The prevalence of vitamin B12 deficiency in a random sample from the Australian population

Objective: Vitamin B12 deficiency is common in older adults, and may increase the risk of cognitive impairment. The distribution of B12 insufficiency in younger age groups is less studied. This study aims to assess the prevalence of vitamin B12 deficiency ( < 156mol/L) and subclinical low-normal levels (156-250 mol/L) in a large, random sample of the Australian population across the adult life span. Methods: We examined serum vitamin B12 levels in a random sample of 1085 men and 1125 women aged 20-97 years between 1994 and 2006; in the Barwon statistical division, a regional area in southeastern Australia that is representative of the socioeconomic status of the Australian population. Results: The age-standardized prevalence of vitamin B12 deficiency in this cohort of men and women was 3.6%. Subclinical low-normal vitamin B12 levels (156-250 mol/L) were found in 26%. Serum vitamin B12 levels declined with age among men (P < 0.001) and were lower in men than women (P < 0.001). Vitamin B12 levels were higher among supplements users (8.0% of the cohort). Conclusions: Vitamin B12 levels decline with age, and have been associated with neurodegenerative diseases and cognitive decline. Early intervention by diet education or supplement use to address this age-associated decline vitamin levels may be an effective strategy to prevent cognitive decline in a significant segment of the population. Such intervention may need to start in mid-life (from 50-years of age) before the onset of age-related decline in vitamin B12 levels.