Vitamin B12 is also referred to as the “energy vitamin” thanks to key contributions to energy production. While daily requirements are quite low and your body can easily store large amounts of B12, some conditions and dietary choices can lead to low B12 levels. It is essential for red blood cell formation (needed to transport oxygen to the brain and all other body parts) and helps prevent nerve damage and peripheral neuropathy.

Without adequate B12, your body will struggle to produce energy at a cellular level, as the vitamin is active in many steps in this process. As well as nerve protection, a good B12 supply also acts to decrease the risk of stroke and other cardiovascular disease.

Dietary intakes in western cultures usually provide an adequate to abundant supply of B12, and in fact, deficiencies often stem from problems absorbing the vitamin rather than not eating enough of it. However, if you normally take certain medications or eat a primarily plant based diet, you may want to talk to your doctor to find out if a supplement will be worthwhile for you.

Vitamin B12 is involved in:

• Production of red blood cells
• DNA synthesis and production
• Protection of the myelin sheath, the protective covering around nerves that helps transmit nerve signals
• Support of the cellular processes that produce energy
• Maintaining low blood levels of homocysteine, a protein that in high levels is linked to stroke and cardiovascular disease, including coronary heart disease and peripheral vascular disease

Food sources of vitamin B12 include:

• Fish and shellfish, especially salmon, sardines, tuna, cod, scallops, and shrimp or prawns
• Lamb and beef, especially liver
• Dairy products
• Mushrooms
• Fermented foods like tempeh

Getting too much vitamin B12 can lead to:

It’s almost impossible to get too much B12! There are no known signs of excessive levels.

Not getting enough vitamin B12 can lead to:

• Neurological problems, including memory loss, dementia and Alzheimer’s disease, mania, and psychosis
• Neuropathy, or tingling, burning, or loss of sensation in a part of your body (often in hands or feet)
• Multiple sclerosis (MS)
• Depression
• Migraine
• Macular degeneration
• Kidney disease
• Shingles
• Megaloblastic anemia, a condition where red blood cells are poorly formed
• Fatigue and weakness
• Loss of appetite and weight loss

More on vitamin B12:

• Plant based diets, especially vegan diets, are at higher risks of B12 deficiency as most food sources are animal-based. You may want to consider a supplement.
• If you have acid reflux, and especially if you are taking an antacid, a proton pump inhibitor (PPI) like Nexium or Prilosec, you may not absorb B12 from your diet. Talk to your doctor. You may want to consider a sublingual supplement (placed under the tongue to absorb).
• Your ability to absorb B12 decreases with age, in part due to changes in digestion.
• Some research has shown that vitamin B12 may help maintain bone density and generally support bone health. However, additional research is needed to confirm this.

Vitamin B12 combined with other medications and health conditions:

Taking vitamins may have adverse effects when combined with some over the counter or prescription medications, and some medications can decrease vitamin absorption. Some health conditions can be impacted by high vitamin B12 intakes. Talk to your doctor prior to increasing your vitamin B12 intake if you have or are taking:

• Anticonvulsants
• Some chemotherapy medications. While B12 can interfere with the actions of some chemotherapy drugs, it can also protect against chemotherapy-related neuropathies. It’s highly recommended to have a conversation with your oncologist about whether you can take B12 supplements as a preventative measure for neuropathy.
• Colchicine (also known as Cilicaine or Colcrys), used to treat gout.
• Cholesterol lowering drugs
• Medications used to treat high stomach acid, including proton pump inhibitors like Nexium, Prilosec, and Prevacid, or H2 blockers like Zantac, Pepcid, or Pepzan
• Metformin, used to treat diabetes
• Tetracycline-type antibiotics