How Much B12 Should a Senior Have?

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Changes in your digestive system and interactions with your medications may affect your body’s ability to absorb vitamin B-12, or cobalamin, after the age of 50. This water-soluble vitamin helps you maintain your energy level and cognitive status as you age. Vitamin B-12 may also protect you against cardiovascular disease. As a senior, you may need to supplement your diet with a form of vitamin B-12 that’s easier for your body to absorb. In some cases, you may require larger doses of this nutrient to prevent the health complications of a B-12 deficiency.

Contributing Factors

Up to 30 percent of older adults have atrophic gastritis, a condition that causes your stomach to produce less digestive acid as you age, according to the Office of Dietary Supplements, or ODS. A reduced secretion of stomach acid, which facilitates the breakdown of vitamin B-12 in foods like fish, meat, milk and eggs, decreases your body’s ability to absorb dietary B-12. Seniors who eat a limited diet due to illness or decreased appetite may be at risk for a B-12 deficiency. The widespread use of medications that block the production of stomach acid among older adults may also contribute to a vitamin B-12 deficiency in this population. In an article published in the Mar. 1, 2003 issue of “American Family Physician,” Robert C. Oh and David L. Brown note that the effects of these common medications on vitamin B-12 absorption in the elderly may be higher than statistics indicate.

Health Risks

A lack of vitamin B-12 may lead to anemia, a blood disorder that causes persistent fatigue, shortness of breath and weakness. A B-12 deficiency may also cause tingling, numbness and pain in your hands and feet, irritability, memory loss, depression and an increased risk of heart attack and stroke, according to Oh and Brown. In seniors, the neurological symptoms of B-12 deficiency may resemble the cognitive changes of dementia or Alzheimer’s disease. More clinical research is required to confirm whether vitamin B-12 supplements can improve cognitive function in older adults, according to the ODS.


The Institute of Medicine, or IOM, does not increase the recommended dietary allowance, or RDA, for vitamin B-12 for adults over age 50. The RDA for men and non-pregnant women ages 19 and older is 2.4 mcg. The IOM advises that older adults take supplements and eat fortified foods, which contain a more easily absorbed form of this nutrient, to help meet their daily requirements for B-12. The Linus Pauling Institute recommends that adults over 50 should get 6 to 30 mcg of B-12 daily in fortified cereals or multivitamins. Seniors who are taking medications that interfere with B-12 absorption may require higher doses. If you have a severe vitamin B-12 deficiency, your doctor may prescribe large doses of B-12, which may be given orally or as intramuscular injections.


Shellfish is one of the richest food sources of vitamin B-12. Clams, mussels and crab provide more than the RDA for B-12. Salmon, beef, chicken, turkey, eggs and cheese are also good sources of B-12, according to the Linus Pauling Institute. Seniors who have difficulty absorbing B12 that occurs naturally in foods may increase their absorption by taking cyanocobalamin or methylcobalamin, synthetic forms of vitamin B-12 that are easier for your body to break down and utilize effectively. Synthetic B-12 supplements can be purchased over the counter or may be prescribed by your doctor. Talk with your doctor about the amount of B-12 that you should take to prevent or correct a nutritional deficiency.