Influence of Age and Stomach Function on Serum Vitamin B₁₂ Concentration

Abstract

Serum vitamin B₁₂ (B₁₂), maximal gastric acid output (MAO), and B₁₂ absorption were determined in 82 subjects, age 32 to 85 years, who had normal absorption of radiocyanocobalamin. In 46 of the patients the gastric intrinsic factor (IF) was also measured. Serum B₁₂ concentration and MAO varied widely in all age groups from abnormally low to definitely normal. The mean values for serum B₁₂ and MAO, however, declined very similarly with advancing age owing to an increased incidence of low values for these two measurements in the aged. There was no significant fall in the mean B₁₂ absorption or IF secretion as a function of old age. Achlorhydric and hypochlorhydric patients invariably had lower mean serum B₁₂ concentrations than those with adequate MAO. Conversely, patients with normal MAO all had normal serum B₁₂ levels. Serum B₁₂ concentration, although correlating with both MAO and IF secretion, showed a closer relationship to the former than to the latter. These findings suggest that the stomach, aside from producing the IF, plays an important role in maintaining a normal serum B₁₂ concentration.

Key-words:

• Age
• gastric intrinsic factor
• gastric acid secretion
• vitamin B₁₂, serum concentration, absorption