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PubMed2004

Functional rescue of vitamin C synthesis deficiency in human cells using adenoviral-based expression of murine l-gulono-gamma-lactone oxidase.

l-Gulono-gamma-lactone oxidase (GULO) is a critical enzyme present in most mammalian species that is required for the terminal step in vitamin C biosynthesis. Primates are absolutely dependent on exogenously supplied dietary vitamin C due to inactivation of the Gulo gene by mutation over 40 million years ago. In this study, we report the cloning and expression of the murine l-gulono-gamma-lactone oxidase cDNA and gene. The cDNA (2.3 kb) encodes an open reading frame of 440 amino acids that shows high homology to the rat l-gulono-gamma-lactone oxidase (>94%). The Gulo gene is 22 kb long and contains 12 exons. The 11 introns range in size from 479 to 5641 bp. Northern blot analysis revealed high expression of Gulo transcript in the liver. To investigate whether metabolic loss of vitamin C biosynthesis in human cells can be corrected by heterologous expression of GULO, we constructed a first-generation adenoviral vector expressing the murine GULO cDNA under the transcriptional control of the murine cytomegalovirus (MCMV) early promoter. Low rescue efficiency of Gulo-expressing adenoviral constructs and reduced viral growth in HEK293 cells were observed, suggesting that overexpression of Gulo may be inhibitory to cell growth. Placement of a removable stuffer fragment flanked by lox sites between the MCMV promoter and the Gulo gene resulted in efficient vector rescue and normal viral replication in parental HEK293 cells and high-level expression of Gulo in HEK293 cells expressing Cre recombinase. Cells infected with Gulo-expressing vectors overexpressed an FAD-containing protein that corresponded in size to that predicted for recombinant GULO protein and expressed a functional enzyme as measured by the conversion of l-gulono-gamma-lactone to ascorbic acid in cell-free extracts. The cloning of the murine Gulo cDNA and the construction of Gulo-expressing adenoviral vectors are vital steps toward determining the role of vitamin C in basic metabolism and in disease.

Adenoviridae↗

PubMed1985

Effects of a multivitamin and iron supplement on running performance in Gambian children.

Forty boys and girls between 11 and 14.5 years with evidence of subclinical vitamin deficiencies were allocated to two groups to receive, twice weekly, either a placebo or a multivitamin and iron supplement. Prior to supplementation and on two subsequent occasions about 5 weeks apart, the children performed an exercise regimen on a treadmill during which expired air was collected and heart rate monitored. The supplement resulted in marked improvements in riboflavin and vitamin C status and checked the decline in iron stores seen in the unsupplemented children. During the study the running performance of unsupplemented children deteriorated, and markedly so in a subgroup with initially poor nutrient status. The vitamin and iron supplement prevented this deterioration so as to produce a significant reduction in the energy cost of treadmill running in the more malnourished subgroup, relative to the changes seen in children receiving no supplement.

Adolescent↗

PubMed1998

Ageing, nutritional status and immune response.

The effects of vitamin supplementation on the age-related decline in immune function was studied in a population of elderly subjects with a high prevalence of low and deficient serum values of vitamin C, vitamin E, riboflavin and pyridoxin, as well as iron and zinc. The immune function was examined by measuring delayed cutaneous hypersensitivity (DCH) after intradermal application of a set of 7 antigens in 72 subjects aged 60-89 years living in two homes for the elderly. The results showed an almost linear statistically significant decline in the DCH test with age (p < 0.01). Vitamin supplementation for a period of 10 weeks significantly improved the biochemical parameters for those vitamins and the age related decline in the DCH test was no longer statistically significant (P > 0.05). No statistically significant changes in DCH were observed in the placebo group. The results of this study suggest that nutrition may be an important determinant of immunocompetence in the elderly.

Aged↗

PubMed1992

Effect of vitamin C on sorbitol in the lens of guinea-pigs made diabetic with streptozotocin.

Marginally vitamin C-deficient guinea-pigs treated with the diabetogenic agent streptozotocin were compared with those liberally supplied with vitamin C, for functional indices of vitamin C status, particularly in the eye lens. Weanling male Dunkin-Hartley guinea-pigs were fed on diets with 0.1 g vitamin C/kg (marginally deficient), or 5 g/kg (liberally supplied), and some received intraperitoneal streptozotocin (two doses of 150 mg/kg body-weight). About half the streptozotocin-treated animals had high urinary glucose following an oral glucose dose; these animals also grew more slowly than the others. At 4 months after streptozotocin the animals were killed for measurement of tissue vitamin C, glucose and sorbitol. Streptozotocin moderately increased the concentration of glucose in plasma, lens and aqueous humour. Lens sorbitol levels increased only in the group exposed to streptozotocin plus marginal vitamin C. There was a significant (P less than 0.02) positive correlation between urinary glucose and lens sorbitol levels overall. Liberal vitamin C intake may thus counteract the effect of streptozotocin diabetes on lens sorbitol, suggesting a new function of vitamin C, possibly related to cataractogenesis and to the biochemical lesions associated with diabetes.

Adenosine Triphosphate↗

PubMed1992

Vitamin C depletion and pressure sores in elderly patients with femoral neck fracture.

OBJECTIVE: To evaluate the contribution of specific nutritional deficiencies (as indicated by zinc; vitamin A, C, and E; albumin; and haemoglobin concentrations) to the risk of pressure sores. DESIGN: Observational cohort study. SETTING: St James's University Hospital, Leeds. SUBJECTS: 21 elderly patients presenting consecutively to the orthopaedic unit with femoral neck fracture. MAIN OUTCOME MEASURE: Full thickness epidermal break over a pressure bearing surface. RESULTS: 10 patients (48%) developed a pressure sore during their hospital stay. Indices of zinc status and concentrations of albumin, haemoglobin, and vitamins A and E were similar in patients who developed a pressure sore and those who did not. Mean leucocyte vitamin C concentration, however, was 6.3 (SD 2.2) micrograms/10(8) cells in patients who developed a pressure sore as compared with 12.8 (4.6) micrograms/10(8) cells in patients who did not. CONCLUSIONS: Low concentrations of leucocyte vitamin C appear to be associated with subsequent development of pressure sores in elderly patients with femoral neck fractures.

Aged↗

PubMed1988

[3 problem vitamins in Latin America].

The list of vitamins recognized as essential in human nutrition is extensive. Only some of them, however, are attributed an important role in public health. The present paper deals with three of these selected because their deficiencies still prevail in important sectors of population in the Latin American Region: vitamin A, vitamin C and vitamin D. For each vitamin the paper discusses the scientific bases for their requirements, as well as pragmatic considerations to be taken into account for the derivation of recommended dietary intakes. Reference is made to the logic of applying the concepts of nutrient density when developing guidelines for the design of diets for the family and the community. Adequate nutrient density means that when a diet is consumed in sufficient amounts to satisfy energy requirements, the needs for essential nutrients are also being met. For the above reasons, the principle of expressing the recommended levels of intake of vitamin A and C per 1,000 kilocalories has been followed. This is not the case with vitamin D which, in view of its special feature of being synthesized endogenously, is not really a vitamin in the strict sense of the term and, therefore, a rational and consistent relationship with the energy of the diet cannot be established.

Adolescent↗

PubMed1998

[Changes in the energy needs of the elderly: an often encountered cause of nutritional deficiencies and frailty].

Changes in the body composition of elderly people and diminished physical activity reduce the energy requirement and the daily energy intake. It is especially frail elderly people who run an increased risk of a poor nutritional condition which further enhances fragility. Frailty is often defined as the state of reduced physiologic reserve associated with increased susceptibility to disability. In frail elderly people energy requirement is often reduced. Studies have shown that when energy intake falls below a level of about 6.3 MJ, it is hard to obtain a diet with a sufficient supply of minerals and water soluble vitamins. It is especially the daily intake of vitamins of the B complex and of vitamin C that then prove insufficient. In addition, immobile elderly and elderly of 75 years and older are at risk for an inadequate vitamin D status. An adequate diet is one of the factors that may prevent frail health. Screening lists have been developed to quickly obtain information about the nutritional status of older adults. However, these lists still have to be adapted to the Dutch dietary pattern. Currently, a change of the body weight is the best warning of insufficient nutrition.

Aged↗

PubMedDate not supplied

In search of the cause of gastric cancer.

The purpose of this review was to describe the historical development of each epidemiology, experimental pathology, endocrinology (including vitaminology), and thermodynamics surrounding the genesis of gastric cancer in humans and non-human mammals. Epidemiological studies from other and our laboratories were unanimous in counting the intake of carbohydrate-rich and salty diet with vitamin C deficiency as the risk factor of key importance. Information from experimental pathology suggested the possible implication of some nitroso compounds in a subject with atrophic gastritis and/or in a state of vitamin C deficiency of which the establishment should have led to a perturbation of the steroid milieu of the host. In endocrinology, the association of a specific steroid disorder (depression of androgen and progestin combined with glucocorticoid excess in urine) with gastric cancer, as noted in the case-control study of this neoplasia, was reproduced in mice maintained under biased nutritional conditions. The use of scurvy-prone ODS rats was found useful in elucidating the interrelation between vitamin C and steroid metabolism. Finally, thermodynamic analysis of the data distribution of gastric cancer risk parameter of both sexes revealed the presence of an interaction between oncogene activation and tumor suppressor gene inactivation in the course of the maintenance of the positive correlation with male predominance between male gastric cancer and female gastric cancer as regards the changes of age-adjusted incidence rate (AAIR) in space. In conclusion, all of the information available in the field of gastric cancer etiology is in support of the pertinence of the steroid criminal hypothesis of gastric cancer in humans and in non-human mammals.

Animals↗

PubMed2003

Pharmacological, morphological and behavioral analysis of motor impairment in experimentally vitamin C deficient guinea pigs.

The scurvy shows an inflammatory disease and gingival bleeding. Nevertheless, in an animal model for guinea pigs, described by Den Hartog Jager in 1985, scurvy was associated with a motor neuron disease with demyelinization of the pyramidal tract, provoking neurogenic atrophy of muscles. Aiming at searching the protective role of vitamin C in nervous system, a pharmacological, morphological and behavioral study was conducted. Three experimental groups were used: A100, animals receiving 100 mg/ vitamin C/ day; A5.0, animals receiving 5.0 mg/vitamin C/ day; and A0, animals without vitamin C. We analyzed the weight gain, muscular diameter and behavioral tests. In all tests examined, we found significant differences between the supplemented groups in comparison with scorbutic group (p<0.05). Thereafter, the animals were killed for histopathology of gastrocnemius muscle, spinal cord and tooth tissues. In addition, a morphometric study of periodontal thickness and alpha-motor neuron cell body diameter were done. The vitamin C-diet free regimen seemed to induce a disruption in spinal cord morphology, involving the lower motor neuron, as confirmed by a significant reduction in neuron perycaria diameter and muscular atrophy, complicated by increased nutritional deficit.

Animals↗

PubMed2003

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.

Adult↗

PubMed2004

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.

Adolescent↗

PubMed1994

Circulating insulin-like growth factor binding proteins (IGFBPs) 1 and 2 induced in vitamin C-deficient or fasted guinea pigs inhibit IGF-I action in cultured cells.

Collagen gene expression and proteoglycan synthesis are decreased in vitamin C-deficient guinea pigs losing weight and in fasted guinea pigs receiving ascorbate. Sera from such guinea pigs contain an insulin-like growth factor (IGF)-I-reversible inhibitor of collagen, proteoglycan and DNA synthesis and elevated levels of 29 and 35-kDa IGF binding proteins (IGFBPs). We now have identified the induced proteins as IGFBPs 1 and 2 and investigated their role as inhibitors. Guinea pig sera were treated with antibodies to IGFBPs 1 and 2 and antibody-IGFBP complexes were removed by passage through a Protein A-Sepharose column. Inhibitor content of fasted and scorbutic sera, and Protein A pass-through fractions derived from them, was assessed by their level of stimulation of DNA and collagen synthesis in 3T3 cells, compared to analogously treated normal guinea pig serum. Removal of IGFBP-1 from scorbutic serum reversed inhibition of collagen and DNA synthesis by more than half but removal of IGFBP-2 was less effective. Removal of both IGFBPs reversed inhibition almost completely. Similar results were obtained with fasted guinea pig serum. Conversely, purified rat IGFBPs 1 and 2 inhibited DNA and collagen synthesis in cells cultured in normal guinea pig serum or IGF-I-stimulated DNA synthesis, with IGFBP-1 being more potent. Thus, IGFBP-1 and, to a lesser extent IGFBP-2, cause inhibition of IGF-I action by sera from fasted and scorbutic guinea pigs and may inhibit collagen gene expression in vivo.

3T3 Cells↗

PubMed2003

Vitamin C and bone markers: investigations in a Gambian population.

Vitamin C is an essential micronutrient. Absence from the diet will result in the deficiency disease scurvy, typically characterised by weakening of collagenous structures. High intakes of vitamin C have been associated with decreased incidence or severity of a number of diseases, including cancer and cardiovascular disease. These beneficial effects may be attributed to its antioxidant properties, although the exact mechanisms of action remain elusive. It is also unclear what intake levels are required for optimal health benefits. The task of defining optimal intakes is hindered by the lack of a reliable functional marker of tissue vitamin C status in man. Many different pathways have been investigated, but none of them have measurable outcome variables relating directly to scorbutic changes. The bone-collagen formation pathway has the potential to provide a functional index of tissue vitamin C adequacy. Vitamin C acts as a cofactor for the enzyme lysyl hydroxylase, which is required for the hydroxylation of lysine residues in procollagen chains. Pyridinoline is a mature collagen cross-link formed from three hydroxylysine residues, deoxypyridinoline is formed from two hydroxylysine and one lysine residue. Guinea-pig studies have shown an alteration in the pyridinium cross-link ratios in response to graded vitamin C intakes (Tsuchiya & Bates, 1998). In order to investigate whether these changes can be seen in a human population group, a study was carried out in rural Gambia, where there is a marked seasonal variation in dietary vitamin C. The present review discusses the rationale behind the study and presents some preliminary results.

Amino Acids↗

PubMed1986

Mechanism for the decreased biosynthesis of cartilage proteoglycan in the scorbutic guinea pig.

Our previous work showed that vitamin C deficiency caused about a 70-80% decrease in the incorporation of [35S]sulfate into proteoglycan of guinea pig costal cartilage, coordinately with a decrease in collagen synthesis (Bird, T. A., Spanheimer, R. G., and Peterkofsky, B. (1986) Arch. Biochem. Biophys. 246, 42-51). We examined the mechanism for decreased proteoglycan synthesis by labeling normal and scorbutic cartilage in vitro with radioactive precursors. Proteoglycan monomers from scorbutic tissue were of a slightly smaller average hydrodynamic size than normal but there was no difference in the size of the glycosaminoglycan chains isolated after papain digestion. The type of glycosaminoglycans synthesized and the degree of sulfation were unaffected as determined by chondroitinase ABC digestion and duel labeling with [35S]sulfate and [3H]glucosamine. Conversion of [3H]glucosamine to [3H]galactosamine also was unimpaired. There was about a 40% decrease in core protein synthesis, measured by [14C]serine incorporation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Nevertheless, decreased incorporation of [35S]sulfate into scorbutic tissue persisted in the presence of p-nitrophenyl-beta-D-xyloside and cycloheximide, which indicated that the site of the scorbutic defect was beyond core protein synthesis and xylosylation. Galactosyltransferase activity in scorbutic cartilage decreased to about one-third the levels in control samples in parallel with the decreases in proteoglycan and collagen synthesis. Our results suggest that the step catalyzed by this enzyme activity, the addition of galactose to xylose prior to chondroitin sulfate chain elongation, is the major site of the scorbutic defect in proteoglycan synthesis. Decreased enzyme activity may be related to increased cortisol levels in scorbutic serum.

Animals↗

PubMed2005

Low total vitamin C plasma level is a risk factor for cardiovascular morbidity and mortality in hemodialysis patients.

Hemodialysis patients are prone to deficiency of vitamin C, which constitutes the most abundant nonenzymatic antioxidant in blood. Because antioxidants are involved in the pathogenesis of atherosclerosis, the authors examined the association of total vitamin C plasma level with cardiovascular outcomes in such patients. One hundred thirty-eight consecutive maintenance hemodialysis patients (median age 61 yr, 90 males) were enrolled in a single-center study. At baseline, routine laboratory parameters were recorded, and predialysis total vitamin C plasma levels were measured by high-pressure liquid chromatography. Patients were prospectively followed-up for the occurrence of a primary composite endpoint consisting of fatal and nonfatal major adverse cardiovascular events (MACE) and for all-cause and cardiovascular mortality. MACE occurred in 35 patients (25%) over a period of median 30 mo, and 42 patients (30%) died [29 cardiovascular deaths (21% of total)]. Using Cox proportional hazards modeling, adjusted hazard ratios for the occurrence of MACE were 3.90 (95% confidence interval [CI]: 1.42 to 10.67; P = 0.008) and 3.03 (95% CI: 1.03 to 8.92; P = 0.044) for patients in the lower (<32 micromol/L) and middle (32 to 60 micromol/L) tertile of total vitamin C levels, compared with patients in the upper tertile (>60 micromol/L). Hazard ratios for cardiovascular death were 3.79 (95% CI: 1.23 to 11.66; P = 0.020) and 2.89 (95% CI: 0.89 to 9.37; P = 0.076). Total vitamin C levels were not independently associated with all-cause mortality. This study concludes that low total vitamin C plasma levels predict adverse cardiovascular outcomes among maintenance hemodialysis patients. Future studies should address the potential protective effect of an adequate vitamin C supplementation.

Aged↗

PubMed2003

Comparison of vitamin C deficiency with food restriction on collagen cross-link ratios in bone, urine and skin of weanling guinea-pigs.

Mild-to-moderate vitamin C depletion in weanling guinea-pigs affects pyridinoline:deoxypyridinoline (collagen cross-link) ratios in femur shaft and urine, attributed to impairment of hydroxylation of collagen lysine. We investigated: (1). whether the picture at two time points is compatible with progressive accumulation of abnormal collagen; (2). whether any changes are seen in skin, where little deoxypyridinoline occurs; (3). whether total food restriction has similar effects. Male weanling Dunkin-Hartley guinea-pigs were fed diets containing either 0.5 (vitamin C-restricted) or 160.0-320.0 (vitamin C-adequate) mg vitamin C/d. Two groups receiving the vitamin C-adequate diet received it ad libitum. Two other groups received the vitamin C-adequate diet in a restricted amount, limited to that which permitted nearly the same growth rate as in the vitamin C-restricted groups. Animals were fed for 4 or 8 weeks; urine was collected, and vitamin C and collagen indices were measured. In the femur shaft, the hydroxyproline content per unit weight was unaffected by vitamin C restriction or by total food restriction. Deoxypyridinoline was increased and the pyridinoline:deoxypyridinoline ratio was decreased in vitamin C-restricted groups, but not in food-restricted groups. Changes in the value of the ratio were greater after 8 than after 4 weeks. Urine indices mirrored bone indices. In skin, the main effect of vitamin C restriction was to reduce hydroxyproline. Here, the cross-link ratios changed less markedly than in bone, and there was less deoxypyridinoline. We conclude that the picture at two time points is compatible with a progressive accumulation of pyridinoline-enriched collagen in vitamin C-deprived animals, that the picture in skin differs from that of bone and urine, and that cross-link changes are not produced by total food restriction.

Amino Acids↗

PubMed1987

Retinal photic injury in normal and scorbutic monkeys.

Mild and severe retinal photic injuries were inflicted on 22 eyes of seven monkeys fed a vitamin C-deficient diet and four monkeys given a vitamin C-enriched diet. The retinal lesions were studied by fundus examination, fluorescein angiography, and light and electron microscopy. While the general cellular response to photic injury in the retina of scorbutic animals was not different qualitatively from that in the normal animals, scurvy appeared to cause more severe tissue damage, an exaggerated repair response, and more advanced retinal degeneration. In the four groups of eyes, representing mild and severe photic injury in normal and scorbutic animals, a continuous spectrum of changes was produced. The least damage occurred from mild photic injury in the normal animals, and the most detrimental insult resulted from severe photic injury in the scorbutic animals. We propose that the basic mechanism by which ascorbate mitigates retinal photic injury depends on its redox properties. Ascorbate functions as an antioxidant in the retina. It scavenges superoxide radicals and hydroxyl radicals, quenches singlet oxygen, and reduces hydrogen peroxide, all of which are formed in retinal photic injury. This hypothesis provides an explanation for the high level of ascorbate in the retina. The pathogenetic mechanisms that correspond to the three distinct phases of pathologic changes observed in retinal photic injury are characterized. In phase 1, single oxygen is generated in a photodynamic reaction that damages the photoreceptor elements and pigment epithelium. In phase 2, macrophages attracted from the systemic circulation invade the subretinal space, and a photo-oxidative reaction generates superoxide radicals, hydrogen peroxide, and hydroxyl radicals. These free radicals attack the photoreceptor cells and pigment epithelium to cause further retinal damage. In phase 3, macrophages remain in the subretinal space for as long as 8 months after injury, causing persistent disruption of the blood-retinal barrier. The photo-oxidative reaction appears to linger, resulting in chronic retinal degeneration. It is hypothesized that in some forms of age-related macular degeneration, patients suffer from repeated mild photic insult throughout their lifetime. Aging has been associated with subclinical scurvy, which leads to even greater susceptibility to photic injury. Although ascorbate moderates many biochemical functions of the body and helps the retina ameliorate photo-oxidative injury, it should be regarded as a nutritional supplement to maintain health when consumed in appropriate amounts and not as a therapeutic agent for the treatment of severe insults.

Animals↗

PubMed1999

Effect of daily and weekly micronutrient supplementation on micronutrient deficiencies and growth in young Vietnamese children.

BACKGROUND: Micronutrient deficiencies remain common in preschool children in developing countries. Interventions focus on single micronutrients and often lack effectiveness. Weekly instead of daily supplementation may improve effectiveness. OBJECTIVE: The efficacy of weekly and daily supplementation in reducing anemia prevalence and in improving the zinc, vitamin A, and growth status of 6-24-mo-old Vietnamese children was investigated. DESIGN: In this double-blind, placebo-controlled trial, the daily group (n = 55) received 8 mg elemental Fe (as iron sulfate), 5 mg elemental Zn (as zinc sulfate), 333 microg retinol, and 20 mg vitamin C 5 d/wk for 3 mo. The weekly group (n = 54) received 20 mg Fe, 17 mg Zn, 1700 microg retinol, and 20 mg vitamin C once a week. A third group (n = 54) received a placebo only. Venous blood samples were collected at the start and end of the supplementation period and anthropometric measurements were taken at the start and 3 mo after the end of supplementation. RESULTS: At baseline, 45.6% of subjects had hemoglobin concentrations < 110 g/L, 36.3% had zinc concentrations < 10.71 micromol/L, and 45.6% had retinol concentrations <0.70 micromol/L. Hemoglobin, retinol, and zinc concentrations of both the weekly and daily groups increased similarly compared with the placebo group (P < 0.001). There was no significant difference in growth between the supplemented groups and the placebo group. However, the height-for-age of subjects stunted at baseline increased with z scores of 0.48 (P < 0.001) and 0.37 (P < 0.001) for the daily and weekly groups, respectively. CONCLUSIONS: Weekly and daily supplementation improved hemoglobin, zinc, and retinol concentrations similarly. Neither intervention affected growth of the overall population, but growth of children stunted at baseline was improved through both types of supplementation.

Ascorbic Acid Deficiency↗