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.     

Vitamin C Deficiency in a University Teaching Hospital

Objectives: There is almost no information regarding the vitamin C status of patients treated in Canadian and American hospitals. We determined the prevalence and predictors of vitamin C deficiency in patients hospitalized on the acute-care wards of a Canadian teaching hospital, and tracked their plasma vitamin C concentrations while they were there.

Methods: This was a population-based cross-sectional and time course survey of 149 medical patients shortly after admission to a university teaching hospital. The procedure for sample handling, storage and analysis was validated by measuring the vitamin C concentrations of a reference sample of 141 presumably well nourished people and comparing the results with published norms.

Results: In keeping with published norms, 13% of people in the reference group had a subnormal vitamin C concentration (<28.4 μmol/L) and 3% were vitamin C deficient (<11.4 μmol/L). By contrast, 60% of hospitalized patients had a subnormal vitamin C concentration and 19% were deficient. A history of inadequate nutrition or failure to use a vitamin supplement prior to admission, low serum albumin, and male sex predicted plasma vitamin C deficiency, whereas use of a vitamin supplement prior to admission was associated with adequate vitamin C status in hospital. In a second measurement, obtained in 52 patients after an average of 17 days in hospital, vitamin C status had not improved.

Conclusions: Vitamin C deficiency is prevalent and sustained in patients in a Canadian teaching hospital. The abnormality can be prevented by providing a diet sufficient in vitamin C or by prescribing a multiple vitamin tablet.     

Vitamin C attenuates hypochlorite-mediated loss of paraoxonase-1 activity from human plasma

Paraoxonase 1 (PON1) is a cardioprotective enzyme associated with high-density lipoprotein (HDL). We tested the hypothesis that vitamin C protects HDL and PON1 from deleterious effects of hypochlorous acid, a proinflammatory oxidant. In our experiments, HDL (from human plasma) or diluted human plasma was incubated with hypochlorite in either the absence (control) or presence of vitamin C before measuring chemical modification and PON1 activities. Vitamin C minimized chemical modification of HDL, as assessed by lysine modification and accumulation of chloramines. In the absence of vitamin C, chloramines accumulated to 114 ± 4 μmol/L in HDL incubated with a 200-fold molar excess of hypochlorite; but addition of vitamin C (200 μmol/L) limited formation to 36 ± 6 μmol/L (P < .001). In plasma exposed to hypochlorite, IC₅₀ values of 1.2 ± 0.1, 9.5 ± 1.0, and 5.0 ± 0.6 mmol/L were determined for PON1's phosphotriesterase, arylesterase, and (physiologic) lactonase activities, respectively. Vitamin C lessened this inhibitory effect of hypochlorite on PON1 activities. In plasma supplemented with vitamin C (400 μmol/L), PON1 phosphotriesterase activity was 72% ± 17% of normal after incubation with hypochlorite (2 mmol/L), compared with 42% ± 6% for unsupplemented plasma (P < .05). Similar effects were seen for other PON1 activities. In some experiments, vitamin C also appeared to reverse hypochlorite-mediated loss of PON1 phosphotriesterase activity; but this effect was not observed for the other PON1 activities. In conclusion, vitamin C attenuated hypochlorite-mediated loss of PON1 activity in vitro and may, therefore, preserve cardioprotective properties of HDL during inflammation.     

Metabolic origin of hypovitaminosis C in acutely hospitalized patients

ObjectiveRecent studies have indicated a high prevalence of hypovitaminosis C in acutely hospitalized patients. It is unclear whether hypovitaminosis C in this setting represents deficiency or tissue redistribution of the vitamin as part of the acute-phase response.MethodsWe administered vitamin C for 1 wk to acutely hospitalized, but not critically ill patients with hypovitaminosis C, on the assumption that a large increase in plasma and mononuclear leukocyte vitamin C concentrations, a decrease in metabolic markers of oxidative stress, or an improvement in psychologic mood state would implicate the initial condition as nutritional deficiency rather than tissue redistribution.ResultsVitamin C administration increased plasma and mononuclear leukocyte vitamin C concentrations from subnormal (16.3 ± 12.4 μmol/L and 6.5 ± 5.5 mmol/L, respectively) to normal (71.0 ± 30.9 μmol/L, P < 0.0001, and 8.2 ± 6.8 mmol/L, P < 0.015); the mood disturbance score improved by 33% (P < 0.008). There was no increase in plasma glutathione concentrations or a reduction in plasma or mononuclear leukocyte malondialdehyde concentrations. An inverse relation was observed between plasma C-reactive protein and plasma vitamin C concentrations (P = 0.006).ConclusionAlthough associated with systemic inflammation, the metabolic features of hypovitaminosis C in acutely hospitalized, non-critically ill patients are more consistent with deficiency than with tissue redistribution.     

Evidence for Anti-Inflammatory Effects of Combined Administration of Vitamin E and C in Older Persons with Impaired Fasting Glucose: Impact on Insulin Action

Objective: Vitamin E and C given separately improve insulin sensitivity due to an inhibitory effect on oxidative stress and inflammation, however their combined effect on glucose control and inflammation is unknown. To investigate combined effect of Vitamin E and C in elderly with Impaired Fasting Glucose (IFG) on insulin action and substrate oxidation.

Design: Controlled-trial administration of Vitamin E (1000 mg/day) and Vitamin C (1000 UI/day) for four weeks. Hyperinsulinemic euglycemic glucose clamp was performed before and following supplementation.

Setting: Out-patient clinic.

Participants: Thirteen older men with IFG.

Main Outcome Parameters: Variations in whole body glucose disposal (WBGD), anti-oxidant, and inflammatory cytokines plasma levels.

Results: An increase in plasma Vitamin E (8.3 + 0.8 vs. 64.9 + 2.1 μmol/l; p < 0.001] and C (35.9 + 5.4 vs. 79.4 + 7.4 μmol/l; p < 0.001) was found. Vitamin administration reduced insulin, glucose, lipid, TNF-α and [8-]isoprostane levels. Increase in plasma vitamin E levels correlated with decline in both plasma [8-]isoprostane levels (r = ?0.58; p = 0.048) and TNF-α levels (r = ? 0.62; p = 0.025), while no correlations were found for Vitamin C. Whole body glucose disposal (WBGD) (22.7 + 0.6 vs. 30.4 + 0.8 mmol × kg-1 × min-1; p = 0.001) and non-oxidative glucose metabolism rose after supplementation. Rise in plasma levels of Vitamin C and E correlated with WBGD. Multivariate linear regression models showed independent associations among the change in Vitamin E and the decline in TNF-α and [8-]isoprostane levels.

Conclusions: Combined administration of Vitamin E and C lowered inflammation and improved insulin action through a rise in non-oxidative glucose metabolism.     

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.     

Perinatal Vitamin D and Calcium Status of Northern Canadian Mothers and Their Newborn Infants

Objective: This study was undertaken to examine the vitamin D and calcium status of mothers and their newborns.

Methods: The intakes of vitamin D and calcium were determined prenatally in 121 women including 33 Caucasians, 51 Inuits, and 37 Native Indians, living in the Inuvik zone of the Northwest Territories. Plasma concentrations of 25-(OH)-D and calcium were also measured in mothers as well as in their offspring at delivery.

Results: The daily mean vitamin D intake of native mothers, including Inuits and Indians, with (8.1±5.5 μg) and without supplements (3.4±2.5 μg) was significantly lower than that of non-native mothers (13.2±5.9 μg and 5.8±4.3 μg, respectively). According to the predicted prevalence of low vitamin D intake, there existed a higher risk of vitamin D deficiency without supplementation in both native (88.6% vs 48.4%) and non-native (63.5% vs. 15.1%) mothers. The trend for calcium intakes with and without supplementation was similar to vitamin D intake. At the point of delivery, the plasma levels of 25-(OH)-D were lower in native mothers (50.1±19.3 nmol/L) and their offspring (34.2±13.1 nmol/L) than their counterparts (59.8±29.4 nmol/L and 41.4±23.5 nmol/L, respectively). Its plasma levels in newborn infants averaged only 67% of their mothers. None of these infants showed clinical evidence of vitamin D deficiency. In fact, their plasma calcium levels were significantly higher than their mothers.

Conclusions: Plasma 25-(OH)-D concentrations of 60 to 70% of maternal levels may represent a “normal” range for newborn infants. However, a supplementation in native northern Canadian mothers during pregnancy and in their neonates during infancy may have a role to play in the prevention of vitamin D deficiency.     

Vitamin D intake in Australian adults and the modeled effects of milk and breakfast cereal fortification

ObjectiveVitamin D intake from foods or supplements is a safe and attractive means to improve vitamin D status of populations. The aim of this study was to help identify population subgroups that would benefit most from efforts to increase intake. To do so, we investigated which personal characteristics are associated with vitamin D intake in an Australian population and modeled possible effects of expanded food fortification practices.MethodsWe investigated vitamin D intake in a population-based random sample of 785 adults, using a validated food frequency questionnaire, and assessed associations with personal and behavioral characteristics. We identified vitamin D food sources and modeled the hypothetical effects of blanket fortification of milk and breakfast cereals.ResultsAverage total vitamin D intake was 4.4 (±4.0) μg/g and below adequate intake for most participants in all age and sex subgroups. Higher intake was associated with being female, having a serious medical condition, energy intake below the median, and vitamin D supplement use (all P < 0.05). The “meat, fish, and eggs” food group contributed most to total vitamin D intake (51%), followed by dairy products and related foods (43%). If all milk and breakfast cereals were to be fortified with vitamin D, the average intake of vitamin D from foods would increase from 3.6 (±2.4) μg/d to 6.3 (±3.2) μg/d, with similar increases in all age and sex subgroups.ConclusionsVitamin D intake in Australia is generally below recommended levels, and few personal characteristics help to identify subgroups with low intake. Blanket vitamin D fortification of milk and breakfast cereals would substantially increase average vitamin D intake in Australian adults of all ages.     

Vitamin C in Inuit Traditional Food and Women's Diets

Vitamin C values for 37 traditional foods (TFs) of the Inuit of the Canadian Arctic and women's intakes from TF and market food (MF) are reported. This is the first report on vitamin C values in several traditional food samples. There are a variety of rich sources of vitamin C from animal and plant food with the most notable among items with multiple samples being raw fish (Coregonus spp.) eggs (49.6±12.3 mg/100 g, mean± S.D.), raw whale (Delphinapterus leucas and Monodon monoceros) skin, locally termed “mattak”, (36.0±8.7 and 31.5±7.0 mg/10 g), caribou liver (Rangifer tarandus) (23.8±4.9 mg/100 g), ringed seal liver (Phoca hispida) (23.8±3.8 mg/100 g), and blueberries (Vaccinium uliginosum) (26.2±4.9 mg/100 g). Dietary analysis of 20–40-year-old women's 24-h recalls for vitamin C as TF and MF revealed total mean intake of 60±8 mg/day (mean± S.E.). TF contributed only 20% of total intake, although there was significant seasonal variation (P<0.02). While rich sources of vitamin C are present as TF, the primary contemporary dietary sources of this nutrient are fortified MF.     

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.     

Alpha-Tocopherol Distribution in Lipoproteins and Anti-Inflammatory Effects Differ between CHD-Patients and Healthy Subjects

Objective: The purpose of this study was to investigate the dose-dependent effects of RRR-α-tocopherol supplementation in coronary heart disease (CHD) patients and healthy subjects on plasma α-tocopherol levels, plasma lipoprotein distribution, LDL oxidation, and inflammatory plasma markers.

Methods: 12 patients with coronary heart disease and 12 healthy subjects were supplemented with increasing dosages of RRR-α-tocopherol at 100, 200 and 400 mg/day for a period of 3 weeks per dose. Lipoproteins were separated by FPLC and ultracentrifugation. α-Tocopherol was measured by HPLC. Resistance of LDL to oxidation was determined by reading the absorption at 234 nm after CuCl₂-induced oxidation. Clinical chemistry and inflammatory markers were measured on automated analysis systems.

Results: Plasma α-tocopherol concentrations at baseline were comparable between CHD-patients and healthy subjects (21.7 ± 4.7 μmol/L and 25.8 ± 7.6 μmol/L, respectively). CHD-patients showed a significant increase (59%) of plasma α-tocopherol concentrations to 34.6 ± 9.8 μmol/L at a dosage of 100 mg/day RRR-α-tocopherol, whereas healthy subjects showed a significant (54%) increase to 39.7 ± 6.1 μmol/L only with 400 mg/day RRR-α-tocopherol. In addition, CHD-patients showed a significantly increased enrichment of α-tocopherol in VLDL. Supplementation (200 mg/day) caused a significant decrease of the acute phase plasma proteins C-reactive protein (CRP) (?65%) and fibrinogen (?24%).

Conclusion: Our data demonstrate that CHD-patients require lower dosages of α-tocopherol supplementation than healthy subjects to exert biological effects on plasma lipoproteins and acute phase response.     

Multinutrient-Fortified Juices Improve Vitamin D and Vitamin E Status in Children: A Randomized Controlled Trial

BackgroundProvision of fortified juices may provide a convenient method to maintain and increase blood fat-soluble vitamins.ObjectiveTo determine whether children consuming orange juice fortified with calcium and combinations of vitamins D, E, and A could increase serum 25-hydroxyvitamin D [25(OH)D], α-tocopherol, and retinol levels.DesignA 12-week randomized, double-blind, controlled trial.Participants/settingOne hundred eighty participants (aged 8.04±1.42 years) were recruited at Tufts (n=70) and Boston University (n=110) during 2005-2006. Of those recruited, 176 children were randomized into three groups: CaD (700 mg calcium+200 IU vitamin D), CaDEA (700 mg calcium+200 IU vitamin D+12 IU vitamin E+2,000 IU vitamin A as beta carotene), or Ca (700 mg calcium). Children consumed two 240-mL glasses of CaD, CaDEA, or Ca fortified orange juice daily for 12 weeks.Main outcome measuresSerum 25(OH)D, α-tocopherol, and retinol concentrations.Statistical analysesChanges in 25(OH)D, α-tocopherol, retinol, and parathyroid hormone concentrations were examined. Covariates included sex, age, race/ethnicity, body mass index, and baseline 25(OH)D, α-tocopherol, retinol, or parathyroid hormone levels. Multivariate models and repeated measures analysis of variance tested for group differences with pre–post measures (n=141).ResultsBaseline 25(OH)D was 68.4±27.7 nmol/L (27.4±11.10 ng/mL) ), with 21.7% of participants having inadequate 25(OH)D (<50 nmol/L [20.03 ng/mL]). The CaD group's 25(OH)D increase was greater than that of the Ca group (12.7 nmol/L [5.09 ng/mL], 95% CI 1.3 to 24.1; P=0.029). The CaDEA group's increase in α-tocopherol concentration was greater than that in the Ca or CaD groups (3.79 μmol/L [0.16 μg/mL], 95% CI 2.5 to 5.1 and 3.09 μmol/L [0.13 μg/mL], 95% CI −1.8 to 4.3), respectively (P<0.0001). Retinol levels did not change, and body weight remained as expected for growth.ConclusionsDaily consumption of orange juice providing 200 IU vitamin D and 12 IU vitamin E increased 25(OH)D and α-tocopherol concentrations in young children within 12 weeks.     

Time Course of Oxidative Stress Status in the Postprandial and Postabsorptive States in Type 1 Diabetes Mellitus: Relationship to Glucose and Lipid Changes

Objective: The aim of this study was to compare oxidative stress status (OSS) with blood glucose and lipid changes during the fasting, postprandial and postabsorptive phases in type 1 diabetes mellitus.

Methods: Twenty-three patients on intensive insulin treatment received a standard fat-rich breakfast and lunch. OSS was monitored at fasting (F), just after the post-breakfast glycemia peak (BP) (identified by continuous subcutaneous glucose monitoring), 3.5-h post-breakfast (B3.5), just after the post-lunch peak (LP), just after the post-lunch dale (LD) and 5 hours after lunch (L5).

Results: Whereas whole blood glutathione and plasma protein thiols increased in the postprandial period (from 6.52 ± 1.20 (F) to 7.08 ± 1.45 μmol/g Hb (BP), p = 0.005), ascorbate decreased gradually from 44 ± 17 (F) to 39 ± 19 μmol/L (LD), p = 0.015. Retinol and α-tocopherol also decreased from 27.1 ± 7.0 (F) to 25.3 ± 5.2 μmol/L (BP), p = 0.005. Uric acid decreased later, from 213 ± 77 (BP) to 204 ± 68 μmol/L (B3.5), p = 0.01, but then increased in LP (231 ± 70 μmol/L) and LD to values higher than F (215 ± 64, μmol/L, p = 0.01). Malondialdehyde increased gradually from 1.02 ± 0.36 (F) to a maximum of 1.14 ± 0.40 μmol/L (LP). In the postabsorptive phase (L5) all parameters except for thiols reverted to fasting concentrations.

Conclusions: In type 1 diabetes lipid peroxidation increases during the postprandial phase in parallel to glucose and triglyceride changes. Blood antioxidants, however, followed diverse patterns of change.     

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 β-carotene to prevent gastric cancer. We originally randomized the participants into four treatment groups using a 2×2 factorial design, whereby 0 or 15 mg/day β-carotene and 50 or 500 mg/day vitamin C were administered in a double-blind manner. The β-carotene component was terminated early after a mean treatment duration of four months. Before and upon early termination of β-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.     

Potential Antioxidant Effects of Zinc and Chromium Supplementation in People with Type 2 Diabetes Mellitus

Objective: To determine the effects of combined zinc (Zn) and chromium (Cr) supplementation on oxidative stress and glucose homeostasis of people with type 2 diabetes.

Design: Tunisian adult subjects with HbA1C >7.5% were supplemented for 6 months with 30 mg/d of Zn as Zn gluconate or 400 μg/d of Cr as Cr pidolate or combined Zn/Cr supplementation or placebo. The effects of supplementation on plasma zinc (Zn), copper (Cu), selenium (Se), urinary Zn, Cr, plasma thiobarbituric acid reactive substances (TBARS), Cu-Zn superoxide dismutase (SOD) and Se glutathione peroxidase (GPx) in red blood cells, blood lipids and lipoproteins, HbA1C and fasting glucose were measured at the beginning of the study and after six months.

Results: At the beginning of the study, more than 30% of the subjects may have been Zn deficient with plasma Zn values less than 10.7 μmol/L, whereas levels of plasma Cu, Se and antioxidant RBC enzyme activities were in the normal ranges. Following supplementation, there were significant decreases of plasma TBARS in the Cr (13.6%), Zn (13.6%) and Zn/Cr (18.2%) groups with no significant changes in the placebo group. The value for the TBARS of the control healthy Tunisian subjects was 2.08 ± 0.04 μmol/L and that of the Tunisian subjects with diabetes was 3.32 ± 0.05 μmol/L. This difference of 1.24 μmol/L between the control group and the subjects with diabetes was reduced from 36% to 50% in the three supplemented groups. Supplementation did not modify significantly HbA1C nor glucose homeostasis. No adverse effects of Zn supplementation were observed on Cu status, HDL cholesterol nor interactions in Zn or Cr.

Conclusions: These data suggest the potential beneficial antioxidant effects of the individual and combined supplementation of Zn and Cr in people with type 2 DM. These results are particularly important in light of the deleterious consequences of oxidative stress in people with diabetes.     

Prevalence of Undernutrition and Vitamin A Deficiency in the Dogon Region,Mali

Objectives: A representative sample of 1510 preschool children living in the Bandiagra circle (Mopti Region, Mali) was examined between March and April 1997 to determine the level of vitamin A deficiency.

Methods: Using a randomized two level cluster sampling, 20 clusters of 75 children aged six months to six years were selected for evaluating xerophthalmia (XN night blindness and/or X1B Bitot spot). Concurrently stature and weight were determined. A semiquantitative seven-day dietary questionnaire was applied to the mothers of 484 infants to assess consumption of vitamin A rich foodstuffs. The prevalence of biochemical deficiency was attested using the Modified Relative Dose Response test (MRDR) on a sub-sample of 192.

Results: Of the studied children, 4.3% (95% Confidence interval [CI]: 3.2–5.3) reported night blindness and 2% (95% CI: 1.3–2.7) had Bitot spots. Prevalence of xerophthalmia attested by at least one of these signs was 5.4% (95% CI: 4.2–6.5). The prevalence reached 10.5% at three years of age. The MRDR test proved abnormal in 77.1% of the subjects (95% CI: 70.3–82.7). Serum retinol was lower than 0.35 μmol/L in 43.8% (95.6% CI: 36.9–51.3) and less than 0.70 μmol/L in 92.7% of the children (95% CI: 87.8–95.8). Weekly consumption of vitamin A rich food was rare: 75.8% had not eaten any animal vitamin A rich food, and 22.1% had consumed less than seven times a vitamin A rich food of either vegetable or animal origin.

Conclusions: These data define vitamin A deficiency as a severe public health problem in the Bandiagara area of Mali.     

Vitamin/Mineral Supplements and Calcium-Based Antacids Increase Maternal Calcium Intake

Objective: The contributions of over-the-counter (OTC) calcium-based antacid medications and calcium-containing vitamin/mineral supplements to total calcium intake during pregnancy, have rarely been assessed. This study estimates the contributions of calcium-based antacids and vitamin/mineral supplements to maternal calcium intake.

Methods: Over an 8-month period, a cohort of 724 prenatal class attendees (out of a possible 1100 participants) at >28 weeks gestation in Calgary, Alberta, completed an anonymous questionnaire on vitamin/mineral supplement intake and the use of calcium-based antacids. A subset of 264 women completed a self-reported calcium-modified food frequency questionnaire.

Results: The use of prenatal vitamins/minerals increased during pregnancy as did use of the single nutrients calcium and iron. Calcium-based antacids were used by 52% (n = 365) of pregnant women. Median intake of calcium from maternal diet alone was 1619 mg/d (mean intake, 1693 ± 94), which rose to 2084 mg/d (mean intake, 2228 ± 116) when diet, vitamin/mineral supplements, and antacids were considered. From diet alone, 18% had less than adequate intake (AI = 1000 mg/d) of calcium and 12% exceeded the tolerable upper intake level (UL = 2500 mg/d). Adding antacids reduced to 5% those below the AI and increased those surpassing the UL to 33%. No adverse events were reported at calcium intakes above the UL.

Conclusions: Vitamin/mineral supplements and calcium-based antacids increased total maternal calcium intake, resulting in fewer women with intakes < AI but also increasing the number of those with intakes > UL. It is suggested that health care providers discuss all sources of nutrient intake with pregnant clients, as cumulative intakes may unintentionally exceed recommended levels.     

Estimation of Vitamin D Intake Based on a Scenario for Fortification of Dairy Products with Vitamin D in a Tehranian Population,Iran

Objective: The aim of this study was to evaluate possible effects of food fortification practices on vitamin D intake in adults.

Design and setting: This was designed as a cross-sectional, population-based study.

Subjects: We investigated vitamin D intake in a population-based sample of 5224 adults, using a validated food frequency questionnaire. A theoretical model was conducted to evaluate the hypothetical effects of dairy product fortification.

Results: Dairy had the highest mean of vitamin D intake among food groups. If all types of milk were fortified by vitamin D (42 IU/100 grams of milk), the mean intake of vitamin D would reach 132 ± 148 (92(180)) IU/day. If both milk and yogurt were fortified to 42 IU/100 g and 89 IU/100 g, respectively, the average mean vitamin D intake from foods in this population would increase from 84 ± 88 IU/day to 308 ± 240 IU/day. As the fortification level increased, the proportions of young people with more than the recommended daily allowance (RDA) of vitamin D increased from 1.1% to 77.4% in men and from 1.4% to 80% in women, but none of them achieved the tolerable upper intake level (UL) of vitamin D.

Conclusion: The proposed fortification scenario would provide enough vitamin D intakes by RDA in a population aged between 18 and 50 years (about 80% of the population), with none of them achieving ULs.     

Nutritional vitamin A status in northeast Brazilian lactating mothers

Background: Vitamin A deficiency is the major cause of morbidity and mortality among children and in women of reproductive age in developing countries. The present study aimed to assess maternal nutritional vitamin A status, as well as analyse the association of preformed vitamin A and pro‐vitamin A consumption on the nutritional status of nursing mothers, based on serum retinol and retinol colostrum concentrations coupled with dietary intake. Methods: Serum and colostrums were collected from 86 healthy parturients, recruited within 16 h postpartum. Blood samples were obtained, the morning after an overnight fast. Retinol was analysed by high‐performance liquid chromatography. Dietary vitamin A was assessed using a food frequency questionnaire and the women were separated into two groups according to the predominant dietary source of vitamin A: group A, >50% preformed vitamin A (n = 37); and group B >50% pro‐vitamin A carotenoids, (n = 49). Results: Serum retinol and total vitamin A ingestion (mean ± SD) were higher in group A than in group B (1.4 ± 0.4 μmol L^?1 and 2072.0 ± 1465.9 μg retinol activity equivalent (RAE) day^?1 versus 1.2 ± 0.6 μmol L^?1 and 1051.6 ± 920.4 μg RAE day^?1, respectively (P < 0.05), but colostrum retinol (3.4 ± 1.7 μmol L^?1 and 3.6 ± 1.9 μmol L^?1) was similar in both groups. In group B, 36.7% (n = 18) of the nursing mothers presented a risk of developing vitamin A deficiency, based on their dietary intake. Conclusions: On the basis of the intake of the pro‐vitamin A carotenoids, some women may be at risk of vitamin A deficiency. However, their status is currently normal, as indicated by serum and milk retinol concentrations.     

Vitamin A intake affects the contribution of chylomicrons vs. retinol-binding protein to milk vitamin A in lactating rats

To investigate the influence of vitamin A intake on the contribution of chylomicrons vs. holo retinol-binding protein to milk vitamin A, female rats were fed diets containing either 10 (n = 6) or 50 micromol vitamin A/kg body (n = 4) during pregnancy and through d 13 of lactation. [3H]Vitamin A was incorporated into each diet beginning on d 6 of lactation. Vitamin A concentrations on d 13 were significantly higher in dam liver (x 3), pup liver (x 2.6), milk (x 2.5) and mammary tissue (x 1.3) in rats consuming the higher level of vitamin A. In both groups, vitamin A specific activities in plasma and milk reached apparent plateaus by 2.33 d after addition of [3H]vitamin A to the diets. Vitamin A specific activity in milk was higher than in plasma at all times in both groups. The estimated minimum contribution of chylomicrons to milk vitamin A was 32 +/- 3% in rats fed the lower level of vitamin A vs. 52 +/- 10% at the higher level (P = 0.014). We concluded that dietary vitamin A, like triglycerides, may be directed to mammary tissue during lactation for preferential secretion into milk; thus, increasing vitamin A intakes will increase the contribution of dietary vitamin A to milk. In contrast to milk, mammary tissue vitamin A turns over very slowly.