Showing papers in "International Journal for Vitamin and Nutrition Research in 1996"

Vitamin C and human health--a review of recent data relevant to human requirements.

Abstract: The recent scientific literature indicates that beyond merely protecting against scurvy vitamin C contributes to many aspects of human health The main areas of research reviewed include: 1 Vitamin C requirements of smokers The data indicate that the vitamin C requirement of smokers is higher by at least 60 mg per day (up to 140 mg per day) than that of nonsmokers 2 Important functions of the body, such as immune response, pulmonary function, and iron absorption are related to vitamin C intakes Daily vitamin C intake of at least 150-200 mg per day enhance these functions 3 Vitamin C may play critical roles in the prevention of CHD, cancer and cataract Based on the available data, vitamin C intakes of at least 80-120 mg per day are associated with lowering the risk of these chronic diseases 4 The literature documents that these and much higher intake levels of vitamin C are safe

Comparative effectiveness of vitamin D3 and dietary vitamin E on peroxidation of lipids and enzymes of the hepatic antioxidant system in Sprague--Dawley rats.

Abstract: The vitamin D-endocrine system has mostly been studied for its role in calcium and phosphorus metabolism and its possible role as an antioxidant has been neglected. This study attempts to elucidate the antioxidative properties of the prohormone with respect to vitamin E, a membrane antioxidant. Results herein show that D3 treatment brought about similar reduction in the extent of lipid peroxidation and induction in superoxide dismutase (SOD) activity, as with vitamin E supplementation. While selenium dependent glutathione peroxidase (Sedep. GPx) activity reflected no change with vitamin D3 treatment, total GPx activity was more significantly influenced by vitamin D3 than by vitamin E. The glutathione (GSH) content in the experimental rats also reflected similar changes. Vitamin E supplementation caused 8.57% increase in glutathione reductase (GR) activity, while vitamin D3 decreased the concerned enzymes activity by 11.11%. Vitamin D3 treatment also caused 25% increase in glucose 6-phosphate dehydrogenase (G6PD) activity. These data thus suggest that vitamin D3 may function as an antioxidant in the liver in vivo and illustrate an effectiveness higher than that observed with vitamin E supplementation.

Preferential increase in chylomicron levels of the xanthophylls lutein and zeaxanthin compared to beta-carotene in the human.

Abstract: The time-course of appearance of five carotenoids in chylomicrons and their distribution pattern were studied following ingestion of a single dose of Betatene, a natural carotenoid source composed of 05% lutein, 075% zeaxanthin, 36% alpha-carotene, 703% all-trans beta-carotene, 227% beta-carotene cis isomers, 21% unidentified carotenoids and no lycopene Lutein, zeaxanthin, alpha-carotene and all-trans beta-carotene but not lycopene levels in chylomicrons increased after Betatene ingestion with a maximum at 9 h and a distinct decline from 9 to 12 h However, the carotenoid pattern in the chylomicron fraction did not match the pattern in Betatene, with a 14-fold and 4-fold higher level of lutein and zeaxanthin, respectively, compared to their content in Betatene The contribution of alpha-carotene to the carotenoid composition in chylomicrons reflected its content in Betatene, whereas the relative amount of all-trans beta-carotene was substantially lower than in Betatene Thus, in the presence of high amounts of beta-carotene, there is a preferential uptake of the xanthophylls lutein and zeaxanthin as compared to all-trans beta-carotene from the intestinal lumen into chylomicrons

Total diet study: estimated dietary intakes of nutritional elements, 1982-1991

Abstract: Dietary intakes of 11 nutritional elements for eight age-sex groups were estimated for the time period 1982 to 1991 on the basis of results from laboratory analyses of 234 core foods of the U.S. food supply and food consumption data from two national food consumption surveys conducted in the late 1970s. Estimated intakes based on the mean and median (50th percentile) levels of the elements in the foods were similar, except for iodine for which intake estimates based on mean values exceeded those based on median values. The high concentration of iodine in some foods resulted in higher mean (than median) values. Estimated intakes of sodium, potassium, phosphorus, selenium, and iodine met or nearly met dietary intake standards set by the National Academy of Sciences (NAS). Estimated intakes of copper were below NAS standards for all eight age-sex groups. Estimated intakes were below NAS standards for magnesium for six age-sex groups, calcium and zinc for five age-sex groups, iron for three age-sex groups, and manganese for one age-sex group. The diets of teenage girls had seven elements below NAS standards, the diets of adult women had five elements below NAS standards, and the diets of 2-year-olds and older men and women had four elements each below NAS standards. The estimated intake of sodium for 6-11-month-old infants showed a decreasing trend from 729 mg/day in 1982/83 to 632 mg/day in 1990/91. There were no other significant trends or changes in estimated element intakes over the 9-year period.

Lymphatic transport of alpha-, gamma- and delta-tocotrienols and alpha-tocopherol in rats.

Abstract: Lymphatic transport of α-, γ- and δ-tocotrienols and α-tocopherol was measured in thoracic duct-cannulated rats. Animals were administered 3 ml of a test emulsion containing 200 mg sodium taurocholate, 50 mgfatty acid free-albumin, 200 mgfat and 100 mg ofa mixture of tocotrienols and α-tocopherol (Exp. 1) or 10 mg of purified α-, γ- or δ-tocotrienol or α-tocopherol (Exp. 2) through a gastric tube. Quantitative lymphatic recovery of oleic acid given as triolein was obtained in these experimental conditions. The 24-hours recovery of tocotrienols and α-tocopherol were 10-20% of the administered dose in Exp. 1. The recovery of α-tocotrienol was about 2-times higher than that of α-tocopherol, while that of δ and δ-tocotrienols was intermediate between these two α-forms. In Exp. 2, where these compounds were administered individually, the 24 hours recovery ranged from 22 to 37% of the administered dose. Again, the recovery of α-tocotrienol was significantly higher than that of the other tocotrienols and α-tocopherol, while that of γ and δ-tocotrienols and α-tocopherol was comparable. Thus, the results show the preferential absorption of α-tocotrienol compared to γ and δ-tocotrienols and α-tocopherol.

The effect of 6'-galactooligosaccharides on bone mineralization of rats adapted to different levels of dietary calcium

Abstract: 6'-galactooligosaccharides (6 '-GOS), a mixture of galactosyl oligosaccharides formed from lactose by the transgalactosyl reaction with β-D-galactosidase derived from Aspergillus oryzae and Streptococcus thermophillus, are unhydrolyzed in the small intestine and are fermented by the intestinal bacteria. The effects of 6'-GOS on calcium (Ca) absorption and bone mineralization were examined in male Wistar rats adapted to different levels of dietary Ca for 30 days. Dietary 6'-GOS (5 g/100 g of diet) were more potent than control in stimulating Ca absorption in rats fed the Normal-Ca diet (0.5 g of Ca/100 g of diet) after 8-10 days and 18-20 days, and the bone (femur and tibia) Ca content of rats fed the Normal-Ca diet with 6'- GOS were significantly higher than those ofthe control animals. However, in rats fed the Low-Ca diet (0.05 g of Ca/100 g of diet), 6'-GOS feeding did not affect both the absorption of Ca and the bone mineralization. Ca content in the liquid phase of the cecal digesta was significantly elevated by 6'-GOSfeeding in the rats fed the Normal-Ca diet, however, this was unchanged in the rats fed the Low-Ca diet. We conclude that the effect of6'-GOS on the bone mineralization is affected by dietary Ca concentration used in the experiment, and the stimulatory effect of 6'-GOS on Ca absorption may be partly associated with increased solubility of Ca in the intestinal digesta.

In vitro measurement of beta-carotene cleavage activity: methodological considerations and the effect of other carotenoids on beta-carotene cleavage.

Abstract: In view of controversies about assessment of the β-carotene cleavage activity, methodological aspects and problems of the dioxygenase assay are described. Using rat and hamster intestinal preparations the method was optimized on retinal formation, the only cleavage product we could demonstrate. It appeared that the cell fraction with the highest cleavage activity was the 9,000g supernatant (S-9). Maximal retinal formation was obtained with SDS, taurocholate and egg lecithin in the buffer and 3 μg β-carotene dissolved in acetone. Ethanol, THF/DMSO (1:1) or propylene glycol as solvent for β-carotene reduced retinal formation to 55, 24, and 19%, respectively. Retinal formation increased proportionally with the amount of protein S-9 used and was linear up to 40-60 minutes of incubation. Incubation with α-carotene or β-cryptoxanthin resulted in a retinal formation of 29 and 55% of the amount formed from β-carotene. Addition of 9 μg of lutein to an incubation with 3 μg β-carotene reduced retinal formation, while lycopene had no effect. In conclusion, the β-carotene cleavage assay with S-9 as enzyme source described in this report, seems a useful tool to study (dietary) determinants of β-carotene cleavage activity, but for other purposes adaptation of the method is required. Chemicals/CAS: alpha-carotene, 432-70-2; Bcdo protein, rat, EC 1.14.99.36; beta Carotene, 7235-40-7; beta-Carotene 15,15'-Monooxygenase, EC 1.14.99.36; Carotenoids, 36-88-4; cryptoxanthin, 472-70-8; lycopene, 502-65-8; Oxygenases, EC 1.13.-; Retinaldehyde, 116-31-4; Tritium, 10028-17-8; Xanthophylls

Validation of a micromethod for determining oxidized and reduced vitamin C in plasma by HPLC-fluorescence.

Abstract: An HPLC micro-method with fluorescence detection has been developed to determine total vitamin C (vit C) and dehydroascorbic acid (DHA) concentrations in human plasma samples. This method is based on the rapid, specific reaction of DHA with dimethyl-o-phenylenediamine (DMPD) to form a fluorescent quinoxaline derivative that is quantified by HPLC in less than 5 minutes. The method was assessed with reference to the direct 2,4-dinitrophenylhydrazine (DNPH) colorimetric method. They were well correlated (r3 = 0.879), but the DMPD-HPLC method had the limit of detection 6 times lower than the standard method and the relative error for a vitamin standard was 10 times better than that of the standard method. The plasma DHA to total vit C ratio varied from 10 to 60%, depending on sample processing. Plasma that were immediately analysed contained 10% DHA whatever the subject's age; frozen deproteinized samples kept 1 week (-67 degrees C) had 20%, and blood samples kept for one hour at room temperature before treatment had up to 60% DHA. The ratio in capillary samples taken from the finger was 11-42%. This rapid, specific and very sensitive micro-method is well suited to routine measurements of plasma vit C.

The effect of preconceptional multivitamin supplementation on fertility.

Abstract: A significantly higher rate of conceptions occurred after preconceptional multivitamin supplementation in comparison with a placebo-like trace element supplementation in the Hungarian randomised, double-blind, controlled trial. This difference was explained by 5% shorter time in the achievement of conception.

Quantitation of vitamin E and a carotenoid pigment in cataractous human lenses, and the effect of a dietary supplement.

Abstract: The quantitation of tocopherols and carotenoids in lipid extracts of cataractous human lenses was performed in parallel with those of matched samples of plasma, which was also analysed at the same time. Alpha-tocopherol in cataractous lenses from elderly human subjects was present at 4.4 mumoles/kg wet weight, much less than the mean of 33 mumoles/l in plasma from these subjects. The mean ratio of alpha- and gamma-tocopherols was 3.5 in the lenses, and 11.3 in plasma. Lens extracts contained no detectable alpha- or beta-carotene, lycopene, or beta-cryptoxanthin. However, all the lens extracts contained a pigment with the retention time and spectrum of lutein and zeaxanthin. Using the molar extinction coefficient of lutein this was present at ca. 0.03 microM, compared with 0.2 microM in plasma. Seven patients with bilateral cataracts had one of their cataractous lenses removed and analysed, and were then given either an oral placebo, or an oral supplement of ascorbate, alpha-tocopherol and beta-carotene. Three months later, the second cataractous lens, and a blood sample, were analysed. Three of the seven had received the active supplement, as confirmed by substantially raised blood levels of alpha-tocopherol and beta-carotene, and raised aqueous humour levels of vitamin C. However, lens tocopherol levels remained unchanged, and no beta-carotene could be detected in the lenses after supplementation. This preliminary evidence needs to be confirmed in larger studies.

Micronutrient status in elderly people. Geriatrie/Min. Vit. Aux Network.

Abstract: A biochemical assessment of the vitamin and trace element status of 756 institutionalized elderly men and women, 66-103 years old (average 83.5 +/- 7.6 y), was conducted in 26 nursing homes in different areas of France. Serum concentrations of beta- and alpha-carotene, beta-cryptoxanthin, lycopene, retinol, alpha- and gamma-tocopherol, vitamin C, zinc and selenium were measured. A difference in biochemical markers according to sex was observed for vitamins E and C: elderly women had higher levels of alpha-tocopherol and vitamin C than elderly men. When expressed as a ratio of cholesterol, the difference between sexes for alpha-tocopherol disappeared. Simple regression analysis showed that most vitamins and trace elements were significantly negatively correlated with age. A high prevalence of low concentrations of vitamin C, zinc and selenium was revealed.

Do hydroxy-carotenoids prevent coronary heart disease? A comparison between Belfast and Toulouse

Abstract: High intakes of antioxidants in fruit, vegetables and wine are thought to protect against coronary heart disease (CHD). Because people in Toulouse have a much lower incidence of CHD compared with Belfast, the plasma concentrations of antioxidant vitamins and carotenoids in the two populations have been compared. The major difference was in some of the plasma carotenoids. Hydroxy-carotenoids were twice as high in Toulouse in both sexes, notably lutein which occurs principally in dark green vegetables and beta-cryptoxanthin which occurs chiefly in citrus fruits. In addition, alpha-carotene was 50% higher in Toulouse, gamma-tocopherol was 50% higher in Belfast. Other plasma vitamins and carotenoids were nor significantly different. If antioxidants play a role in preventing CHD, then the hydroxy-carotenoids are major candidates for further investigation.

Contributions of food groups to estimated intakes of nutritional elements: results from the FDA total diet studies, 1982-1991.

Abstract: The contributions of 12 food groups to the estimated dietary intakes of 11 nutritional elements in the diets of eight age-sex groups was determined from analyses of 234 core foods in the U.S. food supply and consumption data from national food consumption surveys. The major contributors of each element were grain products for sodium, iron, manganese, and iodine; vegetables for potassium ; milk and cheese for calcium ; milk and cheese and animal flesh for phosphorus ; vegetables and grain products for magnesium ; and animal flesh for zinc, copper, and selenium. For the infant diet, the milk and cheese group (which includes infant formula) was the major contributor to the estimated intakes of sodium, potassium, calcium, phosphorus, magnesium, zinc, copper, and iodine. Grain products were the primary sources for iron, manganese, and selenium in the infant diet. The diet of 2-year-olds, which includes a considerable amount of milk, contains larger percentages of sodium, potassium, calcium, phosphorus, magnesium, zinc, and iodine from milk and cheese than do the diets of older age-sex groups. For teenagers, milk and cheese make a greater contribution to potassium, calcium, phosphorus, magnesium, zinc, manganese, and iodine intakes than they do for the adult age-sex groups.

beta-Carotene accumulation in mouse tissues and a protective role against lipid peroxidation.

Abstract: Mice were supplemented with beta-carotene in beverage for 10 days. After the supplement, beta-carotene accumulated mainly in the liver and to some extent in the blood plasma, kidney and lung. The beta-carotene administration was associated with an increase in the amount of retinyl ester and retinol in the liver, but not in the amount of retinol in blood plasma. Lipid peroxidation in vivo was induced by the injection of carbon tetrachloride under the dorsal skin of mice. As an index of lipid peroxidation, thiobarbituric acid-reacting substances (TBARS) were assayed in urine and tissue homogenates. Urine and kidney TBARS were reduced by the supplementation of beta-carotene. The amounts of TBARS in kidney, liver and lung, decreased with increasing amounts of beta-carotene accumulated in these tissues, i.e. inverse correlations were obtained. These results indicate that beta-carotene can suppress lipid peroxidation in mouse tissue.

Influence of maternal serum lipids and maternal diet during the third trimester of pregnancy on umbilical cord blood lipids in two populations of Spanish newborns.

Abstract: An analysis was made of the influence of maternal diet and serum lipids during the third trimester of pregnancy upon cord blood lipids in two populations of Spanish newborns. A significant correlation was found to exist between maternal cholesterol concentrations and those of newborn infants (r = 0.3298). A correlation was also found between maternal cholesterol levels and infant HDL-cholesterol (r = 0.2575) and LDL-cholesterol (r = 0.3053) levels. Further, a positive correlation was seen between maternal LDL-cholesterol and infant cholesterol (r = 0.3204) and LDL-cholesterol (r = 0.3507). The relationship between maternal cholesterol and cord blood cholesterol was independent of participants' dietary, anthropometric and personal data. 3.1% of neonates showed total cord blood cholesterol concentrations of > 2.6 mmol/L. The mothers of these children showed the strongest concentrations of cholesterol and LDL-cholesterol in the third trimester of pregnancy, the shortest pregnancies and the smallest newborns of all subjects. Negative correlations were found between birth weight and cord blood cholesterol levels (r = -0.1475) and LDL-cholesterol (r = -0.1686). It might be deduced from these results that a relationship exists between the maternal blood lipid parameters studied and those of the cord. Inverse relationships were also seen to exist between the lipid parameters of cord blood and weight at birth and length of pregnancy. These data have implications that deserve further study.

Brain folates and DNA methylation in rats fed a choline deficient diet or treated with low doses of methotrexate.

Abstract: In a recent study we have demonstrated that induced changes in several parameters of one-carbon metabolism in livers of rats fed either a choline deficient diet or treated with low doses of methotrexate may be reversed through restoration of an adequate choline diet and discontinuing of methotrexate (MTX) administration. The present study was aimed at comparing these two treatments for their effect on brain: total folate was 0.69 +/- 0.35 nmol/g in the control group and was significantly lower in the other two groups (0.25 +/- 0.06 in the MTX and 0.45 +/- 0.24 nmol/g in the choline deficient groups, p < 0.01). Both treatments were associated with elongations of the glutamate chains of the folate molecules: the proportion of hepta- and octaglutamyl folates increased from 16% to 31% in the MTX treated and to 33% in the choline deficient group, accompanied with concomitant decreases in the concentrations of tetra- and pentaglutamyl folates. MTX could not be detected in brain tissue in contrast to previous observations of significant amounts found in liver. DNA was significantly (p < 0.05) undermethylated in both treated groups compared to controls. Results are discussed on the basis of the possibility that choline deficiency and MTX treatment appear to impair the capacity of tissues, either a peripheral one as liver or a central one as brain, to incorporate folate.

High cardiovascular mortality in postcommunist countries : Participation of oxidative stress ?

Abstract: Age-standardized death rates from cardiovascular diseases (0-64 years) of male populations in postcommunistic Central and Eastern Europe are now several times higher than those in Western Europe. This phenomenon is only partly explainable by the higher prevalence of classical cardiovascular risk factors (smoking, hypertension, hypercholesterolemia). Socio-economic background of the cardiovascular epidemic in the USA and Western Europe after 1950, and in the Soviet bloc in 1960-1990 was substantially different. It is suggested that the influence of further risk factors should be considered : - oxidative stress caused by prolonged disorders in life style (alcoholism, smoking) high degree of environmental pollution and nutritional disbalances (chronic deficiency of antioxidants due to low consumption of fruits, vegetables and vegetable oils) ; - psychosocial factors - chronic stress, tension, anger, hostility, frustration and apathy leading to a lowered interest in one's own health. The situation in postcommunist countries is unique and its analysis could provide important new information about the etiology of cardiovascular diseases and their prevention.

Effect of sesame oil on serum and liver lipid profiles in the rat.

Abstract: In our previous study (Satchithanandam, S., Reicks, M., Calvert, R.J., Cassidy, M.M. and Kritchevsky, D. (1993) J. Nutr. 123, 1852-1858), we found that the absorption of lymphatic cholesterol by rats fed diets containing 24% sesame oil was about 50% less than that by rats fed the control diet containing no sesame oil. The effect of sesame oil on serum cholesterol levels was not determined at that time. In the present study, three groups of male Wistar rats (75-100 g) were fed a control diet or a diet containing 12 or 24% sesame oil. To increase serum cholesterol levels, 1% cholesterol and 0.5% cholic acid were added to each diet. After rats were fed for 4 weeks, total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglyceride levels were measured in the serum. Liver weight and cholesterol and triglyceride levels were determined. Liver cholesterol levels were significantly lower in rats fed the 24% sesame oil diet, and the liver lipid level was significantly higher in the 24% sesame oil-fed group, compared with levels in the group fed the control diet. Liver weights and esterified cholesterol and liver triglyceride levels were not significantly different among the groups. Levels of serum total cholesterol and LDL-cholesterol were significantly lower in rats fed the 24% sesame oil diet, compared with levels in the control group. Serum triglyceride and HDL-cholesterol levels did not differ significantly among the groups. The mechanism by which a diet containing 24% sesame oil reduces levels of serum and liver cholesterol, liver LDL cholesterol, and liver lipids is not known. However, the high degree of unsaturation (85%) of sesame oil and the presence of linoleic acid may be important factors.

Effect of vitamin K2 on experimental calcinosis induced by vitamin D2 in rat soft tissue

Abstract: The effect of vitamin K2 on calcium (Ca) and inorganic phosphorus (P) levels in the aorta and kidney obtained from experimental calcinosis induced by vitamin D2(2.5 x 10(5) I.U./ kg b.w.) of male rats was investigated. A high dose of vitamin K2 (100 mg/kg b.w.) inhibited the increase in the aortic Ca and P or in the renal Ca and P induced by vitamin D2, and a low dose of vitamin K2 (10 mg/kg b.w.) showed the same tendency, but the degree of the efficacy was small. It may be suggested that a high dose of vitamin K2 suppressed experimental calcification of soft tissues induced by vitamin D2. Therefore, a pharmacological dose of vitamin K2 might have a usefulness for the prevention and treatment of arteriosclerosis with calcification.

Changes of phylloquinone and menaquinone-4 concentrations in rat liver after oral, intravenous and intraperitoneal administration

Abstract: To study the metabolism of K Vitamins (VK) in the liver, two types of natural VK, phylloquinone (K1) and menaquinone-4 (MK-4), were administered to male Wistar rats orally (P.O.), intravenously (I.V.) and intraperitoneally (I.P.). Blood and a small portion of the liver (and ascites by I.P.) were collected 8 times up to 72 h (P.O.) or 24 h (I.V. and I.P.). A modified assay procedure followed by high performance liquid chromatography (HPLC) was developed to detect VK from small amounts of liver tissue. After oral administration of both K1 and MK-4 (10 mumol/kg-P.O.), their concentrations in the liver increased from 1 h then reached a maximum at 6 h (10 nmol/g v.s. 0.35 nmol/g). After intravenous or intraperitoneal administration of K1 and MK-4 (0.5 mumol/kg-I.V. and I.P.), MK-4 concentrations in the liver reached a maximum faster than those of K1 (1.2 nmol/g -3 h vs. 1.3 nmol/g -0.5 h I.V. and 0.97 nmol/g -6 h vs. 0.47 nmol/g -1 h I.P.). MK-4 also increased in the liver from 6 h to 12 h (0.11 nmol/g -12 h) after oral administration of K1 (P.O.). These results indicate that K1 stays in plasma and liver longer than MK-4 and orally administered K1 might be transformed partially into MK-4 in the liver.

The identification and kinetics of 7α-hydroxyriboflavin (7- hydroxymethylriboflavin) in blood plasma from humans following oral administration of riboflavin supplements

Abstract: Following the administration of different oral (20, 40, 60 mg) and intravenous (11.6 mg) doses of riboflavin to healthy humans and female patients with liver cirrhosis (oral 40-mg dose), 7 alpha-hydroxyriboflavin (7-hydroxymethylriboflavin) was identified in blood plasma by fluorescence after high-performance liquid and thin-layer chromatographies, and by its absorbance spectrum. The apparent first-order absorption rate constant of 7 alpha-hydroxyriboflavin was 1.2 per hour in healthy subjects. Plasma peak concentrations of 40 nmol/l in males and 20 nmol/l in females (p 0.05). No significant influence of different oral riboflavin doses on 7 alpha-hydroxyriboflavin kinetics was found (p > 0.05). Liver cirrhosis had no significant effect on the amount of 7 alpha-hydroxyriboflavin released into blood plasma (p > 0.05). However, the failure to detect this metabolite following intravenous riboflavin administration indicates a substantial influence of gastrointestinal- or liver-passage.

Antioxidant vitamins and immunodeficiency

Abstract: On the plasma of 20 children from 1 to 6 years old with HIV infection, the following analyses were carried out: vitamin assays (vitamin E and beta-carotene), hematochemical assays, and immunoassays. From the body of our results it emerged that in the seropositive children considered, in addition to the already well-known alterations of the hematic and immune situation, there is a state of hypovitaminosis involving the most important antioxidant vitamins.

Vitamin B12 levels in human milk during the first nine months of lactation.

Abstract: Vitamin B 12 concentration was measured by competitive binding radioassay in 48 samples of human milk from healthy mothers eating unrestricted diets. Specimens were collected 1-35 weeks after full-term delivery and were subjected to proteolytic digestion before radioassay in order to destroy binding proteins. The distribution of the results was skewed, but the distribution of the logged values was not significantly different from normal. The geometric mean vitamin B 12 level remained almost unchanged during the first 12 weeks postpartum (261-297 pmol/l) and then declined to a low of 139 pmol/l at 27-35 weeks. A significant (P = 0.033) decline in vitamin B 12 concentration between 6-12 weeks and 19-25 weeks postpartum was observed.

Plasma concentrations of carotenoids and tocopherols in male long-term tobacco chewers, smokers and nonusers.

Abstract: Plasma carotenoid and tocopherol concentrations of men, aged 25 to 55 years, who were long-term chewers, smokers, or tobacco nonusers were determined. Tobacco users had either chewed (n = 11) or smoked (n = 23) for > 15 years. Nonusers (n = 10) had never smoked > 1 pack or chewed > 34 g. Food energy, mono- and poly-unsaturated and saturated fats, cholesterol, vitamin A, vitamin E, and carotenoid intakes of the three groups were not significantly different. Chewers and smokers reported consuming significantly less cryptoxanthin, found primarily in some fruits, and had significantly lower plasma cryptoxanthin levels than nonusers. Nonusers had significantly higher concentrations of plasma alpha-tocopherol than smokers; whereas those of chewers were intermediate. Nonusers had significantly higher concentrations of plasma gamma-tocopherol and total tocopherols than chewers or smokers. Plasma delta-tocopherol concentrations of the groups were not significantly different. Nonusers had significantly higher levels of beta-carotene than smokers but not chewers. Plasma lutein and lycopene concentrations of all groups were not significantly different. Dietary intakes of total carotenoids and tocopherols of the three groups were not significantly different, yet nonusers had higher plasma concentrations of total and most individual carotenoids and tocopherols than smokers with values for chewers being intermediate.

Modulation of ultraviolet light-induced oxidative stress in mice skin related to dietary vitamin A and selenium intake.

Abstract: Weanling female SKH1 hairless mice were randomly divided into 4 groups. Each group was fed a particular regimen for 20 weeks: 1) normal basal diet with 5 IU vitamin A/g and 0.45 microgram selenium/g, 2) vitamin A deficient, 3) selenium deficient, and 4) vitamin A plus selenium deficient. Three hours before being sacrificed, half of the animals were subjected to UV A + B irradiation (3 J/cm2). Superoxide dismutases (SOD), catalase, Se glutathione peroxidase activities were determined in dorsal skin homogenates, as well as the concentrations of GSH and of thiobarbituric acid-reactive substances (TBARS), the latter being an index of lipid peroxidation. Ultraviolet light altered the antioxidant defense of mouse skin tissue: GSH level, catalase and Se glutathione peroxidase activities were lowered and SOD was unequally enhanced according to the nutritional status. Vitamin A and Se deficiencies did not perceptibly aggravate the UV-induced oxidative stress, although the former enhanced the decline of catalase expression induced by the irradiation. Probably through an adaptive mechanism, both dietary deficiencies increased the skin reserve of antioxidant GSH and thus appear to modulate the effects caused by reactive oxygen species.

The contribution of dietary iron to iron status in a group of elderly subjects.

Abstract: Although it is widely accepted that body iron stores of elderly individuals are largely adequate, recent findings from our laboratory suggest that as many as 9% of a "healthy" sample showed signs of an inadequate body store of this nutrient. In an attempt to see if iron consumption may be a contributing factor, we compared dietary intakes of total iron, heme iron, nonheme iron, ascorbic acid, calcium, dietary fibre, tea and coffee between 19 healthy seniors with inadequate iron stores and 108 healthy seniors with good iron status. The daily consumption of total iron was significantly higher in those with good iron stores. Thus, dietary iron is an important contributor to iron status in old age.

Intermediate cancer biomarkers and their use in beta-carotene studies in humans.

Abstract: The most effective means of avoiding the development of squamous cell carcinomas is the elimination of risk factors such as tobacco smoke and alcohol and of exposure to occupational and dietary carcinogens. In addition, chemoprevention by micronutrients such as beta-carotene may be promising. However, studies verifying such effects using cancer incidence or mortality as study endpoint are extremely costly of financial and manpower resources. Therefore, premalignant intermediate biomarkers such as histological lesions (dysplasias/leukoplakias/ polyps), genetic changes (DNA damage, mutations) or enzymatic changes (protein kinase C or ornithine decarboxylase activation) are increasingly being used as surrogate endpoints. Even though most preneoplastic biomarkers still need to be verified and shown to be linked to malignancy, their use in clusters may enhance their predictability. In human trials beta-carotene has reversed some lesions such as micronuclei, leukoplakias and dysplasias in the oral cavity, whereas other lesions, e.g. colorectal polyps (i.e. their recurrence after resection) have not been found to respond. But proliferation markers in the colon mucosa have been modified by beta-carotene. Preliminary findings are also available of a potential reduction of esophageal dysplasias in a high-risk Chinese population and of cervical dysplasias in a group of American women. The available beta-carotene data are sufficiently encouraging to justify continuation of trials using intermediate cancer markers.

The vitamin A status of Zambian children attending an under five clinic as evaluated by the modified relative dose response (MRDR) test

Abstract: The vitamin A status of 87 children, 7-29 months of age, who were randomly selected from attendees at a pediatric clinic in Ndola, Zambia, were evaluated by the modified relative dose response (MRDR) test. By using a MRDR ratio cut-off point of 0.06, 78% of the children had inadequate vitamin A status. Both male and female children were equally affected. Of those with inadequate vitamin A status, 82% were between 7-19 months of age. A significant inverse relationship (p < 0.005) existed between vitamin A inadequacy and Z scores for height for age, weight for age and weight for height. Children with lower Z scores showed a better vitamin A status in comparison to those with a higher Z score. This unexpected relationship is probably due to an increased demand for vitamin A in children with a higher weight and rapid growth rate. Serum vitamin A values correlated poorly with MRDR values except at extreme ends of the distribution. Although clinical vitamin A deficiency is relatively infrequent in Zambia, we conclude that the vitamin A status of our children nonetheless needs to be improved.

Early effect of a low dose (30 μg) ethinyl estradiol-containing triphasil® on vitamin B6 status. A follow-up study on six menstrual cycles

Abstract: The objectives of the study were to follow-up six artificial menstrual cycles induced by Triphasil® in order to determine: 1) the time of apparition of B6 metabolic side-effects, in the eventuality they occur, and 2) the existence or non-existence of a normalization process and if so, when it is initiated. The choice of this triphasic OC preparation was based on its current popularity among modern gynecologists. Among the selected twenty-three young women who had never used oral contraceptives (OC), fourteen consented to try a new contraceptive method. Their nutritional status including anthropometric, hematologic, biochemical and dietetic (including vitamin B6 intake) parameters was found to be adequate. A functional enzymatic test coupled to a direct measurement of vitamin B6 was employed to obtain a complete assessment of their vitamin B6 status. By using both approaches, only one case (7%) of deficiency due to OC was evidenced. This well-controlled study revealed that a short-term use of a relatively low dose estrogen-containing OC (30 μg) did not alter PLP concentrations in plasma and erythrocytes in the majority of our young subjects consuming adequate diets. However, a disturbance in vitamin B6 metabolism was detected. PL levels in both blood components have increased steadily and did not subside to pretreatment values at the end of the experiment. In conclusion, the single use of the PLP vitamer can be misleading as demonstrated by other investigators. To assess B6-status during oral contraception, in addition to a functional enzymatic test, it may be necessary to include the other aidehydic form of vitamin B6, to fully establish and comprehend hormone-induced adverse effects on this metabolism, particularly those of progesterone/progestin that have not yet been explored. Chemicals/CAS: Contraceptives, Oral, Hormonal; Ethinyl Estradiol, 57-63-6; Ethinyl Estradiol-Norgestrel Combination, 8056-51-7; Norgestrel, 6533-00-2; Pyridoxal Phosphate, 54-47-7; Pyridoxal, 66-72-8; Pyridoxine, 65-23-6

Calcium absorption in rats with distal intestinal resection: influence of type of dietary fat, cholecalciferol and nature of the adaptative response.

Abstract: The effects of dietary fat and supplementation with cholecalciferol on calcium absorption at different luminal concentrations (2.07 mmol/l and 2.07 mmol/l with 0.5 mmol/l 2,4-dinitrophenol and 8.20 mmol/l) were studied in vivo in the perfused duodenum, residual jejunum and proximal colon of rats with resection of 50% of the distal small intestine, as well as the nature of the adaptative response (passive or active). Changing the source of dietary fat (diet B, containing 1/3 medium chain triglycerides, 1/3 olive oil, 1/3 sunflower oil) increased calcium absorption, preferentially via active transport, in both transected and resected rats. Supplementation of diet B with cholecalciferol further enhanced intestinal calcium absorption, especially in the colon. These results suggest the importance of diet in the adaptive processes and confirm that active mechanisms of transport adapt more readily to intestinal resection than do passive mechanisms.