Direct correlation of glutathione and ascorbate and their dependence on age and season in human lymphocytes

BACKGROUND: Endogenous reactive oxygen species appear to contribute to aging and cancer and dietary antioxidants, present in fruit and vegetables, counteract these effects. OBJECTIVE: The objective was to examine the association between intracellular glutathione, ascorbate (vitamin C), and alpha-tocopherol (vitamin E) in human lymphocytes. DESIGN: The study group consisted of 240 healthy nonsmoking volunteers with an approximately equal number of male and female subjects subdivided into 3 age groups: 18-39, 40-59, and >/=60 y). Glutathione, glutathione disulfide, ascorbate, and alpha-tocopherol were measured in lymphocytes by HPLC. RESULTS: The average concentration of antioxidants in lymphocytes was 27 +/- 8 nmol/mg protein for glutathione, 21 +/- 8 nmol/mg protein for ascorbate, and 0.4 +/- 0.2 nmol/mg protein for alpha-tocopherol. There was a strong positive correlation between glutathione and ascorbate (r = 0.62, P < 0.001). No correlation was observed for glutathione and ascorbate with alpha-tocopherol. The concentration of glutathione in lymphocytes was inversely correlated with age (r = -0.19, P < 0.01), as was that of ascorbate (r = -0.22, P < 0.01), with 10-20% lower values in elderly than in young and elderly subjects. The concentrations of glutathione in lymphocytes were as much as 25% higher and those of ascorbate were as much as 38% higher during the summer than during the winter. The seasonal variation of ascorbate in lymphocytes was described by a linear function for age and a periodic sine function for season. CONCLUSION: Glutathione and ascorbate are directly correlated in human lymphocytes.     

Effects of oral vitamin E and beta-carotene supplementation on ultraviolet radiation-induced oxidative stress in human skin

BACKGROUND: Ultraviolet radiation (UVR) generates reactive oxygen species in skin that can play a role in skin damage, but reports about the photoprotective properties of oral antioxidant supplements are conflicting. OBJECTIVE: We examined the ability of 2 lipid-soluble antioxidants, vitamin E and beta-carotene, to reduce markers of oxidative stress and erythema in human skin exposed to UVR. DESIGN: Sixteen healthy subjects took either alpha-tocopherol (n = 8; 400 IU/d) or beta-carotene (n = 8; 15 mg/d) for 8 wk. Biopsy samples before and after supplementation were taken from unexposed skin and skin 6 h after 120 mJ/cm(2) UVR. The effects of supplements on markers of oxidative stress in skin and the minimal erythema dose to UVR were assessed. RESULTS: Supplementary vitamin E was bioavailable, the plasma concentration increased from 14.0 +/- 0.66 (x +/- SEM) to 18.2 +/- 0.64 mug/mL (P < 0.01), and the skin concentration increased from 0.55 +/- 0.09 to 1.6 +/- 0.19 ng/mg protein (P < 0.01). Supplementary beta-carotene increased plasma concentrations from 1 +/- 0.3 to 2.25 +/- 0.3 mug/mL (P < 0.05), but skin concentrations were undetectable. Before vitamin E supplementation, UVR increased the skin malondialdehyde concentration from 0.42 +/- 0.07 to 1.24 +/- 0.16 nmol/mg protein (P < 0.01), whereas oxidized or total glutathione increased from 9.98 +/- 0.4% to 12.0 +/- 1.0% (P < 0.05). Vitamin E supplementation significantly decreased the skin malondialdehyde concentration, but neither vitamin E nor beta-carotene significantly influenced other measures of oxidation in basal or UVR-exposed skin. CONCLUSIONS: Vitamin E or beta-carotene supplementation had no effect on skin sensitivity to UVR. Although vitamin E supplements significantly reduced the skin malondialdehyde concentration, neither supplement affected other measures of UVR-induced oxidative stress in human skin, which suggested no photoprotection of supplementation.     

Effects of supplementation with folic acid and antioxidant vitamins on homocysteine levels and LDL oxidation in coronary patients

Hyperhomocysteinemia is an important cardiovascular risk factor. Serum homocysteine levels are specially dependent on folate nutritional status. In addition, the oxidative modification of low-density lipoproteins (LDLs) in the endothelial microenvironment is a damaging factor that can be modified with fat-soluble antioxidant vitamins. The present study was done to assess the effect of a supplementation of folic acid and antioxidant vitamins on homocysteine levels and in vitro LDL oxidation in patients with coronary artery disease. Twenty-three patients with angiographically proven coronary artery disease were given supplements for 15 d consisting of one capsule twice a day of a multivitamin preparation containing 0.65 mg folic acid, 150 mg alpha-tocopherol, 150 mg ascorbic acid, 12.5 mg beta-carotene, and 0.4 microgram vitamin B12. Serum lipids, vitamin and homocysteine levels, and in vitro LDL oxidation were measured before and after the supplementation period. During the supplementation period, serum folate levels increased from 5.0 +/- 1.5 to 10.8 +/- 3.8 ng/mL (P < 0.001), vitamin B12 increased from 317.4 +/- 130.4 to 334.5 +/- 123.8 pg/mL (P < 0.05), and alpha-tocopherol increased from 8.2 +/- 5.1 to 13.7 +/- 7.9 mg/L (P < 0.001). Serum homocysteine levels decreased from 8.7 +/- 4.3 to 6.3 +/- 2.2 mumol/L (P < 0.001). In vitro LDL oxidation decreased from 2.6 +/- 1.1 to 1.6 +/- 1.1 nmol malondialdehyde/mg protein (P < 0.001). In comparing patients with healthy controls, basal levels of folate were lower in the patients, whereas vitamin B12, alpha-tocopherol, and homocysteine levels were similar. No changes in serum lipid levels or body weight were observed. In conclusion, a short-term supplementation with folic acid and antioxidant vitamins can reduce serum homocysteine levels and in vitro LDL oxidation in patients with coronary artery disease.     

Improved antioxidant and fatty acid status of patients with cystic fibrosis after antioxidant supplementation is linked to improved lung function

BACKGROUND: Oxidative stress, as measured by 8-iso-prostaglandin F(2)(alpha) (8-iso-PGF(2)(alpha)), and depleted antioxidant defenses were shown in stable cystic fibrosis (CF) patients. The plasma fatty acid status of CF patients was linked to oxidative stress after respiratory exacerbations. OBJECTIVE: We examined changes in plasma 8-iso-PGF(2)(alpha), antioxidant defenses, plasma fatty acid status, and clinical markers resulting from short-term antioxidant supplementation. DESIGN: Forty-six CF patients were randomly assigned to either group A [low dose of supplement (10 mg vitamin E and 500 micro g vitamin A)] or group B [high dose of supplement (200 mg vitamin E, 300 mg vitamin C, 25 mg beta-carotene, 90 micro g Se, and 500 micro g vitamin A)]. Plasma concentrations of 8-iso-PGF(2)(alpha), vitamins E and C, beta-carotene, zinc, selenium, and copper; plasma fatty acid composition; erythrocyte glutathione peroxidase (EC 1.11.1.9) and superoxide dismutase (EC 1.15.1.1) activities; lung function; and dietary intake were measured before and after 8 wk of supplementation. RESULTS: Antioxidant defenses in group B improved, whereas those in group A did not: in groups B and A, the mean (+/- SEM) changes (Delta) in vitamin E were 10.6 +/- 1.5 and -1.9 +/- 0.9 micro mol/L, respectively (P < 0.001), (Delta)beta-carotene were 0.1 +/- 0.04 and -0.01 +/- 0.02 micro mol/L, respectively (P = 0.007), (Delta)selenium were 0.51 +/- 0.10 and -0.09 +/- 0.04 micro mol/L, respectively (P < 0.001), and (Delta)glutathione peroxidase activity were 1.3 +/- 0.3 and -0.3 +/- 0.6 U/g hemoglobin, respectively (P = 0.016). There were no significant differences between the groups in Delta8-iso-PGF(2)(alpha), (Delta)vitamin C, (Delta)fatty acid composition, (Delta)superoxide dismutase activity, (Delta)lung function, or (Delta)white cell count. Within group B, (Delta)beta-carotene correlated with (Delta)percentage of forced vital capacity (r = 0.586, P = 0.005), (Delta)selenium correlated with (Delta)percentage of forced expiratory volume in 1 s (r = 0.440, P = 0.046), and (Delta)plasma fatty acid concentrations correlated with (Delta)percentage of forced expiratory volume in 1 s (r = 0.583, P = 0.006) and Delta8-iso-PGF(2)(alpha) (r = 0.538, P = 0.010). CONCLUSIONS: Whereas increased beta-carotene, selenium, and fatty acid concentrations are linked to improved lung function, increased plasma fatty acid concentrations are linked to oxidative stress. If oxidative stress is deemed to be important to the clinical outcome of CF patients, means of reducing oxidative stress while maintaining a high-fat, high-energy diet must be investigated.     

Calcium and vitamin D3 supplements in calcium and vitamin D3 sufficient early postmenopausal healthy women

OBJECTIVE: To study the calcium homeostasis in healthy, calcium and vitamin D replete early postmenopausal women during oral supplementation with calcium and vitamin D3. DESIGN: A prospective, placebo-controlled, randomised, double-single-blind, 3-week study. SETTING: Outpatient clinic at Copenhagen University Hospital, Denmark. SUBJECTS: In all, 17 started, one was excluded. Totally, 16 healthy women, 45-61 y of age (mean 57.3 y) who were at least 4 y after menopause (mean 6.7 y) completed. INTERVENTIONS: All underwent three consecutive 7-day study periods. Each began with 4 days of normal diet followed by 3 days treatment of either C: one tablet of 1.250 mg calcium carbonate (ie 500 mg Ca2+ per tablet) twice daily (breakfast and dinner), or CD3: as in C but plus 400 IU vitamin D3 b.i.d., or P (only) placebo tablets b.i.d. RESULTS: At baseline plasma 25-hydroxycholecalciferol was normal (66+/-22 nmol/l) and the calcium intake without supplements 850 mg/day. In group C, the 24-h urinary calcium increased by 35% (6.9+/-2.0 mmol), vs the placebo group P (5.1+/-1.6 mmol) (P < 0.05). Addition of 800 IU vitamin D3 daily (CD3) did not increase calcium excretion further (6.6+/-2.1 mmol) but decreased plasma 1,25-(OH)2-vitamin D3 by 21% (P < 0.05). CONCLUSIONS: In this carefully controlled study calcium plus vitamin D3 supplements only had minor influences of uncertain significance on the calcium balance in healthy, calcium and vitamin D sufficient early postmenopausal women.     

Oxidative stress in smokers supplemented with vitamin C

The ability of vitamin C supplement to influence lipid peroxidation and pulmonary function tests in healthy smokers was investigated. In this randomized double blind controlled trail, 56 smokers (S) received either 500 mg of vitamin C (C) or placebo (P) daily for 4 weeks. All completed the trial. Both groups were comparable and the number of cigarettes smoked were C: 14.2 +/- 1.8 and P: 18.3 +/- 2.0 pack-years. Plasma vitamin C concentrations increased significantly (p < 0.005) only in the group supplemented with vitamin C. Lipid peroxidation measured by breath pentane output (BPO) (C: 7.5 +/- 1.4 vs P: 7.0 +/- 1.3 pmol.kg-1.min-1) and plasma HPLC-separated malondialdehyde (MDA) (C: 0.58 +/- 0.05 vs P: 0.47 +/- 0.05 nmol.ml-1) were not significantly different between the 2 groups at baseline and did not change after four weeks of vitamin C supplementation (BPO: C: 5.3 +/- 0.9 vs P: 5.5 +/- 0.9 pmol.kg-1.min-1; HPLC-MDA: C: 0.50 +/- 0.07 vs P: 0.42 +/- 0.07 nmol.ml-1). No changes were detected in pulmonary function tests even in heavy smokers. Therefore, 4 week supplementation with 500 mg of vitamin C did not change lipid peroxidation indices and had no effect on pulmonary function tests.     

Do iron and vitamin C co-supplementation influence platelet function or LDL oxidizability in healthy volunteers?

OBJECTIVE: To examine the effect of co-supplementation with iron and vitamin C on antioxidant status, platelet function and low density lipoprotein oxidation in normal healthy volunteers. DESIGN: The study was carried out with two groups of 20 subjects each acting as their own control, comparing presupplemention with postsupplemention. One group was supplemented with iron and the RDA level of vitamin C and the second group with iron and 260 mg/d vitamin C. SETTING: The International Antioxidant Research Centre, The Guy's, King's College and St Thomas's School of Biomedical Science, Guy's Campus, London. SUBJECTS: Forty normal healthy volunteers, recruited from the staff of the Medical School and Hospital in which two volunteers withdrew during the study. INTERVENTIONS: Subjects in both studies were randomly assigned to one of two groups (5 males and 5 females group) and received supplements containing iron (14 mg/d) and either 60 mg/d (Group A) or 260 mg/d (Group B) vitamin C for 12 wk. Blood samples were taken at 6 wk and 12 wk, and prior to supplementation and analysed for iron and antioxidant status (transferrin bound iron, vitamin C and E, and beta-carotene levels) in both studies. Samples from the first study were analysed for the susceptibility of LDL isolated from plasma to Cu2+-induced oxidation and samples from the second for platelet function. RESULTS: Transferrin-bound iron was significantly increased (P < 0.05) at 12 wk, in Group A subjects (from 14.9+/-5.3 micromol/1 to 19.5+/-2.3 micromol/l; mean+/-s.d.; n=19), whereas those in Group B showed a significant increase (P < 0.05) after 6 wk (from 15.8+/-4.5 micromol/l to 20.4+/-6.6 micromol/l; n = 19) which decreased at 12 wk (16.3+/-5.0 micromol/l). Plasma total ascorbate significantly increased from an initial level of 59.3+/-21.3 micromol/l to 87.6+/-29.0 micromol/l after 6 wk and 81.7+/-11.4 micromol/l after 12 wk following the Group B supplementation, but only after 12 wk in Group A (from 64.0+/-24.8 micromol/l to 77.2+/-13.2 micromol/l). Plasma alpha-tocopherol concentrations were significantly increased after 6 wk and 12 wk with both levels of supplementation (from 24.2+/-5.71 micromol/l Group A and 23.4+/-5.3 micromol/l Group B to 26.3+/-5.5 micromol/l and 25.71+/-4.7 micromol/1 respectively at 12wk). The mean lag phase to oxidation of low density lipoprotein (LDL) was significantly increased in subjects in Group B after 12 wk ingestion of iron and 260 mg vitamin C (from 80.0+/-14.8 min to 97.2+/-16.9 min; n = 9). Platelet sensitivity to ADP-induced aggregation was significantly decreased (P < 0.05) by 12 wk in Group A (from EC50 2.3 < or = 1.3 microM to 3.7+/-2.2 microM; n = 10), whereas those receiving higher vitamin C showed a significant decrease (P < 0.05; from EC50 1.9+/-0.6 microM to 3.1+/-1.8 microM) after 6wk which subsequently increased towards presupplemental levels (2.6+/-1.6 microM). Platelets from the latter subjects showed a significant reduction in ADP-induced ATP secretion at both 6wk and 12 wk. CONCLUSION: The results show modest beneficial effects on LDL oxidation and platelet function following supplementation with iron and vitamin C. No evidence for pro-oxidant effects was observed.     

Serum calcidiol and calcitriol concentrations in elderly people: variations with age, sex, season and disease

The influence of age, sex, seasonal variations and vitamin D supplementation on serum concentrations (s-conc.) of calcidiol and calcitriol were studied in 311 hospitalized and 106 home-living people aged 70 years and over, residing at 60 degrees latitude. The serum calcidiol conc. (mean + SD, nmol/L) was reduced in the hospital group compared to the home-living group (males: 40.6 +/- 23.2 compared to 59.6 +/- 28.9; females: 37.3 +/- 22.6 compared to 48.5 +/- 20.3) and showed no seasonal variation. The home-living group showed highest levels in August-September (62.2 +/- 26), and lowest levels in January-March (42.9 +/- 21). Serum calcidiol declined with age, most prominent in the home group (males: r = -0.13, P = 0.036;females: r = -0.33, P = 0.001). A positive correlation was shown between s-calcitriol and s-calcidiol conc. (r = 0.26, P > 0.001). An increased s-conc. of calcidol was present in those with vitamin supplementation (home: 59.9 +/- 26; hospital: 43.4 +/- 22) compared to those without supplementation (home: 46.6 +/- 22; hospital: 36.2 +/- 22), but s-calcidiol conc. did not correlate to nutritional vitamin D intake. Vitamin D deficiency (s-calcidiol conc. < 30 nmol/L) was more common in old people recently admitted to hospital, compared to those living at home. Only the home-living group had the benefit of sunlight exposure, but both groups may benefit from vitamin supplementation.     

Decreasing ascorbate intake does not affect the levels of glutathione, tocopherol or retinol in the ascorbate-requiring osteogenic disorder shionogi rats.

Levels of glutathione in liver and kidney, and other nutrients in plasma were evaluated in male and female ascorbate-requiring osteogenic disorder Shionogi (ODS) rats fed semipurified diets in which the concentrations of ascorbate were gradually decreased from 1965 to 180 mg/kg. Plasma ascorbate levels in ODS rats were unaffected when ascorbate levels in the diet were decreased from 1965 to 768 mg/kg. However, plasma ascorbate levels decreased progressively when levels of ascorbate in the diet were decreased from 527 to 180 mg/kg. Plasma ascorbate levels decreased up to 77% when the dietary ascorbate concentration decreased from 1965 to 180 mg/kg. Ascorbate levels in liver and kidney fell as much as 60-70% when the dietary ascorbate levels were reduced from 1965 to 180 mg/kg. However, the glutathione levels in these tissues were not affected. Plasma retinol and vitamin E levels were not affected by decreasing dietary ascorbate intake. Total cholesterol levels increased significantly in female rats as dietary ascorbate intake declined. Levels of glycated hemoglobin decreased significantly when dietary ascorbate levels decreased from 1965 to 527 mg/kg. This study suggests that levels of vitamin E, retinol and glutathione are not affected by decreased dietary intake of ascorbate under nonscorbutic conditions, whereas elevated ascorbate intake is associated with a decrease in levels of plasma cholesterol in female ODS rats. However, excessive intake of ascorbate may be associated with elevated glycation of hemoglobin. To achieve the maximal health benefit of ascorbate supplementation, further studies are necessary to define optimal ascorbate intakes.     

Soy isoflavone and ascorbic acid supplementation alone or in combination minimally affect plasma lipid peroxides in healthy postmenopausal women

The objective of this study was to assess synergistic antioxidant properties of vitamin C and isoflavones. The design was a placebo-controlled crossover trial: 500 mg vitamin C, 5 mg/kg body weight isoflavones, 500 mg vitamin C plus 5 mg/kg body weight isoflavones, or placebo. Total lipid peroxides, plasma vitamin C, and blood pressure were measured. Eight of 10 healthy postmenopausal women completed the study. A multiple analysis of variance was performed and least-squares difference post-hoc test utilized to determine where differences occurred. Significance was defined as P <.05. There was a significant reduction in total lipid peroxides between baseline and isoflavone treatments (3.22+/-0.72 vs 2.47+/-0.82 nmol/mL, P <.05). Mean systolic blood pressure was higher during isoflavone intervention than placebo (117+/-14 vs 125+/-15 mm Hg, P= .042). Supplementation with vitamin C and isoflavones did not produce a synergistic antioxidant effect. A slight but significant increase in systolic blood pressure occurred with isoflavone supplementation. A larger study should be conducted to fully explore the potential interactions between these antioxidants.     

Vitamin E supplementation decreases basal levels of F(2)-isoprostanes and prostaglandin f(2alpha) in rats

Lipid peroxidation is thought to be an important factor in the pathophysiology of a number of diseases and in the process of aging. We investigated the effects of supplementation with vitamin E on lipid peroxidation in rats. Both free radical-induced nonenzymatic- and cyclooxygenase-catalyzed enzymatic lipid peroxidation were investigated by measuring the levels of F(2)-isoprostanes (8-iso-PGF(2alpha)) and PGF(2alpha)-metabolite (15-K-DH-PGF(2alpha)), respectively, in blood, urine and liver. Samples were collected from control rats (n = 6) and from rats supplemented with vitamin E in the diet for 3 wk (n = 8, 20 g/kg diet of DL-alpha-tocopherol hydrogen succinate). Plasma alpha-tocopherol concentration and antioxidative capacity were greater in the vitamin E-supplemented rats than in the control rats (17.9 +/- 1.7 vs. 50.4 +/- 10.4 micromol/L, P < 0.001 and 181 +/- 6 vs. 275 +/- 27 micromol/L trolox equivalents, P < 0.001). Urine 8-iso-PGF(2alpha) tended to be lower in the vitamin E-supplemented rats (0.72 +/- 0.40 vs. 0.34 +/- 0.19 nmol/mmol creatinine, P = 0.056). Urine 15-K-DH-PGF(2alpha) was lower due to vitamin E supplementation (0.97 +/- 0.38 vs. 0.56 +/- 0. 21 nmol/mmol creatinine, P < 0.05), as was liver-free 8-iso-PGF(2alpha) concentration (0.47 +/- 0.11 vs. 0.18 +/- 0.04 nmol/g, P < 0.001). Supplementation with vitamin E did not affect plasma 8-iso-PGF(2alpha) or 15-K-DH-PGF(2alpha) concentrations, liver total 8-iso-PGF(2alpha) or plasma malondialdehyde levels. Thus, vitamin E supplementation reduced urine basal levels of biomarkers of both nonenzymatic and enzymatic lipid peroxidation. In liver, vitamin E reduced the basal level of free 8-iso-PGF(2alpha) but not total 8-iso-PGF(2alpha).     

A mixed fruit and vegetable concentrate increases plasma antioxidant vitamins and folate and lowers plasma homocysteine in men

Fruit and vegetable consumption is inversely associated with coronary heart disease (CHD) risk. The aim of the present study was to determine the effect of supplementation with dehydrated juice concentrates from mixed fruit and vegetables on selected plasma vitamins and antioxidant status. We assessed CHD risk by measuring the concentrations of homocysteine, lipids, lipoproteins, glucose and insulin. Men were recruited to participate in a randomized double-blind, crossover trial with 2 periods of 6 wk, separated by a 3-wk wash-out period. Supplementation with the encapsulated mixed extract (Juice Plus) was compared with physically similar placebo capsules. Thirty-two men (13 smokers, 19 nonsmokers) completed the study with a mean compliance of 88%. Compared with placebo, supplementation increased the concentrations of plasma beta-carotene (0.24 +/- 0.15 vs. 1.12 +/- 0.70 micro mol/L; mean +/- SD; P < 0.0001), retinol (1.87 +/- 0.33 vs. 2.00 +/- 0.43 micro mol/L; P < 0.05), alpha-tocopherol (16.8 +/- 7.3 vs. 19.3 +/- 6.8 micro mol/L; P < 0.01), ascorbic acid (72.1 +/- 19.4 vs. 84.1 +/- 13.5 micro mol/L; P < 0.002) and folic acid (24.5 +/- 10.0 vs. 44.9 +/- 16.9 nmol/L; P < 0.0001). Plasma homocysteine was reduced (8.2 +/- 1.5 vs. 7.6 +/- 1.1; P < 0.05) and inversely related (r = -0.40, P < 0.001) with serum folate concentrations. Plasma vitamin C was positively correlated with the resistance of LDL to oxidation (r = 0.26, P < 0.05) and the plasma ferric reducing/antioxidant power (FRAP) tended to be greater after supplementation than after the placebo period (1125.5 +/- 144.1 vs. 1180.3 +/- 158.1 micro mol/L; P < 0.065). Plasma glucose, insulin and lipid concentrations were unaffected. Responses of smokers and nonsmokers did not differ. In the absence of dietary modification, supplementation with a fruit and vegetable concentrate produced responses consistent with a reduction in CHD risk.     

Differential response of plasma and immune cell's vitamin E levels to physical activity and antioxidant vitamin supplementation

OBJECTIVE: To assess the differential response of plasma, lymphocyte and neutrophil vitamin E levels to high-intensity physical activity and to vitamin C and E supplementation. SUBJECTS: In all, 14 male trained amateur runners (32-36 y old) were randomly divided in two groups (supplemented and placebo), and participated in a half marathon race. The subjects did not take any other supplements than the ones provided for this study. INTERVENTION: Vitamin C (152 mg/day) and E (50 mg/day) supplementation was administrated to athletes for a month, using a new almond-based isotonic and energetic beverage (supplemented group). The usual dietary habits of participants were assessed using a self-reported 7-day 24-h recall before the day of the study. To avoid the beverage influence, nonenriched vitamin C and E almond-based isotonic and energetic beverage was given to the placebo group. After 1 month, subjects participated in a half marathon race (21 km run). Vitamin E concentration was determined in plasma, neutrophils and lymphocytes before and immediately after the race, and 3 h after finishing the race. RESULTS: Daily energy intake and caloric profile of supplemented and placebo group were not different except for vitamin C and E supplementation. Vitamin supplementation and exercise had no effect on vitamins E levels in plasma. The exercise significantly (P<0.05) increased the lymphocyte vitamin E concentration both in the placebo (+119%) and supplemented groups (+128%), and neutrophil vitamin E content in the supplemented group (+88%). These levels remained significantly (P<0.05) high after the short recovery. After exercise, vitamin E levels in lymphocytes and neutrophils of supplemented subjects were practically twice the levels before exercise, whereas neutrophil vitamin E content of the placebo group was close to those in plasma. CONCLUSION: After endurance exercise, lymphocytes increased their vitamin E content in the supplemented and placebo subjects whereas this trend in neutrophils was just observed in the supplemented group. The determination of vitamin E content in lymphocytes and neutrophils after exercise is a useful tool to assess the functional status of vitamin E.     

Calcium absorption varies within the reference range for serum 25-hydroxyvitamin D

BACKGROUND: Calcium absorption is generally considered to be impaired under conditions of vitamin D deficiency, but the vitamin D status that fully normalizes absorption is not known for humans. OBJECTIVE: To quantify calcium absorption at two levels of vitamin D repletion, using pharmacokinetic methods and commercially marketed calcium supplements. DESIGN: Two experiments performed in the spring of the year, one year apart. In the first, in which participants were pretreated with 25-hydroxyvitamin D (25OHD), mean serum 25OHD concentration was 86.5 nmol/L; and in the other, with no pretreatment, mean serum concentration was 50.2 nmol/L. Participants received 500 mg oral calcium loads as a part of a standard low calcium breakfast. A low calcium lunch was provided at mid-day. Blood was obtained fasting and at frequent intervals for 10 to 12 hours thereafter. METHODS: Relative calcium absorption at the two 25OHD concentrations was estimated from the area under the curve (AUC) for the load-induced increment in serum total calcium. RESULTS: AUC(9) (+/- SEM), was 3.63 mg hr/dL +/- 0.234 in participants pretreated with 25OHD and 2.20 +/- 0.240 in those not pretreated (P < 0.001). In brief, absorption was 65% higher at serum 25OHD levels averaging 86.5 nmol/L than at levels averaging 50 nmol/L (both values within the nominal reference range for this analyte). CONCLUSIONS: Despite the fact that the mean serum 25OHD level in the experiment without supplementation was within the current reference ranges, calcium absorptive performance at 50 nmol/L was significantly reduced relative to that at a mean 25OHD level of 86 nmol/L. Thus, individuals with serum 25-hydroxyvitamin D levels at the low end of the current reference ranges may not be getting the full benefit from their calcium intake. We conclude that the lower end of the current reference range is set too low.     

Hyperhomocysteinemia and vitamin B-12 deficiency in elderly using Title IIIc nutrition services

BACKGROUND: The effect of the folate food fortification program on the prevalence of hyperhomocysteinemia in the older population with coexisting vitamin B-12 deficiency is not known. OBJECTIVE: The objective was to determine the prevalence of hyperhomocysteinemia and vitamin B-12 deficiency in elderly who were using Title IIIc nutrition services, after folate food fortification in the United States. DESIGN: Demographic, nutritional, cognitive, routine diagnostic, and serum methylmalonic acid (MMA) and total homocysteine (tHcy) tests were performed in a convenience sample of 103 elderly enrolled in nutrition service programs in rural northeast Georgia. A subgroup (n = 27) was treated with vitamin B-12, 2.5 mg, and a multivitamin with 400 micro g folic acid, 2 mg vitamin B-6, and 27 mg ferrous fumarate. RESULTS: The total cohort included 103 participants (+/- SD age: 76.4 +/- 8.1; 80% female; 68% white, 32% African American). Vitamin B-12 deficiency (serum vitamin B-12 < 258 pmol/L and MMA > 271 nmol/L) was present in 23%. Mean serum folate was high, 39.3 nmol/L, and no subject had serum folate < 6.8 nmol/L. Mean tHcy was 17.6 +/- 7.2 micro mol/L in vitamin B-12-deficient subjects and 10.8 +/- 3.6 micro mol/L in those who were nondeficient. Determinants of high tHcy were vitamin B-12 deficiency, high serum creatinine, and low red blood cell folate. Those with vitamin B-12 deficiency were more likely to have poor cognition (58% compared with 20%, P < 0.001) and anemia (38% compared with 18%, P = 0.042). High-dose oral B-12 therapy lowered mean MMA and tHcy by 49% and 32%, respectively. CONCLUSION: Vitamin B-12 deficiency was prevalent and was associated with poor cognition, anemia, and hyperhomocysteinemia.     

Riboflavin levels in maternal milk: the influence of vitamin B2 status during the third trimester of pregnancy

OBJECTIVE: The aim of the present investigation was to study the relationship between riboflavin status during the third trimester of pregnancy and levels of this vitamin in transition milk (days 13 to 14 of lactation) and mature milk (day 40 of lactation). METHODS: The pregnancies and lactation periods of 57 healthy women between 18 and 35 years of age (27+/-3.7 years) were monitored, vitamin intake during the third trimester was determined by recording the consumption of foods over five days and by registering the quantities provided by dietary supplements. Riboflavin status during this stage of pregnancy was determined via the measurement of the activation of erythrocyte glutathione reductase (EGR) by flavine adenine dinucleotide (FAD). Milk riboflavin levels were determined by fluorometry. RESULTS: Those subjects with riboflavin intakes below recommended (1.6 mg/day) (Group L) showed lower consumption of milk products (305.2+/-88.5 g/day) than did those with greater intakes (Group H) (507.9+/-137.2 g/day). The consumption of riboflavin containing supplements was very low and was seen only in two H subjects. Transition and mature milk riboflavin levels were significantly higher in H subjects (948.1+/-700.1 nmol/L for transition milk and 993.8+/-436.6 nmol/L for mature milk) than L subjects (574.9+/-258.7 nmol/L for transition milk and 725.4+/-254.3 nmol/L for mature milk). Subjects with alpha-EGR coefficients over 1.2 in the third trimester showed significantly lower mature milk riboflavin levels (704.1+/-241.8 nmol/L) than did subjects with more satisfactory alpha-EGR coefficients (996.4+/-302.9 nmol/L). CONCLUSION: The influence of maternal vitamin B2 status during pregnancy on breast milk riboflavin levels was confirmed.     

Efficacy of daily and monthly high-dose calciferol in vitamin D-deficient nulliparous and lactating women

BACKGROUND: We previously found a high prevalence of vitamin D deficiency and low medication regimen compliance in Arab and East Indian women residing in the United Arab Emirates (UAE). The appropriate dosing regimen for improving vitamin D status in this population is not known. OBJECTIVE: We aimed to determine the efficacy of daily and monthly supplementation with vitamin D2, the only high-dose calciferol available in the UAE, in lactating and nulliparous women. DESIGN: Healthy lactating (n = 90) and nulliparous (n = 88) women were randomly assigned to consume 2000 IU vitamin D2/d or 60,000 IU vitamin D2/mo for 3 mo. Serum 25-hydroxyvitamin D [25(OH)D] concentrations were measured by radioimmunoassay at baseline and every month. RESULTS: Most women had vitamin D deficiency [ie, 25(OH)D < 50 nmol/L] at study entry. Mean +/- SD 25(OH)D concentrations at 3 mo were significantly higher than baseline in both lactating (39.8 +/- 12.4 and 25.2 +/- 10.7 nmol/L, respectively) and nulliparous (40.4 +/- 23.4 and 19.3 +/- 12.2 nmol/L, respectively) women (P < 0.001 for both). In total, vitamin D supplementation was effective in achieving serum 25(OH)D concentrations of >or=50 nmol/L in 21 (30%) of 71 women at endpoint. CONCLUSIONS: Oral vitamin D2 supplementation with 2000 IU/d or 60,000 IU/mo for 3 mo was safe, and it increased serum 25(OH)D concentrations significantly; however, only a small proportion of the women studied achieved concentrations of >or=50 nmol/L. This suggests that, when sunlight exposure is limited, doses of vitamin D2 higher than those currently studied may be needed. Monthly dosing appears to be a safe and effective alternative to daily dosing.     

Does vitamin C supplementation influence the levels of circulating oxidized LDL, sICAM-1, sVCAM-1 and vWF-antigen in healthy male smokers?

OBJECTIVE: To examine the effects of vitamin C supplementation on the concentration of oxidation markers, in particular, circulating oxidized LDL (OxLDL) and on endothelial activation markers. DESIGN: Randomized double-blind, placebo-controlled crossover trial. SETTING: Belgian population of the city of Leuven. SUBJECTS: A total of 34 healthy male smokers aged 26-73 y. INTERVENTION: Smokers were randomly assigned to receive either vitamin C (250 mg twice daily) or placebo capsules, each to be taken for 4 weeks. After a 1-week washout period, participants then crossed over to the alternative capsules for further 4 weeks. MEAN OUTCOME MEASURES: Markers of oxidation (bilirubin, uric acid, alpha-tocopherol, retinol, malondialdehyde, circulating Oxidized LDL (OxLDL)) and markers of endothelial activation (sICAM-1, sVCAM-1, vWF-antigen) were analysed. RESULTS: Plasma ascorbate concentrations significantly increased from 46.6+/-17.6 to 70.1+/-21.2 mumol/l after a 4-week treatment with 500 mg vitamin C per day. The other plasma antioxidants concentrations, including bilirubin, uric acid, alpha-tocopherol and retinol, were similar in both treatment periods. Vitamin C did not change plasma malondialdehyde and circulating OxLDL compared with placebo (vitamin C 0.73+/-0.25 mg/dl OxLDL; placebo 0.72+/-0.21 mg/dl OxLDL). After vitamin C supplementation, neither sICAM-1 and sVCAM-1 levels nor the concentration of vWF-antigen significantly differed from placebo condition. CONCLUSIONS: Oral supplementation of vitamin C is not associated with changes in markers of oxidation or endothelial activation in healthy male smokers.     

Effect of vitamin E supplementation on the vitamin content of lipoprotein in young men and women

The effect of supplementary Vitamin E on the vitamin content of lipoproteins in young men and women. Inappropriate vitamin and trace element supplementation may facilitate the development of atherosclerosis. It is known that Vitamin E protects lipids from oxidative stress, while clinical signs of atherosclerosis appear later in women compared to men. AIMS: (1) The increase of vitamin E in plasma and plasma lipoproteins after 4 weeks of supplementation vitamin E was investigated, (2) furthermore it was tested whether a proportion shift occurs in alpha-tocopherol content of lipoproteins, (3) and checked for gender-related differences in plasma and plasma lipoprotein vitamin E levels before, during and after treatment, (4) plasma CRP levels as a marker of lipid peroxidation were also followed. METHODS: 5-5 young healthy men and women took part in the study, receiving 700 IU/day Vitamin E for one month. Each subject was studied before and at the end of treatment, and also one month after treatment. HDL and LDL-VLDL containing lipoproteins were separated. Vitamin E and hsCRP levels were measured (by HPLC and an immunoturbidimetric method, respectively). RESULTS: Vitamin E treatment induced in both genders an approximately threefold increase in vitamin E concentration in HDL-cholesterol (8.1 +/- 1.7 micromol/l vs. 22.5 +/- 7.5 micromol/l, p < 0.001), and a twofold increase in LDL-VLDL-cholesterol (22.0 +/- 3.7 micromol/l vs. 49.0 +/- 9.0 micromol/l, p < 0.001). Plasma and HDL vitamin E levels were higher in women than in men at the onset of treatment (6.8 +/- 0.96 micromol/l vs. 9.5 +/- 1.10 micromol/l), but during the treatment these gender-related differences disappeared. When plasma vitamin E concentration were considered 100% and the changes of the vitamin E concentrations of lipoproteins were calculated, it was found that supplementation with vitamin E in men increased the vitamin E concentration of LDL-VLDL cholesterol to a higher extent compared to women (LDL-VLDL % in men: 59.8 +/- 7.43%, in women: 49.3 +/- 7.41%, p < 0.05). All the observed changes regressed one month after cessation of supplementation. The level of hsCRP decreased during vitamin E treatment (1.07 +/- 0.9 mg/l vs. 0.2 +/- 0.14 mg/l, p < 0.001), and remained suppressed after the cessation of treatment (0.37 +/- 0.4, p < 0.01). CONCLUSIONS: These results support the hypothesis that women at young age are better protected against lipid-peroxidation as compared to men because of higher HDL vitamin E concentrations. Vitamin E supplementation in men eliminates this concentration difference between genders, and also increases LDL-VLDL vitamin E. In both genders high concentration of vitamin E in lipoproteins was associated with low hsCRP concentration.     

Dietary plasma proteins modulate the immune response of diffuse gut-associated lymphoid tissue in rats challenged with Staphylococcus aureus enterotoxin B

We have previously shown that plasma protein supplementation prevents the activation of lymphocyte populations of Peyer's patches and mesenteric lymph nodes, which is known as organized gut-associated lymphoid tissue (GALT). Here, we examined the effects of spray-dried plasma proteins (SDAP) and Ig concentrate (IgC) supplements on lamina propria and intraepithelial lymphocytes (diffuse GALT) in a model of mild intestinal inflammation induced by the intraperitoneal administration of Staphylococcus aureus enterotoxin B (SEB). Wistar-Lewis rats were fed diets supplemented with SDAP (8% wt:wt), IgC (1.5% wt:wt), or bovine milk proteins (control diet) from weaning (d 21) to d 34 after birth. On d 30 and 33, rats were given SEB (0.5 mg/kg body weight) or PBS (control). Experimental groups were designated control, SEB, SEB-SDAP, and SEB-IgC. Lymphocyte populations were analyzed by immunohistochemistry. In lamina propria, SEB increased the cytotoxic lymphocyte populations of T-gammadelta cells (38%; P < 0.001) and natural killer cells (59%; P < 0.05) and the number of activated T lymphocytes (148%; P < 0.001). Both SDAP and IgC decreased the effects of SEB on these lymphocyte subsets (P < 0.05). In the epithelium, SEB induced a 117% increase in intraepithelial-activated lymphocytes that was reduced by SDAP supplementation (P < 0.01). The effects of plasma supplements on intestinal lymphocyte populations suggest that oral plasma proteins can modulate the degree of activation of diffuse GALT.