Should Adults Over 70 Get Tested for Vitamin B12?

Should everyone over 70 take vitamin B12?

No. Older age alone does not mean everyone needs a supplement. The NIH Office of Dietary Supplements gives adults a recommended allowance of 2.4 micrograms per day; that recommendation does not increase with age. The amount needed and the amount absorbed are different questions.

The National Institute on Aging says older adults need as much B12 as other adults, while some have trouble absorbing the vitamin naturally found in food. The National Academies report estimates that 10%–30% of older people may be unable to absorb naturally occurring B12. These estimates describe risk in groups, not a diagnosis for any one person.

Food sources include animal foods, while fortified foods and supplements provide B12 in a form that skips the initial release from food protein. The NIA notes that strict vegetarians and vegans have greater risk because natural B12 sources are limited to animal foods. When food absorption is a problem, fortified cereals or a supplement may be options to discuss with a doctor, dietitian, or pharmacist.

Injections are a clinician-directed treatment option when the cause requires medical treatment, such as a lack of intrinsic factor. The National Academies notes that people whose deficiency is caused by lack of intrinsic factor require medical treatment. The right approach depends on the cause; age by itself does not settle it.

Why are older adults more likely to have low B12?

Some older adults absorb less B12 from food because stomach changes can interfere with the steps needed for absorption. Food-bound B12 must first be released from protein by stomach acid. The NIH Office of Dietary Supplements explains that atrophic gastritis can reduce stomach acid and intrinsic factor, a protein needed for B12 absorption.

The NIH reports that atrophic gastritis affects 8%–9% of adults aged 65 and older. That figure points to one reason risk rises with age; it does not mean every older adult has the condition or a B12 deficiency. The National Academies estimates that 10%–30% of older people may have difficulty absorbing naturally occurring B12, a broader estimate that reflects a different measure.

Diet is another part of the picture. Someone who eats few or no animal foods has fewer natural sources, while fortified foods can supply B12 without the food-protein release step. Supplements work similarly at that early step, though the body still needs intrinsic factor for absorption.

These are distinct routes to low B12: not enough in the diet, difficulty releasing it from food, or trouble absorbing it. Identifying the likely route helps a clinician decide whether testing and which form of replacement fit the situation.

Can metformin or acid-reducing medicine affect B12 levels?

Yes. Long-term use of metformin or acid-reducing medicines can affect B12 levels or absorption, so medication history is relevant when discussing symptoms or testing. The NIH Office of Dietary Supplements says proton pump inhibitors and H2 blockers can interfere with absorption of food-bound B12, while metformin may reduce absorption and lower blood B12 levels.

NICE lists metformin, proton pump inhibitors, and H2-receptor antagonists among risk factors for deficiency. It recommends offering an initial B12 test when a person has at least one common symptom or sign and at least one risk factor. Symptoms named in its guidance include unexplained fatigue, memory or concentration difficulties, balance problems or falls, impaired gait, pins and needles or numbness, and a sore or inflamed tongue.

A symptom does not prove B12 deficiency. Fatigue, memory changes, or unsteadiness can have more than one explanation. The useful signal is the combination: a compatible symptom plus a risk factor, such as a low-B12 diet, a relevant medicine, atrophic gastritis, or certain gastrointestinal surgeries.

NICE recommends total serum B12 or active B12 as an initial test when deficiency is suspected and advises collecting blood before starting B12 replacement when feasible. The NIH notes that methylmalonic acid is sometimes used to clarify borderline serum B12 results. NICE also cautions that absence of anemia does not rule out deficiency; nerve-related symptoms can appear without anemia.

For a practical conversation, bring a list of medicines and supplements, describe the symptoms and when they began, and mention dietary patterns or digestive surgery. A healthcare professional can use that history to decide whether testing is appropriate and how to interpret the result. Do not treat a risk factor as proof, or a normal-looking blood count as a reason to dismiss symptoms.