Best Vitamin B12 Supplement Benefits and Dosages - Dr. Axe

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How to Get the Best Vitamin B12 Supplement Benefits


Vitamin B12 supplement - Dr. Axe

There’s a reason that vitamin B12 supplements are some of the most popular supplements on the market. Vitamin B12 benefits include increasing energy levels, improving mood, protecting memory and more. While it’s certainly possible to get all the vitamin B12 you need naturally from B12 foods like grass-fed meats, eggs and wild-caught fish, certain people can benefit from taking a vitamin B12 supplement as well. This is especially true if someone has already been diagnosed with vitamin B12 deficiency, which is most likely to affect vegetarians/vegans, older adults and people with malabsorption issues due to underlying health conditions.

Which is the best vitamin B12 supplement for you?

This depends on factors like your diet, level of deficiency, general health status, and whether or not you have any symptoms. With a number of different B12 supplement options available, let’s look at what kind may be best for you, in addition to dosage recommendations and warnings.

Who Needs a Vitamin B12 Supplement?

Vitamin B12 is a water-soluble vitamin that the body needs in small amounts, ideally daily, to function properly.

The single best reason to take a vitamin B12 supplement is to prevent vitamin B12 deficiency — which can lead to a number of symptoms and even long-term health issues, such as chronic fatigue, mood disorders, neurodegenerative disorders, heart issues, anemia and neural tube defects in infants.

What are the symptoms of B12 deficiency to look out for?

These include ongoing fatigue/lethargy; brain fog; muscle aches and weakness; joint pain; inability to concentrate well; numbness and tingling; digestive problems like nausea, diarrhea or cramping; and many others.


According to the National Institutes of Health (NIH):

Most people in the United States get enough vitamin B12 from the foods they eat. But some people have trouble absorbing vitamin B12 from food. As a result, vitamin B12 deficiency affects between 1.5% and 15% of the population.

People who can benefit most from taking a vitamin B12 supplement include those who:

  • Are over the age of 50, since aging can result in a decline in hydrochloric acid production in the stomach, which is needed to absorb the vitamin B12 present in foods.
  • Have had gastrointestinal surgery, such as weight loss surgery.
  • Have digestive disorders, such as celiac disease or Crohn’s disease, which can lead to malabsorption.
  • Avoid eating animal products, which are the richest sources of B12.
  • Have pernicious anemia, which means they don’t make intrinsic factor that’s needed to absorb vitamin B12.
  • Have a history of alcoholism or heavy smoking, which can hinder absorption.
  • Have a history of long-term antibiotic use, which can reduce the ability of the stomach to absorb and use vitamin B12.
  • Regularly use stomach acid-controlling medications.
  • Regularly take potassium supplements.
  • Are pregnant or breastfeeding.
  • Have bowel or pancreatic cancer.

It’s ideal to get vitamin B12 from food sources, whether or not you choose to also supplement. Some of the best B12 vitamin foods include beef liver, sardines, Atlantic mackerel, lamb, wild-caught salmon, nutritional yeast, cheese, beef and eggs.

Should you take B12 vitamins if you’re a vegetarian/vegan?

Most health authorities would answer yes. That’s because plant foods have no vitamin B12. In addition to supplementing with B12, eating nutritional yeast (a deactivated yeast strain of Saccharomyces cerevisiae) is another great way to increase your vitamin B12 levels when you don’t eat meat.

Health Benefits

B12 is an essential vitamin for adrenal health, cognitive functioning, multiple metabolic functions, enzyme production, DNA synthesis, hormonal balance and more. In supplement form, some vitamin B12 benefits may include:

  • Supporting a healthy metabolism and facilitating nutrient absorption/conversions.
  • Fighting fatigue, sluggishness and other symptoms related to low energy.
  • Helping improve concentration/focus.
  • Treating pernicious anemia (vitamin B12 shots or high oral doses of vitamin B12 are usually used in this case).
  • During pregnancy, ensuring that the mother and unborn baby both get enough vitamin B12, which is important for brain development and other functions.
  • Helping reduce elevated homocysteine levels, considered a major risk factor for heart disease.
  • Benefiting skin health by reducing redness, dryness, inflammation and acne blemishes.
  • Lowering the risk for cognitive issues tied to deficiency, such as difficulty focusing, poor memory and an increased risk for attention disorders.
  • Preventing mood disturbances.
  • Preventing nerve damage and muscle weakness caused by deficiency.
  • Treating headaches, nausea and dizziness.

What to Look for in a Vitamin B12 Supplement

If you regularly take a multivitamin, you likely already get the vitamin B12 you need. In addition to multivitamins, B12 is found in dietary supplements that contain vitamin B12 alone in high doses or vitamin B12 combined with nutrients like other B vitamins (this is called a B complex vitamin) or folic acid.

There are several different types of vitamin B12 supplements available today:

  • Capsules/pills that are taken by mouth
  • Sublingual forms of B12, which are dissolved under the tongue
  • Nasal gel form, which is usually a prescription that is taken through the nose to treat deficiency
  • B12 injections, which are usually given by prescription but sometimes are given over-the-counter
  • B12 ointments and creams, used to treat skin conditions like sores, dermatitis, eczema or psoriasis

The vitamin B12 supplement brand that is best for you depends on the dose you need, how well you can absorb B12 and how you prefer to take supplements. For some people, sublingual and dissolvable B12 supplements may cause gas, bloating and diarrhea due to sugars they contain. Some people may prefer to avoid injections, while others need injections to reach or maintain high enough B12 levels.

What is the best vitamin B12 supplement for vegans?

Vitamin B12 supplements and fortified foods contain B12 derived from microorganisms, such as yeasts and bacteria. While spirulina, dried nori, barley grass and most other seaweeds contain some B12 (dirt even contains some), consuming these foods hasn’t been shown to provide enough B12 to vegans. Therefore, supplementing is still recommended.

Dosage Recommendations

Compounds with vitamin B12 are collectively called cobalamins. There are different forms of B12 available in supplement form — including cyanocobalamin, methylcobalamin and hydroxocobalamin — that for the most part are believed to be equally effective.

How much B12 should you take?

Most adults need between 2.4 and 2.8 micrograms per day. Vitamin B12 dosage recommendations and needs depend on your age and gender. The NIH states that the following are  the “average daily recommended amounts” of B12 for different age groups:

  • Infants 0–6 months: 0.4 microgram
  • Infants 7–12 months: 0.5 microgram
  • Toddlers 1–3 years: 0.9 microgram
  • Children 4–8 years: 1.2 micrograms
  • Children 9–13 years: 1.8 micrograms
  • Adult men and women over age 14: 2.4 micrograms
  • Women who are pregnant: 2.6 micrograms
  • Women who are breastfeeding: 2.8 micrograms

Here are some tips for how to choose the vitamin B12 dosage that is right for you:

  • If you know that you are deficient in B12, you may need to take a high dose to begin with, up to 10,000 micrograms per day in some cases, to bring your levels up. According to WebMD, to treat B12 deficiency:
  • Injecting 0.2 mcg/kg of vitamin B12 into the muscle or under the skin once daily for 2 days, followed by a 1000 mcg injection daily for 2-7 days and another 100 mcg injection weekly for 4 weeks thereafter has been used. Additional injections of 100 mcg monthly may be needed depending on level of symptom improvement and cause of vitamin B12 deficiency.
  • Many health authorities recommend that adults over 50 years take a daily vitamin B12 supplement, usually in the range of 25–100 micrograms per day, and/or consume foods fortified with vitamin B12.
  • If you are under 50 and generally healthy, and you eat a balanced/varied diet, you likely don’t need to supplement. However, if you have a condition that puts you at risk for deficiency, supplementing with at least 2.5 micrograms daily is recommended. In some cases you may need a higher dose, such as 25 to 50 micrograms daily, but this should be determined by your doctor if you’re supplementing to treat symptoms.
  • It’s recommended that pregnant women supplement with at least 2.6 micrograms per day of vitamin B12 in order to prevent birth defects. Breastfeeding women are advised to supplement with 2.8 micrograms per day.
  • If you’re a vegetarian/vegan, supplementing with three to six micrograms/day should be enough to meet your needs. The Vegan Society website states:
  • To get the full benefit of a vegan diet, vegans should do one of the following: eat fortified foods two or three times a day to get at least three micrograms (mcg or µg) of B12 a day, OR take one B12 supplement daily providing at least 10 micrograms, OR take a weekly B12 supplement providing at least 2000 micrograms.
  • If you have an issue with absorption, such as due to Crohn’s disease or other gastrointestinal issues, B12 injections may be most effective. You should talk to your doctor about the dosage is right for you in this case.

Remember that you can also naturally boost your vitamin B12 levels by consuming more food sources of vitamin B12, including beef liver, organic meats and wild-caught salmon. You can also increase absorption of B12 by taking a probiotic daily and working on the health of your gut by eliminating processed, inflammatory foods.

To absorb the most B12, divide your dose over the course of the day. Take B12 supplements separately from a B12-containing meal if possible.


Risks, Side Effects and Interactions

What happens when you have too much vitamin B12 in your body?

Vitamin B12 overdose is very unlikely to happen because vitamin B12 is a water-soluble vitamin, meaning the body has the ability to flush out any excess through urine that it doesn’t need.

While vitamin B12 supplements are considered safe and non-toxic, taking large doses of around 1,000 milligrams can still be problematic. According to Consumer Lab, “Although no ‘Upper Tolerable Intake Level’ has been established, there are risks associated with getting too much B-12 from supplements.”

What are the side effects of B12?

Although vitamin B12 side effects are rare, some people may experience headache, swelling, anxiousness and itching when they’ve consumed too much vitamin B12 or have a reaction to a dietary supplement.

Some people have trouble properly absorbing vitamin B12 because of GI/digestive issues and underlying health conditions. For example, people who have pernicious anemia, a condition in which they cannot make intrinsic factor — which is needed for B12 absorption — are not able to use vitamin B12 from foods or dietary supplements. These individuals should consult with a doctor first before taking a vitamin B12 supplement.

Vitamin B12 supplements can also interact with certain medicines, and some drugs can alter how the body absorbs vitamin B12. These drugs include:

  • Chloramphenicol (Chloromycetin®), an antibiotic that is used to treat certain infections.
  • Proton pump inhibitors, such as omeprazole (Prilosec®) and lansoprazole (Prevacid®), that are used to treat acid reflux and peptic ulcer disease.
  • Histamine H2 receptor antagonists, such as cimetidine (Tagamet®), famotidine (Pepcid®), and ranitidine (Zantac®), that are used to treat peptic ulcer disease.
  • Metformin, a drug used to treat diabetes/insulin resistance and sometimes PCOS.

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