TABLE 3.

Questions relating to causes, correction, and assessment of vitamin B-12 deficiency relating to fortification

Causes and correction of deficiency: questions

· What are the respective contributions of pernicious anemia, food vitamin B-12 malabsorption, and dietary insufficiency to the prevalence of vitamin B-12 deficiency in the elderly?

· Is the absorption of crystalline vitamin B-12 completely normal in food vitamin B-12 malabsorption?

· Are all causes of “simple” atrophic gastritis equal with respect to vitamin B-12 malabsorption?

· What is the role of Helicobacter pylori?

Assessment of deficiency: questions

· What is the best way to assess vitamin B-12 status and to monitor response?

· Is there a single best marker for vitamin B-12 deficiency? If not, what is the best combination of markers?

· Which combination of nutrient concentrations (vitamin B-12/folate) is best? Which is worst? Does it matter?

· Why does high folate (with low vitamin B-12) result in high homocysteine, high methylmalonate, and low holotranscobalamin concentrations?

· Will addition of vitamin B-12 alleviate the potentially harmful effects of excess folic acid? Will addition of vitamin B-12 aggravate some harmful effects?

· Will addition of vitamin B-12 enhance any beneficial effects of folic acid?