The Effect of Vitamin E and Vitamin C Supplementation on LDL Oxidizability and Neutrophil Respiratory Burst in Young Smokers

Objective: The purpose of this study was to determine the effect of vitamin E and/or vitamin C supplementation on low-density lipoprotein (LDL) oxidizability and neutrophil (PMN) superoxide anion production in young smokers.

Methods: Thirty smokers with a <5 pack-year history were randomly assigned to take placebo; vitamin C (1 g/day); vitamin E (400 IU/day); or both vitamins in a double-blind fashion. Subjects took the supplements for 8 weeks. At weeks 0 and 8, blood was collected for isolation of LDL and PMN, and for antioxidant vitamin analysis. LDL was oxidized with a copper (Cu) catalyst, and oxidation was measured by formation of conjugated dienes over a 5-hour time course. Lag times and maximum oxidation rates were calculated from the time course data. PMN superoxide anion release was assessed by respiratory burst after stimulation with phorbol ester and opsonized zymosan, and their ability to oxidize autologous LDL following treatment with the above stimuli was measured with the conjugated diene assay.

Results: Subjects who received vitamin E alone had a significant increase in the lag phase of Cu-catalyzed LDL oxidation (week 0, 118 ± 31 min vs. week 8, 193 ± 80 min, mean ± SD, p < 0.05), whereas the vitamin C and placebo groups had no changes in LDL oxidation kinetics. The group receiving both vitamins E and C had a significant reduction in oxidation rate (week 0, 7.4 ± 2.3 vs. week 8, 5.1 ± 2.1, p < 0.05). There were no significant changes for any group in PMN superoxide anion production or PMN LDL oxidation after stimulation with either phorbol ester or opsonized zymosan. Plasma and LDL vitamin E concentrations were significantly increased in both groups that received vitamin E. The subjects who received vitamin C alone had no significant change in plasma vitamin C concentrations; however, when data were pooled from both groups who received vitamin C, the increases were significant.

Conclusion: Vitamin E supplementation of young smokers was effective in reducing Cu-catalyzed LDL oxidizability; however, vitamin E and/or C supplementation showed few significant effects on the more physiologically relevant PMN function. This casts doubt on the ability of antioxidant supplementation to reduce oxidative stress in smokers in vivo. Therefore, smoking cessation remains the only means by which young smokers can prevent premature coronary heart disease.     

Validity of a diet history questionnaire estimating β-carotene,vitamin C and α-tocopherol intakes in Japanese pregnant women

Abstract

We investigated the validity and reproducibility of a self-administered diet history questionnaire (DHQ) that estimates the intakes of β-carotene, vitamin C and α-tocopherol. Ninety-five healthy women with singleton pregnancies in the second trimester were examined at a university hospital in Tokyo. The intakes of β-carotene, vitamin C and α-tocopherol assessed by the DHQ were compared to the corresponding serum concentrations. To assess the reproducibility, 58 pregnant women completed it in two sessions within a 4–5 week interval. We found significantly positive correlations between the energy-adjusted intakes and serum concentrations of β-carotene and vitamin C (r?=?0.254 and r?=?0.323, respectively). However, α-tocopherol intake was not associated with the corresponding serum concentration. The intraclass correlation coefficients of the two-time DHQ were 0.743 (β-carotene), 0.665 (vitamin C) and 0.718 (α-tocopherol). DHQ has acceptable validity and reproducibility for β-carotene and vitamin C intakes in Japanese pregnant women.     

Effect of five-year supplementation of vitamin C on serum vitamin C concentration and consumption of vegetables and fruits in middle-aged Japanese: a randomized controlled trial

OBJECTIVE: This study was aimed at evaluating the effect of long-term vitamin C supplementation on serum and dietary vitamin C and identifying the factors associated with change in serum concentration. METHODS: A total of 439 subjects with atrophic gastritis initially participated in a randomized clinical trial using vitamin C and beta-carotene to prevent gastric cancer. We originally randomized the participants into four treatment groups using a 2x2 factorial design, whereby 0 or 15 mg/day beta-carotene and 50 or 500 mg/day vitamin C were administered in a double-blind manner. The beta-carotene component was terminated early after a mean treatment duration of four months. Before and upon early termination of beta-carotene supplementation, 134 subjects dropped out this trial, while 120 and 124 subjects took the vitamin C supplement at either 50 mg or 500 mg daily for five years. RESULTS: Changes in serum vitamin C were significantly higher in the high-dose group (38.5% increase, 95% CI = 27.0-49.9) than in the low-dose group (13.0% increase, 5.1-20.9) or in the dropout group (3.3% increase, -2.1-8.6) after five-year supplementation. The serum vitamin C at baseline was negatively associated with changes in serum vitamin C (p < 0.0001), while high-dose (p < 0.0001) and low-dose (p < 0.05) supplementation and female gender (p < 0.001) were positively associated. Dietary intake of vitamin C in the supplementation group was almost identical before and after five-year supplementation of vitamin C (2.31 mg/day decrease, 95% CI = -15.3-10.7), while a 17.7 mg/day decrease (95% CI = -44.2-8.86) was observed in the drop-out group. CONCLUSION: Five-year vitamin C supplementation induces a remarkable increase in serum vitamin C concentration, and our intervention program appears to have no effect on dietary vitamin C intake.     

The Influence of Smoking on Vitamin C Status During the Third Trimester of Pregnancy and on Vitamin C Levels in Maternal Milk

Objective: The aim of the present investigation was to determine the differences in vitamin C status of 57 Spanish women smokers (S) and nonsmokers (N) in their third trimester of pregnancy, and the concentrations of vitamin C in their milk.

Methods: Vitamin C intake during the third trimester was determined by recording the consumption of foods over a 5-day period (including a Sunday) and by registering vitamin C provided by dietary supplements. Vitamin C levels in maternal serum during this stage of pregnancy and in transition (days 13 to 14 of lactation) and mature milk (day 40 of lactation) were determined colorimetrically. Subjects also answered a questionnaire on their smoking habits during pregnancy.

Results: S subjects (n=16) showed a lower intake of fruits, vegetables and vitamin C than did N subjects (n=41), though these differences were not significant (17.1% of N subjects and 31.2% of S subjects took less than 80 mg of vitamin C per day). Neither were any differences found between the two groups in serum vitamin C levels. However, N subjects showed significantly greater vitamin C levels in both transition and mature milk (431.6±296.5 μmol/L and 496.1±325.6 μmol/L, respectively for N subjects, and 233.7±202.9 μmol/L and 241.3±293.1 μmol/L for S subjects). Further investigations are necessary to determine the clinical consequences of these observations, though it is already known that maternal smoking favors peroxidation events in newborn infants.

Conclusions: If the concentration of antioxidants (vitamin C) in smokers’ breast milk is also lower, this might aggravate the peroxidation problems of their newborn.     

Vitamin C Supplementation Slightly Improves Physical Activity Levels and Reduces Cold Incidence in Men with Marginal Vitamin C Status: A Randomized Controlled Trial

The early indications of vitamin C deficiency are unremarkable (fatigue, malaise, depression) and may manifest as a reduced desire to be physically active; moreover, hypovitaminosis C may be associated with increased cold duration and severity. This study examined the impact of vitamin C on physical activity and respiratory tract infections during the peak of the cold season. Healthy non-smoking adult men (18–35 years; BMI < 34 kg/m²; plasma vitamin C < 45 µmol/L) received either 1000 mg of vitamin C daily (n = 15) or placebo (n = 13) in a randomized, double-blind, eight-week trial. All participants completed the Wisconsin Upper Respiratory Symptom Survey-21 daily and the Godin Leisure-Time Exercise Questionnaire weekly. In the final two weeks of the trial, the physical activity score rose modestly for the vitamin C group vs. placebo after adjusting for baseline values: +39.6% (95% CI [−4.5,83.7]; p = 0.10). The number of participants reporting cold episodes was 7 and 11 for the vitamin C and placebo groups respectively during the eight-week trial (RR = 0.55; 95% CI [0.33,0.94]; p = 0.04) and cold duration was reduced 59% in the vitamin C versus placebo groups (−3.2 days; 95% CI [−7.0,0.6]; p = 0.06). These data suggest measurable health advantages associated with vitamin C supplementation in a population with adequate-to-low vitamin C status.     

Body Size and Serum 25 Hydroxy Vitamin D Response to Oral Supplements in Healthy Older Adults

Background: Vitamin D insufficiency is prevalent in the northeast United States. Since vitamin D insufficiency is readily amenable to supplementation, it is important to understand what factors are associated with serum 25 hydroxy vitamin D (25(OH)D) response to vitamin D supplementation.

Objective: In this study we examined the association of serum 25(OH)D response to vitamin D supplementation with body size in a population of elderly subjects.

Methods: 257 healthy, ambulatory men and women 65 years of age or older were randomly assigned to treatment with either 700 IU/day (17.5 μg/d) of supplemental vitamin D₃ and 500 mg/day (12.5 mmol/d) of supplemental calcium, or to placebo.

Results: In multivariate regression analyses, after adjusting for baseline 25(OH)D, season, and sex, we found change in 25(OH)D to be inversely associated with baseline BMI (p = 0.01) in subjects treated with supplements for one year. Change in 25(OH)D was also negatively associated with other baseline anthropometric measurements in these subjects.

Conclusion: Our study implies that body size should be taken into account when estimating the amount of vitamin D intake needed to raise 25(OH)D to the desired level.     

Intakes of Vitamin C,Vegetables and Fruits: Which Schoolchildren Are at Risk?

Objective: The purpose of this study was to determine vitamin C intakes among American schoolchildren. We investigated the leading sources of vitamin C in children’s diets, the leading vegetables and fruits consumed by children and differences in dietary intake associated with vitamin C consumption.

Methods: Data from 1,350 7- to 12-year-old and 908 13- to 18-year-old schoolchildren were obtained from the 1994–1996 Continuing Survey of Food Intakes by Individuals (CSFII). The children were stratified by age and gender and then split into three vitamin C consumption groups based upon two 24-hour recalls: low (0 to 30.0 mg), marginal (30.1 to 59.9 mg), and desirable (>60.0 mg). Data were analyzed by tabulation and by ANOVA followed by post hoc Scheffe’s test. Outcome measures included food groups and energy-adjusted intakes of micro- and macronutrients.

Results: Among the 7- to 12-year-olds, 12% of boys and 13% of girls had mean vitamin C intakes that were less than 30 mg/day, and, among 13- to 18-year-olds, 14% of boys and 20% of girls had low vitamin C intakes. In addition to consuming significantly more vitamin C, children with desirable vitamin C intakes also consumed significantly more (p <0.001) energy-adjusted folate and vitamin B₆; children with low vitamin C intakes tended to have significantly greater (p <0.001) energy-adjusted intakes of fat and saturated fat. Children with desirable vitamin C intakes consumed significantly more (p <0.006) high-vitamin C fruit juice, low-vitamin C vegetables and whole milk. Children with low vitamin C intakes on average consumed two daily servings of vegetables and fruits, of which less than ? of a serving was citrus, while children with desirable vitamin C intakes consumed an average of one daily serving of citrus.

Conclusions: A considerable number of children drastically under-consumed vitamin C and total vegetables and fruits. Overall, children with desirable vitamin C intakes had healthier diets, including more milk and vegetables, than did their peers with low vitamin C intakes. Health care professionals should continue to promote at least five daily servings of vegetables and fruits and should advise parents that at least one of these should be rich in vitamin C.     

Orange Juice Ingestion and Supplemental Vitamin C Are Equally Effective at Reducing Plasma Lipid Peroxidation in Healthy Adult Women

Objective: To directly examine the contribution of vitamin C to the antioxidant potential of fruits and vegetables, the antioxidant effect of orange juice consumption (8 and 16 fl. oz.) was compared to the antioxidant effect of supplemental vitamin C (dosage equivalent to that supplied by 8 fl. oz. of orange juice).

Methods: Subjects (n = 11; 28.6 ± 2.1 years) received each treatment in a 3 × 3 randomized crossover design, and each two-week treatment was preceded by a two-week washout. During the entire trial, subjects restricted fruit and vegetable consumption to ≤3 servings per day except the vitamin C-rich foods (items containing >20 mg/serving), which were restricted to ≤3 servings per week. A fasting blood sample was collected at the end of each washout and each treatment period.

Results: Following washouts, plasma vitamin C and lipid peroxidation (plasma TBARS) were similar by treatment group and averaged 25.4 ± 3.6 μmol/L and 3.82 ± 0.10 nmol/mL respectively. Plasma vitamin C concentrations were similar following each treatment period, 37.9 ± 8.1, 45.8 ± 9.4, and 38.3 ± 12.4 μmol/L for the 8 and 16 fl. oz. orange juice treatments and the supplement treatment, respectively. All intervention treatments reduced plasma TBARS as compared to pretreatment values: ?47% (p = 0.013), ?40% (p = 0.083), and ?46% (p = 0.015) for the 8 and 16 fl. oz. orange juice treatments and supplement treatment respectively.

Conclusions:These data indicate that the regular consumption of 8 fl. oz. orange juice or supplemental vitamin C (～70 mg/day) effectively reduced a marker of lipid peroxidation in plasma.     

The Effect of Vitamin A Supplementation on Thyroid Function in Premenopausal Women

Objective: Vitamin A and its retinoid derivates play an important role in regulation of normal growth and development. Vitamin A has been shown to regulate thyroid hormone metabolism and inhibit thyroid-stimulating hormone (TSH) secretion via down regulation of TSH-β gene expression; however, the effect of vitamin A on thyroid function in obese individuals who are at higher risk of subclinical hypothyroidism is still unclear. In the present study we investigate the impact of vitamin A supplementation on thyroid function in obese women.

Method: A 4-month randomized, double blind controlled trial was conducted among 84 healthy women aged 17–50 years old: 56 were obese (body mass index [BMI] 30–35 kg/m²) and 28 were nonobese (BMI 18.5–24.9 kg/m²). Obese women were randomly allocated to receive either vitamin A (25,000 IU/d retinyl palmitate) or placebo. Nonobese women received vitamin A. At baseline and 4 months after intervention, serum concentrations of TSH, total thyroxine (T4), total triiodothyronine (T3), retinol-binding protein (RBP), and transthyretin (TTR) were measured.

Results: Baseline concentrations of thyroid hormones, RBP and TTR were not significantly different between groups. Vitamin A caused a significant reduction in serum TSH concentrations in obese (p = 0.004) and nonobese (p = 0.001) groups. Serum T3 concentrations also increased in both obese and nonobese vitamin A–treated groups (p < 0.001). Serum T4 decreased in all 3 groups after treatment. The results showed a significant reduction in serum RBP in the obese group after vitamin A supplementation (p = 0.007), but no significant change was seen in serum TTR.

Conclusions: Serum TSH concentrations in vitamin A–treated subjects were significantly reduced; therefore, vitamin A supplementation might reduce the risk of subclinical hypothyroidism in premenopausal women.     

Vitamin A and Zinc Supplementation of Preschool Children

Objective: To determine whether supplementation of vitamin A and/or zinc (Zn) improved serum levels of these nutrients and/or height and weight gains in preschool children, 22 to 66 months, living in Belize, Central America.

Methods: Subjects received either Zn, vitamin A, Zn and vitamin A or a placebo, (70 mg Zn and/or 3030 RE vitamin A, once per week) for 6 months in a 2×2 factorial design. Forty-three children, from a population of 104 prescreened, completed the study; they were selected, prior to treatment, for low/marginal serum concentrations of these micronutrients.

Results: Serum Zn levels were greater (16%, p<0.001) for those who received Zn. In contrast, after vitamin A treatment there were no differences in serum vitamin A among groups. Although increases in height (+4.4 cm, p<0.001) and weight (+0.79 kg, p<0.001), compared with baseline values, were numerically greatest for children who received both supplements, only the vitamin A supplementation effect was significant, resulting in increased height (+1.4 cm, p<0.002) and greater weight gain (+0.15 kg, p<0.03) compared to those receiving no vitamin A. Vitamin A supplementation alone significantly increased (p<0.001) hemoglobin concentration.

Conclusion: The results suggest that the preschool children in this study, prescreened for low/marginal serum concentrations from a larger population prior to treatment, were enduring inadequate vitamin A and, to a lesser degree, Zn nutriture. Height and weight gain were significantly increased in the subjects who received a single weekly supplement 3030 RE of vitamin A.     

Serum concentrations of antioxidant vitamins and carotenoids are low in individuals with a history of attempted suicide

Primary objective: Low consumption of fruits and vegetable has been reported in individuals with psychiatric disorders. We tested the hypothesis that antioxidant vitamins and carotenoids rich in fruits and vegetable may be consequently low among attempters.

Design and methods: As a part of the Third National Health and Nutrition Examination Survey (NHANES III), 1988 – 1994, serum vitamins and carotenoids were measured in 6680 adults aged 17 – 39 years, who also completed a mental disorder diagnostic interview. Serum levels below gender-specific 1st quartile of the population were defined as low, otherwise as normal.

Results: Compared with non-attempters, prevalence ratios (PRs) of low α-carotene, β-cryptoxanthin in attempters were 1.45 (95% CI = 1.06 – 1.98) and 2.12 (1.47 – 3.08), respectively, the mean differences (nonattempter–attempter) of vitamin C, lutein/zeaxanthin and lycopene were 6.071 mmol/l (SE = 1.948, p < 0.005), 0.041 μmol/l (0.015, p < 0.005) and 0.045 μmol/l (0.015, p < 0.005) respectively. Total carotenoid was significantly lower (PR = 2.34 (1.56 – 3.49) and mean difference = 0.142 (0.058) μmol/l). These differences were reduced by adjustment for fruit/vegetables consumption, vitamin supplementation and serum cotinine, but remain significant for β-cryptoxanthin, lycopene and total carotenoids.

Conclusion: A history of attempted suicide is associated with low levels of antioxidant vitamins and carotenoids. Clinical importance of low antioxidants in attempters and interventional opportunity warrant further examination.     

Vitamin D Deficiency and Insufficiency in the Georgia Older Americans Nutrition Program

ABSTRACT

Serum 25-hydroxyvitamin D (25(OH)D) status in older adults enrolled in community-based meal programs is not well characterized. The objective was to identify predictors of poor serum 25(OH)D status and the response to vitamin D supplementation in a convenience sample from the Older Americans Act Nutrition Program (OAANP) in northeast Georgia (N = 158, mean age = 77 years, 81% women, 69% Caucasian, 31% African American). Mean serum 25(OH)D was 55 nmol/l, and intakes of vitamin D and calcium from foods were very low. Vitamin D insufficiency (25(OH)D 25- < 50 nmol/l) occurred in 36.7%. Vitamin D deficiency occurred in 8.2% (25(OH)D < 25 nmol/l) and was associated with low milk intake, low sunlight exposure, receiving meals at home, tobacco use, depression, dementia, antianxiety medication, poor instrumental activities of daily living, and low calf circumference (p ≤ 0.05). When non-supplement users (n = 28) were given a multivitamin with vitamin D (10 µg/d) and calcium (450 mg/d) for 4 months, 25(OH)D increased from 50 to 78 nmol/l, the prevalence of poor vitamin D status (25(OH)D < 50 nmol/l) decreased from 61% to 14%, and serum alkaline phosphatase decreased by 10% (p < 0.01). High body weight appeared to attenuate the increase in 25(OH)D in response to the multivitamin supplement (p ≤ 0.05). In conclusion, OAANP services did not prevent poor vitamin D and calcium status, but a supplement with vitamin D and calcium was beneficial.     

The Effect of a Low Carotenoid Diet on Malondialdehyde-Thiobarbituric Acid (MDA-TBA) Concentrations in Women: A Placebo-Controlled Double-Blind Study

Objective: The purpose of the study was to evaluate the effect of a low carotenoid diet (83 μg β-carotene) on malondialdehyde-thiobarbituric acid (MDA-TBA) concentrations of nine pre-menopausal women.

Methods: Subjects lived on the metabolic research unit of the Western Human Nutrition Research Center (WHNRC), where diet, exercise and other activities were controlled. Five subjects (Group C, control group) consumed a low carotenoid diet and received an additional 0.5 mg/day of β-carotene while four subjects (Group P, placebo group) received only the low carotenoid diet during days 1 to 60 (period 1). All subjects received 0.5 mg/day of β-carotene during days 60 to 100 (period 2), plus three capsules/day mixed carotenoid supplement (Neo-Life Company) during study days 100 to 120. Changes in MDA-TBA concentrations were analyzed during the study periods and between the groups.

Results: At the start of the study (day 1), no significant difference in the MDA-TBA concentration was observed between the control (Group C) and the placebo (Group P) subjects. During period 1 (days 2 to 60), when Group P subjects consumed the low carotenoid diet without supplementation, the MDA-TBA values for Group P rose markedly and were significantly (p<0.05) higher than the MDA-TBA values for Group C subjects who were receiving carotenoid supplementation. During period 2 (days 60 to 100) when both groups received carotenoid supplementation, the MDA-TBA values of Group P subjects were significantly (p<0.05) reduced to the point where they were similar to the MDA-TBA values for Group C subjects.

Conclusions: These findings provide evidence to support the beneficial effects of carotenoids in preventing lipid peroxidation in the cells. Further studies are needed to identify the exact mechanism by which carotenoids prevent lipid peroxidation and the amount needed for normal activity.     

Relation of Serum Ascorbic Acid to Helicobacter pylori Serology in US Adults: the Third National Health and Nutrition Examination Survey

Purpose: To examine the relation between serum ascorbic acid and Helicobacter pylori serology from a probability sample of US adults.

Subjects and Methods: Data from 6,746 adults (ages 20 to 90 years) enrolled in the Third National Health and Nutrition Examination Survey (NHANES III), 1988–1994 were analyzed. Multiple logistic regression models were examined taking into account sample weights and the complex survey design of NHANES III, and controlling for the effects of potential confounders. Because race appeared to modify the association between serum ascorbic acid and seropositivity to H. pylori, we conducted the analyses stratified by race.

Results: A total of 2,189 adults (32%) had a positive serology for H. pylori, and, of these, 1,175 (54%) were positive for the CagA antigen. Among whites, a 0.50 mg/dL increase in serum ascorbic acid level was associated with decreased seroprevalence of H. pylori (Odds Ratio (OR) = 0.89, 95% confidence interval (CI) CI 0.82–0.96, p < 0.01). In analyses that controlled for seroprevalence of H. pylori, a 0.50 mg/dL increase in serum ascorbic acid level among whites was independently associated with a decreased seroprevalence of the pathogenic cagA-positive strain of H. pylori (OR = 0.31, 95% CI 0.12–0.79, p < 0.05). Serum ascorbic acid levels were not significantly associated with H. pylori serology among non-whites (all p > 0.05).

Conclusions: Higher serum levels of ascorbic acid were associated with a decreased seroprevalence of H. pylori and of the pathogenic cagA-positive strain of H. pylori among whites. If these associations are related causally and are not the result of residual confounding by factors such as socioeconomic status, ascorbic acid may affect the risk of H. pylori infection and in turn, the risk for peptic ulcer disease and gastric cancer among white Americans.     

Airway and Circulating Levels of Carotenoids in Asthma and Healthy Controls

Background: Elevated oxidative stress and impaired antioxidant defences are increasingly recognised features of asthma. Carotenoids are potent dietary antioxidants that may protect against asthma by reducing oxidative damage.

Objectives: This study aimed firstly, to characterise circulating and airway levels of carotenoids in asthma compared to healthy controls, in relation to dietary intake. Secondly, the study aimed to test whether airway lycopene defences can be improved using oral supplements.

Methods: Induced sputum and peripheral blood samples were collected from subjects with asthma (n = 15) and healthy controls (n = 16). Dietary carotenoid intakes were estimated using the 24-hour recall method and analysed using a modified version of the Foodworks 210 Nutrient Calculation Software. Another group of healthy controls (n = 9) were supplemented with 20 mg/day lycopene for 4 weeks. Carotenoids (β-carotene, lycopene, α-carotene, β-cryptoxanthin, lutein/zeaxanthin) were measured by HPLC.

Results: Despite similar dietary intake, whole blood levels of total carotenoids, lycopene, lutein, β-cryptoxanthin, α-carotene and β-carotene were significantly lower in asthma than controls. However, there were no differences in plasma or sputum carotenoid levels. Induced sputum carotenoid levels were significantly lower than plasma and whole blood levels, but correlated strongly with plasma levels (r = 0.798, p < 0.001). Although there were no overall increases in either plasma or sputum lycopene levels following supplementation, changes in airway lycopene levels correlated with changes in plasma levels (r = 0.908, p < 0.002).

Conclusions: Whole blood, but not plasma or sputum, carotenoid levels are deficient in asthma. Plasma carotenoid levels reflect airway carotenoid levels and when plasma levels are improved using oral supplements this is reflected in the airways.     

Vitamin E Improves Serum Paraoxonase-1 Activity and Some Metabolic Factors in Patients with Type 2 Diabetes: No Effects on Nitrite/Nitrate Levels

Objective: It is known that markers of oxidative stress and nitrite/nitrate anion (NO_x) increase and activity of antioxidative enzyme paraoxonase-1 decline in type 2 diabetes mellitus (DM). The effects of vitamin E on paraoxonase-1 activity and NO_x in patients with type 2 diabetes are not known. The purpose of this study was to examine the hypothesis that vitamin E supplementation would affect paraoxonase-1 activity, metabolic factors, and NO_x in patients with DM.

Methods: This double-blind, randomized, controlled clinical trial was conducted on 83 patients with DM aged 30–60 years. Forty-two of the subjects had taken 400 IU/day vitamin E and 41 were given placebo over 8 weeks. Fasting blood samples, anthropometric measurements, and dietary intake data were collected at the baseline and at the end of the trial.

Results: Vitamin E significantly increased serum vitamin E level, paraoxonase-1 activity, and total antioxidant status (TAS) and decreased fasting blood sugar (FBS) compared to the control group (p < 0.05). Hemoglobin A1c, serum insulin, and insulin resistance significantly decreased in the vitamin E group compared to baseline values (p < 0.05). Alterations in serum levels of malondialdehyde and NO_x were not significant in any of groups (p > 0.05).

Conclusions: Vitamin E improved serum vitamin E level, paraoxonase-1 activity, TAS, and FBS in patients with type 2 diabetes. Longitudinal studies are warranted to assess the outcome of these results in reducing complications of diabetes in patients with type 2 diabetes.     

Vitamin D Deficiency in Cord Plasma from Multiethnic Subjects Living in the Tropics

Background: Vitamin D deficiency is commonly reported in high-latitude areas and in dark-pigmented individuals. However, nothing is known about vitamin D in cord blood from multiethnic subjects living in the tropics.

Objective: Our study objective was to determine the prevalence of vitamin D deficiency in summer and winter in cord blood from multiethnic individuals in Hawai’i where sufficient sun irradiance occurs year-round for cutaneous vitamin D production.

Methods: 25-Hydroxyvitamin D (25(OH)D) levels were quantified by enzyme immunoassay in 100 cord plasma samples from apparently healthy full-term newborns and their mothers. Stratification was performed by birth season and ethnicity.

Results: Mean 25(OH)D levels were 24.5 ng/mL (9.1–68.3 ng/mL). Overall, 28% of samples were vitamin D deficient (<20 ng/mL) and 50% were insufficient (20–30 ng/mL). 25(OH)D levels (ng/mL) were highest in Caucasians (30.5, n = 19), followed by Asians (25.1, n = 43), Hispanics (21.5, n = 3), Pacific Islanders (20.0, n = 25), and African Americans (19.6, n = 2). Differences among groups were significant (p = 0.008). Cord plasmas from summer versus winter were higher overall (p = 0.001) and among Asians (p = 0.0003). Seasonal changes were correlated with sun irradiance overall (r = 0.43, p = 0.0001), among Caucasians (r = 0.45, p = 0.05), and among Asians (r = 0.45, p = 0.0001).

Conclusion: Our results suggest that prenatal supplement recommendations of 400 IU vitamin D/day do not protect against vitamin D deficiency, even in subjects living in the tropics where ample sun irradiance exists for cutaneous vitamin D synthesis. The high prevalence of vitamin D deficiency we observed emphasizes the necessity for regular 25(OH)D monitoring, particularly during pregnancy and lactation, in dark-pigmented individuals, and during winter months.     

Association between Vitamin D Receptor Polymorphism and Serum Vitamin D Levels in Children with Low-Energy Fractures

Objective: Fractures of bones, especially forearm fractures, are very common in children and their number is increasing. This study was designed to determine the impact of vitamin D serum levels and vitamin D receptor (VDR) polymorphisms on the occurrence of low-energy fractures in children.

Methods: The study group consisted of 100 children with clinically relevant bone fractures and a control group consisted of 127 children without fractures. Total vitamin D [25(OH)D3 plus 25(OH)D2] serum concentrations were evaluated in every patient. Genotypes for 4 restriction fragment length polymorphisms of the vitamin D receptor gene (FokI, ApaI, TaqI, and BsmI) were determined by standard polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) techniques.

Results: Differences in concentrations of vitamin D were observed between the group with bone fractures (median = 12 ng/ml) and the control group (median = 16 ng/ml; p = 0.000044).

Higher levels of vitamin D reduced the risk of fracture by 1.06 times (p = 0.0005). No impact of particular VDR polymorphism on the occurrence of low-energy fractures in children was detected. However, there were significant differences in the prevalence of FokI polymorphism genotypes between the fracture and control groups (p = 0.05). Furthermore, the recessive “aa” genotype of ApaI polymorphism and the dominant “TT” genotype of TaqI polymorphism were associated with higher levels of vitamin D (p = 0.005 and p = 0.036, respectively).

Conclusions: Vitamin D deficiency is an independent risk factor for fractures in children. ApaI polymorphism recessive “aa” and TaqI polymorphism dominant “TT” genotypes are associated with higher levels of vitamin D in serum.     

Vitamin C supplementation decreases oxidative DNA damage in mononuclear blood cells of smokers

Summary. Background: Antioxidants, in particular vitamin C, have been suggested to decrease oxidative DNA damage. Such effects have been shown in mononuclear blood cells in the first few hours after ingestion, whereas studies of longer-term effects in well-nourished humans have been mainly negative. Aim: To investigate the antioxidant effect of vitamin C in terms of oxidative DNA damage measured by the comet assay and DNA repair measured by expression of OGG1 mRNA in blood cells of male smokers given 2 × 250 mg vitamin C daily as plain or slow release tablets combined with plain release vitamin E 2 × 91mg, or placebo for 4 wk. Results: This study showed a difference in DNA protective effects between a slow release and a plain release vitamin C formulation. Ingestion of slow release vitamin C formulation was associated with fewer endonuclease III and formamidopyrimidine DNA glycosylase sensitive sites measured by the comet assay in mononuclear blood cells obtained 4 h and 8 h after a single tablet and 4 wk after two tablets a day. Ingestion of the vitamin formulation with plain release only indicated a damage-reducing effect 4 h after intake of a single tablet, and the effect was more apparent on endonuclease III than formamidopyrimidine DNA glycosylase sites. Overall the slow release tablets of vitamin C formulation had a more pronounced and a sustained protective effect on base damage compared with the plain release tablets. Plasma vitamin E was unaltered in the first 12 h after ingestion of a single tablet, suggesting that the antioxidant effect was mediated by vitamin C. Differences in plasma vitamin C levels at steady state could not explain the difference between the two vitamin C formulations, whereas wider amplitudes of plasma vitamin C were seen after ingestion of plain release formulation compared to slow release formulation. Assessment of OGG1 mRNA levels by RT-PCR did not indicate increased expression of this DNA repair gene after 4 wk of vitamin supplementation. Conclusion: This study suggests that long-term vitamin C supplementation at high dose, i. e. 500 mg together with vitamin E in moderate dose, 182mg, decreases the steady-state level of oxidative DNA damage in mononuclear blood cells of smokers.     

Enhanced Human Neutrophil Vitamin C Status,Chemotaxis and Oxidant Generation Following Dietary Supplementation with Vitamin C-Rich SunGold Kiwifruit

Neutrophils are the body’s primary defenders against invading pathogens. These cells migrate to loci of infection where they engulf micro-organisms and subject them to an array of reactive oxygen species and antimicrobial proteins to effect killing. Spent neutrophils subsequently undergo apoptosis and are cleared by macrophages, thereby resolving the inflammatory episode. Neutrophils contain high concentrations of vitamin C (ascorbate) and this is thought to be essential for their function. This may be one mechanism whereby vitamin C enhances immune function. The aim of our study was to assess the effect of dietary supplementation with vitamin C-rich SunGold kiwifruit on four important functions of neutrophils: chemotaxis, oxidant generation, extracellular trap formation, and apoptosis. Fourteen young men (aged 18–30 years) with suboptimal plasma vitamin C status (<50 μmol/L) were supplemented for four weeks with two SunGold kiwifruit/day. Plasma vitamin C status was monitored weekly and neutrophil vitamin C levels were assessed at baseline and post-intervention. Neutrophil function assays were carried out on cells isolated at baseline and post-intervention. Plasma vitamin C levels increased to >70 μmol/L (p < 0.001) within one week of supplementation and there was a significant increase in neutrophil vitamin C status following four weeks’ intervention (p = 0.016). We observed a significant 20% increase in neutrophil chemotaxis post-intervention (p = 0.041) and also a comparable increase in oxidant generation (p = 0.031). Supplementation did not affect neutrophil extracellular trap formation or spontaneous apoptosis. Our data indicate that supplementation with vitamin C-rich kiwifruit is associated with improvement of important neutrophil functions, which would be expected to translate into enhanced immunity.