REVIEW OF: Laird E et al, Br J Nutr 2021;1–22

STUDY TYPE: Prospective cohort study

Deficiencies of both vitamin B12 and folate are highly prevalent among older adults. Depending on the study, 5%–40% of adults older than 50 years have B12 deficiency. Folate deficiency ranges from 1.2% among older adults in countries that mandate folate fortification (such as the US) to 31% in countries without this policy (such as the UK). Low concentrations of both B12 and folate have been correlated with depression in cross-sectional studies; this recent large longitudinal study adds to the evidence base.

The Irish Longitudinal Study on Aging followed 3,849 people who were all at least 50 years old. At baseline, participants underwent measurements including B12 and folate levels, as well as depression screenings with the Center for Epidemiological Studies Depression Scale (CES-D-8); they were reevaluated after two and four years. Participants with deficient-low B12 status at baseline (<185 pmol/L) were 51% more likely to develop depression over four years. There was no association between folate status and depression. These findings remained robust after controlling for physical activity, chronic disease burden, vitamin D levels, cardiovascular disease, and antidepressant use.

Carlat Take

Checking a B12 level in older adults is reasonable, especially given the high rates of B12 deficiency in this population. Supplementation is a low-cost intervention that may decrease a patient’s risk for depression.