Folate and phototherapy: What should we inform our patients?

• Published in: Journal of the American Academy of Dermatology Vol. 77; no. 5; pp. 958 - 964
• Main Authors: Zhang, Myron, Goyert, Gregory, Lim, Henry W.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.11.2017
• Subjects: Adult; Dietary Supplements; Female; folate; folic acid; Folic Acid - blood; Folic Acid - metabolism; Folic Acid - radiation effects; Humans; narrowband ultraviolet B; neural tube defects; Neural Tube Defects - prevention & control; phototherapy; Phototherapy - methods; Pregnancy; psoralen plus ultraviolet A; Treatment Outcome; ultraviolet A1; Ultraviolet Therapy - adverse effects; Ultraviolet Therapy - methods; psoralen plus ultraviolet A; UV; neural tube defects; narrowband ultraviolet B; folate; NB; 5MTHF; PUVA; phototherapy; folic acid; ultraviolet A1; NTD; PTB
• ISSN: 0190-9622; 1097-6787; 1097-6787
• DOI: 10.1016/j.jaad.2016.10.016

Ultraviolet (UV) degradation of folate has been studied in vitro and in vivo, but comprehensive reviews of the subject and recommendations for supplementing folate are lacking, especially for women of childbearing age, in whom decreases in folate predisposes newborns to neural tube defects. We reviewed the effects of phototherapy on folate and provide a recommendation for women of childbearing age on phototherapy. PubMed was searched for in vivo studies comparing folate levels before and after phototherapy. There is no evidence of decreased folate levels after UVA exposure. Decreased folate levels after sun exposure were limited to subjects taking folate supplements. Studies using narrowband UVB showed mixed results, potentially explained by dose-dependent degradation of folate; exposure >40 J/cm2 cumulatively and >2 J/cm2 per treatment were associated with 19%-27% decreases in serum folate levels, while lower doses did not affect folate levels. Extensive variability in results from studies and lack of considering confounders. We recommend all women of childbearing age on phototherapy take 0.8 mg/day of folate supplements, as suggested by current guidelines for women of childbearing age, to reduce the risk of neural tube defects in unplanned pregnancy.