MTHFR and vitamin B12 deficiency: Mild hyperhomocysteinemia in fasting conditions can be attributed to any of the following factors: mild impairment in the methylation pathway (i.e. folate or vitamin B12 deficiencies or methylenetetrahydrofolate reductase (MTHFR) thermolability), heterozygous cystathionine beta-synthase defect, vitamin B6 deficiency, or due to smoking, nutritional, hormonal and pharmacological factors [7,8].