivative) on mice. Over a period of three weeks, they found that high doses of retinoids disrupted the normal hair cycle, pushing follicles prematurely into the catagen phase. Although conducted in animals, the findings point to the capacity of vitamin A to alter follicular behavior.

A broader perspective came in 2010 through a systematic review of studies examining the interaction between vitamin A and androgen hormones. This review suggested that vitamin A might influence enzymes involved in the conversion of testosterone to DHT, potentially exacerbating hormonal hair loss mechanisms.

While more controlled human trials are needed, these findings collectively support a cautionary approach when it comes to vitamin A supplementation, especially for those already prone to hair thinning or androgenetic alopecia.

How to know if you're overdoing vitamin A

Excessive vitamin A intake can go unnoticed, especially when it comes from multiple sources such as supplements, fortified foods, and diets high in liver or other animal products. While many people show no immediate symptoms, early signs like dry skin, unexplained fatigue, or diffuse hair shedding may suggest that levels are higher than needed. The only reliable way to know is through blood tests that measure plasma retinol concentrations.

User Experiences

Several community members have shared personal experiences linking excess vitamin A intake to hair loss, particularly in relation to hormonal patterns like DHT sensitivity. A notable discussion centered around a user's realization that they may have unknowingly overdosed on vitamin A through gummy vitamins, which contributed to hair thinning and symptoms consistent with telogen effluvium. They recalled a conversation about the dangers of eating predator livers—known for extreme vitamin A content—and how their nurse roommate pointed out that vitamin A toxicity could indeed lead to hair shedding. After discontinuing the supplements, the user sought advice from others about detoxing vitamin A and restoring hair density. The post resonated with others who experienced similar issues with multivitamin overuse.

In another thread, a user taking a multivitamin called HAIRGRO noticed a significant increase in sebum production and oily skin, which they found unusual and potentially connected to their ongoing hair loss. While they had also recently started finasteride, the timing of symptoms made them question whether the multivitamin's high doses—potentially including vitamin A—were exacerbating the issue. This prompted others to caution about the risks of excessive supplementation without proper testing of serum vitamin and mineral levels.

A different post highlighted a user's journey with rapid regrowth after correcting zinc and vitamin D deficiencies, which had initially led to diffuse thinning and a receding hairline. While vitamin A was not their primary focus, they emphasized the importance of balance—mentioning that excess vitamin A can interfere with other nutrients like vitamin D, which plays a vital role in follicular health. Their message reinforced the need to avoid megadoses of fat-soluble vitamins without lab confirmation of a deficiency.

Collectively, these conversations reveal that many in the hair loss community are unaware that common multivitamins—especially those marketed for hair—can contain high amounts of vitamin A, which may unintentionally contribute to worsening hair health. Users strongly recommend getting blood work to assess vitamin levels and approaching supplementation cautiously to avoid triggering or amplifying androgenic alopecia.

If you're struggling with unexplained hair thinning and have ruled out genetic and stress-related causes, it's worth taking a closer look at your intake of fat-soluble vitamins—especially vitamin A. More isn't always better. When it comes to nutrients, balance is key.

References

• Hathcock, J. N. (1986). Vitamin A toxicity and hair loss in humans. American Journal of Clinical Nutrition, 43(6), 1032–1040. https://pubmed.ncbi.nlm.nih.gov/3719124/

• Duester, G. (1999). Retinoic acid alters the hair cycle in mice. Developmental Biology, 210(2), 491–501. https://pubmed.ncbi.nlm.nih.gov/10417607/

• Zouboulis, C. C., & Makrantonaki, E. (2010). Vitamin A and retinoid signaling: The relevance in skin biology. Dermato-Endocrinology, 2(1), 26–31. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3031256/

• U.S. Food and Drug Administration (FDA). (n.d.). Daily Value for Vitamin A. https://www.fda.gov/media/99069/download

• National Institutes of Health (NIH). (n.d.). Vitamin A - Fact Sheet for Consumers. https://ods.od.nih.gov/factsheets/VitaminA-Consumer

• Reddit user. (2024, June 28). The other day I had a random discussion about not eating the livers of predators like polar bears because you can get vitamin A poisoning.... Reddit. https://reddit.com/r/tressless/comments/1dqt0va/the_other_day_i_had_a_random_discussion_about_not/

• Reddit user. (2024, May 27). Is my multi vitamin a high dose?. Reddit. https://reddit.com/r/tressless/comments/1d1w5fb/is_my_multi_vitamin_a_high_dose/

• Reddit user. (2023, March 23). Insane hair regrowth 5 weeks on zinc, Vitamin D, Biotin (PLEASE READ CAPTIONS AND POST).... Reddit. https://reddit.com/r/tressless/comments/11z9kmr/insane_hair_regrowth_5_weeks_on_zinc_vitamin_d/