毒理性
◉ 母乳喂养期间使用总结：维生素A（视黄醇）和前维生素A类胡萝卜素是人类母乳的正常成分。哺乳期妇女的推荐膳食摄入量为每天1300微克视黄醇，相比之下，孕期为每天770微克。6个月或以下婴儿的推荐每日摄入量为400微克。维生素A缺乏并不少见，哺乳期间可能需要补充维生素A以达到推荐的每日维生素A摄入量。在发展中国家，孕期和哺乳期补充维生素A并没有降低母乳喂养婴儿的死亡率或贫血风险，但可能与改善抗氧化能力和免疫功能的健康益处有关。哺乳期妇女单次剂量最高可达120,000微克或每日剂量最高可达1500微克，预计不会对母乳喂养的婴儿造成伤害。母亲应避免每日剂量超过3000微克。
母乳中的维生素A具有抗氧化性质。Holder巴氏杀菌法（62.5°C，30分钟）不会降低牛奶的抗氧化能力。
◉ 对母乳喂养婴儿的影响：印度100名纯母乳喂养的母亲在分娩后24小时内单次口服200,000 IU维生素A或安慰剂。两组婴儿在产后住院期间的体重增长没有差异，维生素A组的婴儿没有出现维生素A过量的症状，如过度哭泣、囟门隆起和呕吐。所有婴儿在出生后48至72小时接受了口服脊髓灰质炎疫苗（OPV）。两组在6周时的OPV血清转化率或抗体滴度没有差异。同样，加纳1,085名纯母乳喂养的母亲在产后3至4周接受了200,000 IU维生素A或安慰剂。在6周和6个月大时，婴儿对脊髓灰质炎或破伤风疫苗接种的免疫反应没有差异。
冈比亚197名母亲在分娩后第一周给予200,000或400,000 IU维生素A，12个月的随访期间未出现维生素A不良反应的迹象。
中国南京245名健康、纯母乳喂养的母亲在产后1至2个月随机接受每日1800 IU维生素A补充剂或安慰剂，持续2个月。在2个月研究结束时，两组婴儿的发热性疾病、呼吸道感染、腹泻和湿疹的发生率相似，尽管没有说明这些数据是如何收集的。
◉ 对泌乳和母乳的影响：坦桑尼亚的HIV感染母亲在孕期和产后服用每日维生素A补充剂时，严重亚临床乳腺炎的发病率（36%）高于服用安慰剂的母亲（23%）。服用不含维生素A的多种维生素的母亲也有较高的发病率（38%），这表明与维生素A无关的影响。鉴于多种维生素补充剂对这一特定病人群体有许多其他益处，作者不建议因乳腺炎的风险而避免补充。
在一项巴西研究中，57名母亲在分娩后2天内接受了200,000 IU维生素A或未接受维生素A。在给药后24小时，接受维生素A的母亲初乳中的平均α-生育酚（维生素E）水平降低了16.4%（28微摩尔/升与24.5微摩尔/升），但在给药后30天，大约6微摩尔/升时，差异不再显著。该研究中报告的维生素E初乳水平在正常范围内，因此维生素A补充剂母亲的轻微降低可能不具有临床意义。一个不同的巴西研究小组使用添加了低剂量维生素E 110 IU作为防腐剂的维生素A补充剂进行了相同的实验，发现维生素A对初乳α-生育酚没有影响。
◉ Summary of Use during Lactation:Vitamin A (retinol) and provitamin A carotenoids are normal components of human milk. The recommend dietary intake in lactating women is 1300 mcg retinol daily, compared to 770 mcg daily during pregnancy. The recommended daily intake for infants aged 6 months or less is 400 mcg. Vitamin A deficiency is not uncommon, and maternal supplementation may be needed during lactation to achieve the recommended daily vitamin A intake. Maternal vitamin A supplementation during pregnancy and lactation has not reduced mortality or the risk of anemia in breastfed infants living in developing regions, but there may be health benefits related to improved antioxidant capacity and immune function. Maternal single doses up to 120,000 mcg or daily doses up to 1500 mcg are not expected to harm the breastfed infant. Daily doses above 3,000 mcg should be avoided in the mother.
Vitamin A in milk has antioxidant properties. Holder pasteurization (62.5 degrees C for 30 minutes) does not reduce milk antioxidant capacity.
◉ Effects in Breastfed Infants:One hundred exclusively breastfeeding mothers in India were given 200,000 IU vitamin A or placebo as a single oral dose within 24 hours after delivery. There were no differences in weight gain of their infants during postpartum hospitalization between the groups, and no infants in the vitamin A group had symptoms of hypervitaminosis A, such as excessive crying, raised fontanelle and vomiting. All the infants received a dose of oral polio vaccine (OPV) between 48 and 72 hours after birth. There were no differences between the two groups in OPV seroconversion rates or antibody titers at 6 weeks. Similarly, 1,085 exclusively breastfeeding mothers in Ghana were given 200,000 IU vitamin A or placebo at 3 to 4 weeks postpartum. There were no differences in infant immune response to polio or tetanus vaccination at 6 weeks and 6 months of age.
The infants of 197 mothers in Gambia given either 200,000 or 400,000 IU vitamin A in the first week after delivery showed no signs of adverse reactions to vitamin A during the 12-month follow-up period.
Two hundred forty-five healthy, exclusively breastfeeding mothers in Nanjing, China were randomized to receive a daily vitamin A 1800 IU supplement or placebo for 2 months beginning at 1 to 2 months postpartum. By the end of the 2 month study, infants in both groups had similar rates of febrile illnesses, respiratory tract infections, diarrhea, and eczema, although it was not stated how these data were collected.
◉ Effects on Lactation and Breastmilk:HIV-infected mothers in Tanzania had a higher rate of severe subclinical mastitis (36%), determined by measuring serial milk electrolyte concentrations, when taking a daily vitamin A supplement during pregnancy and postpartum compared to placebo (23%). Mothers taking a multivitamin without vitamin A also had a higher rate (38%) than placebo, suggesting a vitamin A-independent effect. Given the many other benefits of multivitamin supplementation in this specific patient population, the authors did not recommend avoiding supplementation due to a potential risk of mastitis.
In a Brazilian study, 57 mothers received either 200,000 IU vitamin A or no vitamin A within 2 days after birth. At 24 hours after administration, the average level of alpha-tocopherol (vitamin E) was 16.4% lower in the colostrum of mothers who received in the vitamin A (28 micromoles/L compared to 24.5 micromoles/L), but it was not significantly different at 30 days after administration, at about 6 micromoles/L. The reported vitamin E colostrum levels in this study are within normal limits, thus the small reduction in the vitamin A-supplemented mothers may not be clinically important. A different Brazilian research group conducting the same experiment using a vitamin A supplement with low-dose vitamin E 110 IU added as a preservative found no effect of vitamin A on colostrum alpha-tocopherol.
来源:Drugs and Lactation Database (LactMed)
