Vitamin B12 & The Heart

By Charles Li, MD

TL;DR: Vitamin D vs. Depression

Role of Vitamin B12
Vitamin B12 plays essential roles in hundreds of chemical reactions in your body.
Vitamin B12 & Heart Disease
In particular, Vitamin B12 helps convert homocysteine, which is believed to play a key role in heart disease.
Inconclusive Trials
However, clinical trials have so far not been able to find a conclusive link between Vitamin B12 and heart disease. While Vitamin B12 may reduce your risk of stroke, scientists have so far been unable to find a conclusive link between Vitamin B12 and heart attacks.

Heart disease is the leading cause of death in the United States. It kills more than cancer, car accidents, and even COVID-19.

Heart disease is also preventable, which is why scientists work so hard to find ways of reducing risk.

One potential way of reducing risk is good nutrition. Eating a balanced diet with lots of fruits and vegetables has been shown to reduce heart disease risk. 

However, we’re still not entirely sure why. What is it about healthy food that makes them healthy, is it the vitamins?

Vitamin B12: Key Facts

Vitamin B12 is a key vitamin for metabolism. It has also been linked to processes that are known to play a role of heart disease.

Vitamin B12 Fact Sheet

Vitamin B12 is a water soluble vitamin, otherwise known as cobalamin, that you obtain from your diet. It plays key roles in metabolism, nerve health, and red blood cell generation.

Vitamin B12 is a key vitamin for metabolism. It has also been linked to processes that are known to play a role of heart disease.

When you eat meat, you consume an amino acid call homocysteine. In order to metabolize this amino acid, your body needs Vitamin B12. Without enough Vitamin B12, homocysteine build up. In the paper below, scientist explain how homocysteine has been linked to heart disease. Homocysteine leads to more plaque buildup in your blood vessels, which increases the risk of a blood clot blocking off blood circulation in a vessel.

Review Paper
Homocysteine: role and implications in atherosclerosis

"Elevated homocysteine promotes atherosclerosis through increased oxidant stress, impaired endothelial function, and induction of thrombosis. Prospective studies have shown that elevated plasma homocysteine concentrations increase risk of cardiovascular disease by twofold and risk of cerebrovascular disease to a lesser degree. "

Homocysteine: role and implications in atherosclerosis

Trials on Vitamin B12 and Homocysteine

Trials have shown that Vitamin B12 reduces your levels of homocystine, which makes sense given Vitamin b12’s role in removing homocysteine from your body.

However, whether Vitamin B12 causes a reduction in your risk of heart disease remains unclear.

Study on Vitamin B12, Folic Acid, and Homocysteine Reduction

A meta-analysis of 12 clinical trials has shown that both Vitamin B12 and Folic Acid can lower homocysteine levels in the blood.

Study Source
From the abstract:

" Typically in Western populations, daily supplementation with both 0.5-5 mg folic acid and about 0.5 mg vitamin B-12 would be expected to reduce blood homocysteine concentrations by about a quarter to a third (for example, from about 12 mumol/l to 8-9 mumol/l)."

Lowering blood homocysteine with folic acid based supplements: meta-analysis of randomised trials. Homocysteine Lowering Trialists' Collaboration

Vitamin B12 and Heart Disease

Clinical trials of Vitamin B12 and heart disease have so far shown mixed results.

In the trial below, Vitamin B12 was shown to reduce your risk of stroke, which shares the same mechanism as a heart attack.

However, researchers were unable to find significant differences in heart attack risk.

Clinical Trial visualization for Vitamin B12 and Heart Disease

A clinical trial of B Vitamins and Heart Disease showed that a cocktail of B Vitamins can potentially reduce your risk of stroke by around 25%. However, the study did not show a significant reduction in heart attack risk.

Study Source
From the abstract:

"Supplements combining folic acid and vitamins B6 and B12 did not reduce the risk of major cardiovascular events in patients with vascular disease."

Homocysteine lowering with folic acid and B vitamins in vascular disease

At this point, there’s not enough evidence to recommend Vitamin B12 as a way to prevent heart disease. We need to do more studies. However, there’s an overwhelming amount of evidence that eating a balanced diet, in which you will get lots of Vitamin B12 among other nutrients, is a great way of preventing heart disease.

Expert Opinion
Vitamin B12 & Heart Disease

"The American Heart Association has concluded that the available evidence is inadequate to support a role for B vitamins in reducing cardiovascular risk"

Vitamin B12: Fact Sheet for Health Professionals