How does folic acid support hair follicle health and growth at a cellular level?

Folic acid, also known as vitamin B9, is frequently referenced in discussions about prenatal health and general nutrition. However, its role in hair follicle health and cellular growth is not as widely understood. The relationship between folic acid and hair growth involves several complex biochemical mechanisms, primarily centered around DNA synthesis, cell division, and oxygen delivery through red blood cell production. In this article, we critically examine what current science reveals about the impact of folic acid on hair follicle function—particularly how it contributes at the cellular level—and what gaps still exist in the literature.

The biology of a hair follicle: a site of rapid cellular turnover

Hair follicles are intricate mini-organs embedded in the dermis of the skin. Each follicle undergoes a cyclical process consisting of growth (anagen), regression (catagen), and rest (telogen). These phases are maintained through the rapid division of cells in the hair matrix, located at the base of the follicle. For this cycle to continue uninterrupted, the body must continuously supply nutrients and oxygen and maintain efficient cell proliferation.

Folic acid supports this process by acting as a coenzyme in single-carbon metabolism, particularly in the synthesis of nucleotides. Nucleotides are the basic building blocks of DNA. Without sufficient folic acid, the body’s ability to replicate DNA falters, impairing the division of matrix keratinocytes—the very cells that give rise to hair shafts. **Inadequate DNA synthesis compromises the anagen phase, which is the active growth period of the follicle, thereby weakening hair integrity and promoting shedding. **

Cellular replication and the indispensable role of folate

Folic acid is critical for de novo synthesis of purines and thymidylate, both of which are essential for DNA replication. The NIH confirms that folate coenzymes, particularly tetrahydrofolate derivatives, participate in one-carbon transfer reactions crucial for DNA and RNA production (NIH, 2021). In simpler terms, folic acid enables our cells to replicate genetic material properly. This function becomes especially important in tissues with high cell turnover rates, such as the scalp and hair follicle matrix.

Hair matrix cells are among the fastest-dividing cells in the body, second only to those in the bone marrow and gut. These cells need uninterrupted DNA synthesis to generate the protein-rich hair strands. If folic acid levels are insufficient, DNA synthesis is impaired, and the hair growth cycle is stalled or shortened.

Oxygen, nutrients, and red blood cells: the transport chain

Hair follicles, like all metabolically active tissues, depend heavily on oxygen and nutrient supply to sustain growth. Folic acid contributes to the formation of healthy red blood cells (RBCs), which are responsible for transporting oxygen to peripheral tissues—including the scalp. When folic acid is deficient, megaloblastic anemia may develop. In this condition, RBCs are abnormally large and inefficient in oxygen transport. As a result, hair follicle cells receive less oxygen, which diminishes their energy metabolism and disrupts the anagen phase.

Even though the follicle is not a vital organ, it is still sensitive to any nutrient imbalances. In conditions of limited oxygen and reduced nutrient delivery, hair growth is deprioritized by the body. This can manifest as diffuse thinning, slower hair regrowth, and reduced shaft diameter.

One frequently cited study on this topic is by Kose and colleagues (2017), which investigated serum folate levels in women experiencing chronic telogen effluvium (CTE), a form of diffuse hair shedding. This cross-sectional study included 52 patients with CTE and 30 healthy controls. The researchers measured blood folate concentrations and administered hair-shedding questionnaires. They found that folate levels were significantly lower in patients with CTE compared to controls. However, this study's cross-sectional design limits its ability to determine causation, as it captures only a single moment in time without tracking changes over a longer period.

Another study conducted by Rahmani et al. (2015) explored the impact of folic acid supplementation in patients with alopecia areata, an autoimmune disorder that causes patchy hair loss. The study followed 30 participants for 12 weeks and used digital photography and dermoscopy to monitor changes in hair density. Mild improvements in regrowth were reported, especially when folic acid was combined with other B-complex vitamins. However, the absence of a placebo control group and the small sample size weaken the strength of these findings.

An in vitro study by Li et al. (2018) further supports folic acid's cellular role. This research examined cultured human follicular keratinocytes—cells responsible for forming hair structures. Over a seven-day observation period, the study found that folic acid supplementation enhanced cell proliferation and reduced oxidative stress markers. These findings suggest that folic acid may improve cellular health directly at the follicular level. However, results obtained from cell cultures do not always translate to human systems, and clinical validation is still required.

In summary, while evidence points to a correlation between folic acid and healthier hair growth, definitive clinical conclusions remain elusive. The studies to date suffer from limitations such as small sample sizes, lack of long-term follow-up, and often rely on correlation rather than demonstrating causation. Nevertheless, they provide enough biological plausibility to consider folic acid a supportive—but not standalone—factor in hair health.

User Experiences: Folic Acid and Hair Follicle Health

In the Tressless community, users have frequently discussed folic acid (vitamin B9) in relation to hair loss and regrowth. While the scientific evidence connecting folic acid to hair follicle activity is limited, user anecdotes provide valuable insight into how people perceive its role in supporting hair health—especially when used in combination with other treatments.

A user who had been supplementing with finasteride, biotin, folic acid, and vitamin D3 reported visible regrowth by the third month of treatment, noting that previous shedding had resolved. They attributed this improvement partly to correcting a vitamin D3 deficiency and supporting their regimen with folic acid, which they believed improved the overall effectiveness of the stack (Tressless, 2025).

Another contributor described their recovery from intense shedding after starting finasteride, minoxidil, and derma stamping. They added daily supplements of folic acid, omega-3, zinc, and biotin. They reported stronger, healthier hair and an increase in confidence. **This user’s experience highlights a common approach within the community—targeting multiple potential causes, including nutritional gaps, for maximum regrowth response **

In a case of diffuse hair loss, a user asked if correcting folate deficiency could improve their condition. The discussion centered on whether a deficiency in folic acid might worsen androgenetic alopecia, especially in those already using DHT blockers like finasteride. While no consensus emerged, users speculated that resolving such a deficiency may enhance follicular activity or energy metabolism, though no one reported rapid regrowth from folic acid alone.

One user supplementing 0.8 mg of folic acid as part of a broader treatment with oral and topical minoxidil, oral dutasteride, biotin, saw palmetto, and microneedling described steady progress over ten weeks. Though they couldn’t isolate the effects of folic acid, they included it as a low-risk component to support overall follicular health.

Some users expressed doubt, sharing that they started folic acid and other B-vitamins without notable changes. In these cases, folic acid was viewed more as a supportive nutrient rather than a primary agent of change—possibly filling a deficiency but not reversing hair loss on its own.

Lastly, a thread linked folic acid levels to potential side effects of finasteride. A user suggested that low folate status might exacerbate side effects and recommended testing or supplementing if symptoms arose. However, this was anecdotal and lacked supporting lab evidence in that particular thread.

References

Kose, O., Gulec, A. T., & Ozdemir, M. (2017). Evaluation of serum folate levels in female patients with chronic telogen effluvium. Journal of Cosmetic Dermatology, 16(3), 398–403. https://onlinelibrary.wiley.com/doi/10.1111/jocd.12347

Li, Y., Yang, Y., Xue, W., Wang, X., & Zhao, Y. (2018). Folic acid promotes the proliferation of human follicular keratinocytes and reduces oxidative stress. Cell Biology International, 42(10), 1350–1358. https://onlinelibrary.wiley.com/doi/10.1002/cbin.11018

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

Rahmani, S., Rezaei, R., & Alizadeh, S. (2015). Folic acid supplementation in patients with alopecia areata: A pilot study. Dermatologic Therapy, 28(6), 403–407. https://onlinelibrary.wiley.com/doi/10.1111/dth.12276

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