Serum folate, certain diseases linked to cobalamin status
Neither cobalamin intake nor age per se significantly predicts cobalamin status in community-dwelling older adults, a study has shown. Serum folate proves to be a significant predictor of serum cobalamin, whereas diseases such as cancer or inflammatory bowel disease (IBD) may influence cobalamin status.
“[I]ndependent of serum folate and other potential confounders, serum cobalamin is inversely associated with plasma homocysteine,” according to the researchers.
The respective median values for serum cobalamin, plasma homocysteine and dietary cobalamin intake were 256 pmol/L, 9.7 µmol/L and 5.7 µg/day. Cobalamin intake, sex, body composition, serum creatinine and smoking did not predict serum cobalamin, as indicated in multiple regression analysis (p-all>0.05). [Eur J Clin Nutr 2019;73:1307-1315]
On the other hand, serum cobalamin positively correlated with age (β, 0.111; p=0.031), serum folate (β, 0.410; p<0.001) and diagnosis of chronic IBD (β, 0.101; p=0.037) and negatively correlated with cancer diagnosis (β, −0.142; p=0.003). The model explained 23 percent of the variability of cobalamin status.
Serum folate was the sole positive predictor of serum cobalamin (β, 0.407; p<0.001) after excluding patients with IBD/cancer diagnosis and/or vitamin B/multivitamin supplementation. Furthermore, serum cobalamin showed a positive correlation with inverse-transformed plasma homocysteine before (β, 0.298; p<0.001) and after (β, 0.199; p<0.001) multiple adjustments.
Several studies have reported the significant associations between serum folate and serum cobalamin. [Public Health Nutr 2002;5:505-511; Clin Chem 2006;52:129-137; Br J Nutr 2013;110:1672-1679; Am J Clin Nutr 2015;102:943-950]
“In our cohort, besides serum folate, only IBD and cancer proved as robust predictors of serum cobalamin,” the researchers said. “Cobalamin and folic acid deficiencies are common in patients with IBD for which reason cobalamin preparations may be advised or given parenterally.” [World J Gastroenterol 2016;22:895-905]
With regard to the negative relation between cancer and serum cobalamin, previous studies have reported a low cobalamin status in patients with cancer of the gastrointestinal tract and multiple myeloma. [Eur J Clin Nutr 2016;70:990-994; Neth J Med 2003;61:249-252]
“The underlying mechanisms of the strong positive association between serum folate and cobalamin, as well as the robust independent negative association between serum cobalamin and homocysteine warrant further research,” the researchers said.
The present study measured serum cobalamin and plasma homocysteine using SimulTRAC-SNB radio assay and high-performance liquid chromatography, respectively. Linear multiple regression analyses were conducted with cross-sectional data of 352 participants (aged 60–90 years) to examine the predictors of serum cobalamin and the association between cobalamin and homocysteine status.
The following were considered as potential predicting/confounding factors: age, sex, body composition, diet, supplement use, smoking, serum folate, serum pyridoxal 5´-phosphate, serum creatinine and selected diseases.
The study had certain limitations, such as its cross-sectional design and use of only one biomarker to assess cobalamin status, according to the researchers. Genetic profiles were also not included in the assessment. In addition, results should be interpreted with caution due to the low prevalence of IBD and cancer.