As we age, the B12 absorption rate drops due to digestive deficiencies or poor appetite and diet. The reduction of this nutrient has been linked to mental decline, which has been further supported by this recent research. Data was extracted from the Framingham Heart Study, a large study that spanned several decades, on 549 adults in their 60s and 70s. Researchers looked at the results from their mini-mental state examinations over the course of eight years, to determine if low levels of B12 and folate were correlated with accelerated mental decline. It was found that those in the group with lower levels of B12 experienced significantly faster cognitive decline as compared to those with higher levels of B12. It was also found that having an imbalance of B12 to folic acid, particularly high levels of folate paired with low levels of B12, contributed to a more rapid mental weakening.
Vegetarians are also at risk for low B12 levels as the richest source is from meat, and would benefit from supplementation. Cyanocobalamin is considered an inferior source of B12, as compared to methylcobalamin and hydroxycobalamin. In most cases, lozenges and capsules have the same absorption rates.
J Am Geriatr Soc. 2012 Aug;60(8):1457-64