As a woman of a certain age who consumes a well-balanced diet of all the usual food groups, including reasonable amounts of animal protein, I tend to dismiss advice to take a multivitamin supplement. I’ve been told repeatedly by nutrition experts that the overuse of dietary supplements for “nutritional insurance” has given Americans the most expensive urine in the world.

I do take a daily supplement of vitamin D, based on considerable evidence of its multiple health benefits, especially for older people. However, based on advice from the National Academy of Medicine and an examination of accumulating research, I’m prompted to consider also taking a vitamin B12 supplement in hopes of protecting my aging brain.

Animal protein foods — meat, fish, milk, cheese and eggs — are the only reliable natural dietary sources of B12, and I do get ample amounts of several in my regular diet. But now at age 75, I wonder whether I’m still able to reap the full benefit of what I ingest.

You see, the ability to absorb B12 naturally present in foods depends on the presence of adequate stomach acid, the enzyme pepsin and a gastric protein called intrinsic factor to release the vitamin from the food protein it is attached to. Only then can the vitamin be absorbed by the small intestine. As people age, acid-producing cells in the stomach may gradually cease to function, a condition called atrophic gastritis.


A century ago, researchers discovered that some people — most likely including Mary Todd Lincoln — had a condition called pernicious anemia, a deficiency of red blood cells ultimately identified as an autoimmune disease that causes a loss of stomach cells needed for B12 absorption. Mrs. Lincoln was known to behave erratically and was ultimately committed to a mental hospital.

“Depression, dementia and mental impairment are often associated with” a deficiency of B12 and its companion B vitamin folate, “especially in the elderly,” Dr. Rajaprabhakaran Rajarethinam, a psychiatrist at Wayne State University School of Medicine, has written.

He described a 66-year-old woman hospitalized with severe depression, psychosis and a loss of energy and interest in life who had extremely low blood levels of B12 and whose symptoms were almost entirely reversed by injections of the vitamin.

European researchers have also shown that giving B12 to people deficient in the vitamin helped protect many of the areas of the brain damaged by Alzheimer’s disease. In a two-year study at the University of Oxford of 270 people older than 70 with mild cognitive impairment and low B12 levels, Dr. Helga Refsum, a professor of nutrition at the University of Oslo, found reduced cerebral atrophy in those treated with high doses of the vitamin.

What Makes Vitamin B12 Such a Big Deal?

Vitamin B12 plays a big role in brain health. As Patrick J. Skerrett over at the Harvard Health Blog suggests, not only is vitamin B12 needed “to make red blood cells, nerves, DNA, and carry out other functions,” it cannot actually be made innately by the human body; it has to come from an external source—ie, food or supplements.

Experts suggest that vitamin B12 deficiency can lead to a number cognition-related symptoms including trouble concentrating, forgetfulness, feelings of disorientation, dementia, and changes in mood.1 As such, getting enough of this micronutrient on a regular basis is critical to vital living.

Groups at Risk of Vitamin B12 Deficiency:

According to Skerrett, because the body cannot produce its own supply of B12, many individuals are unable to maintain or properly absorb it in high enough levels. “As a result,” he states, “vitamin B12 deficiency is relatively common, especially among older people,” with up to a fifth of adults over 50 already at or nearing deficiency.
An article published by AARP notes similar concerns: seniors are more likely to develop a B12 deficiency as the stomach lining tends to thin with age and “prescription medications used to treat heartburn, stomach ulcers and type 2 diabetes can limit the absorption of B12.”

Haven’t yet reached your golden years? You may still be at risk, particularly if you follow a vegetarian or vegan diet—all natural sources of B12 occur in animal products like meat, poultry, eggs, dairy, fish, etc.

Individuals who had weight loss surgery done at some time in their lives also have a higher likelihood of deficiency, as do those with stomach- and bowel-related disorders. As with the older population, these groups tend to experience reduced absorption of the vitamin due to a weakened stomach lining.

Protecting Vitamin B12 Levels in All Individuals:

Many studies have been conducted on the effectiveness of supplementing with B vitamins to improve brain function and reduce cognitive decline; for the most part, the results have been mixed. However, some research does suggest supplementing with vitamin B12 may slow the advance of Alzheimer’s in its early stages.
Jane E. Brody, writing for the New York Times, notes that researchers in Europe found that for patients experiencing Alzheimer’s and who were B12 deficient, increasing levels of B12 helped to protect areas of the patients’ brains. She goes on to note, “In a two-year study at the University of Oxford of 270 people older than 70 with mild cognitive impairment and low B12 levels, Dr. Helga Refsum, a professor of nutrition at the University of Oslo, found reduced cerebral atrophy in those treated with high doses of the vitamin.”

Brody also suggests that taking synthetic B12—as in supplement form—may help with the absorption of the multivitamin since it “is not attached to protein and thus bypasses the need for stomach acid.” Individuals who struggle to get enough B12 in their daily diet or who have compromised stomach linings may benefit more from a supplement than from trying to up their intake via natural sources.


In an online posting in July, David G. Schardt, the senior nutritionist for the Center for Science in the Public Interest, noted that symptoms of B12 deficiency include fatigue, tingling and numbness in the hands and feet, muscle weakness and loss of reflexes, which may progress to confusion, depression, memory loss and dementia as the deficiency grows more severe.

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