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Vitamin B12 Benefits and Dosage

Low levels of vitamin B12 can double your chances of developing a mood disorder.

ingredients 13 vitamin-B12 illustration
Sophie Medlin
Sophie Medlin
Head of Nutritional Research
November 11, 2020
7 min read

In this article we're highlighting everything you need to know about vitamin B12 benefits, functions and dosage.

Article breakdown

Vitamin B12 benefits & functions

A water-soluble vitamin needed for:

  • Keeping the body’s blood cells healthy

  • Aiding with DNA production

  • Encouraging antibodies after vaccination or infection

  • Vital for healthy nerve function

  • Our bodies do not produce it so it must be sourced from food or supplements

  • Deficiency can result in irreversible neurological damage

How much vitamin B12 should I take?

The Nutrient Reference Value (NRV—formerly RDA) is around 2.4mg per day.

Benefits of B12 on the brain

As the most structurally complex and largest vitamin, B12 (also known as methylcobalamin—try saying that after a few sherries) is essential for our brains. Every single cell in the body is dependent on vitamin B12 for metabolism—for brains that means energy for neurons to communicate.

Low levels of B12 can double your chances of developing a mood disorder, such as depression, as it has a major effect on the production of serotonin—a chemical in the brain that regulates mood.

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Benefits of vitamin B12 on the body

B12 has a myriad of benefits for the body—it’s needed to create DNA, which could help us to age in a healthier way. It also helps our bodies to break down homocysteine, harmful levels of which could result in strokes and heart disease.

Vitamin B12 deficiency symptoms

B12 is a bit of a superstar—and there are many reasons why it’s dangerous to be deficient. 

As it’s largely found in animal sources, fortified foods, and supplements, vegans and vegetarians need to keep an eye on their levels—in a 2019 study, 20% of the 172 vegan participants were deficient. And it’s not just those who avoid animal products. In one study, up to 20% of the general population were predicted as being B12 deficient, and this rose to 30-40% in older people.

Healthy nerve function is dependent on vitamin B12, and if you don’t absorb or consume enough, this could lead to nerve damage in the spinal cord, which—if left untreated—could result in a rare condition called sub-acute. 

This nifty vitamin is also essential for creating antibodies and fighting infections—a lack of it has been associated with inflammation of the stomach lining, which can lead to stomach ulcers, and in worse cases, gastric cancer. 

Low B12 levels also cause red blood cells to become larger and irregular in shape, which means they struggle to move into the bloodstream at a normal rate. This can result in a type of anaemia called megaloblastic anaemia, which can bring on fatigue and weakness.

Signs of B12 deficiency include:

  • A smooth, sore tongue

  • Tiredness

  • Exhaustion

  • Lack of concentration

  • Confusion

  • Dizziness

  • Depression

  • Menstrual disorders

  • Difficulty walking

  • Poor memory

  • Pale or jaundiced skin

  • Pins and needles

Vitamin B12 Foods

The following foods are great sources of vitamin B12:

  • Fish

  • Eggs

  • Meat

  • Milk

  • Cheese

  • Fortified cereals

Ways to supplement vitamin B12

As B12 is largely derived from meat and dairy products, people following a plant-based or vegetarian diet may choose to supplement to ensure they are getting enough vitamin B12.

Those who do eat meat may also want to consider supplementing, especially as they age, as the body’s capacity for absorption lowers.

What other vitamins and minerals should I take with vitamin B12?

  • Folic acid: B12 is essential for making sure the body uses folic acid effectively—which helps our bodies to produce DNA. For pregnant women, there’s evidence that both these elements lead to a smaller chance of congenital birth defects.

  • Calcium: in preliminary studies, calcium was shown to help the absorption of B12.

  • Iron: it helps iron to make red blood cells and studies have shown an association between a lack of the vitamin and osteoporosis.

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FAQ on vitamin B12 supplements

Below we've summarised the most asked questions and answers on vitamin B12:

  • What are vitamin B12 supplements good for?

To ensure that the body can produce DNA, help our cells to metabolise energy, and to keep nerves healthy (along with many other benefits)—and to avoid deficiency, it may be necessary to supplement.

  • Who should take a B12 supplement?

Vegans and vegetarians are particularly at risk of deficiency due to cutting out animal products from their diet (though it is also possible to source it from fortified products). Older people may also choose to use supplements as rates of absorption lower as we age, meaning it can be hard for the body to source the vitamin from food alone.

  • How much vitamin B12 should I take?

There is no minimum, while the NRV is 2.5mg, Heights includes 25mcg of vitamin B12 which has been scientifically proven to be safe and effective in caring for your brain. 

  • How long does it take for a B12 supplement to start working?

There is no single answer—B12 is one of the few water-soluble vitamins that can be stored in the liver for long periods of time, however, if you are deficient it is best to start taking it as soon as possible.

  • Is taking a B12 supplement safe?

Yes, no studies have shown that taking B12 is dangerous.

  • Can you overdose on a vitamin B12 supplement?

No, you can’t—excess vitamin B12 is excreted through urine.

  • What are the side effects of a B12 supplement?

None have been found.

How we use vitamin B12 in Heights’ Smart Supplement

We use a bio-active form of B12 in our smart supplement—this is the same kind found naturally in food and in our bodies—rather than the more commonly used cyanocobalamin. As B12 is essential for the body to absorb folic acid, we’ve also included a meaningful dose of that in our capsule, so that the two can work side by side.

Read more on how to improve your brain health here.


Here’s a handful of relevant scientific studies on vitamin B12.

  • Horvat, P., Gardiner, J., Kubinova, R., Pajak, A., Tamosiunas, A., Schöttker, B., ... & Bobak, M. (2016). Serum folate, vitamin B-12 and cognitive function in middle and older age: The HAPIEE study. Experimental gerontology, 76, 33-38.

  • Leishear, K., Boudreau, R. M., Studenski, S. A., Ferrucci, L., Rosano, C., De Rekeneire, N., ... & Hogervorst, E. (2012). Relationship between vitamin B 12 and sensory and motor peripheral nerve function in older adults. Journal of the American Geriatrics Society, 60(6), 1057-1063.

  • Penninx, B. W., Guralnik, J. M., Ferrucci, L., Fried, L. P., Allen, R. H., & Stabler, S. P. (2000). Vitamin B12 deficiency and depression in physically disabled older women: epidemiologic evidence from the Women’s Health and Aging Study. American Journal of Psychiatry, 157(5), 715-721.

  • Iqbal, S. P., Kakepoto, G. N., & Iqbal, S. P. (2009). Vitamin B12 deficiency--a major cause of megaloblastic anaemia in patients attending a tertiary care hospital. Journal of Ayub Medical College, 21(3), 92.

  • Syed, E. U., Wasay, M., & Awan, S. (2013). Vitamin B12 supplementation in treating major depressive disorder: a randomized controlled trial. The open neurology journal, 7, 44.

  • Hintikka, J., Tolmunen, T., Tanskanen, A., & Viinamäki, H. (2003). High vitamin B 12 level and good treatment outcome may be associated in major depressive disorder. BMC psychiatry, 3(1), 17.

  • Köbe, T., Witte, A. V., Schnelle, A., Grittner, U., Tesky, V. A., Pantel, J., ... & Flöel, A. (2016). Vitamin B-12 concentration, memory performance, and hippocampal structure in patients with mild cognitive impairment. The American journal of clinical nutrition, 103(4), 1045-1054.

  • Oulhaj, A., Jernerén, F., Refsum, H., Smith, A. D., & de Jager, C. A. (2016). Omega-3 fatty acid status enhances the prevention of cognitive decline by B vitamins in mild cognitive impairment. Journal of Alzheimer's Disease, 50(2), 547-557.

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