Health Professionals:

Other Health Benefits and Special Considerations

Many seniors may be at risk for vitamin B12 deficiency because of reduced absorption of food-bound vitamin B12. This may be due to hypochlorhydria associated with atrophic gastritis or reduced levels of intrinsic factor caused by pernicious anemia. Similar to a folate deficiency, a vitamin B12 deficiency is manifested as megaloblastic anemia. However, if not treated, a vitamin B12 deficiency can progress into neurological abnormalities that are serious and irreversible.

The megaloblastic anemia resulting from a vitamin B12 deficiency can be resolved through indiscriminate folate supplementation (i.e., the so called "masking" effect) while the central nervous system degeneration continues undiagnosed. The masking effect is uncommon, but is of concern given the prevalence of vitamin B12 deficiency in older persons.
The potential masking effect of folic acid was considered when the Institute of Medicine (now known as the National Academy of Medicine) established the Tolerable Upper Intake Level (UL) of 1,000 micrograms/day for folic acid ( ”Folate”, 1998 ). This was a conservative estimate of the upper level of synthetic folic acid intake (from vitamin supplements or fortified foods) that is unlikely to mask a vitamin B12 deficiency. To decrease the chances of vitamin B12 deficiency, individuals over age 50 are urged to obtain their vitamin B12 from synthetic sources (e.g., vitamin supplements, fortified foods) ( ”Vitamin B12”, 1998 ) since absorption of this form of the vitamin is not adversely affected by atrophic gastritis.

The impact of folic acid fortification of cereal grains on folate intake and the prevalence of vitamin B12 deficiency in older populations has been evaluated in the representative U.S. population using National Health and Nutrition Examination Survey (NHANES) data (Qi et al., 2014).  Prevalence of low vitamin B12 status in individuals aged >50 y was compared using NHANES 1991-1994 (pre-fortification) and NHANES 2001-2006 (post-fortification). Based on pre- and post-fortification data, the prevalence of vitamin B12 deficiency (<148 pmol/L) without anemia was 4.0% and 3.9%, respectively, and B12 deficiency without macrocytosis was 4.2% and 4.1%, respectively. The prevalence of marginal deficiency (148-258 pmol/L) without anemia was 25.1% and 20.7% pre- and post-fortification, respectively, and without macrocytosis 25.9% and 21.3% pre- and post-fortification, respectively. Results show that prevalence of vitamin B12 deficiency and marginal deficiency did not change significantly after folic acid fortification among the elderly in the United States. In fact, this study showed that better serum vitamin B12 status was seen among adults with higher folic acid intake, which may be explained by higher amounts of vitamin B12 in fortified foods and supplements.

Health care providers should be aware of the prevalence of vitamin B12 malabsorption in the elderly and the possibility for higher intakes of synthetic folic acid through concurrent intake of multivitamins or other folic acid containing supplements and fortified foods including fortified ready-to-eat breakfast cereals and liquid nutritional supplement beverages.