Do vitamin B12 supplements help increase energy?

If you look at any marketing materials surrounding vitamin B12 supplements, you’ll often see things like “helps increase energy”. But, will vitamin B12 actually help increase energy?

While vitamin B12 supplementation can help improve energy in someone who is deficient in vitamin B12, it would not be expected to have any effect on those who aren’t actually deficient.

Where do we normally get vitamin B12 from?

Vitamin B12, like any other vitamin, is a chemical substance that our body uses but that it can’t make on its own. This means our bodies evolved to require us to get them via an external source.

Vitamin B12 is normally found in the following foods (which are primarily animal products):

  • Meat
  • Fish
  • Poultry
  • Eggs
  • Milk (or milk products)

However, today vitamin B12 is also added to some non-animal derived foods. These sources, which would be great for those following a plant-based diet, can include:

  • B12-fortified nut milks (e.g. almond milk)
  • B12-fortified nutritional yeast
  • B12-fortified breakfast cereals

You might be surprised to learn that the only organisms that naturally create vitamin B12 are bacteria. So, when you’re getting B12 from animal products, it’s because that animal had ingested B12 from a bacterial source.

What is the role of vitamin B12 in the body?

Vitamin B12 has many important roles in the body. Two main areas where vitamin B12 plays a role are:

  1. Red blood cells
  2. Nervous system

Vitamin B12’s role in the formation of red blood cells

Many aren’t aware of this, but the amount of red blood cells in our body is not static. Through normal day-to-day functions, our body will replace about 1% of our red blood cells everyday. Because of this, the formation of blood cells tends to be faster than many other types of cells in our body. This is why the blood is one of the first places to show signs of certain deficiencies or toxicities.

Vitamin B12 is one of the many essential ingredients that our body uses in the production of new red blood cells. So, if there isn’t enough vitamin B12, our body can’t always keep up with replacing daily losses.

Think of vitamin B12 as building materials, and red blood cells as houses. If you don’t have enough building materials, you’ll struggle to make houses.

Vitamin B12’s role in the nervous system

Vitamin B12’s exact role in the function of the nervous system isn’t quite as well understood as its role in red blood cell formation, so I won’t go into specifics on the proposed mechanisms involved.

However, what has been observed is that in the setting of B12 deficiency some neurological problems can occur. See the section further below on symptoms for more details.

What can cause low vitamin B12 levels?

There are 2 primary ways for vitamin B12 deficiency to develop: not ingesting enough; or your body can’t absorb it well enough.

Many of these are more common in older adults; this is why vitamin B12 deficiency is much more common in adults over 60 years old (around 20%) compared to those under 60 years old (around 6%).

The main risk factors that may lead to vitamin B12 deficiency can include:

  • Age 75 and over
  • Eating a strict plant-based diet
  • Alcoholism (or other conditions associated with malnutrition)
  • Crohn’s Disease
  • Certain gastrointestinal surgeries (e.g. some bariatric surgeries, ileal resection)
  • Pernicious anemia
  • Certain genetic disorders
  • H. pylori infection
  • Taking certain medications long term (such as proton pump inhibitors or metformin)

Most of these risk factors impact the absorption of vitamin B12. However, there are ways to overcome this by using different forms of supplements (see my other post here for more information on choosing a vitamin B12 supplement).

What are the symptoms of low vitamin B12?

There are a variety of symptoms that can be associated with low vitamin B12 levels (severity will depend on the level and duration of the deficiency):

  • Fatigue (from anemia)
  • Irritability
  • Numbness/tingling sensation in extremities
  • Tongue pain and/or inflammation
  • Jaundice
  • Mood impairments (e.g. depression)
  • Cognitive decline (which in severe cases can be similar to dementia or even psychosis)
  • Balance problems
  • Reflex problems
  • Difficultly controlling and coordinating muscles
  • Weakness

Why wouldn’t more vitamin B12 improve energy in someone who isn’t deficient?

Lack of energy is a symptom that can occur with anemia from low vitamin B12 levels. While supplements will help in this setting of deficiency, someone who isn’t deficient won’t see an improvement.

This is because giving the body more vitamin B12 than it needs won’t lead to a greater than usual production of red blood cells. The first reason is that excess vitamin B12 is just peed out instead of stored. The second reason is that even if you had a way to store more vitamin B12 it wouldn’t amount to anything.

Remember my analogy earlier about how vitamin B12 was like building materials and red blood cells were like houses built using that lumber?

Giving more vitamin B12 to someone who isn’t deficient in the hopes of boosting energy is like giving a contractor more building materials (with no extra labor) and expecting them to build more houses in the same amount of time.

For those that are more visual, here’s a (low-budget) simplified visual representation:

The Bottom Line

In those who are deficient in vitamin B12, supplementation could help improve energy levels. However, the same cannot be said for those who are not deficient.

If you have some of the symptoms listed above, or think you may be deficient in vitamin B12, make an appointment with your primary care provider in order for them to do the necessary tests (+/- recommend a supplement if needed).

Unless you’re deficient in vitamin B12, or just enjoy having expensive pee, you probably don’t need to take a B12 supplement.

Dan Landry

Daniel (Dan) Landry, founder of, is an infectious diseases pharmacist at the Dr-Georges-L.-Dumont University Hospital Centre in Moncton, NB, Canada.

Recent Posts