Is folic acid deficiency a common cause of chronic or sudden hair shedding?

Folic acid, the synthetic version of folate (vitamin B9), is crucial for multiple cellular processes, particularly for DNA synthesis, red blood cell formation, and tissue regeneration. Since hair follicles are among the most rapidly dividing cells in the human body, there is a reasonable biological concern that low levels of folic acid could impact hair health. When folate levels drop, it’s hypothesized that hair follicles may not receive the necessary cellular support to maintain growth, potentially leading to increased hair shedding or reduced regrowth. But how often does this actually happen?

Hair loss can be either chronic—occurring gradually over time—or sudden, manifesting in abrupt clumps or widespread thinning. When trying to pinpoint a nutritional deficiency as a cause, folic acid is often mentioned, along with iron, biotin, and vitamin D. However, assessing folic acid’s role requires not speculation but careful examination of scientific evidence.

Does folate deficiency interrupt the hair growth cycle?

Theoretically, yes. Hair growth is driven by the hair follicle matrix, a group of cells that divide quickly to form the hair shaft. These cells require a constant supply of nucleotides, which depend on folate for synthesis. In the absence of sufficient folate, the proliferation of these cells could slow, disrupting the anagen (growth) phase of the hair cycle and potentially pushing more hairs into the telogen (resting) or exogen (shedding) phases. In addition, folate contributes to the production of red blood cells. A deficiency can result in megaloblastic anemia, which reduces oxygen delivery to peripheral tissues such as the scalp. In a hypoxic environment, hair follicles may weaken and become less active, but this is more likely in severe or chronic deficiencies.

However, the physiological plausibility of these mechanisms does not confirm their relevance in common hair loss cases. The gap between theory and clinical relevance is where research must be examined.

What does the evidence really say?

In 2017, a systematic review conducted by Almohanna et al. analyzed existing literature on vitamin and mineral deficiencies and hair loss. The review concluded that while folate is important for general health, its role in hair shedding remains uncertain due to limited and inconsistent data across studies. More robust links were found between hair loss and deficiencies in iron and vitamin D. Importantly, the review highlighted that much of the available research was either observational or lacked sufficient control groups, making it difficult to establish a cause-effect relationship for folate.

The U.S. National Institutes of Health Office of Dietary Supplements corroborates this cautious view. According to its fact sheet on folate, the most commonly reported deficiency symptoms include fatigue, poor growth, and megaloblastic anemia. Hair loss is not typically included in this list, indicating that only severe or long-term deficiencies may contribute to this symptom, and even then, it is not guaranteed. While Rushton et al. in a 2002 review did observe lower folate levels in some women experiencing chronic telogen effluvium (a form of diffuse hair loss), the study stopped short of concluding folate was the primary factor. Other underlying conditions, lifestyle factors, or overlapping deficiencies were not ruled out. The study’s design—a retrospective analysis of clinical histories and blood tests—limits its ability to assign causality.

Who might experience hair loss due to folate deficiency?

Even though folate deficiency is not commonly responsible for hair loss, certain populations could be more susceptible to its effects. These include pregnant individuals, people with malabsorption disorders such as celiac disease or Crohn’s disease, those taking medications that interfere with folate metabolism (e.g., methotrexate or anticonvulsants), and individuals with alcohol use disorders. In these groups, folate deficiency can become severe enough to disrupt normal cell division, potentially contributing to tissue-level symptoms, including hair fragility. However, it remains unclear whether this symptom would manifest without the presence of other health issues.

So, is folic acid deficiency a common cause of chronic or sudden hair shedding?

The short answer is no. Despite folate's biological importance, scientific evidence does not support folic acid deficiency as a common or primary cause of either chronic or sudden hair shedding. While a profound deficiency may affect hair follicles, such scenarios are relatively rare and usually occur in individuals already affected by broader nutritional or systemic issues. In the general population, especially in countries with folate-fortified foods, folic acid deficiency is uncommon. When people experience hair loss, iron deficiency, thyroid imbalances, hormonal shifts, genetic predisposition, and stress are far more likely contributors.

Maintaining adequate folate levels is unquestionably important for overall cellular health. But addressing hair shedding requires a holistic diagnostic approach that examines multiple nutritional, hormonal, and environmental factors—not just folate in isolation.

Final reflection

As individuals confronting sudden or ongoing hair shedding, it's natural to wonder whether something as seemingly simple as a missing vitamin could be the cause. But the science points elsewhere. Unless a folate deficiency is confirmed through clinical blood work and occurs alongside other symptoms such as fatigue or anemia, it is unlikely to be at the root of the problem. Understanding the complexity of hair loss means turning to a broad spectrum of causes and reserving folate deficiency as a possibility only in very specific and clinically supported contexts.

User Experiences

Across the Tressless community, folic acid deficiency is not widely regarded as a primary cause of hair loss, but several users have discussed its potential contribution to chronic or sudden shedding. While not universally emphasized, correcting a deficiency may improve overall hair health, especially when it occurs alongside other nutrient deficiencies.

One user reported having both vitamin D and folic acid deficiency during a period of noticeable hair shedding. After beginning supplementation, they observed only minor changes. This suggested that while folic acid deficiency might be involved, it was not the sole driver of their condition. In other words, folic acid may play a role, but often in combination with other underlying factors. Another discussion revolved around users correcting deficiencies in vitamin D3, B12, and folic acid. Some noticed a reduction in shedding and an improvement in hair texture after restoring their nutrient levels. Others, however, shared that they saw no noticeable difference. The overall consensus was that while correcting folic acid deficiency may benefit general hair health, the improvement is usually subtle unless the deficiency is severe.

A specific question raised in the community asked whether a folate deficiency could worsen androgenetic alopecia while on finasteride. Most users felt that fixing the deficiency could support hair health in a general sense, but they did not believe it would alter the course of androgenetic alopecia, which is primarily driven by DHT. Folic acid was viewed more as a supportive element in a broader treatment plan.

One user shared a positive experience using a regimen that included finasteride, biotin, folic acid, vitamin D3, and microneedling. They experienced noticeable regrowth after correcting a vitamin D3 deficiency and using folic acid regularly. While folic acid was part of their routine, it was difficult to determine whether it had a central effect or simply supported other more effective treatments. In discussions about supplementation following hair transplants or general regrowth efforts, folic acid was occasionally included in multivitamin plans. It was not commonly singled out, but included alongside iron, vitamin C, and NAC as part of an overall strategy to prevent shedding and improve recovery. Users typically emphasized that supplementation without correcting underlying causes, like androgenic factors or scalp inflammation, would offer limited benefits.

References

Almohanna, H. M., Ahmed, A. A., Tsatalis, J. P., & Tosti, A. (2018). The role of vitamins and minerals in hair loss: A review. Skin Appendage Disorders, 4(4), 236–244. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5315033/

Rushton, D. H., Norris, M. J., Dover, R., & Busuttil, N. (2002). Nutritional factors and hair loss. Clinical and Experimental Dermatology, 27(5), 396–404. https://pubmed.ncbi.nlm.nih.gov/11966678/

National Institutes of Health Office of Dietary Supplements. (2021). Folate: Fact sheet for health professionals. https://ods.od.nih.gov/factsheets/Folate-HealthProfessional/

U.S. Food and Drug Administration. (2023). Folic acid. https://www.fda.gov/food/food-additives-petitions/folic-acid Tressless Community. (2024, May 19). Can vitamin d and b9 (folic acid) deficiency cause hair loss? Retrieved from https://reddit.com/r/tressless/comments/1cvdsqb/can_vitamin_d_and_b9_folic_acid_deficiency_cause/

Tressless Community. (2019, September 20). Did anyone see a difference in hair growth after correcting a folic acid (folate) deficiency? Retrieved from https://reddit.com/r/tressless/comments/d6tuyh/did_anyone_see_a_difference_in_hair_growth_after/

Tressless Community. (2024, January 20). Can a folate deficiency make androgenetic alopecia worse? Retrieved from https://reddit.com/r/tressless/comments/19blwbi/can_a_folate_deficiency_make_androgenetic/

Tressless Community. (2025, July 15). 2nd month vs 3rd month .fin 1 mg,5mg biotin and folic acid, weekly once 60k vitamin d3. Retrieved from https://reddit.com/r/tressless/comments/1m06ld0/2nd_month_vs_3rd_month_fin_1_mg5mg_biotin_and/

Tressless Community. (2023, December 13). Whats best vitamins and supplements before and after hair transplant? Retrieved from https://reddit.com/r/tressless/comments/18h7mcr/whats_best_vitamins_and_supplements_before_and/