你需要哪些维生素？

译者 lucyhi2008

What you need, and how to get it

By Amanda Gardner

你需要哪些维生素，如何科学地进补

作者：阿曼达·加德纳

Vitamins and minerals are essential to any diet, and research suggests they may help prevent cancer and heart disease, not to mention other health problems. But reality check: Many studies have been conducted on vitamin-containing food, but not necessarily supplements.

    维生素和矿物质是任何饮食中不可或缺的成分。研究表明，维生素和矿物质可能有利于预防癌症和心脏病，以及很多其它疾病。但是，经过多次科研的实践证明：许多富含维生素的食品，并不需要一定进补。

In fact, if you eat a diet rich in fruits, vegetables, and fortified food, you're probably getting all you need. But supplements do offer an easy, just-in-case form of health insurance.

    事实上，如果你的日常饮食含有丰富的水果、蔬菜和强化食品，你的身体可能已经获取所需维生素的数量。但是，补品的确很方便地为您的健康增加了一道保险。

Do you need them? Here's a quick guide to beneficial nutrients and what they can do for you.

    你真的需要它们吗？以下是关于一些营养成分及其作用的一个简明指南。

Beta-carotene

Found in carrots, sweet potatoes, and green peppers, among other foods, this antioxidant is converted in the body to vitamin A and is important for healthy vision, a functioning immune system, and good skin. But the evidence isn't really there to recommend it for staving off cancer. In fact, a 2004 study found that supplements may actually raise the risk of lung cancer in smokers.

Bottom line: Skip the supplements if you're a smoker, and try to get your beta-carotene from fruits and veggies, whether you smoke or not.

β-胡萝卜素

β-胡萝卜素存在胡萝卜、红薯、青椒及其它食物中，它是一种抗氧化剂，被人体吸收后转化成维生素A，有利于视力健康、增强身体免疫系统的功能以及改善皮肤。但是，并没有证据足够证明它能预防癌症。事实上，一项2004年的研究发现，药进补β-胡萝卜素实际上增加了吸烟者罹患肺癌的风险。

忠告：如果你吸烟，就不要采取药物进补β-胡萝卜素的方式。当然，不管你吸不吸烟，最好都尽量从水果和蔬菜中直接获取所需β-胡萝卜素。

Calcium

Our bodies need calcium—mostly found in dairy products like milk, yogurt, and cheese—to maintain healthy bones and prevent osteoporosis.

Bottom line: Supplements aren't a bad idea if you hate dairy (and can eat only so much kale and canned sardines), but you may want to skip them if you're prone to kidney stones or are a female over 70. A 2010 report linked supplements to heart-attack risk in older postmenopausal women. If you decide to go with supplements, don't take more than 500 milligrams at a time, and pair them with vitamin D to improve calcium absorption.

钙

我们的身体需要钙——它们主要存在乳制品中，如牛奶、酸奶和奶酪——来维持骨骼健康和预防骨质疏松症。

忠告：如果你不喜欢奶制品（并且只能吃大量芥蓝菜和罐装沙丁鱼），那么通过药物补钙的主意并不差，但是，如果你是肾结石体质或70岁以上的女性，也许你就不能考虑这种方式。2010年的一项报告表明，补钙药物与绝经后的老年妇女心脏病风险增加有关联。如果你决意服用补钙药品，一次不要超过500毫克，与维生素D搭配服用，更有利于钙的吸收。

Folic acid

Folic acid, which prevents neural tube defects such as spina bifida in babies, is found in fortified breakfast cereal, dark green vegetables, legumes, citrus fruit juice, bread, and pasta.

Bottom line: Getting 400 micrograms a day of this B vitamin, and 600 if you are pregnant or lactating, is a no-brainer. That amount should come from food, supplements, or both, according to the National Institutes of Health (NIH). The jury's still out as to whether folate combats cancer, heart disease, or mental illness.

叶酸

叶酸，可以预防神经缺陷类疾病，如胎儿的脊骨裂，在强化早餐麦片、深绿色蔬菜、豆类、柑橘果汁、面包和面食里均含有。

忠告：每天需要补充400毫克的这种B族维生素，如果你怀孕了或在哺乳期内，补充600毫克是很明智的。按照国家卫生研究院（NIH）的说法，你应该通过食物、保健品，或者结合以上两种方式来获取所需叶酸量。至于叶酸是否有抗癌、防治心脏病和精神疾病的作用，还有待分晓。

Iron

You may not love the foods highest in iron (liver and other organ meats), but the mineral is critical for the proper functioning of red blood cells and, therefore, the prevention of anemia.

Bottom line: Try to get iron from dietary sources, which also include lean meats, seafood, nuts, and green, leafy vegetables. However, you may need a supplement if you're anemic, or your doctor might prescribe them before surgery, says Jessica Anderson, a registered dietitian with the Coastal Bend Health Education Center, at the Texas A&M Health Science Center, in Corpus Christi. Women, especially those who are pregnant or menstruating, might also benefit.

铁

你也许不喜欢吃富含铁的食物（肝脏类食物或其它内脏类食物），但是铁对于红细胞功能的正常动作至关重要，可以预防贫血。

忠告：尽量从饮食中获取铁，如瘦肉、海产品、坚果和多叶的绿色蔬菜。但是，如果你贫血，你就需要通过服用补铁药物来进补了，或者在手术前，医生也可能会开这类药给你，杰西卡.安德森说。她是科珀斯克里斯蒂市，德克萨斯A&M 健康科学中心的海岸健康教育中心的注册营养专家。口服补铁药物特别对怀孕或处于生理周期的女人是有益的。

Multivitamin

There is limited evidence that multivitamins may help prevent breast cancer, and an NIH panel in 2006 wasn't convinced that popping the pills was worth it. Neither is the Agency for Healthcare Research and Quality, which said the only benefit could be to reduce cancer risk in people with poor nutrition. And a large 2009 study failed to find any beneficial effects of the vitamins for cancer or deaths among postmenopausal women.

Bottom line: Multivitamins aren't a bad idea if "you're on the go," Anderson says. "But don't expect major lifesaving benefits."

复合维生素

目前，支持复合维生素可能预防乳癌的证据很有限，2006年，国家健康协会（NIH）专项研究小组研究表明，并不确定每天把复合维生素药丸丢到口中有什么价值。国家卫生健康研究与质量机构也没什么证据，他们说，复合维生素仅对营养不良人们来说，有降低罹患癌症的风险。在2009年进行的一次大规模的调查研究，并没有发现，复合维生素对降低绝经后妇女罹患癌症和死亡风险有什么实际效果。

忠告：如果你的身体已“衰败垂危”，进补复合维生素是一个好主意，安德森说。“但可别把它当成你的救命稻草。”

Potassium

Potassium can lower blood pressure, even out irregular heart rhythms, and counteract the effects of too much sodium. It's found in bananas, raisins, leafy greens, oranges, and milk.

Bottom line: Consider a supplement if you're taking potassium-depleting diuretics for a heart condition, or if you're African American, a group that's at higher risk for hypertension and heart disease. Keep in mind that too much potassium can be harmful to older people and people with kidney disease.

钾

钾可以降低血压，甚至可以调节心律和消解食用过多钠盐而产生的副作用。在香蕉、葡萄干、多叶绿色蔬菜、柑橘和牛奶里均含有。

忠告：如果你因心脏不好在服用耗钾利尿剂，或者你是非裔美国人——罹患高血压和心脏疾病风险较高的群体，需要要考虑一下药物补钾。谨记，补钾过多对老年人和肾脏有病的人有害。

Selenium

The body needs only small amounts of this antioxidant, found in meats, seafood, eggs, and bread. A study found that taking 200 micrograms daily reduced the risk of prostate, lung, and colorectal cancers, but other studies have been "complete flops," Anderson says. That includes a 2011 analysis.

Bottom line: Don't count on selenium to lower your chances of getting or dying from cancer. It's likely you're getting enough from food sources, anyway.

硒

我们的身体只需少量这种抗氧化剂，在肉类、海产品、鸡蛋和面包里均含有。一项研究表明，每天摄取200毫克的硒，会降低患前列腺癌、肺癌和直肠癌的风险，但是，包括2011年在内的其它一些研究分析，均以“失败告吹”，并没有得出以上结论，安德森说。

忠告：不要指望硒会降低你患癌症和死于癌症的风险。总之，你基本上能够从日常食物中获取足够量的硒。

Vitamin C

This much-touted cure-all, found in citrus fruits, berries, broccoli, and green peppers, just doesn't make the grade when it comes to common-cold prevention. One study did suggest that taking vitamin C regularly might reduce the length of a cold by a day.

Bottom line: Try to get enough vitamin C through your diet. It's fine to take a supplement, especially if you're a smoker or nonsmoker who is often exposed to secondhand smoke. But there seems to be little point in upping your intake to combat sniffling and coughing.

维生素C

这种倍受吹捧的百宝丹，存在柑橘类水果、莓果、花椰菜和青椒里，并不能够成功地预防感冒。但是有一项研究的确表明，定期地服用维生素C可以缩短感冒的病程。

忠告：尽量通过饮食中获取足够的维生素C。尤其是如果你吸烟，或虽然你不吸烟但经常被动吸二手烟，通过药物进补维生素C也没关系，但是增加进补量对于防治感冒流鼻涕和咳嗽不会有什么效果。

Vitamin D

Vitamin D, which helps the body absorb calcium, is necessary for bone health. It's mostly accessible through sun exposure, not food. Too little vitamin D can contribute to osteoporosis and rickets in children. Some evidence suggests that the vitamin may reduce the risk of type 1 and 2 diabetes and multiple sclerosis, but the jury's still out on these benefits.

Bottom line: Even though very little sun is needed to get your quota of vitamin D, and some foods are fortified with it, deficiencies aren't unusual. Supplements might be a good idea, especially if you don't have much sun exposure, are over 50, or have dark skin.

维生素D

维生素D促进身体对钙的吸收，是骨骼强健的必要物质。主要是通过晒太阳而不是从食物中获取。体内维生素D含量过少，可能引发骨质疏松症和儿童的佝偻病。有证据表明，此种维生素可以降低1型、2型糖尿病和脑脊髓多发性硬化疾病的风险，但是还有待于论证。

忠告：非常少量的阳光就能让你获得所需的维生素D，而且一些食物里也加添加了这种营养物质，所以，维生素D缺乏症并不常见。但是，如果你不经常晒太阳且年过50或肤色暗沉，药物进充维生素D也许是一个好办法。

Vitamin E

Once upon a time, researchers thought this antioxidant could protect the heart, but a large trial published in 2005 found that 600 international units (IUs) every other day neither prevented cancer nor lowered the risk of heart attack or stroke in middle-aged and older women. (More recently, a 2008 study found no benefit of 400 IUs every other day in middle-aged and older men.)

Bottom line: Forget the supplements and get your vitamin E from food (oils like safflower, peanuts, eggs, fortified cereals, fruits, and green, leafy vegetables). Bear in mind that cooking and storing foods with vitamin E can reduce the amount you're getting.

维生素E

研究人员曾经一度认为，这种抗氧化剂可以保护我们的心脏。但是在2005年公布的一次大规模试验表明，每两天服用一次600（国际）单位剂量的维生素E即不能防癌，也不会降低中年或老年妇女心脏病发作和中风的风险。（近些时间，一项2008年的调查研究发现，中年人和老年人每两天服用一次400（国际）单位剂量，也没发现有任何好处）

忠告：不要使用药物进补，从食物中直接获取维生素E（如红花籽油、花生油、鸡蛋、强化麦片、水果和叶类绿色蔬菜）。谨记，含有维生素E的食物经烹调或者储存后，会降低维生素的含量。