Can You Take Too Much Vitamin B12 Supplement?

Vitamin B 12 is an essential vitamin that our bodies need for many important functions. It helps to make DNA, red blood cells, and nerves. Vitamin B 12 is found naturally in animal products, such as meat, fish, poultry, eggs, and dairy. 

Most people get enough vitamin B 12 from their diet. However, some people may not get enough vitamin B 12 because they have trouble absorbing it from food. They may need to take vitamin B 12 supplements.

The body does not store vitamin B 12, so it is important to get enough of this essential nutrient every day. But is It OK to take too much vitamin B12 supplement? Let's discuss this topic further.

Why Is Vitamin B12 Important?

Vitamin B12 is vital for many functions in the body, according to NIH. It helps to:

  • Make DNA
  • Build red blood cells
  • Keep nerves healthy

If you don't get enough vitamin B12, you may have trouble making red blood cells and DNA and keeping your nerves healthy. Vitamin B12 deficiency can lead to problems such as anemia, balance problems, and neuropathy. You can learn more about vitamins by reading, Vitamins How They Work And Their Sources.

However, only a small percentage of people are actually deficient in vitamin B12.

Who Needs Vitamin B12 Supplements?

Who Needs Vitamin B12 Supplements?

According to a MedlinePlus study on Vitamin B12, there are four categories of people who are prone to Vitamin B 12 deficiency.

  • People who are over the age of 50

Older people are at risk for vitamin B12 deficiency because they may have trouble absorbing vitamin B12 from food. This is due to a decrease in stomach acid production as we age, as stated by Pubmed. Less stomach acid cause less vitamin B12 to be absorbed, hence the need for supplementation.

  • People who follow vegetarian or vegan diets

Vitamin B12 deficiency is a problem that affects vegans and vegetarians since they do not consume animal products, which are the main source of this vitamin.

  • People with digestive disorders

People with digestive disorders, such as Crohn's disease, celiac disease, and pernicious anemia, may have trouble absorbing vitamin B12 from food.

  • People who have had weight-loss surgery or other stomach or intestinal surgery

People who have had weight-loss surgery or other stomach or intestinal surgery may have trouble absorbing vitamin B12 from food.

If any of the following categories applies to you, you may need a vitamin B12 supplement.

How Much B12 Can You Safely Take A Day?

The recommended daily allowance (RDA) for vitamin B12 is 2.4 mcg per day for adults over the age of 14. However, the requirements can vary depending on your age, health status, and other factors.

According to MedlinePlus, Pregnant women and breastfeeding mothers need slightly more vitamin B12 than other adults. Pregnant women require 2.6 mcg of vitamin D daily, whereas breastfeeding women require 2.8 mcg per day.

The RDA for vitamin B12 in a vitamin supplement is the same as it is in food. The maximum daily dose of vitamin B12 from oral supplements is set at 2,000 mcg per day, as recommended in a systematic review about Oral vitamin B 12 versus intramuscular vitamin B 12 for vitamin B 12 deficiency.

Is It OK to Take Too Much Vitamin B12 Supplement?

Vitamin B12 is a water-soluble vitamin, which means your body does not store it. You need to get enough of this vitamin every day.

Did You Know? There are two types of vitamins; water-soluble vitamins and fat-soluble vitamins. Water soluble vitamins quickly absorb into the bloodstream and are excreted in the urine. They include vitamin C and all the B vitamins. Vitamins that are fat-soluble are stored in the liver and fatty tissues. They include vitamins A, D, E, and K.

Vitamin B12 has no Tolerable Upper Intake Level (UL), as stated by the Harvard School of Public Health because there is no evidence of adverse effects from high doses of this vitamin. However, taking very high doses of this vitamin (more than ten times the RDA) can lead to some adverse effects on your health.

What Happens If Your B12 Is Too High?

What Happens If Your B12 Is Too High?

Megadoses of Vitamin B12 can have adverse health effects, as too much of any nutrient can be harmful. The following are some of the possible health concerns of taking too much vitamin B12 supplement:

Acne Outbreaks

Several studies have shown that taking large doses of vitamin B12 can cause acne outbreaks. A case report in the National Library of Medicine found that taking Vitamin B12 Injection may induce acneform eruption, followed by a few other studies in 20132014, and 2018.

However, you should note that all of these studies were focused on high doses of Vitamin B12 injections which are not the same as taking oral supplements.

Several Side Effects on Diabetic Nephropathy Patients

"Effect Of B-Vitamin Therapy" published at NIH found that people with diabetic nephropathy have a rapid decline in kidney function when supplemented with mega doses of B vitamins, including 1 mg per day of B12. This is likely because high doses of B12 can worsen kidney function in people with diabetes.

Another randomized controlled trial about the Effect of B-vitamin therapy on the progression of diabetic nephropathy has found that Vitamin B supplementation increases the risk of vascular events such as heart attack, stroke, and death.

Increases Risk of Autism Spectrum Disorder

Autism spectrum disorder is a neurodevelopmental disorder that affects communication and social skills. According to CDC, it is estimated that one in 68 children in the United States is affected by autism spectrum disorder. Autism spectrum disorder(ASD) can be caused by a variety of factors, including genetics and environmental factors.

Vitamin B12 has long been considered essential for a variety of neurological functions. However, its role in the development of autism spectrum disorder is becoming increasingly controversial.

A study publicly released in the National Library of Medicine showed that extremely high levels of B12 due to supplementation increase the risk of autism spectrum disorder in unborn children. The study found that children whose mothers had taken high doses of B12 during pregnancy were up to 2.5 times more likely to develop autism spectrum disorder than children whose mothers had taken lower doses of B12 or no B12 supplements at all.

The findings of this study are alarming, but it is important to note that further research is needed to confirm these results. In the meantime, pregnant women should avoid taking high doses of B12 supplements unless advised to do so by their doctor.

To avoid these complications, you can take one of The Highest Ranking Pregnancy Supplements so that you can get the recommended amount of nutrients, including B12, during pregnancy.

Increases the Risk of Cancer

Thin cohort studies are valuable for identifying potential risk factors for diseases, but they are not as powerful as randomized controlled trials in confirming those risks. In a thin cohort study, the researcher looks at a specific population and compares the rates of a disease in that population to rates of the disease in a different population. This type of study can be useful in identifying potential risk factors for diseases, but it cannot confirm whether those risk factors actually cause the disease.

One such study, Elevated Vitamin B12 Levels and Cancer Risk, looked at the relationship between elevated vitamin B12 levels and cancer risk. The study found that persons with elevated B12 levels were at increased risk for liver cancer, pancreas cancer, and myeloid malignancies. While these findings are suggestive of a link between B12 and cancer, more research is needed to confirm this relationship.

Further, the study was based on elevated B12 levels in the blood. It doesn't state whether it is due to supplementation or not. As a result, making definitive statements is difficult.

Increases Lung Cancer Risk in Men

Research suggests that there is a 30-40% increased lung cancer risk associated with the use of vitamins B6 and B12 from individual supplements in men. Researchers found no association in women or for B vitamins from multivitamin sources. However, the extended use of vitamin B6 or B12 (mostly from individual supplements) was associated with a nearly two-fold increased risk of lung cancer in men. This correlation was especially strong among men who smoked at baseline.

The same study found that there is no association between the intake of folic acid and the risk of lung cancer.

So, it is clear that taking high doses of vitamin B6 and B12 supplements can increase the risk of lung cancer in men.

Increases the Risk of Hip Fracture in Postmenopausal Women

A study about Association of High Intakes of Vitamins B6 and B12 From Food and Supplements With Risk of Hip Fracture Among Postmenopausal Women found, that there was an increased risk of hip fracture in postmenopausal women who had high intakes of vitamins B6 and B12.

The risk was highest in women who had a combined high intake of both vitamins, exhibiting an almost 50% increased risk of hip fracture compared with women with a low intake of both vitamins. This suggests that vitamin supplements should be used cautiously because adverse effects can occur.

Bottom Line

Vitamin B 12 is a water-soluble vitamin that is found naturally in some foods and is also available as a dietary supplement and medication. Vitamin B12 is required for the formation of red blood cells, neurological function, and DNA synthesis.

There is no limit on the amount of vitamin B12 that can be obtained from food. The Dietary Reference Intake (DRI) for vitamin B12 is 2.4 micrograms per day for adults and children over age 14.

Vitamin supplements containing vitamin B12 are generally considered safe, but there is some concern that high doses of B12 may worsen kidney function in people with diabetes and increase the risk of cancer. Pregnant mums should avoid taking high doses of B12 supplements unless it is prescribed by a healthcare professional.

Vitamin B12 supplementation is linked to several other health conditions. It should be used with caution in people who have diabetes, kidney disease, or cancer.

The Bottom Line is that you should consult your doctor before taking a Vitamin B12 supplement, especially in high doses. If you are in good health, you may not need any dietary supplements at all. It is always best to get vitamins and minerals from whole foods instead of supplements. This way, you are sure to get other important nutrients that are found in foods.


Is It OK To Take 1000 Mcg B12 Daily?

Yes, it is safe to take up to 1000 mcg of vitamin B12 daily. The body will excrete any excess vitamin B12 in the urine.

What Foods Are High In Vitamin B12?

Meat, fish, poultry, eggs, and dairy products are all natural sources of vitamin B12. Some foods, such as fortified breakfast cereals, contain it as well.

How To Check Vitamin B12 Level In Your Body?

You can have your vitamin B12 levels checked with a simple blood test. Your doctor can order this test for you. You must prepare for the test by avoiding foods and supplements for at least 6 hours before the test. This ensures that your results are accurate.

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