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Vitamin B12 benefits, dosage & deficiencies

Everything you need to know about vitamin B12 benefits (and why you don't want to be deficient!)

ingredients 13 vitamin-B12 illustration
Sophie Medlin
Sophie Medlin
Head of Nutritional Research
June 23, 2022
7 min read

Here's the thing about Vitamin B12: it's an essential vitamin that the body needs, but on its own it can't produce. Luckily, certain foods and supplements can help you get the vitamin B12 benefits and avoid the symptoms of deficiency.

Article breakdown

Vitamin B12 benefits

Vitamin B12 is 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

  • Deficiency can result in irreversible neurological damage.

It's part of the vitamin B complex, and you can read more about each of the other B vitamins here:

  • Vitamin B1

  • Vitamin B2

  • Vitamin B3

  • Vitamin B5

  • Vitamin B6

  • Vitamin B7

  • Vitamin B9

(p.s. Did you know the Smart Supplement contains all 8 B vitamins + 12 other essential nutrients? Discover more)

What are the benefits and side effects of vitamin B12?

Health benefits of vitamin B12 for 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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What does B12 do for your body?

B12 also 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.

Studies also suggest there are specific vitamin B12 benefits for women who are pregnant and breastfeeding, and they're recommended to take a higher dose.

Is vitamin B12 safe? What are the side effects?

There are no studies that have shown that taking B12 is dangerous or has any negative side effects. You can't overdose on vitamin B12 as excess is excreted through urine.

What happens when your vitamin B12 is low?

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

  • Difficulty walking

  • Poor memory

  • Pale or jaundiced skin

  • Pins and needles

  • Menstrual disorders

Simply avoiding these nasty symptoms is one of the main benefits of vitamin B12!

How to get enough Vitamin B12

Vitamin B12 Foods

The following foods are great sources of vitamin B12:

  • Fish

  • Eggs

  • Meat

  • Milk

  • Cheese

  • Fortified cereals

Who should take a vitamin B12 supplement?

As you can see, vitamin B12 is largely derived from meat and dairy products, and so 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.

Is taking B12 everyday good for you?

Yes! The Nutrient Reference Value (NRV—formerly RDA) is around 2.4mg per day to get vitamin b12 benefits.

Heights includes 25mcg of vitamin B12 in our Smart Supplement which has been scientifically proven to be safe and effective in caring for your brain. 

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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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.

So, what is vitamin B12 good for? what are the benefits of taking vitamin B12?

To sum up, B12 ensures that the body can produce DNA, helps our cells to metabolise energy, and keeps nerves healthy (along with many other benefits). There are benefits of taking B12 as a supplement to avoid deficiency.

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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