The vitamin E, vitamin B-6, vitamin B-12, and folate status of 22 gastric bypass subjects aged 23 to 60 years was evaluated before surgery and at 6 and 12 months after surgery. Before surgery, 77% of subjects had adequate plasma vitamin E levels; 36%, adequate plasma pyridoxal phosphate levels; 100%, adequate plasma vitamin B-12 levels; and 45%, adequate plasma folate levels. The food intake of all subjects was sharply reduced after surgery. After surgery, subjects were classified into three vitamin supplement groups on the basis of average daily vitamin supplement intake. Subjects taking higher levels of supplements containing the vitamins in question had significantly higher plasma concentrations of the vitamins than those taking low or moderate levels. The mean plasma vitamin values in the moderate supplement group were indicative of adequate status for all vitamins, but plasma vitamin B-12 levels at 12 months post-surgery were significantly lower than pre-surgery levels. In the low supplement group, mean plasma vitamin levels were in or near marginal or deficient ranges. The majority of subjects consuming supplements of vitamin E, vitamin B-6, and folate near the US RDA maintained normal vitamin status. Subjects taking more than 100 micrograms vitamin B-12 daily had adequate vitamin B-12 status. Significant correlations (r = .67 to .94) were observed between vitamin supplement levels and the respective plasma vitamin concentrations.

The vitamin B-12 and folate intakes and plasma levels of 39 healthy black female adolescents were evaluated. Estimated dietary folate intakes of 97% of the subjects were less than 2/3 of the RDA, and 74% had plasma folate levels indicative of marginal (3.0 to 5.9 ng/ml [less than 6 nmol/:]), nmol/L]), and 3%, deficient (below 3.0 ng/ml [less than 6 nmol/L]) folate status. Thirteen percent of the subjects had estimated dietary intakes below 2/3 of the RDA for vitamin B-12; all subjects had plasma levels indicative of adequate vitamin B-12 status.

Liebman, M.; Driskell, J.; Smith, M.; Thye, F.; Gwazdauskas, F.; Herbert, W. Author Information

NADH-FMN oxidoreductase has been proposed as an enzyme involved in the release of iron from ferritin. The effects of riboflavin and/or iron deficiencies and of dietary allopurinol on the activities of this enzyme and on the iron contents of liver, kidney and duodenum were investigated. Allopurinol, a xanthine oxidase inhibitor, did not affect organ enzyme activities nor iron contents. Riboflavin-deficient rats and iron-deficient rats both had significantly lower organ enzyme activities and iron contrnts than controls. Organ enzyme activities and iron contents of rats fed a diet deficient in both iron and riboflavin were significantly lower than those of controls. After dietary iron and/or riboflavin repletion, organ enzyme activities and iron contents increased. Rats fed an irons-overload diet had enzyme activities similar to that of controls, but organ iron contents were significantly increased over those of controls. Effects of riboflavin and/or deficiencies in rats on NADH-FMN oxidoreductase activities and iron contents of liver, kidney and duodenum appeared to be reversible by riboflavin and/or iron supplementation. The data support the view that NADH-FMN oxidoreductase may be a controlling enxyme in iron release from ferritin.