Research
Population prevalence, attributable risk, and attributable risk percentage for high methylmalonic acid concentrations in the post-folic acid fortification period in the US
Nutrition & Metabolism 2012, 9:2 doi:10.1186/1743-7075-9-2
Published: 11 January 2012Abstract (provisional)
Background
Serum methylmalonic acid (MMA) is regarded as a sensitive marker of vitamin B-12 status. Elevated circulating MMA is linked to neurological abnormalities. Contribution of age, supplement use, kidney dysfunction, and vitamin B-12 deficiency to high serum MMA in post-folic acid fortification period is unknown.
Methods
We investigated prevalence, population attributable risk (PAR), and PAR% for high MMA concentrations in the US. Data from 3 cross-sectional National Health and Nutrition Examination Surveys conducted in post-folic acid fortification period were used (n=18569). Results: Likelihood of having high serum MMA for white relative to black was 2.5 (P<0.0001), [greater than or equal to]60 y old persons relative to <60 y old persons was 4.0 (P<0.0001), non-supplement users relative to supplement users was 1.8 (P<0.0001), persons with serum creatinine [greater than or equal to]130 umol/L relative to those with <130 umol/L was 12.6 (P<0.0001), and persons with serum vitamin B-12 <148 pmol/L relative to those with [greater than or equal to]148 pmol/L was 13.5 (P<0.0001). PAR% for high MMA for old age, vitamin B-12 deficiency, kidney dysfunction, and non-supplement use were 40.5, 16.2, 13.3, and 11.8, respectively. By improving serum vitamin B-12 ([greater than or equal to]148 pmol/L), prevalence of high MMA would be reduced by 16-18% regardless of kidney dysfunction.
Conclusions
Old age is the strongest determinant of PAR for high MMA. About 5 cases of high serum MMA/1000 people would be reduced if vitamin B-12 deficiency (<148 pmol/L) is eliminated. Large portion of high MMA cases are not attributable to serum vitamin B-12. Thus, caution should be used in attributing high serum MMA to vitamin B-12 deficiency.