Exploring trajectories in dietary adequacy of the B vitamins folate, riboflavin, vitamins B6 and B12, with advancing older age: a systematic review.

Maintaining nutritional adequacy contributes to successful ageing. B vitamins involved in one carbon metabolism regulation (folate, riboflavin, vitamins B6 and B12) are critical nutrients contributing to homocysteine and epigenetic regulation, and DNA synthesis. Although cross-sectional B vitamin intake has been characterised in various ageing populations, longitudinal changes are infrequently reported. This systematic review explores age-related changes in dietary adequacy of folate, riboflavin, vitamins B6 and B12 in community-dwelling older adults (≥65 years at follow-up). Following PRISMA guidelines, relevant databases (Medline, EMBASE, Biosis, CINAHL) were systematically screened, yielding 1579 records; 8 studies were included (n = 3119 participants, 2-25 years of follow-up). Quality assessment using a modified Newcastle-Ottawa quality scale rated all studies of moderate-high quality. The estimated average requirement cut-point method estimated the baseline and follow-up population prevalence of dietary inadequacy. Notably, riboflavin (7 studies, n=1953) inadequacy appears to progressively increase with age, with the prevalence of inadequacy increasing from baseline by up to 22.6% and 9.3% in males and females, respectively. Dietary folate adequacy (3 studies, n=2321) improved in two studies (by up to 22.4%), but the third showed increasing (8.1%) inadequacy. Evidence was similarly limited (2 studies respectively) and inconsistent for changes in dietary inadequacy of vitamins B6 (n=559; -9.9 - 47.9%) and B12 (n=1410; -4.6 - 7.2%). This review emphasises the scarcity of evidence regarding micronutrient intake changes with age, and highlights the demand for improved reporting of longitudinal changes in nutrient intake that can better direct micronutrient recommendations for older adults. This review was registered with Prospero (CRD42018104364).