Vitamin B12 deficiency in relation to functional disabilities

Area of Science:

• Gerontology
• Nutritional Science
• Neurology

Background:

• Vitamin B12 deficiency is a concern in older adults, potentially leading to functional decline.
• Existing definitions of deficiency vary, impacting clinical identification and intervention.

Purpose of the Study:

• To assess the association between three definitions of vitamin B12 deficiency and functional measures/disabilities in older adults.
• To determine which definition best identifies older adults with symptoms and disabilities.

Main Methods:

• Analysis of 1999-2002 National Health and Nutrition Examination Surveys (NHANES) data from adults aged 60+.
• Categorization of participants based on three vitamin B12 deficiency definitions involving serum B12, homocysteine, and methylmalonic acid.
• Assessment of peripheral neuropathy, balance, cognition, gait speed, and self-reported disability using standardized instruments.

Main Results:

• Vitamin B12 deficiency, defined by elevated homocysteine or methylmalonic acid, was significantly associated with peripheral neuropathy and total disability.
• Definition 2 (serum B12 < 200 pmol/L and homocysteine > 20 μmol/L) showed strong associations: OR 9.70 for neuropathy and OR 19.61 for disability.
• Definition 3 (serum B12 < 258 pmol/L or methylmalonic acid > 0.21 μmol/L) also showed significant associations, though smaller.

Conclusions:

• Definitions of vitamin B12 deficiency incorporating biomarkers like homocysteine or methylmalonic acid are more strongly associated with functional impairments in older adults.
• These definitions may help identify subclinical vitamin B12 deficiency, enabling timely intervention to prevent or correct functional decline.