Vitamin D was once thought to be mostly important to bone health because of its role in the metabolism of calcium. It is now understood to be a hormone that influences our health in a number of additional ways.¹ Some of these effects that may benefit acne patients include vitamin D’s antioxidant and anti-comedogenic properties.²

Evidence Supporting Vitamin D for Acne Therapy The biologically active form of vitamin D is its metabolite, commonly referred to as vitamin D3.³ Skin is the only known site for synthesis of vitamin D from sunlight, including in the active vitamin D3 form.³ The use of vitamin D3 is an approved treatment in the inflammatory skin disease psoriasis, and older studies on vitamin D metabolites have demonstrated the ability to break up comedones to open clogged pores.^2-3 It has also been recently discovered that the cells of sebaceous glands that produce sebum (important to the formation of pimples) are sensitive to vitamin D3.³

More recently, studies in mice have shown that topical application of a vitamin D3 analogue resulted in comedolysis.⁴ In addition, researchers have reported the role of vitamin D3 in expression of cathelicidins (a family of antimicrobial peptides in sebocytes. In vitro tests demonstrate the antimicrobial activity of cathelicidins against Propionibacterium acnes (P. acnes)—the bacteria known to promote acne and the inflammation related to the condition.⁵

Possible Contradictory Evidence in Acne Rosacea

Other evidence indicates that cathelicidins are found at abnormally high levels in the skin of patients with acne rosacea, suggesting that they are produced as an inflammatory immune response to the presence of P. acnes.⁵ However, the cathelicidins produced in response to rosacea are different than those expressed in normal skin (as a result of an epidermal abnormality), and although similar to common acne, rosacea is a different condition that does not present with comedones.^5-6 In any event, vitamin D3 appears to play a regulatory role in cathelicidin production, but researchers do not currently have a clear picture of how vitamin D3 can balance cathelicidin’s antimicrobial effects with its inflammatory response to P. acnes.⁷

What about the Link between Milk and Acne?

An evaluation of dietary surveys on over 6000 adolescent and teenaged girls (as well as a number of other population reviews) suggests that there is a positive correlation with milk consumption and the incidence of acne. However, researchers believe that while evidence supports that there may be pro-acne metabolic effects of milk due to increased levels of insulin-like growth factor, there was no correlation between vitamin D intake and prevalence of acne.⁸

Vitamin D May Counteract Emotional Stress of Acne

Acne can be a disfiguring condition well into adulthood. Multiple studies indicate that levels of depression, anxiety, and even suicide are much higher in people suffering from acne. Emerging evidence suggests that the emotional stress of acne is not only emotive—it may also be due to oxidative stress on brain tissue related to P. acnes. Evidence indicates acne patients have high levels of free radicals, low levels of antioxidants, and decreased MAO enzyme activity. Low levels of MAO activity are associated with depression and anxiety disorders due to imbalances of the brain neurotransmitters (e.g., serotonin) associated with mood.^2,9

Insufficient levels of vitamin D have also been linked to anxiety and depression.² This may be because vitamin D is closely related to the neurotransmitter serotonin and helps in its production.¹ Vitamin D’s antioxidant properties also help protect nerve cells in the brain.¹ Both of these properties suggest that vitamin D supplements may help prevent or counteract the stress effects of acne.