Department of Dermatology, Henry Ford Hospital, Detroit, Michigan.
Women's Health Services, Henry Ford Hospital, Detroit, Michigan.
J Am Acad Dermatol. 2017 Nov;77(5):958-964. 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/cm cumulatively and >2 J/cm 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.
叶酸的紫外线（UV）降解已在体外和体内进行了研究，但缺乏对该主题的综合审查和补充叶酸的建议，特别是对于育龄妇女，叶酸的减少会使新生儿易患神经管缺陷。
我们回顾了光疗对叶酸的影响，并为育龄妇女提供了光疗建议。
在 PubMed 上搜索了比较光疗前后叶酸水平的体内研究。
没有证据表明 UVA 暴露会降低叶酸水平。只有在服用叶酸补充剂的受试者中，阳光照射后叶酸水平才会降低。使用窄带 UVB 的研究结果不一，这可能是由于叶酸的剂量依赖性降解所致；累积暴露量>40 J/cm 且每次治疗暴露量>2 J/cm 与血清叶酸水平降低 19%-27%相关，而较低的剂量不会影响叶酸水平。
研究结果存在广泛的差异，并且缺乏对混杂因素的考虑。
我们建议所有接受光疗的育龄妇女服用 0.8 毫克/天的叶酸补充剂，这是目前针对育龄妇女的建议，以降低非计划妊娠中神经管缺陷的风险。
