What happens to your body when you take vitamin B12

Our bodies need a variety of vitamins and minerals to function properly, including eight B vitamins, of which vitamin B12 is the best known. But what exactly is vitamin B12, and do we need to take it daily? Vitamin B12 supplements are often marketed as energy and mood boosters, but this vitamin plays a much more important role in the body. It’s an essential vitamin that’s needed for the production of healthy red blood cells, nerve and brain function, and for the production of DNA, the genetic material contained in all cells. Most people get enough vitamin B12 from a variety of foods, but taking a supplement to prevent a deficiency is usually not harmful. In addition, some people, such as those following a vegan or vegetarian diet or those with conditions that cause vitamin B12 malabsorption, may benefit from taking a vitamin B12 supplement.

What is Vitamin B12?

Vitamin B12, sometimes called cobalamin, is a water-soluble vitamin that contains the mineral cobalt. It is found naturally in some foods, such as tuna, beef, and dairy products, added to fortified foods such as breakfast cereals, and is available as a dietary supplement and prescription drug. B12 is a nutrient necessary for the development of brain and nerve cells, red blood cells, and DNA synthesis. It is primarily absent from plant foods (though some, such as seaweed and mushrooms, may contain small amounts), making B12 supplementation or fortified foods essential for those following a vegan or vegetarian diet.

Vitamin B12 deficiency

Most people in the U.S. get enough vitamin B12. Data show that only 4% of U.S. men and 8% of women have vitamin B12 intakes from food and beverages below the Estimated Average Requirement (EAR). There are several causes of vitamin B12 deficiency. You may develop a B12 deficiency if you don’t get enough B12 in your diet, if you have trouble absorbing B12 from food, if you have a condition called pernicious anemia, if you have had gastrointestinal surgery in which part of your digestive tract was removed, or if you use certain medications for a long time, such as metformin, oral contraceptives, proton pump inhibitors, or H2 blockers. However, because most people get enough vitamin B12 from food and the body stores significant amounts of vitamin B12 in the liver, it can take years for vitamin B12 symptoms to appear.

Recommended Daily Intake of Vitamin B12

The recommended daily allowance (RDA) of vitamin B12 for adults aged 19 years and older is 2.4 micrograms. However, if you’re pregnant or breastfeeding, that amount increases to 2.6 micrograms and 2.8 micrograms, respectively.

The bioavailability of B12 – the degree to which the nutrient can be absorbed and used by the body – varies depending on its source. For example, the bioavailability of B12 in dairy products is about three times higher than that found in meat, fish or poultry, and the bioavailability of B12 in supplements is 50% higher than that found in all food sources. That being said, including a variety of nutritious whole foods in your diet is the best way to meet your needs for vitamin B12 and other nutrients.

Health Benefits of Vitamin B12

Research has shown that Vitamin B12 plays an important role in health. Benefits include:

Erythropoiesis

Adequate vitamin B12 is needed to produce healthy red blood cells and prevent megaloblastic anemia, a type of anemia in which cells become large and underdeveloped. Symptoms of megaloblastic anemia include fatigue, pale skin, palpitations, loss of appetite, weight loss, and infertility.

Brain and Nervous System Health

B12 is necessary for nerve function and maintaining healthy nerve cells. Therefore, vitamin B12 deficiency can interfere with maintaining healthy functioning of the nervous system and may even lead to permanent nerve damage over time.

Infant Development

An infant’s brain develops rapidly, so they need enough vitamin B12 to support healthy brain development and produce red blood cells. B12 is abundant in breast milk and is also fortified in formula, so your baby’s needs can easily be met through regular consumption of these foods. Though rare, B12 deficiency can cause stunted growth and delays in developmental milestones in infants. If left untreated, vitamin B12 deficiency can cause permanent brain damage over time. Always talk to your doctor and healthcare team about any concerns you may have about your child.

Healthy Energy Metabolism

Vitamin B12 plays a key role in energy metabolism. Because of this, a deficiency in Vitamin B12 can make you feel tired and weak. Fortunately, a Vitamin B12 deficiency is typically easy to treat with increased food sources, supplements, or, in cases of malabsorption, high-dose injections or nasal sprays. In many cases, treatment works very quickly, within 48-72 hours. Talk to your doctor to determine a personalized plan that’s right for you.

Scientists are studying the effects of vitamin B12 supplementation on cancer, heart disease, stroke, dementia, or as an adjunct treatment for viral infections, but more evidence is needed to clarify its long-term health effects.

Sources of Vitamin B12

Vitamin B12 is bound to protein, so foods rich in B12 include:

• Fish, meat, poultry, eggs, dairy products
• Clams, oysters, beef liver
• Fortified breakfast cereals, nutritional yeast, and plant-based milk alternatives

“If you want to add foods high in vitamin B12 to your diet, find foods you really love. You’re much more likely to stick to eating foods that are easy to add to your daily diet,” says Michelle Saari, MS, RD, health expert at the eHealth Project. “Try to add at least one food per day. This might mean having a bowl of fortified cereal with milk as a snack. You don’t need to have vitamin B12 at every meal, but try to add more to your diet and at least one food per day throughout the week.”

“If you’re following a vegan diet, supplement your diet with enriched nutritional yeast and fortified foods: sprinkle it on pasta, pizza, or salads for a cheesy flavor, or mix it into soups and stews,” says Laura M. Ali, MS, RDN, a culinary nutritionist based in Pittsburgh, Pennsylvania. We couldn’t agree more, and love adding it to recipes like vegan mac & cheese. and a vegan chickpea frittata.

“If a product is fortified with vitamin B12, the percentage of your daily value will be listed in the vitamins and minerals section of the food label. Natural vitamin B12 will not be listed on the food label,” says Grace Scarborough, RDN, CD, a dietitian based in Seattle, Washington. “While reading labels can be confusing, checking them and choosing plant-based products that are high in vitamin B12 can help you increase the amount you get in your diet.”

Potential risks and side effects

Vitamin B12 is water-soluble, so the body does not store more than it needs, and so it is generally considered safe to take large amounts. Any excess is excreted in urine. However, taking large amounts of vitamin B12 to treat a deficiency can cause side effects, including nausea, vomiting, and diarrhea, and in some people, itching and skin rashes. Always check with a healthcare professional before taking high doses of supplements, and be sure to monitor any side effects.

Vitamin B12 may interact with certain medications, including those used to treat gastroesophageal reflux disease and peptic ulcers, because these drugs slow the release of stomach acid needed to release vitamin B12 from food. Another common medication that can interfere with vitamin B12 absorption is metformin, which is often prescribed for people with prediabetes and diabetes.

Who can benefit from Vitamin B12 supplements?

Most people get enough from the foods in their diet, but people who have a vitamin B12 deficiency or who have the following conditions should consider taking a supplement:

• People following a vegan or vegetarian diet: Because B12 is only found naturally in animal foods, studies have shown that people who follow vegetarian and vegan diets tend to have lower B12 stores. This is especially important for pregnant women, as it is necessary for the normal development of the fetus’ brain and nervous system.
• People who lack intrinsic factor: Pernicious anemia is an autoimmune disease that impairs the intestine’s ability to produce intrinsic factor, a protein necessary for the absorption of vitamin B12.
• If you have low stomach acid or are taking medications to reduce stomach acid: Lack of stomach acid is the most common cause of vitamin B12 deficiency, especially in older adults. Between 3% and 43% of older adults suffer from vitamin B12 deficiency. Regularly taking certain medications that reduce or suppress stomach acid, such as medications for gastroesophageal reflux disease (GERD) or peptic ulcer disease and antacids, can make it harder to absorb vitamin B12 from food. However, fortified foods and supplements are a good option for people taking these medications because they don’t require stomach acid.
• People who have had intestinal surgery or digestive disorders: Surgery affecting parts of the stomach or small intestine and diseases such as Crohn’s disease or celiac disease can cause impaired or malabsorption of vitamin B12. Talk to your doctor about the best treatment plan for you.
• If you are taking other medications that interfere with absorption: Metformin, a commonly prescribed drug for the treatment of prediabetes and diabetes, inhibits the absorption of vitamin B12 and is closely associated with vitamin B12 deficiency.

Although rare, people with known hypersensitivity or allergies to vitamin B12, cobalt, or any other ingredients listed on the supplement label should avoid taking the supplement.

What to look for when choosing a vitamin B12 supplement

Vitamin B12 is available as a multivitamin supplement, a vitamin B-complex supplement, or a supplement that contains only vitamin B12. The amount of vitamin B12 in supplements can vary widely, from 500 micrograms to 1,000 micrograms. “The most important thing when choosing a vitamin B12 supplement is to make sure you’re getting the right dose for you,” says Saari. Talk to your healthcare provider before taking a new supplement.

B12 comes in several forms, including adenosylcobalamin, methylcobalamin, and hydroxycobalamin. However, “methylcobalamin is the more highly absorbed form of vitamin B12,” says Lisa Andrews, M.Ed., RD, LD, a registered dietitian at Health Insiders.

“If you have the budget, choose products that are USP or NSF certified, which is a (voluntary) third-party verification that ensures the ingredients listed are actually present, and that they don’t contain harmful levels of contaminants or heavy metals that shouldn’t be there,” says Lori McCall, MS, RD, LDN.

Conclusion

Vitamin B12 is an essential water-soluble vitamin that should be obtained from a variety of animal and fortified plant foods, or as a supplement. Health benefits of vitamin B12 include a healthy brain, a healthy nervous system, red blood cell production, and supporting DNA synthesis. Vitamin B12 deficiency can be a very serious condition if left untreated, especially in pregnant women and those with developing infants, but it is usually easily treatable with a variety of supplements, including foods, tablets, injections, and sprays, and is generally considered safe, even in high doses.