Vitamin C, or ascorbic acid is an essential vitamin naturally present in foods such as citrus fruits, along with other fruits and vegetables. Many supplements promote vitamin C as an ingredient supporting hair health and growth. But is there evidence to support these claims?

In this mini-review, we will take a deep dive into the evidence surrounding vitamin C and determine if any data suggests that it might benefit hair growth in humans with hair loss.

Key Takeaways

• What is it? Vitamin C, also known as ascorbic acid is a water-soluble vitamin that is naturally present in citrus fruits and other fruits and vegetables. Vitamin C cannot be synthesized within the body, so it needs to be taken in through the diet, therefore it is used as an ingredient in many different supplements touted for immune health, skin health and hair health, and growth.
• Evidence Quality: The evidence quality is 3/100 based on our metrics
• Clinical Data: There is no clinical data associating vitamin C supplementation with hair growth in individuals with hair loss disorders or even healthy individuals.
• Safety: There is a low risk of toxicity or serious health issues with vitamin C intake. However, some may experience gastrointestinal issues including nausea, abdominal cramps, and diarrhea with increased intake.
• Who Might Vitamin C Benefit: There is no clinical evidence to suggest that vitamin C supplementation can benefit people with any type of hair loss disorder. However, it is thought that because vitamin C facilitates iron uptake in the intestines it may benefit those with iron deficiency-related diffuse hair loss. Unfortunately, there is currently no data to support this. 

What is vitamin C?

Vitamin C, or ascorbic acid, is an essential nutrient present in fruits and vegetables. Because humans lack an enzyme called gulonolactone oxidase, vitamin C must be taken up through the diet. Lack of vitamin C can cause a disease called scurvy.^[1]Valdes, F., (2006). Vitamin C. Actas Dermo-Sifiliográficas. 97(9). 557-568. Available at: https://doi.org/10.1016/S0001-7310(06)73466-4 While vitamin C is included in many hair growth supplements because of its antioxidant properties and its involvement in collagen synthesis.^[2]Almohanna, H.M., Ahmed, A.A., Tsatalis, J.P., Tosti, A. (2019). The role of vitamins and minerals in hair loss: a review. Dermatology and Therapy. 9, 51-70. Available at: … Continue reading But, is there any evidence to suggest that vitamin C can actually treat hair loss?

Is there evidence of an effect of vitamin C on hair follicles?

The majority of evidence concerning vitamin C and its potential for hair growth is within in vitro (in cells) and in animal studies. The only evidence that vitamin C deficiency might affect hair in humans is a case study in which scurvy (an illness arising from vitamin C deficiency) caused the growth of thick corkscrew-like hairs on the legs of the patient.^[3]Fleming, J.D., Martin, B., Card, D.J., Mellerio, J.E. (2013). Pain, purpura, and curly hairs. Clinical and Experimental Dermatology. 38(8). 940-942. Available at: https://doi.org/10.1111/ced.12118

One in vitro (in cells) study was completed in which human dermal papilla cells were treated with either vitamin C or silymarin – also known as milk thistle (another ingredient purported to have some effects on hair health).^[4]Ashtiani, H.R.A., Dadgar, A., Akaberi, M. (2020). Improvement of Cell Proliferation and Antioxidant Activity of Silymarin in Hair Follicles Dermal Papillae Isolated from the Human Scalp: Comparison … Continue reading

Dermal papillae were isolated from skin biopsies taken from 5 individuals who were referred for treatments to the skin and hair clinic (however it is unclear what the treatments were for). The papillae were then transferred to Petri dishes where they collapsed and the cells migrated out to grow on the Petri dish, in what is known as an explant.

The cells were then split into four treatment groups, and treated for 14 days total with measurements of proliferation, reactive oxygen species, inducible nitric oxide synthase, and COX2 – which are involved in the inflammatory response and the production of reactive oxygen species.
Treatment groups:

• Control – no treatment
• 50 µM silymarin
• 100 µM silymarin
• 50 µM vitamin C

By the 14th day of treatment, vitamin C had induced a notable increase in dermal papilla cell proliferation compared to both the control and both concentrations of silymarin (Figure 1). However, it is not clear what the translational relevance is for enhancing dermal papilla proliferation in the hair follicle. This is because, in the hair follicle, dermal papilla cells do not make the hair by dividing, but signal to the hair matrix cells, which make the hair shaft.^[5]Taghiabadi, E., Nilforoushzadeh, M.A., Aghdami, N. Maintaining Hair Inductivity in Human Dermal Papilla Cells: A Review of Effective Methods. Skin Pharmacology and Physiology. 33:280-292. Available … Continue reading

The researchers then investigated the effect of silymarin and vitamin C on inducible nitric oxide synthase levels. Inducible nitric oxide synthase (iNOS) is an enzyme that produces large amounts of nitric oxide. This can happen spontaneously or can be induced by inflammation or an increase in hormones such as dihydrotestosterone, indicating a role in hair follicle cycling.^[7]Wolf, R., Schonfelder, G., Paul, M., Blume-Peytavi, U. (2002). Nitric oxide in the human hair follicle: constitutive and dihydrotestosterone-induced nitric oxide synthase expression and NO production … Continue reading In mice, iNOS inhibitors enhance the transition from the non-growing to the growing phase of the hair follicle cycle.^[8]Sasaki, M., Shinozaki, S., Morinaga, H., Kaneki, M., Nishimura, E., Shimokado. (2018). iNOS inhibits hair regeneration in obese diabetic (ob/ob) mice. Biochemical and Biophysical Research … Continue reading

Whilst iNOS levels decreased naturally in the control over the 14 days, both the silymarin and the vitamin C treatments further reduced iNOS concentration (Figure 2). The 100 µM silymarin and the 50 µM vitamin C treatments led to a similar overall decrease in iNOS levels by the 14th day.

The researchers also measured levels of cyclooxygenase -2 (COX2) after treatment (Figure 3). COX2 is an enzyme involved in the production of prostaglandins implicated in the inflammatory response and hair growth and loss.^[10]Shin, D.W. (2022). The physiological and pharmacological roles of prostaglandins in hair growth. Korean Journal of Physiology and Pharmacology. 1(26). 405-413. Available at: … Continue reading Similar to iNOS levels, the COX2 levels were reduced in all treatments in comparison to the control. The decrease in COX2 however was very slight (around 0.2 – 0.4 ng/ml).

Next measured was anti-oxidant capacity. This was completed using a total antioxidant capacity assay. By the 14th day, all treatments notably increased the antioxidant capacity of human dermal papilla cells (Figure 4), however, vitamin C showed the highest antioxidant capacity.

To complement the above result, reactive oxygen species (ROS) levels were also measured as you would expect a lower level of ROS with an increase in antioxidant capacity (Figure 5). By the 14th day, the vitamin C treatment showed the lowest levels of ROS, indicating a potential protective role of vitamin C in the hair follicle.

So to summarize, vitamin C has anti-inflammatory, antioxidant, and pro-growth properties that may be beneficial to human hair growth. Unfortunately, there does not appear to be further research to confirm this.

So, what other evidence is there?

A derivative of vitamin C, called ascorbic acid 2-phosphate (Asc2-P) was also investigated to determine its effects on human dermal papilla cells and mouse hair follicle growth.^[14]Sung, Y.W., Hwang, Y.S., Kim, S.R., Park, S.Y. Kim, M.K., Kim, C.J. (2005). The hair growth-promoting effect of ascorbic acid 2-phosphate, a long-acting vitamin C derivative. Journal of … Continue reading Hair specimens were obtained from the non-balding occipital scalp region of patients with androgenetic alopecia. Dermal papilla cells and outer root sheath keratinocytes were isolated from the donated hair follicles and grown alongside isolated hair follicles in the study.

In dermal papilla cells, the 0.25 mM treatment of Asc2-P showed the highest cell growth over 5 days, with a slight decrease in growth in the higher treatments, however, there did not appear to be any effect on the growth of outer root sheath keratinocytes (Figure 6). Hair follicles cultured with either 0.05 mM or 0.25 mM showed a statistically significant increase in hair follicle length after 9 days (*P<0.05). Furthermore, the growth factor insulin-like growth factor-1 (IGF-1), which is involved in hair follicle growth and cycling, was found to be upregulated at the protein and mRNA levels of dermal papilla cells after treatment indicating that Asc2-P may induce hair regrowth through an increase in IGF-1 expression.

Because the researchers used hair follicles from the non-balding areas of the scalp of patients with androgenetic alopecia, they may not react the same way to treatments as those in the affected areas. Therefore, we cannot say whether this treatment could be effective at treating androgenetic alopecia.
The researchers next conducted a small mouse experiment.

7-week-old mice were shaved and treated with either a control or 250 mM Asc2-P via a process called iontophoresis. Iontophoresis is a process of drug delivery in which the therapeutic agent is placed under an anode or cathode, and a low voltage and low current density is applied. The ions are then repelled into and through the skin through a process called electron repulsion.^[16]Rawat, S., Vengurlekar, S., Rakesh, B., Jain, S., Srikarti, G. (2008). Transdermal Delivery by Iontophoresis. Indian Journal of Pharmaceutical Sciences. 70(1). 5-10. Available at: … Continue reading Iontophoresis was conducted for 15 minutes a day over 4 weeks.

Compared to the control-treated mice, the 250 mM Asc2-P-treated mice showed a notable increase in hair cover on the shaved back indicating that it may induce the entrance of the treated mice into the growing phase from the non-growing phase (Figure 7). The stained skin sections also showed that the hair follicles in the treated group appeared to be in the growing stage and resided deeper in the skin whereas in the control group, the hair follicles appeared to be in the non-growing stage and did not reside as deep.

So there is some evidence that vitamin C treatment might induce hair growth in mice, and it certainly has some anti-inflammatory and antioxidant properties. But, is there any evidence that these properties actually benefit people with hair loss disorders?

Clinical Data

Unfortunately, there does not appear to be any clinical evidence to suggest that vitamin C alone enhances hair growth.

Is Vitamin C Supplementation Safe?

The recommended dietary allowance of vitamin C in adults is 90 mg per day for men and 75 mg for women (which increases to 85 mg if pregnant and 120 mg when lactating). Although vitamin C has a low risk of toxicity and is not believed to cause serious adverse effects at high intakes, the most common complaints are diarrhea, nausea, abdominal cramps, and other gastrointestinal disturbances.^[18]NIH, (no date), Vitamin C. Available at: https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/ (Accessed: 28 April 2024)

Who Might Benefit from Vitamin C Supplementation?

Because of the lack of clinical data, we do not recommend taking vitamin C by itself. Vitamin C plays a role in the intestinal absorption of iron and so it is thought that supplementation may be beneficial for those with iron-related diffuse hair loss.^[19]Almohanna, H.M., Ahmed, A.A., Tsatalis, J.P., Tosti, A. (2019). The role of vitamins and minerals in hair loss: a review. Dermatology and Therapy. 9(1). 51-70. Available at: … Continue reading However, there is no clinical evidence that supports this hypothesis.