Vitamin B12 was the subject of an article in the New York Times by Jane Brody entitled, Vitamin B12 as Protection for the Aging Brain. However, she mentions that “insufficient absorption of B12 from foods may even be common among adults aged 26 to 49” and that the advice to take a vitamin B12 supplement may apply to young people as well. This is particularly true for vegans and vegetarians, as well as people with stomach problems and those on PPIs – drugs for ulcers and heartburn, such as Prilosec, Nexium, Aciphex, etc.
Vitamin B12 deficiency can cause “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”. Severe deficiency leads to peripheral and central nervous system damage (so called subacute combined degeneration), which eventually becomes irreversible and leads to death.
Jane Brody does not mention that besides Alzheimer’s, other chronic diseases, such as multiple sclerosis, diabetes, and cancer are also associated with low vitamin B12 levels. Vitamin B12 with vitamin B6 and folic acid has been shown to help some migraine sufferers
You can ask your doctor to check your vitamin B12 level, but unfortunately it is not reliable. Most laboratories cite as normal blood levels of above 200 or 250, but there are reports of rare cases where severe deficiency is present with a level of 700. I recommend taking a supplement if the level is below 500. In severe cases or in people with stomach problems, a monthly injection is a better choice. Patients can easily self-inject vitamin B12, but it does require a doctor’s prescription. Some of my patients feel the need to inject themselves with vitamin B12 more often than once a month. Whenever they start feeling tired or having other symptoms, they take a shot. Unlike some vitamins, such as B6 and A, vitamin B12 does not cause any negative effects even at high levels. As an oral supplement I usually recommend tablets of methylcobalamin, rather than cyanocobalamin form of vitamin B12 because of better absorption. The usual dose is 1 mg (or 1,000 mcg) daily. If you are deficient and stop taking the supplement, the deficiency can return within a few months.
