Overview

维生素B12是一种水溶性营养素，需要在您的身体中许多关键过程所需的水溶性营养素。

The ideal dose of vitamin B12 varies based on your gender, age, and reasons for taking it.

本文审查了不同人员建议的B12后剂量背后的证据。

Vitamin B12is an essential nutrient that plays a critical role in several of your body’s processes.

It’s necessary for proper red blood cell production, DNA formation, nerve function, and metabolism ( 1 ).

Vitamin B12 also plays a key role in reducing levels of an amino acid called homocysteine, high levels of which have been linked to chronic conditions like heart disease, stroke, and Alzheimer’s ( 2 ).

Additionally, vitamin B12 is important for energy production. However, there’s currently no evidence that taking B12 supplements increases energy levels in people who are not deficient in this nutrient ( 3. ).

维生素B12主要是在动物产品中，包括肉类，海鲜，乳制品和鸡蛋。它还添加到一些加工食品中，例如谷物和非金属牛奶。

Because your body can store B12 for several years, serious B12 deficiency is rare, but up to 26% of the population may have a mild deficiency. Over time, B12 deficiency can lead to complications like anemia, nerve damage, and fatigue.

Vitamin B12deficiency可以通过饮食而无法获得足够的维生素，吸收它的问题，或者服用干扰其吸收的药物（ 4. ).

以下因素可以让您处于更高的风险，不能仅获得足够的维生素B12（ 5. 那 6. ):

  • 素食或素食饮食
  • being over 50 years old
  • gastrointestinal disorders, including Crohn’s disease and celiac disease
  • 在消化道上进行手术，例如减肥手术或肠切除术
  • 二甲双胍和减少酸性药物
  • 特异性遗传突变，如MTHFR，MTRR和CBS
  • regular consumption of alcoholic beverages

如果您有缺乏危险的情况，请采取补充可以帮助您满足您的需求。

Summary

Vitamin B12 is an important nutrient that plays a critical role in your body. It’s mainly found in animal products, and some people may be at risk of not getting enough from diet alone.

The recommended daily intake (RDI) for vitamin B12 for people over 14 is 2.4 mcg ( 1 ).

但是，您可能希望根据您的年龄，生活方式和具体情况或多或少地服用或更少。

Note that the percent of vitamin B12 your body can absorb from supplements is not very high — it’s estimated that your body only absorbs 10 mcg of a 500-mcg B12 supplement ( 7. ).

以下是用于特定情况的B12剂量的一些建议。

Adults under age 50

For people over 14, the RDI for vitamin B12 is 2.4 mcg ( 1 ).

Most people meet this requirement through diet.

For example, if you ate twoeggsfor breakfast (1.2 mcg of B12), 3 ounces (85 grams) of tuna for lunch (2.5 mcg of B12), and 3 ounces (85 grams) of beef for dinner (1.4 mcg of B12), you would consume more than double your daily B12 needs ( 1 ).

因此，不建议在该年龄组中的健康人员补充B12。

However, if you have any of the factors described above that interfere with vitamin B12 intake or absorption, you may want to consider taking a supplement.

Adults over age 50

老年人更容易受到维生素B12缺乏的影响。虽然比较小的成年人在B12缺乏较少的情况下，65岁以上的成年人占65岁的成年人少于这种营养素的最佳血液水平（ 8. 那9.).

As you age, your body naturally makes less stomach acid and intrinsic factor — both of which can affect the absorption of vitamin B12.

胃酸是必要进入发现的维生素B12自然是食物那and intrinsic factor is required for its absorption.

Due to this increased risk of poor absorption, the National Academy of Medicine recommends that adults over the age of 50 meet most of their vitamin B12 needs through supplements and fortified foods ( 1 ).

在一个100年的8周研究老年人,supplementing with 500 mcg of vitamin B12 were found to normalize B12 levels in 90% of participants. Higher doses of up to 1,000 mcg (1 mg) may be necessary for some ( 10. ).

Pregnant women

Pregnant womenhave slightly higher vitamin B12 needs than the general population.

这种维生素的低母体水平与婴儿出生缺陷有关（ 11. ).

Additionally, a large systematic review showed that B12 deficiency is associated with a higher risk of premature birth and low birth weight in newborns ( 12. ).

Therefore, the RDI for vitamin B12 during pregnancy is 2.6 mcg. This level can be met through diet alone or with aprenatal vitamin（ 1 ).

母乳喂养女性

Vitamin B12 deficiency in breastfed infants has been linked to developmental delay ( 13. ).

此外，婴儿的B12缺乏可能导致烦躁，胃口减少，并且未能茁壮成长（ 14. ).

For these reasons, the RDI for this vitamin for breastfeeding women is higher than that for pregnant women — namely 2.8 mcg ( 1 ).

素食主义者和素食主义者

Vitamin B12 recommendations do not differ for people following aplant-based diet。

然而，50岁以下人员为2.4麦克的RDI更难见面素食主义者或素食主义者饮食 （ 1 ).

In a review of 40 studies on vitamin B12 in vegetarians, up to 86.5% of vegetarian adults — including older adults — were found to have low levels of vitamin B12 ( 15. ).

There are currently no government recommendations for B12 supplement dosages for vegetarians.

However, one study suggests that doses up to 6 mcg of vitamin B12 per day may be appropriate for vegans ( 16. ).

B12 for improved energy

Though vitamin B12 is commonly taken to增加能量水平，证据表明，B12补充剂的证据缺乏没有缺陷的人们的能量水平。

然而，已经发现B12补充剂可以改善这种营养素缺乏的能量水平（ 17. ).

一篇审查建议使用维生素B12缺乏的人每天服用1毫克维生素B12，然后每天进行维持剂量为125-250麦克（ 18. ).

People who have issues absorbing vitamin B12, such as those with Crohn’s disease or other gastrointestinal issues, may benefit from B12 injections, which bypass the need for absorption by the digestive tract ( 17. ).

B12 for memory and mood

It’s commonly thought that taking vitamin B12 canboost your memoryand mood. However, there’s not a lot of evidence to support this theory.

Animal studies suggest that vitamin B12 deficiency has been associated with memory impairment. Yet, there’s currently no evidence that B12 supplements improve memory in humans who aren’t deficient ( 19. ).

在大综述中，维生素B12补充剂对短期内没有对抑郁症状的影响，但可能有助于防止长期复发（ 20. ).

There are no specific dosage recommendations for B12 supplements for mental performance or mood.

Summary

维生素B12的最佳剂量因年龄，生活方式和膳食需求而异。成人的一般建议是2.4麦格。老年人以及怀孕和母乳喂养女性需要更高的剂量。

Vitamin B12 is awater-soluble vitamin那meaning that your body excretes what you don’t need in your urine.

Because it’s relatively safe, no tolerable upper intake level (UL) has been set for vitamin B12. UL is considered the maximum amount of a substance that can be taken safely without side effects.

However, vitamin B12 has been shown to cause rare side effects in some cases.

Vitamin B12 injectionsmay lead to skin conditions, such as acne and dermatitis (rash) ( 21. ).

High doses of B vitamins over 1,000 mcg have also been associated with complications in people with kidney disease ( 22. ).

此外，母亲中B12的极高血液水平与儿童自闭症的风险相连（ 23. ).

Summary

虽然高剂量的维生素B12补充剂与某些群体中的罕见副作用有关，但它通常是安全的，并且目前没有推荐的维生素的最大数量。

Vitamin B12 is a nutrient that plays many essential roles in your body.

维生素B12的RDI为2.4麦克的成人为2.8麦克母乳喂养女性。

大多数人通过单独饮食满足这些需求，但老年人，严格的植物饮食中的人和消化系统障碍的人可能会受益于补充剂，但剂量因个人需求而异。