The physiologically active form of vitamin B_6, pyridoxal 5'-phosphate (PLP), is known to function as a cofactor in many enzyme reactions in amino acid metabolism. Recent studies have shown that, apart from its role as a coenzyme, PLP act as a modulator of steroid hormone receptor-mediated gene expression. The induction of cytosolic aspartate aminotransferase (cAspAT) in rat liver by hydrocortisone is suppressed by the administration of pyridoxine. The suppression of the cAspAT induction by pyridoxine is caused by a decrease in the expression of the cAspAT gene, which is brought about by inactivation of the binding activity of the glucocorticoid receptor to the glucocorticoid-responsive element in the regulatory region of the cAspAT gene. Vitamin B_6 has recently been found to modulate gene expression not only for steroid hormone-responsive or PLP-dependent enzymes but also for steroid- and PLP-unrelated protein such as serum albumin. Albumin gene expression was found to be modulated by vitamin B_6 through a novel mechanism that involved inactivation of tissue-specific transcription factors, such as HNF-1 or C/EBP, by direct interaction with PLP in a similar manner to glucocorticoid receptor. We also found that the growth of human hepatoma HepG2 cells was completely inhibited in medium supplemented with pyridoxine in the millimolar range. The anti-tumor effect of vitamin B_6 is not limited to liver cancer alone. Recent studies have shown that dietary supplementation of vitamin B_6 markedly suppresses colon carcinogenesis in mice and mammary tumorigenesis in rats. We further found that antioxidant activity of vitamin B_6 delays homocysteine-induced atherosclerosis in rats. These findings add a new dimension to the hitherto recognized function of vitamin B_6 as a cofactor of enzyme action.

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UDP-glucuronosyltransferases (UGT) isoforms catalyze the glucuronidation towards many lipophilic endogenous and exogenous chemicals to excrete from the body. Dietary compounds are also glucuronidated by UGT isoforms and its biological effects depend, in part, on formation of the glucuronides. To evaluate the contribution of each UGT for glucuronidation towards the dietary bioflavonoid, quercetin, we have constructed yeast expression system of human UGT1As and analyzed the glucuronidation using the recombinant UGTs. UGT1A1 catalyzed glucuronidation towards 3'- and 4'-hydroxyl moiety of quercetin with high catalytic efficiency and substrate inhibition kinetics. UGT1A9 produced 3'-, 4'-, 3- and 7-glucuronides. Extrahepatic human UGT1A7, 1A8 and 1A10, which were found throughout the gastrointestinal tract, showed the high glucuronidation efficiency towards 3'- and 4'-hydroxyl moiety. These results suggest that glucuronidation towards quercetin is catalyzed by several UGT isoforms, and recombinant human UGT expression system in yeast provides information on the regioselectivity of glucuronidation of dietary bioflavonoids.

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The elderly have an increased susceptibility to a number of age-related chronic diseases that may be delayed or ameliorated by nutritional intervention, including cardiovascular diseases, neurologic disease, hypertension, diabetes, and cancers. The use of medical therapies tends to escalate with age; thus, dietary interventions to preserve health in the elderly may help to reduce future health care expenditures in this population. Older adults have more complex and more often health problems than other population subgroups. Thus, defining and meeting the unique nutritional needs including vitamins of older adults, in terms of both basal requirements and the prevention or delay of chronic diseases linked to diet, will be an important challenge for the field of nutritional science.

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Vitamin C (L-ascorbic acid) has a well-documented, strong anti-oxidant function, evident as its ability to scavenge reactive oxygen species (ROS) in cells and blood. Additionally, an anti-aging effect has been attributed to vitamin C stemming from its deletion of ROS; however, no scientific evidence has yet proven this assertion. This report gives a full account of the relationship between vitamin C and the aging process while describing our study results.

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Dietary intake studies of nutrients demonstrated that Japanese elderly people ingested enough amounts of vitamin B_<12> from certain foods. However, there is a high prevalence of low vitamin B_<12> status in this age group worldwide. Gastrointestinal absorption of vitamin B_<12> from foods is decreased in elderly people because of a high prevalence of atrophic gastritis with a low acid-pepsin secretion, which reduced release of free vitamin B12 from food proteins (food protein-bound vitamin B_<12> malabsorption). As the ability to absorb crystalline vitamin B_<12> remains intact in the elderly people with atrophic gastritis, elderly people should try to obtain vitamin B_<12> from crystalline vitamin B_<12>-fortified foods or -supplements.

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Cognitive impairment and dementia increase with ageing. Considering the late age of onset it is reasonable to consider that environmental factors are as likely to contribute to the dementia. Diet and ultimately nutrition are major environmental factors that may play a role in this late-onset disease. However, environmental risk factors have not been identified with certainly. Alzheimer's disease (AD) is the most common cause of dementia. Epidemiological studies have explored the associations between nutrients and AD, and some studies suggest that high intake of vitamin C, E, B_6 and B_<12>, and folate are related to a low risk of AD, but reports are inconsistent. Epidemiological studies assessing the effect of vitamin E in healthy individuals have yielded conflicting results. The objective in this paper is to review data relating to the effects of antioxidant vitamins and homocysteine-related vitamins (B-vitamins) on cognitive decline and dementia, especially AD.

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Amrit is an elixir of immortality, which men has pursued for thousands years. Malignant tumor, cardiac disease, and cerebrovascular disease are three major cause of death in Japan, where is the world's top country for longevity. It is next to impossible to suppress physiological aging; preventing or retarding pathological aging improves people's quality of life. Not a few diseases, lifestyle related diseases including cancer, are caused by inappropriate dietary habit. Dietary supplements might play a certain role to prevent elderly people from lack of sufficient nourishment. Anti-oxidant activities, suppression of cell proliferation, inhibition of atherogenic action, and antidepressive effect have been reported as potencies of dietary supplements. Those mechanisms seem to be promising agents for the treatment of age-related diseases, whereas further clinical studies will be required to access the efficacy and safety for administration.

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