维生素补充剂非常受欢迎。
People often believe they’ll act as a safety net and help to ensure adequate nutrient intake.
Supplementing with vitamin B12 is particularly common, because deficiency is widespread.
In fact, many people regularly getinjections维生素B12。
这些声称可以帮助能量水平，大脑功能和体重减轻，仅举几例。
This article reviews B12 injections and whether they are something you should consider.
维生素B12是一种水溶性维生素，也称为钴胺素。
它在大脑功能以及DNA和红细胞的产生中起着至关重要的作用。
Chemically, vitamin B12 can exist in a number of different forms, but all of them contain the mineral cobalt.
维生素可以长时间储存在肝脏中，因此缺乏症状可能需要几年的时间（
底线：Vitamin B12 is a water-soluble vitamin that plays an important role in brain function and red blood cell production.
The recommended daily intake (RDI) of vitamin B12 is 6 micrograms per day.
指出不足很常见,尤其是在人low a vegetarian or vegan diet.
实际上，据认为，遵循这些饮食的人中有多达90％的人缺乏（
这是因为B12是only foundnaturally in animal foods.
However, vegans and vegetarians are not the only ones who are deficient. Even some meat eaters don’t absorb it very well (
Unlike other vitamins, the absorption of vitamin B12 depends on a蛋白质在您的胃中产生，称为固有因素。
Intrinsic factor binds to vitamin B12, so that you can absorb it into the blood. People who don’t produce enough intrinsic factor can become deficient.
Deficiency is particularly common in elderly people, because the ability to absorb vitamin B12 can decrease with age (
其他有缺陷风险的人包括那些接受过肠道手术的人，包括减肥手术。那些患有影响肠道的疾病的人，例如克罗恩病或腹腔疾病，也有风险（
底线：Those at greatest risk of vitamin B12 deficiency are vegans and vegetarians, who get little to no B12 from the diet. Deficiency can also be caused by poor absorption.
未经治疗的维生素B12缺乏症会导致神经系统疾病或恶性贫血，当您的身体没有足够的B12来产生所需的红细胞量时，就会发生这种情况（
Vitamin B12 shots are the most common way to prevent or treat a deficiency. The injections are prescribed by a doctor and given intramuscularly, or into muscle.
注射通常为羟豆制素或氰钴胺素。这些非常有效地提高B12的血液水平并防止/逆转缺乏症。
底线：如果您缺乏维生素B12，则注射非常有效地提高血液水平。
鉴于维生素B12在您体内起的重要作用，缺乏症会带来严重的健康后果。
In fact, low blood levels of the vitamin have been linked to several health problems.
Brain Function
Low levels of vitamin B12 have been linked to a decline in brain function.
Two recent reviews found that there may be a link between low blood levels and the development of dementia (
However, results have been mixed and treatment with vitamin B12 wasn’t effective at improving brain function in people with normal brain function (
Depression
有人提出，低维生素B12水平与抑郁症之间可能存在联系。
但是，一项评论发现，用维生素B12治疗抑郁症并不能减轻症状的严重程度。
Nevertheless, it was suggested that taking the vitamin on a long-term basis could help prevent a relapse into depression (
Currently, there is a lack of quality research in this area. Higher quality studies are needed to find out if there is a link between vitamin B12 and depression (
骨质疏松症
骨质疏松症是一种疾病，其中骨骼质量的损失导致骨骼较弱，骨折风险增加。
Interestingly, low blood levels of vitamin B12 have been linked with reduced bone mass (
因此，建议服用维生素B12可能会降低骨质疏松症的风险。但是，研究提供了不同的结果（
年龄相关性黄斑变性
与年龄相关的黄斑变性是一种使您逐渐失去中央视力的疾病，通常在两只眼睛中。
在50岁以上的人,足够的消费啊f vitamin B12 is thought to be important for maintaining good vision and protecting against macular degeneration.
In one large study, 5,200 women received 1,000 mcg of vitamin B12 daily, as well as other B vitamins andfolic acid（（
7years later, the study found a 35% lower risk of age-related macular degeneration among the women who took the supplements.
Although the reduction in risk can’t be attributed to vitamin B12 only, it does suggest that getting enough may be important.
Other Claims
Recently, vitamin B12 injections and infusions have become popular among healthy people who don’t appear to have a deficiency.
Advocates of this approach claim that regular injections can boost energy levels and help with weight loss and mood.
However, there is little to no evidence to support these claims.
底线：Ensuring that you have enough vitamin B12 is important for brain function and mental, bone and eye health. Injections are probably useless if you don’t have a deficiency.
Vitamin B12 injections are generally considered to be very safe. They have no major side effects.
However, in very rare cases, some people can experience side effects caused by allergic reactions or sensitivity (
如果您遇到任何副作用，请与您的医生交谈。
底线：Vitamin B12 injections are very safe. In rare cases, the injections may cause allergic reactions.
Vitamin B12 is found in animal foods, as well as some fortified foods that have added B12.
Fortified foods vary from country to country, but often include milk alternatives orbreakfast cereals。
一些特别好的维生素B12来源包括：
- Liver:1/3杯（75 g）提供RDI的881％。
- Beef kidney:1/3 cup (75 g) provides 311% of the RDI.
- Trout:1/3杯（75 g）提供RDI的61％。
- 鲑鱼罐头：1/3杯（75 g）提供RDI的61％。
- Ground beef:1/3 cup (75 g) provides 40% of the RDI.
- Eggs:2large eggs provide 25% of the RDI.
- Milk:1cup (250 ml) provides 20% of the RDI.
- Chicken:1/3杯（75 g）提供RDI的3％。
某些人很难满足其维生素B12的要求。对于素食或纯素食的人来说，尤其如此。
在这种情况下，通常建议您用B12射击或口服补充剂补充饮食。
Fortunately, there is increasing evidence that oral B12 supplements are just as good as injections for raising blood levels in most people (
通常建议素食主义者和素食主义者每天至少服用10 mcg，或每周至少服用2,000 mcg。
However, some doctors still prefer the use of injections.
底线：许多动物食品的维生素B12含量很高。口服补充剂也已被证明可有效提高血液水平。
如果您吃均衡的饮食，其中包括富含维生素B12的食物，那么您不太可能需要额外的B12。
For most people, dietary sources provide everything that is needed. However, people who are at risk of deficiency will probably need to take supplements.
在这些情况下，口服补充剂可能与许多人一样有效。
Some experts point out that regular injections should only be used as a last resort if supplements don’t work or if deficiency symptoms are serious.
