6 "Supplemental" reasons the importance of vitamin B12 shouldn't be underestimated

  • 2 Minutes Read
Sue Heikkinen
Sue Heikkinen, MS, RDN, CDCES, BC-ADM, ACE-PT - Registered Dietitian Nutritionist and Certified Diabetes Care and Education Specialist

Dietitians stress the importance of vitamin B12 because deficiency symptoms may become permanent. Do you get enough from your diet or absorb it properly? Learn the best vitamin B12 sources and whether you need a supplement.

Importance of vitamin B12

What is the importance of vitamin B12 to our bodies?

Although vitamin B12 (cobalamin) will not give you a sudden energy boost as some supplement labels imply, we rely on it for nerve function and making red blood cells and DNA.

Symptoms of B12 deficiency include tingling and numbness in the hands and feet, poor balance, memory issues, and loss of concentration. While many of these symptoms improve with treatment, the nerve damage can be permanent.

How is vitamin B12 absorbed?

It takes a two-step process to absorb vitamin B12 from food.

  1. Separating from protein- In food sources, vitamin B12 is attached to protein and cannot be absorbed this way. Our stomach acid helps separate B12 from the protein.
  2. Binding with "intrinsic factor"- In the small intestine, vitamin B12 must bind with intrinsic factor, a protein made in the stomach that allows B12 to get absorbed into the bloodstream.

When stomach acid levels are low, or the stomach does not make intrinsic factor, vitamin B12 absorption reduces, increasing deficiency risk.

Fortified foods and dietary supplements contain the free form of B12 (unbound to protein), so stomach acid is unimportant for digestion and absorption. Very high doses of supplements can overcome a lack of intrinsic factor.

What are sources of vitamin B12?

Food sources

Dietary sources of B12 include animal foods (fish/seafood, meat, poultry, eggs, milk, and cheese) and fortified foods (fortified breakfast cereal, soy milk, etc.).

For healthy adults, the RDA is 2.4 mcg per day. You can meet the RDA with several daily servings of animal or fortified plant foods.

Food Portion B12 (mcg)
Cheerios 1 cup 2.0
Cheese, Swiss 1 ounce 0.9
Chicken breast 3 ounces, cooked 0.2
Cottage cheese, 2% 1/2 cup 0.5
Egg 1 large 0.6
Hamburger 3 ounces, cooked 2.3
Liver, beef 3 ounces, cooked 60.0
Milk, 2% 1 cup 1.1
Nutritional yeast, fortified 1 tablespoon 33.8
Salmon, pink 3 ounces, cooked 4.0
Soy milk 1 cup 3.0
Tuna, canned light 1/2 cup 2.0

When you might need a vitamin B12 supplement

1. Over age 50

The Institute of Medicine (IOM) estimates that 10-30% of people over 50 may be unable to absorb naturally-occurring vitamin B12 due to lower stomach acid production. Therefore, the IOM recommends that people within this age group seek vitamin B12 from fortified foods or supplements.

2. Follow a vegan diet

Because only animal-based foods contain vitamin B12, vegans must take supplements or regularly eat B12-fortified foods.

3. Take heartburn medication

Proton pump inhibitors are acid reflux medications (e.g., Nexium, Prevacid, Prilosec, and Protonix) which reduce acid levels in the stomach, making it harder to absorb vitamin B12. Over time, these medications can increase the risk of B12 deficiency.

4. Take metformin (Glucophage)

People who take this common medication for diabetes or diabetes prevention are at higher risk of vitamin B12 deficiency, likely due to interference with absorption. The American Diabetes Association recommends that people taking metformin have their B12 levels monitored regularly.

5. Had weight loss surgery

Gastric bypass and gastric sleeve surgeries decrease stomach size, meaning less acid and intrinsic factor production, required for B12 absorption vitamin B12. If you have undergone weight-loss surgery, it is critical to take recommended dietary supplements and have your blood vitamin levels monitored regularly.

6. Have a digestive disorder

Many digestive conditions increase the risk of B12 deficiency, including Crohn's disease, celiac disease, small intestinal bacterial overgrowth, and pancreatic insufficiency.

Taking vitamin B12 supplements

If you are at risk of B12 deficiency, ask your doctor about getting your blood levels tested. If you are deficient, your doctor may advise oral or injected supplements. Some people take sublingual (under the tongue) or nasal B12 supplements.

Adapted from original content from Katherine Isacks, MPS, RDN, CDCES

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Foods & Recipes->Fish & Seafood Nutrients->Other Vitamins & Minerals Nutrients->B12
Feb 10, 2021

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