It is known that individuals respond differently to the same dietary intake differently. Nutrigenetics is an essential discipline to study gene-based differences in response to dietary components for nutrition and dietetics practice. One of the best-known examples for nutrigenetics is the polymorphism of methylenetetrahydrofolate reductase (MTHFR) C677T. The presence of the C677T mutation in MTHFR gene is associated with a reduction of MTHFR enzyme activity. This reduction of MTHFR enzyme activity may cause an increase in plasma homocysteine level which becomes risk factors for cardiovascular disease, cognitive impairment and neural tube defects. Plasma homocysteine level is responsive to intervention with folic acid and related vitamin B group. "Sakado Folate Projects" is a health promotion with personalized nutrition intervention based on MTHFR C677T polymorphisms for prevention of these diseases associated with hyperhomocysteinemia. An increase in serum folate level and a decrease in serum homocysteine level were observed at 4 months after the onset of this intervention and these changes were particularly marked in individuals with TT genotype. This finding suggests that personalized nutrition intervention based on genetic information is effective in motivating individuals to change their lifestyle habit.
There are a number of investigations regarding the relationship between fat-soluble vitamins and polymorphisms of their metabolic enzymes. Especially, polymorphisms of vitamin K metabolic enzymes are clinically adopted for warfarin administration. In this report, we show several recent investigations regarding polymorphisms of metabolic enzymes and binding proteins of vitamin A and vitamin E. Genome-wide association study revealed that polymorphisms of retinol-bind protein and transthyretin affected vitamin A status of Caucasian males. CYP26B1 is the metabolizing enzyme of retinoic acid. CYP26B1 polymorphism (rs2241057) has been reported to be associated with the development of Crohn's disease and atherosclerosis. CYP4F2 participates in ω-hydroxylation of vitamin E. Among children and adults with non-alcoholic fatty liver disease who were treated with vitamin E, the effect of CYP4F2 polymorphism on vitamin E status and the outcome were investigated. CYP4F2 polymorphism affected vitamin E pharmacokinetics but had no significant association with hepatic histological end points. It is expected that further studies will clarify the relationship between polymorphism of proteins related to fat-soluble vitamins and disorders.
Deficiency of vitamin D due to an insufficient intake of vitamin D and lack of sunshine exposure in childhood leads to diseases caused by vitamin D deficiency such as hypocalcemic seizures, rickets, infantile convulsion, bowlegs, short stature, and developmental motor skills disorder. Recently, the number of patients with vitamin D deficiency has been increased with changes in environmental factors. However, there are many cases of vitamin D deficiency which cannot be explained by the environmental factors alone. We have analyzed the genetic predisposition for the onset of vitamin D deficiency and have found differences in the polymorphisms or haplotypes of VDR, GC, and NADSYN1 genes in patients with vitamin D deficiency. Thus, genetic factors may predispose to vitamin D deficiency to some extent. Therefore, it has been thought that further examination is needed for establishment of tailor-made intake of vitamin D in the future.