The National Institutes of Health (NIH) say between 1.5% and 15% of the US population experience vitamin B12 deficiency. Most people over the age of 50 have such poor absorption of the vitamin that the NIH recommends older adults supplement with B12, either by eating fortified foods or taking dietary supplements.
From the NIH Office of Dietary Supplements:
Quick Fact Sheet on Vitamin B12
Professional Fact Sheet on Vitamin B12
Groups that may not be getting enough vitamin B12 or that have trouble absorbing it:
- Many older adults, who do not have enough hydrochloric acid in their stomach to absorb the vitamin B12 naturally present in food. People over 50 should get most of their vitamin B12 from fortified foods or dietary supplements because, in most cases, their bodies can absorb vitamin B12 from these sources.
- People with pernicious anemia whose bodies do not make the intrinsic factor needed to absorb vitamin B12. Doctors usually treat pernicious anemia with vitamin B12 shots, although very high oral doses of vitamin B12 might also be effective.
- People who have had gastrointestinal surgery, such as weight loss surgery, or who have digestive disorders, such as celiac disease or Crohn's disease. These conditions can decrease the amount of vitamin B12 that the body can absorb.
- Some people who eat little or no animal foods such as vegetarians and vegans. Only animal foods have vitamin B12 naturally. When pregnant women and women who breastfeed their babies are strict vegetarians or vegans, their babies might also not get enough vitamin B12.
Low levels of vitamin B12 show up as numbness or tingling in the arms and legs, weakness, and loss of balance - symptoms similar to diabetic neuropathy. Other symptoms include constipation, loss of appetite, weight loss, soreness of the mouth or tongue, and megaloblastic anemia. And as we saw in yesterday's post, vitamin B12 deficiency affects cognition, leading to depression, confusion, poor memory, and dementia.
A vitamin B12 deficiency can be detected by a blood test. Also, an elevated mean corpuscular volume (MCV) in a blood test can indicate low B12 status and justifies measurement of serum B12 directly.1