Circulating vitamin C and the risk of cardiovascular diseases: A Mendelian randomization study

BACKGROUND AND AIMS

The impact of vitamin C supplementation on the risk of cardiovascular diseases (CVDs) remains uncertain with inconsistent evidence obtained from observational studies and randomized clinical trials (RCTs). We aimed to assess possible causal associations of vitamin C with major CVD events as well as their risk factors using Mendelian randomization (MR) design.

METHODS AND RESULTS

Nine genetic variants associated with vitamin C at genome-wide significance (p < 5 × 10^-8) were used as instrumental variables to predict plasma vitamin C levels. The primary outcomes were coronary artery disease (Ncase = 122,733 and Ncontrol = 424,528), atrial fibrillation (Ncase = 60,620 and Ncontrol = 970,216), heart failure (Ncase = 47,309 and Ncontrol = 930,014), and ischemic stroke (Ncase = 40,585 and Ncontrol = 406,111). Several CVD risk factors were also evaluated in secondary analyses. Two-sample MR analyses were performed using the inverse variance weighted method, with several sensitivity analyses. Genetically determined higher levels of plasma vitamin C were not significantly associated with any of the four examined CVD events. Likewise, there is no convincing evidence for the associations between genetically determined vitamin C and CVD risk factors, including higher blood lipids, higher blood pressure, and abnormal body composition. Sensitivity analyses using different analytical approaches yielded consistent results. Additionally, MR assumptions did not seem to be violated.

CONCLUSION

This MR study does not support a causal protective role to circulate vitamin C levels on various types of CVD events. In combination with previous RCT results, our findings suggest that vitamin C supplementation to increase circulating vitamin C levels may not help in CVD prevention.

Vitamin C Deficiency in the Young Brain-Findings from Experimental Animal Models

Severe and long-term vitamin C deficiency can lead to fatal scurvy, which is fortunately considered rare today. However, a moderate state of vitamin C (vitC) deficiency (hypovitaminosis C)-defined as a plasma concentration below 23 μM-is estimated to affect up to 10% of the population in the Western world, albeit clinical hallmarks in addition to scurvy have not been linked to vitC deficiency. The brain maintains a high vitC content and uniquely high levels during deficiency, supporting vitC's importance in the brain. Actions include both antioxidant and co-factor functions, rendering vitamin C deficiency likely to affect several targets in the brain, and it could be particularly significant during development where a high cellular metabolism and an immature antioxidant system might increase sensitivity. However, investigations of a non-scorbutic state of vitC deficiency and effects on the developing young brain are scarce. This narrative review provides a comprehensive overview of the complex mechanisms that regulate vitC homeostasis in vivo and in the brain in particular. Functions of vitC in the brain and the potential consequences of deficiency during brain development are highlighted, based primarily on findings from experimental animal models. Perspectives for future investigations of vitC are outlined.

Vitamin C in Home Parenteral Nutrition: A Need for Monitoring

To date, there are no recommendations about screening plasma vitamin C concentration and adjust its supplementation in patients on long-term home parenteral nutrition (HPN). The aim of this study was to evaluate vitamin C status and determine if a commercial multivitamin preparation (CMVP) containing 125 mg of vitamin C is sufficient in stable patients on HPN. All clinically stable patients receiving HPN or an intravenous fluid infusion at least two times per week for at least 6 months, hospitalized for nutritional assessment, were retrospectively included, for a total of 186 patients. We found that 29% of the patients had vitamin C insufficiency (i.e., <25 µmol/L). In univariate analysis, C-reactive protein (CRP) (p = 0.002) and intake of only 125 mg of vitamin C (p = 0.001) were negatively associated with vitamin C levels, and duration of follow-up in our referral center (p = 0.009) was positively associated with vitamin C levels. In multivariate analysis, only CRP (p = 0.001) and intake of 125 mg of vitamin C (p < 0.0001) were independently associated with low plasma vitamin C concentration. Patients receiving only CMVP with a low plasma vitamin C level significantly received personal compounded HPN (p = 0.008) and presented an inflammatory syndrome (p = 0.002). Vitamin C insufficiency is frequent in individuals undergoing home parenteral nutrition; therefore, there is a need to monitor plasma vitamin C levels, especially in patients on HPN with an inflammatory syndrome and only on CMVP.

Food Sources and Potential Determinants of Dietary Vitamin C Intake in Chinese Adults: A Cross-Sectional Study

Vitamin C is essential for human health. It is important to estimate the dietary vitamin C intake in the Chinese population to examine the effects of the nutritional transition occurred in recent decades. The present study aimed to estimate the dietary vitamin C intake in Chinese adults by using cross-sectional data from the 2015 China Nutritional Transition Cohort Study and selecting those aged 18–65 years with complete records of sociodemographic characteristics and dietary measurements (n = 11,357). Wilcoxon rank-sum test, Kruskal-Wallis analysis, Chi-squared test, and multiple logistic regression were employed to analyze the daily dietary vitamin C intake on the basis of three-day 24 h dietary recalls and food sources in relation to demographic factors, to evaluate vitamin C intake status using the estimated average requirement cut-off point, and to explore underlying influencing factors. The mean (SD (standard deviation)) and median (interquartile range) levels of the dietary vitamin C intake in adults were 78.1 (54.6) and 65.4 (61.4) mg/day, respectively. Light vegetables, dark vegetables, fruits, and tubers were the top four food sources, contributing a combined 97.3% of total daily dietary vitamin C intake in the study population. The prevalence of risk of insufficient dietary vitamin C intake was 65.1%. Both the distribution of vitamin C intake and the prevalence of risk of insufficient dietary vitamin C intake differed by several demographic factors. Educational level, residence area, geographic location, vegetable consumption, and total energy intake were independent determinants of the risk of insufficient dietary vitamin C intake. In conclusion, dietary vitamin C intake is inadequate in Chinese adult population, and an increase in vitamin C intake should be recommended especially to the population at risk for vitamin C insufficiency.

Plasma concentrations of ascorbic acid in a cross section of the German population

Objectives Vitamin C deficiency is considered extremely rare in modern industrialized countries. This study was performed to assess vitamin C concentrations in the German population. Methods As part of a consultant-patient seminar on nutrition and food intolerances, patients were asked to participate in this study on a voluntary basis. Blood samples were taken for analysis of serum vitamin C concentrations, and all patients were asked to complete a questionnaire. The vitamin C concentration was determined by high-performance liquid chromatography. Results Of approximately 300 patients attending the seminar, 188 (62.6%) consented to vitamin C blood sample analysis and 178 (59.3%) answered the questionnaire. The mean vitamin C concentration was 7.98 mg/L (range, 0.50-17.40; reference range, 5-15 mg/L). A low plasma level with vitamin C insufficiency (<5 mg/L) was found in 31 patients (17.4%), and a potential scorbutogenic deficiency (<1.5 mg/L) was found in 6 (3.3%). Conclusions Potential vitamin C insufficiency and deficiency is common. It is therefore possible, even in modern developed populations, that certain individuals may require a higher intake of vitamin C.

Inadequate Vitamin C Status in Prediabetes and Type 2 Diabetes Mellitus: Associations with Glycaemic Control, Obesity, and Smoking

Vitamin C (ascorbate) is an essential micronutrient in humans, being required for a number of important biological functions via acting as an enzymatic cofactor and reducing agent. There is some evidence to suggest that people with type 2 diabetes mellitus (T2DM) have lower plasma vitamin C concentrations compared to those with normal glucose tolerance (NGT). The aim of this study was to investigate plasma vitamin C concentrations across the glycaemic spectrum and to explore correlations with indices of metabolic health. This is a cross-sectional observational pilot study in adults across the glycaemic spectrum from NGT to T2DM. Demographic and anthropometric data along with information on physical activity were collected and participants were asked to complete a four-day weighed food diary. Venous blood samples were collected and glycaemic indices, plasma vitamin C concentrations, hormone tests, lipid profiles, and high-sensitivity C-reactive protein (hs-CRP) were analysed. A total of 89 participants completed the study, including individuals with NGT (n = 35), prediabetes (n = 25), and T2DM managed by diet alone or on a regimen of Metformin only (n = 29). Plasma vitamin C concentrations were significantly lower in individuals with T2DM compared to those with NGT (41.2 µmol/L versus 57.4 µmol/L, p < 0.05) and a higher proportion of vitamin C deficiency (i.e. <11.0 µmol/L) was observed in both the prediabetes and T2DM groups. The results showed fasting glucose (p = 0.001), BMI (p = 0.001), smoking history (p = 0.003), and dietary vitamin C intake (p = 0.032) to be significant independent predictors of plasma vitamin C concentrations. In conclusion, these results suggest that adults with a history of smoking, prediabetes or T2DM, and/or obesity, have greater vitamin C requirements. Future research is required to investigate whether eating more vitamin C rich foods and/or taking vitamin C supplements may reduce the risk of progression to, and/or complications associated with, T2DM.

Poor Vitamin C Status Late in Pregnancy Is Associated with Increased Risk of Complications in Type 1 Diabetic Women: A Cross-Sectional Study

Vitamin C (vitC) is essential for normal pregnancy and fetal development and poor vitC status has been related to complications of pregnancy. We have previously shown lower vitC status in diabetic women throughout pregnancy compared to that of non-diabetic controls. Here, we evaluate the relationship between vitC status late in diabetic pregnancy in relation to fetal outcome, complications of pregnancy, diabetic characteristics, and glycemic control based on data of 47 women from the same cohort. We found a significant relationship between the maternal vitC level > or ≤ the 50% percentile of 26.6 μmol/L, respectively, and the umbilical cord blood vitC level (mean (SD)): 101.0 μmol/L (16.6) versus 78.5 μmol/L (27.8), p = 0.02; n = 12/16), while no relation to birth weight or Apgar score was observed. Diabetic women with complications of pregnancy had significantly lower vitC levels compared to the women without complications (mean (SD): 24.2 μmol/L (10.6) vs. 34.6 μmol/L (14.4), p = 0.01; n = 19 and 28, respectively) and the subgroup of women (about 28%) characterized by hypovitaminosis C (<23 μmol/L) had an increased relative risk of complications of pregnancy that was 2.4 fold higher than the one found in the group of women with a vitC status above this level (p = 0.02, 95% confidence interval 1.2-4.4). No correlation between diabetic characteristics of the pregnant women and vitC status was observed, while a negative association of maternal vitC with HbA1c at delivery was found at regression analysis (r = -0.39, p < 0.01, n = 46). In conclusion, our results may suggest that hypovitaminosis C in diabetic women is associated with increased risk of complications of pregnancy.

Micronutrient status and its effect on glycaemic indices in type 2 diabetics with foot ulcer in Ibadan, Nigeria

BACKGROUND

Micronutrients are required by organisms in trace concentrations sufficient to maintain homeostasis. Deficiency of these elements could result in different medical and metabolic abnormalities. There are limited data on micronutrient status in type 2 diabetics with foot ulcer (DM+FU). Premised on this, this study investigated micronutrient levels of DM+FU and examined their effects on glycaemic indices.

METHODS

One hundred and twenty participants, comprising seventy DM+FU and fifty non-diabetic participants (controls) aged 40-60 years, were recruited for the study. Ten millilitres of fasting blood samples were collected from each participant after obtaining their consent and levels of vitamin C, vitamin E, copper, selenium, zinc, FPG and HbAlc were measured. The data were analyzed using 't'- test and Pearson's correlation coefficients. Statistical significant was considered at p<0.05.

RESULTS

FPG and HbAlc were significantly higher in DM+FU (12.98±0.43 mmol/l; 8.63±0.24 %) than in controls (5.09±0.08 mmol/l; 4.08±0.11 %). Vitamin C (3.7610.43 vs. 5.57±0.43 ptmol/l; p=0.003), vitamin E (19.57±1.01 vs. 25.57±0.27 pLimol/l; p=0.000) and selenium (0.48±0.01 vs. 0.81±0.04 srmol/l; p=0.000) were substantially lower in DM+FU compared with controls. However, no significant changes were observed when levels of copper and zinc were compared in all participants. Data revealed inverse associations between micronutrients and glycaemic indices (vitamin C/ FPG: (r= 0.250, p=0.037); Cu/HbA Ic: (r= 0.131, p=0.365)).

CONCLUSIONS

Diabetics with foot ulcer were observed to be deficient in selenium, vitamin C and vitamin E. Therefore, type 2 diabetics with foot ulcer should be advised and encouraged to take more of leafy green vegetables and unsweetened fruits.

Vegetable and fruit consumption, education and plasma vitamin C concentration in Russian and Finnish Karelia, 1992-2002

OBJECTIVE

To examine (i) whether the consumption of fresh vegetables, fruit and berries is associated with plasma vitamin C concentration and (ii) educational differences in plasma vitamin C concentration in two neighbouring areas in Russia and Finland.

DESIGN

Cross-sectional risk factor surveys in 1992, 1997 and 2002. Logistic regression analysis was applied to examine the associations of consumption of selected foods and education with plasma vitamin C concentration.

SETTING

District of Pitkäranta in the Republic of Karelia, Russia and North Karelia, Finland.

SUBJECTS

Adults aged 25-64 years: 579 men and 612 women in Pitkäranta; 974 men and 642 women in North Karelia.

RESULTS

The plasma vitamin C concentration was strikingly low in Pitkäranta, Russia across the study years. During the 10 years of monitoring, the mean plasma vitamin C concentration among men ranged from 2·5 to 8·0 μmol/l in Pitkäranta, Russia and from 27·1 to 53·9 μmol/l in North Karelia, Finland. In both areas, daily consumption of fruit was most strongly associated with plasma vitamin C, while the association of fresh vegetable consumption with plasma vitamin C was less consistent. Consumption of berries was less important in explaining plasma vitamin C. In Pitkäranta, the plasma vitamin C concentration was lower among respondents in the lowest education group.

CONCLUSIONS

Differences in the consumption of fresh vegetables and fruit resulted in notable differences in vitamin C status between Pitkäranta and North Karelia in spring. In comparative settings, knowledge of local food culture and validation pilots are important before conducting large population surveys.

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.

Influence of daily diet on ascorbic acid supply to students

BACKGROUND

Researchers suspect that the accepted adequate ascorbic acid plasma concentration is not being met even after dietary intake of the recommended amount of vitamin C. Current dietary intake recommendation in Poland is 60 mg per day for women and 75 mg per day for man (EAR), while in Western Europe and North America is higher and amounts to 75-90 mg per day.

OBJECTIVE

The paper aimed at studying a correlation between composition of nutrients in daily diet and plasma vitamin C levels in university students. Materials and methods. This study examined diet composition and the nutritional status of ascorbic acid in plasma of 120 university students in Szczecin, Poland. Ascorbic acid was determined in blood plasma using HPLC method. The information concerning diet composition was collected using the method of "7-days food record" prior to blood collection.

RESULTS

Plasma ascorbic acid deficiency (<40 μmol/L) was observed in 23% of women and 28% of men. The average plasma ascorbic acid concentration was 48.65 μmol/L in women and 45.61 μmol/L in men. The average intake of vitamin C in women with observed deficiency was average 46.55 mg/day, whereas in men it was 48.56 mg/day.

CONCLUSIONS

The recommendation of dietary intake of vitamin C in Poland is low in comparison to other countries. Population- based studies are necessary to determine the actual demand for vitamin C in various population groups in Poland. Key words: nutrition, vitamins, dietary intake, diet, ascorbic acid, plasma.

Guinea pig ascorbate status predicts tetrahydrobiopterin plasma concentration and oxidation ratio in vivo

Tetrahydrobiopterin (BH₄) is an essential co-factor of nitric oxide synthases and is easily oxidized to dihydrobiopterin (BH₂) which promotes endothelial nitric oxide synthase uncoupling and deleterious superoxide production. Vitamin C has been shown to improve endothelial function by different mechanisms, some involving BH₄. The hypothesis of the present study was that vitamin C status, in particular low levels, influences biopterin redox status in vivo. Like humans, the guinea pig lacks the ability to synthesize vitamin C and was therefore used as model. Seven day old animals (n = 10/group) were given a diet containing 100, 250, 500, 750, 1000, or 1500 ppm vitamin C until euthanasia at age 60-64 days. Blood samples were drawn from the heart and analyzed for ascorbate, dehydroascorbic acid (DHA), BH₄ and BH₂ by high-performance liquid chromatography. Plasma BH₄ levels were found to be significantly lower in animals fed 100 ppm vitamin C compared to all other groups (P < .05 or less). BH₂ levels were not significantly different between groups but the BH₂-to-BH₄ ratio was higher in the group fed 100 ppm vitamin C (P < .001 all cases). Significant positive correlations between BH4 and ascorbate and between BH₂-to-BH₄ ratio and DHA were observed (P < .0001 both cases). Likewise, BH₂-to-BH₄ ratio was negatively correlated with ascorbate (P < .0001) as was BH₄ and DHA (P < .005). In conclusion, the redox status of plasma biopterins, essentially involved in vasodilation, depends on the vitamin C status in vivo. Thus, ingestion of insufficient quantities of vitamin C not only leads to vitamin C deficiency but also to increased BH₄ oxidation which may promote endothelial dysfunction.

Is vitamin C intake too low in dialysis patients?

Vitamin C has several well-established roles in physiology including synthesis of collagen, carnitine and epinephrine, absorption of dietary iron, and mobilization of storage iron for erythropoeisis. Loss of several of these functions explains the pathology of scurvy, where defective collagen synthesis and anemia are major symptoms. Vitamin C deficiency is very common in dialysis patients and may arise from dialytic vitamin C clearance, restricted intake of vitamin C-rich foods, and increased vitamin C catabolism in vivo from inflammation. In the dialysis population, greater vitamin C intake may be needed for optimal health. Relationships between intake, body distribution, inflammation, and dialytic losses are complex and need further study. Concern about vitamin C metabolism leading to accumulation of tissue oxalate has led to the recommendation that vitamin C intake equals, but not exceeds, the intake recommended for the general population. Vitamin C deficiency in dialysis patients may have clinical consequences; a study in Renal Research Institute clinics found an association with periodontal disease. Data also support a role for vitamin C in prevention of dialysis-related anemia. New research questions are proposed in this editorial, with a discussion of strategies to determine the optimal provision of vitamin C for CKD patients.

Vitamin C in sepsis

Bacterial bloodstream infection causes septic syndromes that range from systemic inflammatory response syndrome (SIRS) and encephalopathy to severe sepsis and septic shock. Microvascular dysfunction, comprising impaired capillary blood flow and arteriolar responsiveness, precedes multiple organ failure. Vitamin C (ascorbate) levels are low in critically ill patients. The impact of ascorbate administered orally is moderate because of its limited bioavailability. However, intravenous injection of ascorbate raises plasma and tissue concentrations of the vitamin and may decrease morbidity. In animal models of polymicrobial sepsis, intravenous ascorbate injection restores microvascular function and increases survival. The protection of capillary blood flow and arteriolar responsiveness by ascorbate may be mediated by inhibition of oxidative stress, modulation of intracellular signaling pathways, and maintenance of homeostatic levels of nitric oxide. Ascorbate scavenges reactive oxygen species (ROS) and also inhibits the NADPH oxidase that synthesizes superoxide in microvascular endothelial cells. The resulting changes in redox-sensitive signaling pathways may diminish endothelial expression of inducible nitric oxide synthase (iNOS), tissue factor and adhesion molecules. Ascorbate also regulates nitric oxide concentration by releasing nitric oxide from adducts and by acting through tetrahydrobiopterin (BH4) to stimulate endothelial nitric oxide synthase (eNOS). Therefore, it may be possible to improve microvascular function in sepsis by using intravenous vitamin C as an adjunct therapy.

Low levels of vitamin C in dialysis patients is associated with decreased prealbumin and increased C-reactive protein

BACKGROUND

Subclinical inflammation is a common phenomenon in patients on either continuous ambulatory peritoneal dialysis (CAPD) or maintenance hemodialysis (MHD). We hypothesized that vitamin C had anti-inflammation effect because of its electron offering ability. The current study was designed to test the relationship of plasma vitamin C level and some inflammatory markers.

METHODS

In this cross-sectional study, 284 dialysis patients were recruited, including 117 MHD and 167 CAPD patients. The demographics were recorded. Plasma vitamin C was measured by high-performance liquid chromatography. And we also measured body mass index (BMI, calculated as weight/height(2)), Kt/V, serum albumin, serum prealbumin, high-sensitivity C-reactive protein (hsCRP), ferritin, hemoglobin. The relationships between vitamin C and albumin, pre-albumin and hsCRP levels were tested by Spearman correlation analysis and multiple regression analysis. Patients were classified into three subgroups by vitamin C level according to previous recommendation 12 in MHD and CAPD patients respectively: group A: < 2 ug/ml (< 11.4 umol/l, deficiency), group B: 2-4 ug/ml (11.4-22.8 umol/l, insufficiency) and group C: > 4 ug/ml (> 22.8 umol/l, normal and above).

RESULTS

Patients showed a widely distribution of plasma vitamin C levels in the total 284 dialysis patients. Vitamin C deficiency (< 2 ug/ml) was present in 95(33.45%) and insufficiency (2-4 ug/ml) in 88(30.99%). 73(25.70%) patients had plasma vitamin C levels within normal range (4-14 ug/ml) and 28(9.86%) at higher than normal levels (> 14 ug/ml). The similar proportion of different vitamin C levels was found in both MHD and CAPD groups. Plasma vitamin C level was inversely associated with hsCRP concentration (Spearman r = -0.201, P = 0.001) and positively associated with prealbumin (Spearman r = 0.268, P < 0.001), albumin levels (Spearman r = 0.161, P = 0.007). In multiple linear regression analysis, plasma vitamin C level was inversely associated with log(10)hsCRP (P = 0.048) and positively with prealbumin levels (P = 0.002) adjusted for gender, age, diabetes, modality of dialysis and some other confounding effects.

CONCLUSIONS

The investigation indicates that vitamin C deficiency is common in both MHD patients and CAPD patients. Plasma vitamin C level is positively associated with serum prealbumin level and negatively associated with hsCRP level in both groups. Vitamin C deficiency may play an important role in the increased inflammatory status in dialysis patients. Further studies are needed to determine whether inflammatory status in dialysis patients can be improved by using vitamin C supplements.

Nocturnal haemoglobin oxygen saturation variability is associated with vitamin C deficiency in Tanzanian children with sickle cell anaemia

Aim

To compare pulse oximetry in children with sickle cell anaemia (SCA) and controls and test the hypothesis that vitamin C deficiency (VCD; <11.4 μmol/L) is associated with nocturnal haemoglobin oxygen desaturation in SCA.

Methods

We undertook nocturnal and daytime pulse oximetry in 23 children with SCA (median age 8 years) with known steady-state plasma vitamin C concentrations and 18 siblings (median 7 years).

Results

Median nocturnal delta 12 s index (delta12 s), a measure of haemoglobin oxygen saturation (SpO₂) variability, was 0.38 (interquartile range 0.28–0.51) in SCA and 0.35 (0.23–0.48) in controls, with 9/23 and 6/18, respectively, having a delta12 s >0.4, compatible with obstructive sleep apnoea (OSA). Eleven of twenty-three with SCA had VCD; logged vitamin C concentrations showed a 66% decrease per 0.1 unit increase in delta12 s ([95% CI −86%, −15%]; p = 0.023) and delta12 s >0.4 was associated with VCD (odds ratio 8.75 [1.24–61.7], p = 0.029). Daytime and mean nocturnal SpO₂ were lower in SCA but there was no association with vitamin C.

Conclusion

Obstructive sleep apnoea (OSA), detected from nocturnal haemoglobin oxygen saturation variability, is common in Tanzanian children and associated with vitamin C Deficiency in SCA. The direction of causality could be determined by comparing OSA treatment with vitamin C supplementation.

Vitamin C requirement in surgical patients

PURPOSE OF REVIEW

To summarize recent findings on vitamin C status and assess the requirement and optimal dose of supplementation in surgical patients.

RECENT FINDINGS

Blood vitamin C concentration falls after uncomplicated surgery and further decreases in surgical intensive care unit patients. The decline may be owing to increased demand caused by increased oxidative stress. To normalize plasma vitamin C concentration, much higher doses than the recommended daily allowance or doses recommended in parenteral nutrition guidelines are needed in these patients. In uncomplicated surgical patients, more than 500 mg/day of vitamin C may be required, with much higher doses in surgical intensive care unit patients. In uncomplicated gastrointestinal surgery, continuous parenteral administration of 500 mg/day of vitamin C reduced postoperative oxidative stress as manifested by reduced urinary excretion of isoprostane. In some studies, postoperative atrial fibrillation was prevented after cardiac surgery by perioperative vitamin C supplementation. In critically ill patients, some prospective randomized controlled trials support parenteral supplementation of high doses of vitamin C, E and trace elements.

SUMMARY

Vitamin C requirement is increased in surgical patients, and the potential advantage of supplementation is to increase the plasma and tissue levels of vitamin C and thereby reduce oxidative stress. Although some clinical benefits of high-dose vitamin C supplementation have been shown in the critically ill, the optimal dose for supplementation and the clinical benefits remain to be investigated in surgical patients.

A delayed response to acute stimulation with human chorionic gonadotropin in scorbutic rats

Since our previous study revealed low basal testosterone (T) levels and a failure in response to an acute stimulation with human chorionic gonadotropin (HCG) despite of a good response to chronic stimulation in scorbutic mutant rats, time course of the response to HCG was studied and plasma LH level was measured in young adult rats deficient in ascorbic acid for 3 weeks. A single subcutaneous injection of HCG (200 IU) elevated T levels only slightly in plasma and not in testicular tissues of scorbutic rats 1 h after the injection when the levels in ascorbutic rats reached a maximum, while it yielded the same response pattern as in ascorbutic rats after 3 h. A pretreatment with HCG to scorbutic rats for 1 or 4 days resulted in the same response of plasma T as in ascorbutic rats. Plasma LH levels in unstimulated scorbutic rats were about 40% of those in ascorbutic rats. These findings indicate that a prolonged deficiency of ascorbic acid decreases plasma LH, and may reduce the sensitivity of testes to LH.

Collagen-related abnormalities, reduction in bone quality, and effects of menatetrenone in rats with a congenital ascorbic acid deficiency

In this study, we focused on collagen metabolism as a factor involved in menatetrenone (MK-4)-related improvement in bone quality. Using rats with a congenital ascorbic acid (AA) deficiency, osteogenic disorder Shionogi (ODS) rats, we established a model in which abnormal collagen metabolism reduced bone mechanical properties, and investigated the effects of MK-4. We divided 13-week-old ODS rats into four groups: Pre, AA sufficiency (AA(+)), AA deficiency-control (AA(-)control), and AA deficiency+ MK-4-treated (AA(-)MK-4). MK-4 was given as a dietary supplement (30 mg/kg). At the beginning (pre) and after two, three, and four weeks, seven rats in each group were killed to measure plasma bone metabolism and femoral bone mass data and bone mechanical properties. In the rats killed after four weeks, histomorphometric data of the tibiae, the total amino acid level in bone collagen, and rates of proline and lysine hydroxylation were determined. In the AA(+)group, both the cortical bone mass data and bone mechanical properties were serially increased. However, in the AA(-)control group, the cortical bone mass data were similar for four weeks and the bone mechanical properties decreased after three to four weeks. After four weeks, the total level of amino acids in bone collagen and rates of proline and lysine hydroxylation were significantly lower in the AA(-)control group than in the AA(+)group. MK-4 increased bone mechanical properties after four weeks without influencing cortical bone mass. Simultaneously, it inhibited decreases in the total level of amino acids in collagen (P = 0.017). The rates of proline and lysine hydroxylation were higher in the AA(-)MK-4 group than in the AA(-)control group, but not significantly. These results suggest the level of collagen and abnormalities of hydroxylation are involved in the AA deficiency-related reduction in bone mechanical properties, and that MK-4 improves bone mechanical properties by restoring collagen metabolism.

Déficit en vitamine C et ulcères de jambe. Résultats d'une enquête cas témoins

Vitamin C is a necessary cofactor for collagen synthesis. A deficiency of vitamin C results in the breakdown of connective tissue in and around the walls of blood vessels. The disease is thus characterized by poor healing of wounds. Chronic leg ulcers are defined as wounds that do not heal.

OBJECTIVE

To investigate whether patients with chronic leg ulcers have vitamin C deficiency.

METHODS

Case control study; vitamin C was assayed in peripheral blood samples of 42 consecutive patients with chronic leg ulcers and in 37 consecutive patients without chronic leg ulcers. Patients without leg ulcers had peripheral vascular disease, or hypertension, or connective disorders. Patients with diabetes, immunodepression (cancer, HIV infection, corticosteroid therapy) and aged under 65 years were excluded. Reference range for plasma vitamin C was above 26 micromol/l (normal levels, group I), hypovitaminosis C as 6-26 micromol/l (group II) and concentrations<6 micromol/l as scurvy (group III).

RESULTS

Mean age was 77.2 years in the ulcers group and 73.8 in the control group (NS), mean weight 73.1 kg in the ulcers group and 67.5 kg in the control group (NS). Smoking was more frequent in the control group (P<0.001). Mean vitamin C levels were lower in the leg ulcers group: 23.9 vs 33.8 micromol/l (P<0.003). Normal levels of vitamin C (group I) were more frequent in the control group: 78.4 vs 50% (P<0.01). Hypovitaminosis C (group II) was more frequent in the leg ulcers group: 23.8 vs 16.2% (P<0.01). Scurvy was more frequent in the leg ulcers group: 26.2 vs 5.4% (P<0.01). C reactive protein levels were higher in the leg ulcers group: 31.8 vs 9.3 mg (P=0.002) and albumin levels were lower in the leg ulcers group: 25 vs 38 g/l (P=0.01) [retrospective data].

CONCLUSION

Patients with chronic leg ulcers have lower levels of vitamin C than patients without leg ulcers, although smoking was more frequent in patients without leg ulcers. The question is whether vitamin C deficiency is a cofactor of impaired healing or is a simple marker of poor healing? It would be interesting to conduct a randomized controlled study about treatment of chronic leg ulcers with vitamin C.

Distribution of Anemia Associated with Micronutrient Deficiencies Other than Iron in a Probabilistic Sample of Mexican Children

BACKGROUND

This investigation aims to explore the association among anemia and vitamins A, C, and folate deficiencies in a probabilistic sample of Mexican children.

METHODS

Data on hemoglobin, serum vitamins A and C and folate concentrations and percent transferrin saturation (PTS) in children 0.5-11 years (n = 1,770) were extracted from the database of the probabilistic Mexican National Nutrition Survey 1999 (NNS-99).

RESULTS

Overall, 16.6% of children were anemic. Iron deficiency children with or without anemia had more frequent low serum retinol (40.6 vs. 16% and 27.7 vs. 11.9%, p < 0.05, respectively) and lower hemoglobin folate (11.5 vs. 22%, p < 0.05) than their non-iron deficiency counterparts. Mean concentrations of serum iron (p < 0.01), folate (p < 0.001) and retinol (p < 0.0001), but not ascorbic acid (p < 0.6), were significantly lower in anemic than in nonanemic children. In a linear regression model, 15% of hemoglobin variation in children was explained by retinol, folate and PTS, but not vitamin C (p <0.0001).

CONCLUSION

Anemia was mostly associated with iron deficiency and with a lesser proportion of folate and vitamin A deficiencies. Vitamin A deficiency might be overestimated since iron deficiency may lower serum retinol concentrations. Interventions aimed to reduce anemia in this population must consider interactions between those micronutrients in designing strategies.

The effect of intravenous iron on oxidative stress in hemodialysis patients at various levels of vitamin C

BACKGROUND/AIMS

Vitamin C levels decrease during hemodialysis (HD), which deteriorates antioxidant defense. Vitamin C may also act pro-oxidatively, via reduction in Fe(III). We sought to determine whether intravenous iron (Fe(iv))-induced oxidative stress differs in HD patients with low and physiological vitamin C levels and whether intravenous vitamin C (C(iv)) administration during HD would change the response to Fe(iv).

PATIENTS AND METHODS

Twenty patients with vitamin C deficiency (median 15.7 micromol/l, range 8.0-22.7) received Fe(iv) (100 mg iron sucrose between 150 and 180 min of HD). After 4 weeks of oral supplementation, the levels of vitamin C were comparable with those of controls (60.1 micromol/l, range 47.4-70.9). Patients were subsequently treated with (1) Fe(iv), (2) Fe(iv) and continuous 2 mg/min C(iv) throughout HD, (3) saline (S), and (4) S+C(iv). Plasma thiobarbituric acid reacting substances (TBARS) and vitamin C were assessed before, during and after FE(iv)(S), and 15, 30 and 60 min after infusion.

RESULTS

Fe(iv) induced a comparable rise in TBARS in patients with vitamin C deficiency (before Fe(iv), 1.9 micromol/l, range 1.4-1.9; after Fe(iv), 2.6 micromol/l, range 2.3-2.9; p < 0.01) and in those with normal vitamin C (before Fe(iv), 1.9 micromol/l, range 1.7-2.1; after Fe(iv), 2.6 micromol/l, range 2.5-2.9; p < 0.01). Fe(iv)+C(iv) resulted in a greater increase in TBARS (after Fe(iv), 3.1 micromol/l, range 2.8-3.2) compared with Fe(iv) (p < 0.01).

CONCLUSION

Iron sucrose-induced oxidative stress is comparable in HD patients with vitamin C deficiency and in those with normal vitamin C. We documented a pro-oxidative effect of vitamin C during Fe(iv)+C(iv) administration.

Vitamin C status in cancer patients and healthy subjects from the local population of Pokhara

OBJECTIVES

To assess vitamin C status by determining plasma ascorbic acid level in 55 cancer patients and 55 matched normal subjects serving as control.

METHODS

The proven cancer patients were selected from those attending Manipal Teaching Hospital, Pokhara. Matched controls were from the staff of Manipal Teaching Hospital or attendants of the patients. Plasma ascorbic acid was determined by the method of Natelson. Unpaired student 't' test was used for the statistical evaluation. Statistical analysis was done by SPSS version 9 software.

RESULTS

The mean level of vitamin C in normal subjects and patients was 1.03+/-0.26 mg/dl and 0.90+/-0.30 mg/dl respectively. None of the subjects in either group had deficient status (<0.2 mg/dl). Although its status was normal in both the groups but patients had lower level than normal subjects. Smokers and alcohol consumers had significantly lower level than non-smoker and non-alcoholics.

CONCLUSION

In the local population, vitamin C deficiency is not an etiologic factor in malignancy. Smoking and alcohol adversely affects the status of this vitamin.

Is sudden death with vitamin C deficiency caused by lack of carnitine?

We investigated the effect of carnitine supplementation during vitamin C (ASC) deficiency by measuring the levels of ASC and carnitine in plasma and cardiac muscle cells (CMC), and histological analysis with electron microscopy. The levels of carnitine were significantly decreased in ASC-deficient rats in plasma and the heart than those in the control. In carnitine supplemented ASC-deficient rats, a significant increase of carnitine levels were observed in both plasma and heart. The number of lipid droplets significantly increased in the ASC-deficient rats compared to the control rats, but did not increase in carnitine supplemented rats. These results indicate that ASC deficiency causes a generalized mitochondrial abnormality and accumulation of lipid droplets in CMC as observed in carnitine deficiency, and supplementation of carnitine prevented these changes even in the presence of ASC deficiency.

Ascorbic acid deficiency, iron overload and alcohol abuse underlie the severe osteoporosis in black African patients with hip fractures--a bone histomorphometric study

Osteoporosis and femoral neck fractures (FNF) are uncommon in black Africans although osteoporosis accompanying iron overload (from traditional beer brewed in iron containers) associated with ascorbic acid deficiency (oxidative catabolism by iron) has been described from sub-Saharan Africa. This study describes histomorphometric findings of iliac crest bone biopsies and serum biochemical markers of iron overload and of alcohol abuse and ascorbic acid levels in 50 black patients with FNFs (29 M, 21 F), age 62 years (40-95) years (median [min-max]), and in age- and gender-matched black controls. We found evidence of iron overload in 88% of patients and elevated markers of alcohol abuse in 72%. Significant correlations between markers of iron overload and of alcohol abuse reflect a close association between the two toxins. Patients had higher levels of iron markers, i.e., siderin deposits in bone marrow (P < 0.0001), chemical non-heme bone iron (P = 0.012), and serum ferritin (P = 0.017) than controls did. Leukocyte ascorbic acid levels were lower (P = 0.0008) than in controls. The alcohol marker mean red blood cell volume was elevated (P = 0.002) but not liver enzymes or uric acid. Bone volume, trabecular thickness, and trabecular number were lower, and trabecular separation was greater in patients than in controls, all at P < 0.0005; volume, surface, and thickness of osteoid were lower and eroded surface was greater, all at P < 0.0001. There was no osteomalacia. Ascorbic acid deficiency accounted significantly for decrease in bone volume and trabecular number, and increase in trabecular separation, osteoid surface, and eroded surface; iron overload accounted for a reduction in mineral apposition rate. Alcohol markers correlated negatively with osteoblast surface and positively with eroded surface. Relative to reported data in white FNF patients, the osteoporosis was more severe, showed lower osteoid variables and greater eroded surface; FNFs occurred 12 years earlier and were more common among men. We conclude that the osteoporosis underlying FNFs in black Africans is severe, with marked uncoupling of resorption and formation in favor of resorption. All three factors--ascorbic acid deficiency, iron overload, and alcohol abuse--contributed to the osteoporosis, in that order.

Comparison of plasma and leukocyte vitamin C status between asthmatic and healthy subjects

In a case-control study the vitamin C status of 50 adults with chronic controlled asthma was compared with that of 50 randomly selected healthy controls. Vitamin C intake was assessed by 3-day dietary recall, and plasma and leukocyte vitamin C concentrations were measured colorimetrically. A positive significant correlation was found between plasma vitamin C and dietary vitamin C intake. Plasma and leukocyte vitamin C levels were significantly lower in the asthma group. Plasma vitamin C was deficient (< 0.4 mg/dL) in significantly more patients than controls (38.0% versus 0%) and leukocyte vitamin C (< 20 microg/10(8) leukocytes) was deficient in 92.0% of asthmatics versus 8.0% of controls. A significant association was observed between duration of asthma and plasma vitamin C level.

Vitamin C deficiency in cancer patients

PURPOSE

To assess the prevalence of vitamin C deficiency within a group of hospice patients. To assess the relationship between plasma vitamin C, dietary intake and subsequent survival.

METHODS

Patients with advanced cancer were recruited from a large hospice. Data were collected on demographic details, physical functioning and smoking history. An estimate was obtained of the number of weekly dietary portions consumed equivalent to 40 mg of vitamin C, the recommended daily intake. Plasma vitamin C was measured by a single blood sample. The study had local ethical approval.

RESULTS

Fifty patients were recruited (mean age 65.2 years, 28 female). Plasma vitamin C deficiency was found in 15 (30%). Dietary intake of vitamin C was correlated to plasma vitamin C (r=0.518, P<0.0001). Low dietary intake, low albumin, high platelet count, high CRP level and shorter survival were all significantly associated with low plasma vitamin C concentrations (<11 micromol/L). There was no correlation between plasma vitamin C, smoking history or physical functioning.

CONCLUSION

Vitamin C deficiency is common in patients with advanced cancer and the most important factors determining plasma levels are dietary intake and markers of the inflammatory response. Patients with low plasma concentrations of vitamin C have a shorter survival.

Elevated blood histamine caused by vaccinations and Vitamin C deficiency may mimic the shaken baby syndrome

The findings of subdural hematoma and retinal hemorrhages in infants, without any documented history of major trauma, do not always indicate child abuse. A combination of ascorbate depletion and the injection of foreign proteins can cause a very high blood histamine level, leading to capillary fragility and venular bleeding. This can be prevented by the administration of vitamin C.

Possible participation of outer mitochondrial membrane cytonchrome B5 in steroidogenesis in zona glomerulosa of rat adrenal cortex

Outer mitochondrial membrane cytochrome b5 (OMb) originally found in rat liver is an isoform of cytochrome b5 (b5) of the endoplasmic reticulum. In contrast to accumulated data on the physiological roles of b5, functions of OMb have not been well characterized except for its involvement in regeneration of ascorbic acid [i.e., in a semidehydroascorbate reductase (SDAR) system]. By using highly specific antibodies against rat OMb, we found immunohistochemically that OMb in the rat adrenal gland was most abundant in the zona glomerulosa (zG) among the three cortical zones, and the expression level was enhanced on angiotensin II-stimulation. SDAR activity was found in zG and inhibited by anti-OMb antibody. Moreover, the increase in plasma aldosterone concentration under Na+ -deficiency was suppressed by limited ascorbic acid (Asc) availability in rat mutants unable to synthesize Asc, while plasma corticosterone concentration was not affected. These data suggest that OMb, present abundantly in zG, participates in aldosterone formation in zG of rat under angiotensin II-stimulation through regeneration of Asc.

Antioxidant deficiency in cystic fibrosis: when is the right time to take action?

BACKGROUND

Little is known about age- and disease-related changes in prooxidant and antioxidant systems in patients with cystic fibrosis (CF).

OBJECTIVE

We investigated changes in antioxidant concentrations and oxidative stress in plasma, buccal mucosal cells (BMCs), and breath condensate in patients with CF in relation to age and disease progression.

DESIGN

We recruited 22 patients with CF as well as 35 healthy control subjects and conducted a cross-sectional study by dividing the participants into 4 age groups (<6 y, 6-11 y, 12-17 y, > or =18 y). We collected fasting blood samples, BMCs, and breath condensate. Carotenoids, alpha-tocopherol, vitamin C, protein carbonyls, thiobarbituric acid-reactive substances, and F(2)alpha-isoprostane were assessed.

RESULTS

In patients with CF, plasma vitamin C concentrations, plasma and BMC alpha-tocopherol concentrations, and forced expiratory volume in 1 s (percentage predicted) decreased significantly with age. Plasma beta-carotene, beta-cryptoxanthin, and total lycopene were significantly lower in patients than in control subjects in all age groups. Furthermore, alpha-tocopherol and vitamin C plasma concentrations as well as alpha-tocopherol concentrations in BMCs were significantly lower in CF patients > or =18 y old, whereas all indicators of oxidative stress assessed were significantly higher than those same indicators in control subjects.

CONCLUSIONS

Adult patients with CF in particular showed distinct vitamin deficits and elevated indicators of oxidative stress in plasma, BMCs, and breath condensate along with a progression of clinical status. We suggest that early in life dietary habits should be improved and that innovative supplementation strategies should be applied to optimize the antioxidant status of patients with CF.

Plasma vitamin A and C status of in-school adolescents and associated factors in Enugu State, Nigeria

The study was undertaken to determine the intake of vitamin A and C and plasma concentrations of these vitamins among in-school adolescents. The factors affecting the vitamin status of these adolescents were also determined. Data for this report were obtained from a cross-sectional survey of 600 in-school adolescents in Nsukka local government area (LGA) of Enugu State, Nigeria. Ninety and 45 of the adolescents were randomly selected for determining plasma concentrations of vitamin A and C and intake of these vitamins respectively. Dietary assessment was done using a three-day weighed food intake method. Venous blood samples were collected and used for determining plasma vitamin A using the trifluoroacetic acid (TFA) method, while plasma vitamin C was determined by the thiourea method. Values obtained were matched against standards. The intake of vitamin A by all the adolescents was adequate (126-137% of recommended intake), while the intake of vitamin C was inadequate (51-91% of recommended intake). The mean intake of vitamin C was higher among males (23.7 +/- 0.71-27.3 +/- 8.0) than among females (15.3 +/- 2.8-19.5 +/- 5.1). Despite the adequate intake of vitamin A, 40% of the male and 32% of the female adolescents had low plasma concentrations of the vitamin (< 20 microg/dL). On the other hand, concentrations of plasma vitamin C were low among about 47% of these adolescents. Using multiple regression analysis, the two most important variables influencing vitamin A status were household size (b = -0.629; p < 0.0 1) and nutrition knowledge (b = -1.372; p < 0.01), while for vitamin C status, these were household size (b = -0.110; p = 0.05) and age (b = 0.226; p < 0.05). The daytime students had a significantly (p < 0.05) better vitamin A and C status than the boarders. The prevalence of vitamin A and C deficiencies among the adolescents may be more than estimated due to inadequate intake and/or poor bioavailability. This may pose a serious health risk for adolescents. There is, therefore, a need for adequate nutrition education and awareness about healthy lifestyles among Nigerian adolescents.

The Assay of Ascorbic Acid in Serum Is Not Affected by Physiological Concentrations of Transferrin and Hemoglobin

Transferrin and hemoglobin have been reported to oxidize L-ascorbic acid (AA) in vitro. The aim of this study was to determine whether or not physiological concentrations of serum transferrin (reference range 22-45 micromol/L) and hemoglobin (reference range 0-3.0 micromol/L) interfer with the measurement of AA in the serum. Transferrin (33 to 41 micromol/L) and hemoglobin (1.9 micromol/L) added to freshly pooled serum significantly decreased measured AA in the serum (p < 0.05). However, we found that the magnitude of the decrease in AA due to transferrin at concentrations within the reference range or up to 80 micromol/L was inconsequential, and had no clinical importance in diagnosing a low AA concentration. Hemoglobin at concentrations within the reference range had little affect on the serum AA measurement. However, when serum specimens were stored at 4 degrees C for more than 1.5 h, the magnitude of the decrease in AA due to hemoglobin at physiological concentrations may cause a misleading clinical diagnostic evaluation of low AA concentration.

Vitamin C augments lymphocyte glutathione in subjects with ascorbate deficiency

BACKGROUND

Ascorbate and glutathione play central roles in the defense against free radicals and oxidants that are implicated in chronic diseases.

OBJECTIVE

The objective was to determine the ability of vitamin C supplements to modulate the concentration of glutathione in human lymphocytes.

DESIGN

The effect of vitamin C supplements was determined in a sequential study with time points before supplementation, after 13 wk of vitamin C supplements (500 or 1000 mg/d), and after 13 wk of matching placebo. The supplementation group was selected on the basis of low plasma ascorbate (<33 mmol/L) and consisted of 48 healthy men and women, smokers and nonsmokers, aged 25-64 y. Ascorbate and glutathione were measured in purified lymphocytes.

RESULTS

At baseline, the mean (+/-SD) concentration of plasma ascorbate was 19.5 +/- 7.2 micro mol/L, 22.5 micro mol/L below the median of normal distribution. The ascorbate concentration in plasma was linearly associated with that in lymphocytes (r = 0.53, P < 0.001). On supplementation with vitamin C, lymphocyte ascorbate increased by 51% (from 16.7 +/- 4.9 to 25.3 +/- 6.9 nmol/mg protein; P < 0.001) and was accompanied by an increase of lymphocyte glutathione by 18% (from 22.5 +/- 4.5 to 26.6 +/- 6.5 nmol/mg protein; P < 0.001). After placebo, the ascorbate and glutathione concentrations fell to near baseline concentrations (17.1 +/- 5.4 and 23.5 +/- 6.4 nmol/mg protein, respectively). No significant interaction was observed for sex and smoking status. Finally, the changes in lymphocyte ascorbate after supplementation were strongly associated with changes in lymphocyte glutathione (r = 0.71, P < 0.001). The association suggests that every 1-mol change in ascorbate is accompanied by a change of approximately 0.5 mol in glutathione.

CONCLUSION

Vitamin C supplements increase glutathione in human lymphocytes.

Anti-oxidant vitamins and steroid responsive nephrotic syndrome in Indian children

OBJECTIVE

In recent years, it has been proposed that nephrotic syndrome is a consequence of an imbalance between oxidant and anti-oxidant activity. In the present study, the levels of micronutrient anti-oxidant vitamins (vitamin E, vitamin C, carotene and riboflavin) in Indian children with steroid responsive nephrotic syndrome were investigated. Their levels were measured during the acute proteinuric phase of the disease, as well as during clinical recovery (remission), in order to understand the possible role of nutritionally modifiable anti-oxidants in the aetiopathogenesis of the disease.

METHODS

The study was a hospital based, prospective cohort study. Serum and erythrocyte vitamin E, leucocyte vitamin C, serum carotene, erythrocyte riboflavin activity and serum malonyldialdehyde (MDA) levels were measured in 30 consecutive cases of children with nephrotic syndrome (International Study of Kidney Diseases in Children (ISKDC) criteria) during the proteinuric phase of the disease and at 4 weeks after remission was induced by steroid therapy. The same biochemical parameters were measured in healthy siblings (controls) of the 30 patients.

RESULTS

Mean vitamin E (serum and erythrocyte), vitamin C and carotene were significantly lower during the proteinuric phase of the disease, and there was decreased erythrocyte riboflavin activity. There was significant elevation in the serum level of MDA during this phase. In addition, all these parameters tended to improve during remission, although complete normalization did not occur.

CONCLUSION

These vitamins were active in performing their anti-oxidant function, as indicated by significant depression in their levels during the acute (proteinuric) phase, followed by partial recovery during remission. It may be concluded that steroid responsive nephrotic syndrome in children is associated with oxidative stress.

Hemorrhage associated with vitamin C deficiency in surgical patients

BACKGROUND

Diffuse hemorrhage in surgical patients with normal coagulation parameters may be caused by vitamin C deficiency and is rapidly reversed by vitamin C replacement.

METHODS

Patients treated on a surgical service were entered into a clinical registry over a 12-month period if they experienced diffuse hemorrhage in the face of normal coagulation parameters and a plasma ascorbic acid level < 0.6 mg/dL (normal 0.6-2.0 mg/dL). Oral vitamin C replacement was administered after determination of plasma ascorbic acid level. Response to therapy, including subsequent bleeding events, need for blood transfusions, and demographic data including social and dietary history were retrospectively reviewed from hospital and outpatient clinic records.

RESULTS

Twelve patients with bleeding diatheses and low plasma ascorbic acid levels were identified. Plasma ascorbic acid levels were 0.1 to 0.5 mg/dL (mean, 0.3 mg/dL). There were 6 men and 6 women; age ranged from 46 to 90 years (mean, 78 years). Coagulation parameters were normal in all patients. Diffuse postoperative bleeding from nonsurgical causes was evident in 10 of 12 patients. Four patients, 2 of whom had operations, presented with chronic recurrent blood loss from the gastrointestinal tract. Each patient received 250 to 1000 mg of vitamin C replacement daily. Within 24 hours of vitamin C administration, there was no further evidence of clinical bleeding nor need for subsequent blood transfusions in any patient.

CONCLUSIONS

Vitamin C deficiency should be included in the differential diagnosis of nonspecific bleeding in surgical patients. Prolonged hospitalization, severe illness, and poor diet create vitamin C deficiency with significant clinical consequences. Oral vitamin C replacement rapidly reverses the effects of this disorder.

Are lifestyle factors good predictors of retinol and vitamin C deficiency in apparently healthy adults?

OBJECTIVE

To examine interrelationships between (1) dietary habits, (2) socioeconomic and (3) environmental factors, and their impact on plasma retinol and plasma ascorbic acid.

DESIGN

Cross-sectional study on adults from Western India.

SETTING

Rural, semi urban, urban higher/middle/lower socioeconomic regions (HSE/MSE/LSE) having diverse dietary habits and environmental conditions.

SUBJECTS

A total of 214 men and 108 women (20-50 y), apparently healthy and non-anemic.

MAIN OUTCOME MEASURES

Food intake by food frequency questionnaire, weight, height, age, smoking, environmental score, education, income, plasma retinol and plasma ascorbic acid.

RESULTS

Mean plasma retinol in women (24.84+/-5.1 microg/dl) and men (24.75+/-4.53 microg/dl) were not significantly different and 21% had plasma retinol below 20 microg/dl. Mean plasma ascorbic acid in women (0.35+/-0.12 mg/dl) and men (0.30+/-0.12 mg/dl) was similar with 75% having plasma ascorbic acid below 0.4 mg/dl. Vitamin A intake (as retinol equivalent) and plasma retinol showed a significant dose response (P<0.05) but not vitamin C intake and plasma ascorbic acid. Plasma retinol showed significant correlation with income (rho=0.24), education (rho=0.27), and environment (rho=0.21; rho=0.0001). Similar correlations with plasma ascorbic acid were 0.29, 031, -0.23 respectively (P=0.0001). Logistic regression showed education, environment, green leafy vegetables (GLV) and milk intake as predictors of plasma retinol deficiency, while non-sweet fruit intake, education and passive smoking for plasma ascorbic acid deficiency (P<0.05).

CONCLUSIONS

Subnormal status of retinol and vitamin C emphasizes the need to increase consumption of fruit, GLV and milk products, and also better education and environment. Avoiding passive smoking demands attention in order to improve levels of these vitamins.

SPONSORSHIP

Department of Science and Technology, India (project no. SP/SO/B39/94).

[Serum levels of vitamin C in young adults who chronically use drugs of abuse]

Few studies have evaluated the relationship between drugs of abuse consumption and plasma levels of vitamin C. Because of the importance of vitamin C due to its role in prevention of acute and chronic diseases, this study was carried out with the purpose of testing the influence of consumption of drugs of abuse on the plasmatic levels of vitamin C (ascorbic acid) of 56 male chronic users of drugs of abuse with an age range of 16 to 40 years. The following was performed: 1) A survey of consumption to determine the kind, frequency and quantity of drug(s) used and 2) The plasmatic levels of vitamin C in fasting condition, using the Rue and Kuether method. The results obtained showed that 89% of the population under study used drugs for the first time before the age of 18, and 78.4% started with marijuana; 60.7% of them were mixed drug users. The average level of plasmatic ascorbic acid was 0.89 +/- 0.06 mg/dL, nevertheless, according to nutritional category, 76% have values greater than 0.4 mg/dL and 23.2% were at moderated risk (0.35 +/- 0.01 mg/dL) of vitamin C deficiency. Likewise, classifying them in the antioxidant category (according to the suggested values of Gey, 1993) it was obtained that 55.4% had suboptimal or inadequate concentrations to carry out its antioxidant protective function. The length of time of drug's consumption influenced on the ascorbic acid level too. It can be concluded that chronic consumption of drugs of abuse can negatively influence the plasmatic levels of ascorbic acid, leading these patients to a latent condition of vitamin C deficiency. Finally it is necessary to deepen the study of vitamin C levels of users of drugs of abuse.

[Diagnostic image (40). Scurvy]

In a 17-year-old woman with anorexia nervosa, scurvy was diagnosed as the cause of fatigue, abdominal pain, vaginal bleeding and several distinctive skin lesions.

The relationship among dental status, nutrient intake, and nutritional status in older people

Dental health status may influence nutrition. The objective of this part of the National Diet and Nutrition Survey was to assess if there is a relationship between dental status in people 65 years and older and intake of certain nutrients and any link between dental status and blood-derived values of key nutrients. Random national samples of independently living subjects and those living in institutions had dental examinations, interviews, four-day food diaries, and blood and urine analyzed. In the sample living independently, intakes of most nutrients were lower in edentate than dentate subjects. Intake of non-starch polysaccharides, protein, calcium, non-heme iron, niacin, and vitamin C was significantly lower in edentate subjects. People with 21 or more teeth consumed more of most nutrients, particularly of non-starch polysaccharide. This relationship in intake was not apparent in the hematological analysis. Plasma ascorbate and plasma retinol were the only analytes significantly associated with dental status.

Fractured neck of femur in black patients: a prospective study

We explored the role of iron overload, deficiency of vitamin C and alcohol abuse in the aetiology of cervical and intertrochanteric fractures of the neck of the femur as a result of minor trauma. We studied prospectively 72 patients (45 men, 27 women). Levels of serum iron markers, vitamin C and alcohol markers were measured. Consumption of alcohol was estimated using questionnaires. The findings were compared with those of an age- and gender-matched control group. The mean age of the men was 59.5 years and of the women 66.9 years, with a male predominance. In the men, iron overload, as shown by high levels of serum ferritin (p < 0.001) and deficiency of vitamin C (p < 0.03), as well as abuse of both Western and the traditional type of alcohol, appear to be important aetiological factors. In women, alcohol abuse was also common, but iron markers and levels of vitamin C did not differ significantly from the control group.

Vitamin C status and mortality in US adults

BACKGROUND

Low vitamin C status may increase the risk of mortality from cancer and cardiovascular disease.

OBJECTIVE

The objective was to test whether an association existed between serum ascorbate concentrations and mortality and whether the association was modified by cigarette smoking status or sex.

DESIGN

Serum ascorbate concentrations were measured in adults as part of the second National Health and Nutrition Examination Survey (1976-1980). Vital status was ascertained 12-16 y later.

RESULTS

The relative risk (RR) of death, adjusted for potential confounders, was estimated by using Cox proportional hazards models. Men in the lowest (<28.4 micromol/L) compared with the highest (>/=73.8 micromol/L) serum ascorbate quartile had a 57% higher risk of dying from any cause (RR: 1.57; 95% CI: 1.21, 2.03) and a 62% higher risk of dying from cancer (RR: 1.62; 95% CI: 1.01, 2.59). In contrast, there was no increased risk among men in the middle 2 quartiles for these outcomes and no increased risk of cardiovascular disease mortality in any quartile. There was no association between serum ascorbate quartile and mortality among women. These findings were consistent when analyses were limited to nonsmokers or further to adults who never smoked, suggesting that the observed relations were not due to cigarette smoking.

CONCLUSIONS

These data suggest that men with low serum ascorbate concentrations may have an increased risk of mortality, probably because of an increased risk of dying from cancer. In contrast, serum ascorbate concentrations were not related to mortality among women.

[Scurvy presenting with ecchymotic purpura and hemorrhagic ulcers of the lower limbs]

INTRODUCTION

The risk of vitamin C deficiency is underestimated in industrialized countries and is only disclosed in rare cases of severe scurvy.

CASE REPORT

We report three cases of scurvy presenting with ecchymotic purpura and hemorrhagic ulcerations of the lower limbs. Vitamin C supplementation led to rapid improvement of the skin lesions.

DISCUSSION

Clinical diagnosis of low-grade deficiency can be difficult. Biological diagnosis requires special care in sample taking and transport.