Aim: Methylmalonic acid (MMA) analysis in urine represents a noninvasive approach to screening for vitamin B12 deficiency in older adults. A method allowing the analysis of MMA/creatinine in fasting urine collected on filter paper was developed/validated. Method: Dry urine specimens were eluted using a solution containing internal standards, filtrated and analyzed by ultra-performance LC-MS/MS. Results: The method allowed the chromatographic separation of MMA from succinic acid. Dried urine samples were stable for 86 days at room temperature. The MMA/creatinine ratios measured in urine collected on filter paper were highly correlated with values derived from the corresponding liquid specimens. Conclusion: This robust filter paper method might greatly improve the accessibility and cost–effectiveness of vitamin B12 deficiency screening in older adults.
Background Vitamin B-12 deficiency can result in irreversible neurological damages. It is most prevalent among older adults (∼5–15%), mainly due to impaired absorption. Vitamin B-12 bioavailability varies between food sources, so their importance in preventing deficiency may also vary. Objective Using the NuAge Database and Biobank, we examined the associations between vitamin B-12 intake – total and by specific food groups – and low vitamin B-12 status and deficiency in older adults. Methods NuAge included 1753 adults aged 67–84 years followed 4 years. Analytic samples comprised 1230 to 1463 individuals. Dietary vitamin B-12 intake was assessed annually using three 24-hour dietary recalls. Vitamin B-12 status was assessed annually as low serum vitamin B-12 (<221 pmol/L), elevated urinary methylmalonic acid (MMA)/creatinine ratio (>2 µmol/mmol), and a combination of both (deficiency). Vitamin B-12 supplement users were excluded. Multilevel logistic regressions, adjusted for relevant confounders, were used. Results Across all study years, 21.8–32.5% of participants had low serum vitamin B-12, 12.5–17.0% had elevated urine MMA/creatinine, and 10.1–12.7% had deficiency. Median [IQR] total vitamin B-12 intake was 3.19 [2.31–4.37] µg/day. Main sources were “dairy” and “meat, poultry and organ meats”. The ORs (95%CI) in the fifth compared to first quintile of total vitamin B-12 intake for low serum vitamin B-12, elevated urine MMA/creatinine and vitamin B-12 deficiency respectively were 0.52 (0.37–0.75; p-trend < 0.0001), 0.63 (0.37–1.08; p-trend = 0.091), and 0.38 (0.18–0.79; p-trend = 0.006). Similarly, ORs (95%CI) in the fourth compared to first quartile of dairy-derived vitamin B-12 intake were 0.46 (0.32–0.66; p-trend < 0.0001), 0.51 (0.30–0.87; p-trend = 0.006), and 0.35 (0.17–0.73; p-trend = 0.003). No associations were observed with vitamin B-12 from “meat, poultry and organ meats”. Conclusion Higher dietary vitamin B-12 intake, especially from dairy, was associated with decreased risk of low vitamin B-12 status and deficiency in older adults. Food groups might contribute differently at reducing risk of deficiency in older populations.
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