10 Important Health Benefits of Vitamin B12

Vitamin B12 is a water-soluble vitamin otherwise known as cobalamin, and it is essential for our health.

The current reference daily intake (RDI) for vitamin B12 is 2.4 mcg, and it is found exclusively in animal foods (1).

This important vitamin has a large number of functions, and it affects every cell within the human body.

This article will examine the health benefits that B12 offers.

Image Showing Foods Rich In Vitamin B12: Meat, Eggs and Seafood.

1) May Help To Fight Depression and Improve Mental Health

As mentioned, vitamin B12 influences every cell in the body, and this includes those in the brain.

Interestingly, research suggests that insufficient vitamin B12 levels may increase the risk of depression and mental health problems (2, 3).

This link may be one of the reasons why vegetarian and vegan diets have been associated with a higher risk of depression. Without careful supplementation, these diets can result in vitamin B12 deficiencies (4, 5, 6).

A systematic review of randomized trials recently looked at whether treatment with vitamin B12 supplementation can reduce depression.

While there was no short-term decrease in symptoms of depression, longer-term consumption (several weeks to years) reduced the risk of depressive episodes (7).

Key Point: Studies show that maintaining adequate levels of vitamin B12 is important for mental health.

2) Vitamin B12 Gives the Body Energy

Vitamin B12 plays an important role in cellular energy metabolism, and it helps to convert the food we eat into usable energy (8).

Providing that we consume sufficient quantities of the vitamin, we should have adequate energy for daily life.

Since vitamin B12 is water-soluble (and any excessive dietary intake is excreted), increasing B12 consumption confers no further benefits (9).

However, for individuals not consuming enough vitamin B12, symptoms such as tiredness and fatigue are among the first signs of deficiency (10, 11).

Increasing the intake of animal foods such as meat, fish, and shellfish (or supplementing with B12) can help to increase plasma levels of the vitamin.

Key Point: An insufficient intake of vitamin B12 can lead to fatigue.

3) Vitamin B12 Reduces the Risk of Birth Defects During Pregnancy

A Pregnant Woman Holding Her Stomach and Smiling.

Ensuring a sufficient intake of vitamin B12 is particularly important during pregnancy.

Again, this is not a case of more is better, but resolving B12 deficiencies can have a positive effect in lowering the risk of birth defects.

On this note, research consistently shows that higher levels of B12 decrease the risk of neural tube defects. One large Canadian population study found that women in the lowest quartile of vitamin B12 status had a three-fold increased risk of neural tube defects (12).

Further to this, a review of the evidence determined that it was “highly probable” that increasing vitamin B12 intake will provide benefits for preventing neural tube defects (13).

Furthermore, in severe cases, clinical B12 deficiency may result in infertility or even spontaneous abortion (14, 15).

Key Point: It is particularly important to ensure an adequate vitamin B12 intake during pregnancy.

4) Helps To Prevent Anemia

Anemia is a condition that develops when the blood is lacking sufficient red blood cells to carry oxygen to tissues and organs.

To make red blood cells, our body needs three main things;

  • Folate
  • Iron
  • Vitamin B12

In other words, ensuring a sufficient intake of dietary vitamin B12 helps to support the healthy production of red blood cells.

When the body does not have enough vitamin B12 to produce the required amount of red blood cells, anemia develops.

We can refer to the resulting condition as megaloblastic anemia, although it is sometimes called vitamin B12 deficiency anemia (16).

Studies show that vitamin B12 intake can both protect against—and reverse—anemia (17, 18).

Key Point: Meeting the dietary requirements for vitamin B12 can help prevent or cure anemia.

5) Sufficient B12 Intake Lowers Homocysteine Levels

Illustration Showing the Molecular Structure of Homocysteine.

Homocysteine is a non-protein amino acid created as a by-product through the metabolism of methionine and cysteine.

Unfortunately, a wealth of research, including systematic reviews, strongly associates high homocysteine levels with cardiovascular disease (19, 20).

There are also strong associations between homocysteine and dementia as well as age-related macular degeneration (21, 22, 23).

Interestingly, a consistent link exists between low levels of vitamin B12 and higher plasma homocysteine (24, 25, 26).

A randomized controlled trial supports these associations too.

In a trial featuring 140 participants with high blood levels of homocysteine, eight weeks of vitamin B12 supplementation “significantly reduced” homocysteine levels (27).

Key Point: Maintaining sufficient B12 levels helps to reduce the risk of developing high homocysteine levels.

In the average person, bone mass density peaks before the age of 30 (28).

After this time, there is a slow and gradual loss of bone which continues into old age.

Over time, extensive bone loss can lead to osteoporosis, a condition that causes fragile bones, decreased mobility, frailty, falls, and injuries (29).

Fortunately, there are many things we can do to help preserve bone mass density, including exercise, ensuring sufficient vitamin and mineral intake, and following a generally healthy lifestyle.

In addition to nutrients such as calcium, phosphorus, and vitamin D, recent research suggests that B vitamins—particularly B12—play an essential role in bone health (30).

While researchers do not understand the precise mechanisms at this stage, a systematic review of trials found numerous associations between low vitamin B12 status and low bone mass density (31).

One possible way that B12 could support bone health is through its ability to lower homocysteine levels. Higher blood levels of homocysteine are associated with lower bone mineral density (32, 33).

Key Point: More research is necessary, but vitamin B12 may help to protect bone health and reduce the risk of osteoporosis.

7) Research Shows Vitamin B12 Can Improve Cognitive Health In the Elderly

An Old Man With Memory Loss Scratching His Head.

Some studies have associated low vitamin B12 status with lower cognitive function scores in the elderly (34, 35).

On this note, one study of 259 patients with vitamin B12 deficiency found that 84.2% of the patients with severe B12 deficiency experienced memory loss (36).

Harvard Medical School supports this link between B12 and memory loss, noting that a typical deficiency symptom is “difficulty thinking and reasoning (cognitive difficulties), or memory loss” (37).

Key Point: Optimal levels of vitamin B12 may improve memory and other markers of cognitive function.

8) B12 Intake Could Potentially Improve Cardiovascular Health

There are many factors—including nutritional status and lifestyle choices—that can affect cardiovascular health.

As we discussed earlier, high homocysteine levels are associated with increased cardiovascular risk.

When we consider that higher plasma levels of B12 appear to lower homocysteine, this suggests that, theoretically, maintaining sufficient levels of B12 may reduce cardiovascular risk (38).

That said, a systematic review of cohort studies found that vitamin B12 supplementation does not reduce the risk of cardiovascular disease (39).

Further research may provide more insights in this area, and the length (and extent) of B12 deficiency may be an important consideration.

For now, there is no conclusive proof of vitamin B12’s cardioprotective properties, but it may reduce cardiovascular risk by lowering homocysteine levels.

Key Point: B12 supplementation may improve cardiovascular health through its effect on reducing homocysteine levels.

9) Vitamin B12 Is Essential For a Healthy Nervous System

An Illustration Showing Myelination of Nerves and the Myelin Sheath.

A substance called myelin is vitally important for the central nervous system. Myelin consists of proteins and fatty acids, and it acts as a sheath that surrounds and insulates nerves (40).

One of the significant functions of myelin is to enable the quick transmission of electrical nerve impulses around the body (41).

However, if myelin becomes damaged, the transmission of these electrical impulses slows down, which can result in neurological problems (42).

Once again, vitamin B12 shows its importance for overall health through its role in synthesizing and maintaining myelin (43).

In other words; getting enough vitamin B12 is essential for keeping our myelin healthy, which in turn is critical for neurological health.

Research also suggests that suboptimal B12 levels can lead to subacute combined degeneration of the spinal cord (SCD), which can develop following damage to myelin (44).

Key Point: Getting sufficient vitamin B12 is important for the central nervous system.

10) May Help Protect/Fight Against Dementia

Firstly, there is no conclusive evidence that vitamin B12 can help to prevent dementia.

A systematic review of the existing data on this topic found that “there was insufficient evidence to show a clear link between serum vitamin B12 levels and dementia” (45).

However, insufficient evidence is precisely that; it means we cannot currently confirm a link, but it does not say that there is no possible benefit.

Given the importance of vitamin B12 to energy systems, the brain, and the neurological system, some researchers feel the vitamin may help to reduce dementia risk (46, 47).

Some research also suggests that keeping levels of B12 high may be important for people living with dementia.

In a recent study featuring 165 Alzheimer’s patients, suboptimal levels of vitamin B12 were significantly associated with “rapid cognitive decline” (48).

Key Point: There are links between low vitamin B12 status and dementia, but there is currently not enough evidence to confirm the association.

Vitamin B12 Deficiency

Research shows that anyone in the following groups may have insufficient levels of vitamin B12 (49);

  • Vegan and vegetarian dieters: avoidance of animal foods is a significant risk for B12 deficiency. This dietary choice necessitates supplementation or consumption of food fortified with B12.
  • People with gastrointestinal problems: gastrointestinal disorders such as Crohn’s disease can reduce the absorption rate of dietary vitamin B12. Anyone with such issues (or suspected issues) should speak to their doctor/medical team.
  • The elderly: Older adults can sometimes develop a condition known as atrophic gastritis, which decreases the secretions of hydrochloric acid in the stomach. As a result, B12 is not properly absorbed.
Key Point: A vitamin B12 deficiency is extremely unlikely in healthy individuals consuming a range of animal foods. However, for other groups of people, supplementation may be necessary.

Final Thoughts

As shown in this article, vitamin B12 is an incredibly important nutrient, and it affects so many different biological systems.

Due to the benefits of the nutrient (and the potential harms of deficiency), it is vital to ensure we consume enough in our diet.

For a helping hand, see this guide to the twenty highest food sources of vitamin B12.

However, bear in mind that animal foods are the only reliable dietary sources.

For anyone choosing to follow a vegan diet, or for anyone consuming low quantities of animal foods, supplementation with B12 is essential.

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Michael Joseph, MSc

Michael works as a nutrition educator in a community setting and holds a Master's Degree in Clinical Nutrition. He believes in providing reliable and objective nutritional information to allow informed decisions.

2 thoughts on “10 Important Health Benefits of Vitamin B12”

  1. Very interesting to c what it helps. Worry though if taking a supplement, , what’s would happen if taking to much vb12

    • B12 can help many different things if there is a deficiency present. It is definitely possible to take too much when using concentrated supplements, though. Make sure to follow the instructions if you go the supplement route.

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