你需要补充维A吗

Chances are, you've seen the aisles at the drug store dedicated to supplements of all kinds. Vitamins and minerals packaged in a variety of pills, gummies, powders, and drinks are readily available. But many of these supplements just aren't necessary. And while you may think you need to supplement your diet with vitamin A to help with bodily functions like vision and immune response, chances are, you're already getting the recommended daily amount through the foods you eat.

你很有可能在药店的货架上看到过各种各样的补充剂。包装在各种药片、软糖、粉末和饮料中的维生素和矿物质随处可见。但很多补充剂都是不必要的。虽然你可能认为你需要在饮食中补充维生素A，以帮助身体功能，如视力和免疫反应，但很有可能，你已经从你所吃的食物中获得了推荐的每日摄入量。

Vitamin A comes in two forms that humans are able to use (via the National Institutes of Health). The first is preformed vitamin A, which only comes from animal products such as dairy, meat, and fish. The second is provitamin A carotenoids. This is a group of plant pigments that the body can turn into vitamin A. The most well-known example of a provitamin A carotenoid is beta-carotene. This is the pigment that gives carrots their orange hue (via the University of Rochester Medical Center). It's also an antioxidant that helps defend cells from damage.

维生素A有两种形式，可供人类可以使用。第一种是预制维生素A，它只来自动物产品，如乳制品、肉类和鱼类。第二种是维生素原A类胡萝卜素。这是一组植物色素，人体可以将其转化为维生素a。维生素原a类胡萝卜素最著名的例子是β-胡萝卜素。罗彻斯特大学医学中心研究发现，正是这种色素使胡萝卜呈现出橙色。它也是一种抗氧化剂，有助于保护细胞免受伤害。

Should you bother with a supplement?

你需要补充吗?

Your body uses vitamin A to produce rhodopsin, a protein that helps absorb light in the retina of the eye. By not getting enough vitamin A, your ability to see color and to see in low light diminishes (via Insider). Vitamin A has been linked to the reduction in the risk of developing macular degeneration in people who are more susceptible to the condition (via Mayo Clinic).

你的身体使用维生素A来产生视紫红质，一种帮助眼睛视网膜吸收光线的蛋白质。由于缺乏足够的维生素A，你看颜色和在弱光下看东西的能力会减弱。维生素A与降低更易患黄斑变性的人群患黄斑变性的风险有关。

Most people get enough vitamin A in their diet by eating a variety of foods like dairy, leafy green vegetables, carrots, and meat. But for people with eye diseases, pancreatic disease, or even measles, supplemental vitamin A can be helpful. If that's not you, it's important to make sure you're not getting too much vitamin A. The recommended daily allowance for vitamin A for healthy adults is 900 mcg of retinol activity equivalents (RAE) for men and 700 mcg of RAE for women. Allowances vary slightly depending on age and other conditions. When you look at the label on a bottle of vitamin A supplements, the units will most likely be in international units (IU), so there may be some conversions to do in order to find out the RAEs in a serving of the supplement. Because too much vitamin A can be harmful, it's always a good idea to talk to a trusted medical professional before taking a vitamin A supplement.

大多数人通过食用各种食物，如乳制品、绿叶蔬菜、胡萝卜和肉类，从饮食中获得足够的维生素A。但是对于患有眼病、胰腺疾病甚至麻疹的人来说，补充维生素A是有帮助的。如果你没有这些症状，那么确保你没有摄入过多的维生素A也很重要。对于健康的成年人来说，每日维生素A的推荐摄入量是男性900微克视黄醇活动当量(RAE)，女性700微克。根据年龄和其他条件，用量略有不同。当你看一瓶维生素a补充剂的标签时，它的单位很可能是国际单位(IU)，所以为了找到每一份补充剂的RAE值，你可能还需要进行一些转换。因为过多的维生素A是有害的，所以在服用维生素A补充剂之前，最好先咨询一下值得信赖的医学专业人士。