Food-bound Malabsorption Research Articles

Impact of food-bound malabsorption on vitamin B12 status in older adults from the TUDA Ageing Cohort Study: preliminary findings

AbstractVitamin B12 deficiency is common among older adults, even with dietary intakes well in excess of current recommendations. Severe clinical B12 deficiency (i.e. pernicious anaemia) leads to irreversible neurological damage, but once diagnosed, can be treated effectively with B12 injections. A much more common cause of low vitamin B12 status in older adults is food-bound malabsorption owing to atrophic gastritis. This in turn leads to reduced gastric acid secretion, thus limiting B12 absorption from food (given the essential role of gastric acid in releasing B12 from food proteins). Proton pump inhibitor (PPI) drugs reduce gastric acid secretion, similar to atrophic gastritis, thus there is a concern that these medications may lead to vitamin B12 malabsorption. Therefore, the aim of this study was to investigate biomarker status of vitamin B12 in relation to atrophic gastritis and PPI usage. Data were accessed from The Trinity Ulster Department of Agriculture (TUDA) Ageing Cohort Study, a cross-sectional study of community-dwelling adults (n 5186, ≥ 60 years) recruited across Northern Ireland and the Republic of Ireland (2008–2012). TUDA participants were classified into 3 groups; ‘healthy’ controls, atrophic gastritis and PPI users. Vitamin B12 status was assessed using a total of four biomarkers: serum total B12; serum holotranscobalamin, holoTC; plasma methylmalonic acid, MMA; plasma homocysteine. Atrophic gastritis was identified using pepsinogen analysis (via ELISA), with a pepsinogen I : II ratio of < 3 considered indicative of atrophic gastritis. Based on results from all four biomarkers, participants with atrophic gastritis were found to have significantly lower B12 status compared to healthy controls: e.g. mean (95% CI) serum total vitamin B12, 188 (156, 218) pmol/L vs. 262 (252, 272) pmol/L P < 0.001; holoTC, 46.0 (38.1, 53.8) pmol/L vs. 60.3 (57.8, 62.8) pmol/L P < 0.001; plasma MMA, 0.65 (0.52, 0.78) μmol/L vs. 0.37 (0.32, 0.42) μmol/L P = 0.001. No differences in B12 biomarker concentrations were observed between PPI users and healthy controls. Regular consumption of fortified foods (i.e. ≥ 5 portions per week) compared to non-regular consumption (i.e. 0–4 portions per week) impacted positively on B12 biomarker status in all participants. This effect however appeared insufficient to restore normal vitamin B12 status in those with atrophic gastritis. These results show that older adults with atrophic gastritis have significantly lower vitamin B12 biomarker status, particularly in those who did not regularly consume fortified foods. Further investigations of the effect of atrophic gastritis and PPI usage on B12 status are warranted.

Causes, Consequences and Public Health Implications of Low B-Vitamin Status in Ageing.

The potential protective roles of folate and the metabolically related B-vitamins (vitamins B12, B6 and riboflavin) in diseases of ageing are of increasing research interest. The most common cause of folate and riboflavin deficiencies in older people is low dietary intake, whereas low B12 status is primarily associated with food-bound malabsorption, while sub-optimal vitamin B6 status is attributed to increased requirements in ageing. Observational evidence links low status of folate and the related B-vitamins (and/or elevated concentrations of homocysteine) with a higher risk of degenerative diseases including cardiovascular disease (CVD), cognitive dysfunction and osteoporosis. Deficient or low status of these B-vitamins alone or in combination with genetic polymorphisms, including the common MTHFR 677 C → T polymorphism, could contribute to greater disease risk in ageing by causing perturbations in one carbon metabolism. Moreover, interventions with the relevant B-vitamins to optimise status may have beneficial effects in preventing degenerative diseases. The precise mechanisms are unknown but many have been proposed involving the role of folate and the related B-vitamins as co-factors for one-carbon transfer reactions, which are fundamental for DNA and RNA biosynthesis and the maintenance of methylation reactions. This review will examine the evidence linking folate and related B-vitamins with health and disease in ageing, associated mechanisms and public health implications.

If High Folic Acid Aggravates Vitamin B12 Deficiency What Should Be Done About It?

The most common cause of vitamin B12 deficiency in older people is malabsorption of food-bound vitamin B12. Thus, it is suggested that the recommended daily allowance of 2.4 microg/d be met primarily with crystalline vitamin B12, which is believed to be well absorbed in individuals who have food-bound malabsorption. There is concern that high intakes of folic acid from fortified food and dietary supplements might mask the macrocytic anemia of vitamin B12 deficiency, thereby eliminating an important diagnostic sign. One recent study indicates that high serum folate levels during vitamin B12 deficiency exacerbate (rather than mask) anemia and worsen cognitive symptoms. Another study suggests that once vitamin B12 deficiency is established in subjects with food-bound malabsorption, 40 microg/d to 80 microg/d of oral crystalline vitamin B12 for 30 d does not reverse the biochemical signs of deficiency. Together, these studies provide further evidence that public health strategies are needed to improve vitamin B12 status in order to decrease the risk of deficiency and any potentially adverse interactions with folic acid.