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Elevated serum methylmalonic acid concentrations are common among elderly Americans
Martha Savaria Morris1, Paul F Jacques, Irwin H Rosenberg
1Jean Mayer U.S. Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111, USA. martha.morris@tufts.edu
The Journal of Nutrition
|September 11, 2002
Summary
Many elderly Americans show signs of low vitamin B-12 status, with elevated serum methylmalonic acid (MMA) levels often appearing without typical deficiency indicators. These findings highlight the need for broader assessment of B-12 status in older populations.
Area of Science:
- Gerontology
- Nutritional Biochemistry
- Public Health
Background:
- Serum methylmalonic acid (MMA) is a sensitive indicator of vitamin B-12 status.
- Prevalence and determinants of elevated MMA in elderly populations require further elucidation.
- National Health and Nutrition Examination Survey (NHANES) data provide valuable insights into the health of US adults.
Purpose of the Study:
- To characterize serum MMA concentrations in elderly Americans.
- To investigate associations between serum MMA and demographic factors, renal function, homocysteine, and vitamin B-12.
- To identify the prevalence of elevated MMA in the elderly, even in the absence of traditional deficiency markers.
Main Methods:
- Utilized surplus serum samples from elderly (n=1145) and young-adult (n=1026) participants in NHANES Phase 2 (1991-1994).
- Analyzed serum MMA, creatinine, homocysteine, and vitamin B-12 concentrations.
- Employed statistical analyses to examine relationships and control for confounding factors.
Main Results:
- Approximately 20% of participants aged 65+ years had serum MMA >370 nmol/L.
- Serum MMA showed positive associations with creatinine and homocysteine, and an inverse relation with vitamin B-12.
- Elevated MMA occurred in ~15% of elderly individuals with normal creatinine and adequate vitamin B-12 levels (>148 pmol/L).
- Geometric mean MMA was lower in non-Hispanic blacks than non-Hispanic whites, but prevalence of elevated MMA did not vary by race/ethnicity.
Conclusions:
- A significant proportion of elderly Americans exhibit metabolic evidence of suboptimal vitamin B-12 status.
- Elevated serum MMA is common in the elderly, often occurring independently of traditional deficiency indicators like low vitamin B-12 or impaired renal function.
- Serum MMA levels in the elderly are influenced by race/ethnicity and renal function, underscoring the complexity of B-12 status assessment.