Vitamin C Deficiency and Scurvy Are Not Only a Dietary Problem but Are Codetermined by the Haptoglobin Polymorphism

Vitamin C supplementation for diabetes management: A comprehensive narrative review

Growing evidence suggests that vitamin C supplementation may be an effective adjunct therapy in the management of people with diabetes. This paper critically reviews the current evidence on effects of vitamin C supplementation and its potential mechanisms in diabetes management. Evidence from meta-analyses of randomized controlled trials (RCTs) show favourable effects of vitamin C on glycaemic control and blood pressure that may be clinically meaningful, and mixed effects on blood lipids and endothelial function. However, evidence is mostly of low evidence certainty. Emerging evidence is promising for effects of vitamin C supplementation on some diabetes complications, particularly diabetic foot ulcers. However, there is a notable lack of robust and well-designed studies exploring effects of vitamin C as a single compound supplement on diabetes prevention and patient-important outcomes (i.e. prevention and amelioration of diabetes complications). RCTs are also required to investigate potential preventative or ameliorative effects of vitamin C on gestational diabetes outcomes. Oral vitamin C doses of 500-1000 mg per day are potentially effective, safe, and affordable for many individuals with diabetes. However, personalisation of supplementation regimens that consider factors such as vitamin C status, disease status, current glycaemic control, vitamin C intake, redox status, and genotype is important to optimize vitamin C's therapeutic effects safely. Finally, given a high prevalence of vitamin C deficiency in patients with complications, it is recommended that plasma vitamin C concentration be measured and monitored in the clinic setting.

Oxidative status in the β-thalassemia syndromes in Sri Lanka; a cross-sectional survey

In the β-thalassemias, oxidative stress, resulting from chronic hemolysis, globin chain imbalance, iron overload and depleted antioxidant defences, likely contributes to cell death, organ damage, anemia, hypoxia and inflammation. We assessed variations in these parameters in β-thalassemia syndromes in Sri Lanka. Between November 2017 and June 2018, we assessed children and adults attending two thalassemia centres in Sri Lanka: 59 patients with HbE β-thalassemia, 50 β-thalassemia major, 40 β-thalassemia intermedia and 13 HbS β-thalassemia. Median age was 26.0 years (IQR 15.3-38.8), 101 (62.3%) were female and 152 (93.8%) of Sinhalese ethnicity. Methemoglobin, plasma hemoglobin, heme and ferritin were measured as sources of oxidants; plasma total antioxidant capacity, haptoglobin, hemopexin and vitamins C and E assessed antioxidant status; plasma thiobarbituric acid reactive substances and 8-hydroxy-2'-deoxyguanosine assessed oxidative damage; hemoglobin, plasma erythropoietin and transferrin receptor assessed anemia and hypoxia and plasma interleukin-6 and C-reactive protein assessed inflammation. Fruit and vegetable intake was determined by dietary recall. Physical fitness was investigated using the 6-min walk test and measurement of handgrip strength. Oxidant sources were frequently increased and antioxidants depleted, with consequent oxidative damage, anemia, hypoxia and inflammation. Biomarkers were generally most abnormal in HbE β-thalassemia and least abnormal in β-thalassemia intermedia but also varied markedly between individuals with the same thalassemia syndrome. Oxidative stress and damage were also more severe in splenectomized patients and/or those receiving iron chelation therapy. Less than 15% of patients ate fresh fruits or raw vegetables frequently, and plasma vitamins C and E were deficient in 132/160 (82.5%) and 140/160 (87.5%) patients respectively. Overall, physical fitness was poor in all syndromes and was likely due to anemic hypoxia. Studies of antioxidant supplements to improve outcomes in patients with thalassemia should consider individual patient variation in oxidative status both between and within the thalassemia syndromes.

Initial Evidence of Variation by Ethnicity in the Relationship between Vitamin C Status and Mental States in Young Adults

Higher fruit and vegetable intake has been associated with improved mood, greater vitality, and lower stress. Although the nutrients driving these benefits are not specifically identified, one potentially important micronutrient is vitamin C, an important co-factor for the production of peptide hormones, carnitine and neurotransmitters that are involved in regulation of physical energy and mood. The aim of our study was to investigate the cross-sectional relationship between blood plasma vitamin C status and mood, vitality and perceived stress. A sample of 419 university students (aged 18 to 35; 67.8% female) of various ethnicities (49.2% European, 16.2% East Asian, 8.1% Southeast/Other Asian, 9.1% Māori/Pasifika, 11.5% Other) provided a fasting blood sample to determine vitamin C status and completed psychological measures consisting of the Profile of Mood States Short Form (POMS-SF), the vitality subscale of the Rand 36-Item Short Form (SF-36), and the Perceived Stress Scale (PSS). Participants were screened for prescription medication, smoking history, vitamin C supplementation, fruit/juice and vegetable consumption, kiwifruit allergies, excessive alcohol consumption and serious health issues, and provided age, gender, ethnicity, and socioeconomic status information, which served as covariates. There were no significant associations between vitamin C status and the psychological measures for the sample overall. However, associations varied by ethnicity. Among Māori/Pasifika participants, higher vitamin C was associated with greater vitality and lower stress, whereas among Southeast Asian participants, higher vitamin C was associated with greater confusion on the POMS-SF subscale. These novel findings demonstrate potential ethnicity-linked differences in the relationship between vitamin C and mental states. Further research is required to determine whether genetic variation or cultural factors are driving these ethnicity differences.

Factors Affecting Vitamin C Status and Prevalence of Deficiency: A Global Health Perspective

A recent review of global vitamin C status has indicated a high prevalence of deficiency, particularly in low- and middle-income countries, as well as in specific subgroups within high-income countries. Here, we provide a narrative review of potential factors influencing vitamin C status globally. The in vivo status of vitamin C is primarily affected by dietary intake and supplement use, with those who supplement having a higher mean status and a lower prevalence of deficiency. Dietary intake can be influenced by cultural aspects such as traditional cooking practices and staple foods, with many staple foods, such as grains, contributing negligible vitamin C to the diet. Environmental factors can also affect vitamin C intake and status; these include geographic region, season, and climate, as well as pollution, the latter partly due to enhanced oxidative stress. Demographic factors such as sex, age, and race are known to affect vitamin C status, as do socioeconomic factors such as deprivation, education and social class, and institutionalization. Various health aspects can affect vitamin C status; these include body weight, pregnancy and lactation, genetic variants, smoking, and disease states, including severe infections as well as various noncommunicable diseases such as cardiovascular disease and cancer. Some of these factors have changed over time; therefore, we also explore if vitamin C status has shown temporal changes. Overall, there are numerous factors that can affect vitamin C status to different extents in various regions of the world. Many of these factors are not taken into consideration during the setting of global dietary intake recommendations for vitamin C.

Haptoglobin 2 Allele is Associated With Histologic Response to Vitamin E in Subjects With Nonalcoholic Steatohepatitis

BACKGROUND

Haptoglobin (Hp) genotype has been linked to oxidative stress and cardiovascular outcomes in response to vitamin E (VitE) among patients with diabetes mellitus. Its effect on histologic response to VitE in nonalcoholic steatohepatitis (NASH) is unknown.

GOALS

Our objective was to determine if Hp genotype associates with response to VitE in patients with NASH.

STUDY

A post hoc analysis of 228 patients receiving VitE or placebo in 2 clinical trials was performed. Regression analysis was used to assess the effect of VitE versus placebo, by Hp genotype (1-1, 2-1, or 2-2), on histologic features and laboratory markers of nonalcoholic fatty liver disease, comparing baseline to end of treatment values. An interaction term was included in the regression models to assess differential treatment effect across Hp genotype.

RESULTS

Hp 2-2 patients treated with VitE versus placebo showed significant histologic improvement (51% vs. 20%; OR=4.2; P=0.006), resolution of steatohepatitis (44% vs. 12%; OR=6.2; P=0.009), decrease in nonalcoholic fatty liver disease Activity Score (NAS) (-2.2 vs. -0.6; P=0.001), and decrease in liver enzymes alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and γ-glutamyl transpeptidase. Hp 2-1 patients on VitE versus placebo showed improved resolution of steatohepatitis, NAS and liver enzymes. Hp 1-1 patients showed no significant improvement in histology or liver enzymes. VitE had no effect on fibrosis stage in any group. Regression analysis showed incremental benefit of having Hp 2-2 or 2-1 versus 1-1 for all liver enzyme.

CONCLUSIONS

Hp 2 allele is associated with greater histologic and biological improvement in NASH with VitE treatment compared with the Hp 1 allele.

Vitamin C deficiency in an Australian cohort of metropolitan surgical patients

Vitamin C is an essential micronutrient in the human diet. While large population studies measuring vitamin C have been performed in other countries, there are few studies of deficiency in the Australian population. This study aimed to quantify vitamin C deficiency, identify scorbutic symptoms and examine dietary associations in a cohort of preoperative general surgical patients. Vitamin C levels were determined in a cohort of patients referred to a single surgeon between January 2011 and December 2013. Baseline data were collected along with data on fruit consumption, weekly citrus fruit intake and presence of scorbutic symptoms. A total of 309 patients were included in the study and 21.4% of our cohort showed a vitamin C level ≤11.4 μmol/L (deficient). Mean citrus fruit intake was significantly higher in the normal vitamin C groups (>28.4 μmol/L) and patients with vitamin C levels ≤28.4 were more likely to consume no fruit (p=0.0004) which was also significant on multivariate analysis. Neither age nor gender appeared predictive of suboptimal vitamin C levels. No symptoms were significantly related to vitamin C levels on multivariate analysis. Vitamin C deficiency was common in Australian adults attending a surgical practice within south western Sydney. Review of the Australian recommended daily allowance for vitamin C is suggested, not only in clinically well patients but particularly in ICU and hospital inpatients. Larger studies examining the prevalence and impact of vitamin C deficiency in the Australian population are required to further investigate these findings.

Plasma levels of Apolipoprotein A1 and Lecithin:Cholesterol Acyltransferase in type 2 diabetes mellitus: Correlations with haptoglobin phenotypes

BACKGROUND

Previous studies have demonstrated that hemoglobin-haptoglobin (Hb-Hp) complex plays a role in developing vascular complications in type 2 diabetes mellitus (T2DM). The complexes bind with Apolipoprotein A1 (ApoA1) of high-density lipoprotein (HDL), affecting the function of Lecithin:Cholesterol Acyltransferase (LCAT), and impairing the reverse cholesterol transport mechanism (RCT). This study investigated the influence of Hp phenotypes on serum levels of ApoA1 and LCAT in patients with T2DM.

METHODS

The study comprised 131 T2DM patients and 111 matching healthy controls. Fasting blood glucose, HbA₁C, and lipid profile were determined by chemistry autoanalyzer, LCAT and ApoA1 by ELISA, and Hp phenotypes by gel electrophoresis.

RESULTS

Irrespective of Hp phenotypes, fasting blood glucose, HbA₁C, and lipid profile were significantly higher in patients than in controls, while HDL-cholesterol, ApoA1, and LCAT were lower. ApoA1 correlated positively with LCAT (r=0.223, p=0.024) and HDL-cholesterol (r=0.255, 0.003) in patients only. When Hp polymorphism was taken into account, the levels of LCAT and ApoA1 were significantly lower in patients with Hp2-2 than that in patients of Hp1-1 and/or Hp2-1. Correlations between ApoA1 and each of HDL-cholesterol and LCAT (r=0.239, p=0.046, and r=0.252, p=0.040, respectively) were also observed, but only in patients with Hp2-2 phenotype.

CONCLUSIONS

The reduced levels of LCAT and ApoA1 observed in this study support the suggestion that T2DM patients with Hp2-2 phenotype could have altered RCT mechanism and increased risk of developing cardiovascular disease.

Brassica foods as a dietary source of vitamin C: a review

Brassica genus includes known horticultural vegetables with major economical importance worldwide, and involves vegetables of economical importance being part of the diet and source of oils for industry in many countries. Brassicales own a broad array of health-promoting compounds, emphasized as healthy rich sources of vitamin C. The adequate management of pre- and postharvest factors including crop varieties, growth conditions, harvesting, handling, storage, and final consumer operations would lead to increase or preserve of the vitamin C content or reduced losses by interfering in the catalysis mechanisms that remains largely unknown, and should be reviewed. Likewise, the importance of the food matrix on the absorption and metabolism of vitamin C is closely related to the range of the health benefits attributed to its intake. However, less beneficial effects were derived when purified compounds were administered in comparison to the ingestion of horticultural products such as Brassicas, which entail a closely relation between this food matrix and the bioavailability of its content in vitamin C. This fact should be here also discussed. These vegetables of immature flowers or leaves are used as food stuffs all over the world and represent a considerable part of both western and non-Western diets, being inexpensive crops widely spread and reachable to all social levels, constituting an important source of dietary vitamin C, which may work synergistically with the wealth of bioactive compounds present in these foods.

A likely case of scurvy in a rural Early Classic Maya burial from Actun Uayazba Kab, Belize

A Maya burial of a late adolescent (Burial 98-3) found in the rockshelter entrance of Actun Uayazba Kab (AUK), Belize, displays a combination of lesions that is consistent with scurvy. Signs include large, active lesions on the posterior surfaces of maxilla; relatively mild porotic hyperostosis along the midline of the skull on the parietals and occipital; cribra orbitalia; potential pinprick lesions on the greater wings of sphenoid and temporal; reactive lesions on the palate, temporal lines of frontal and parietals, and external and internal surfaces of zygomatics; small lesions on the popliteal surfaces of both femora; and periodontal disease. Identification of scurvy at AUK potentially informs the analysis of other primary burials and scattered bone found there and at other nearby sites, which often reveal evidence of nonspecific lesions that are usually attributed to anemia and infection, but that are also consistent with scurvy. The social and ecological context of this Protoclassic (0-AD 300) individual, who lived in a rural agricultural community with no evidence of complex social hierarchy, contrasts with typical discussions of disease among the Maya, which tend to focus on the degrading effects of overcrowding and resource deficiencies. While scurvy has been largely overlooked in the Maya area, this study supports earlier arguments for its presence that were based largely on clinical and ethnographic analogies and suggests the need to incorporate scurvy into broader synergistic models of ancient health.

New criteria for supplementation of selected micronutrients in the era of nutrigenetics and nutrigenomics

Advances in molecular biology, emergence of novel techniques and huge amount of information generated in the post-Human Genome Project era have fostered the emergence of new disciplines in the field of nutritional research: Nutrigenomics deals with the effect of diet on gene expression whereas nutrigenetics refers to the impact of inherited traits on the response to a specific dietary pattern, functional food or supplement. Understanding the role of micronutrient supplementation with specific genetic backgrounds may provide an important contribution to a new optimum health strategy based on individualized nutritional treatment and may provide the strategies for the development of safer and more effective dietary interventions. This overview of the various aspects of supplementation of micronutrients in the era of nutrigenetics and nutrigenomics may provide a better understanding of novel nutritional research approach and provide an additional insight that can be applied to the daily dietary practice.

Epistasis between the haptoglobin common variant and α+thalassemia influences risk of severe malaria in Kenyan children

Haptoglobin (Hp) scavenges free hemoglobin following malaria-induced hemolysis. Few studies have investigated the relationship between the common Hp variants and the risk of severe malaria, and their results are inconclusive. We conducted a case-control study of 996 children with severe Plasmodium falciparum malaria and 1220 community controls and genotyped for Hp, hemoglobin (Hb) S heterozygotes, and α(+)thalassemia. Hb S heterozygotes and α(+)thalassemia homozygotes were protected from severe malaria (odds ratio [OR], 0.12; 95% confidence interval [CI], 0.07-0.18 and OR, 0.69; 95% CI, 0.53-0.91, respectively). The risk of severe malaria also varied by Hp genotype: Hp2-1 was associated with the greatest protection against severe malaria and Hp2-2 with the greatest risk. Meta-analysis of the current and published studies suggests that Hp2-2 is associated with increased risk of severe malaria compared with Hp2-1. We found a significant interaction between Hp genotype and α(+)thalassemia in predicting risk of severe malaria: Hp2-1 in combination with heterozygous or homozygous α(+)thalassemia was associated with protection from severe malaria (OR, 0.73; 95% CI, 0.54-0.99 and OR, 0.48; 95% CI, 0.32-0.73, respectively), but α(+)thalassemia in combination with Hp2-2 was not protective. This epistatic interaction together with varying frequencies of α(+)thalassemia across Africa may explain the inconsistent relationship between Hp genotype and malaria reported in previous studies.

Haptoglobin genotype and functional outcome after aneurysmal subarachnoid hemorrhage

OBJECT

Haptoglobin allele heterogeneity has been implicated in differential reactive oxidant inhibition and inflammation. Haptoglobin α2-α2 has a lower affinity for binding hemoglobin, and when bound to hemoglobin, is cleared less easily by the body. The authors hypothesized that haptoglobin α2-α2 genotype should be less protective for downstream injury after aneurysmal subarachnoid hemorrhage (aSAH) and should portend a worse outcome.

METHODS

Patients with Fisher Grade 2 or higher aSAH were enrolled in the study. Genotyping for haptoglobin genotype was performed from blood and/or CSF. Demographic information, medical condition variables, and hospital course were abstracted from the medical record upon enrollment into the study. Outcome data (modified Rankin Scale score, Glasgow Outcome Scale score, and mortality) were collected at 3 months posthemorrhage.

RESULTS

The authors enrolled 193 patients who ranged in age from 18 to 75 years. Only Caucasians were used in this analysis to minimize bias from variable haptoglobin allele frequencies in populations of different ancestral backgrounds. The sample had more women than men (overall mean age 54.45 years). Haptoglobin α2 homozygotes were older than the other individuals in the study sample (57.27 vs 53.2 years, respectively; p = 0.02) and were more likely to have Fisher Grade 3 SAH (p = 0.02). Haptoglobin α2-α2 genotype, along with Fisher grade and Hunt and Hess grade, was associated with a worse 3-month outcome compared to those with the haptoglobin α1-α1 genotype according to modified Rankin Scale score after controlling for covariates (OR 4.138, p = 0.0463).

CONCLUSIONS

Patients with aSAH who carry the haptoglobin α2-α2 genotype had a worse outcome. Interestingly, the presence of a single α-2 allele was associated with worse outcome, suggesting that the haptoglobin α-2 protein may play a role in the pathology of brain injury following aSAH, although the mechanism for this finding requires further research. The haptoglobin genotype may provide additional information on individual risk of secondary injury and recovery to guide care focused on improving outcomes.

Genetic aspects of scurvy and the European famine of 1845-1848

The view of scurvy being exclusively a nutritional disorder needs to be updated. Genetic polymorphisms of HFE and haptoglobin (Hp) may explain the geographic variability of mortality caused by the European famine of the mid-19th century. In this period, potatoes had fallen victim to the potato blight and Ireland was more severely hit than continental Europe. Hereditary hemochromatosis is a genetic disorder with mutations in the HFE gene, characterized by iron overload (with a reduced vitamin C stability) and with a predominance of affected men. The Irish have the world’s highest frequency of the C282Y mutation and the particular iron metabolism of the Irish helps to understand the size of the catastrophe and the observed overrepresentation of male skeletons showing scurvy. Hp is a plasma α₂-glycoprotein characterized by 3 common phenotypes (Hp 1-1, Hp 2-1 and Hp 2-2). When the antioxidant capacity of Hp is insufficient, its role is taken over by hemopexin and vitamin C. The relative number of scurvy victims corresponds with the Hp 2-2 frequency, which is associated with iron conservation and has an impact on vitamin C stability. As iron is more abundant in males, males are overrepresented in the group of skeletons showing scurvy signs.

Haptoglobin polymorphism in relation to antioxidative enzymes activity in type 2 diabetes mellitus

BACKGROUND

Increased oxidative stress and impaired antioxidative capacity are common findings in diabetics. This study reports on the status of antioxidative enzymes in relation to haptoglobin (Hp) polymorphism in type 2 diabetes.

METHODS

The study comprised 165 type 2 diabetic patients and 94 controls. Erythrocytic superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT), and plasmatic ceruloplasmin ferroxidase (Cp) were measured by spectrophotometry and Hp phenotypes were determined by gel electrophoresis.

RESULTS

Irrespective of Hp phenotype, while the activities of Cp ferroxidase and GPx were significantly higher in patients than in controls, those of SOD were significantly lower. No significant differences observed for CAT. However, significant Hp-phenotype dependent differences were observed between patients and controls regarding the activity of these enzymes. While ferroxidase activity in Hp2-2 patients was significantly higher than that in Hp1-1 or Hp2-1 patients, that of SOD and GPx were significantly lower. When patients were analyzed as a single group, Spearman's univariate analysis has demonstrated that HbA1c positively correlates with ferroxidase activity and negatively correlates with levels of GPx and SOD. However, when patients were treated as separate Hp-dependent groups, similar but stronger correlations between these variable were noted only in the case of Hp2-2 patients.

CONCLUSIONS

These findings suggest that Hp polymorphism has some bearing on the activity of antioxidative enzymes in type 2 diabetes and that Hp2-2 diabetics are under increased oxidative stress as compared with those expressing Hp1-1 or Hp2-1.

Methemoglobinemia and ascorbate deficiency in hemoglobin E β thalassemia: metabolic and clinical implications

During investigations of the phenotypic diversity of hemoglobin (Hb) E β thalassemia, a patient was encountered with persistently high levels of methemoglobin associated with a left-shift in the oxygen dissociation curve, profound ascorbate deficiency, and clinical features of scurvy; these abnormalities were corrected by treatment with vitamin C. Studies of erythropoietin production before and after treatment suggested that, as in an ascorbate-deficient murine model, the human hypoxia induction factor pathway is not totally dependent on ascorbate levels. A follow-up study of 45 patients with HbE β thalassemia showed that methemoglobin levels were significantly increased and that there was also a significant reduction in plasma ascorbate levels. Haptoglobin levels were significantly reduced, and the high frequency of the 2.2 haptoglobin genotype may place an additional pressure on ascorbate as a free-radical scavenger in this population. There was, in addition, a highly significant correlation between methemoglobin levels, splenectomy, and factors that modify the degree of globin-chain imbalance. Because methemoglobin levels are modified by several mechanisms and may play a role in both adaptation to anemia and vascular damage, there is a strong case for its further study in other forms of thalassemia and sickle-cell anemia, particularly when splenic function is defective.

Genetic determinants of dietary antioxidant status

Oxidative stress refers to a physiological state in which an imbalance between pro-oxidants and antioxidants results in oxidative damage. Oxidative stress has been associated with the development of numerous chronic diseases such as type 2 diabetes, cardiovascular disease (CVD), osteoporosis, and cancer. Endogenous production of free radicals occurs during normal physiological processes, such as aerobic metabolism, oxidation of biological molecules, and enzymatic activity. Environmental factors such as ultraviolet radiation, air pollution, and cigarette smoking can also contribute to the accumulation of free radicals in the body. Excess free radicals can damage tissues and promote the upregulation of disease-related pathways such as inflammation. Modulating oxidative stress by dietary supplementation with antioxidant micronutrients such as vitamins C and E or phytochemicals such as different carotenoids may help prevent or delay the development of certain diseases. However, research on antioxidant supplementation and disease has yielded inconsistent findings, which may be due, in part, to interindividual genetic variation. Polymorphisms in genes coding for endogenous antioxidant enzymes or proteins responsible for the absorption, transport, distribution, or metabolism of dietary antioxidants have been shown to affect antioxidant status and response to supplementation. These genetic variants may also interact with environmental factors, such as diet, to determine an individual's overall antioxidant status. This chapter examines current knowledge of the relationship between genetic variation and dietary antioxidant status.

Vitamin C deficiency: more than just a nutritional disorder

Although vitamin C deficiency and scurvy are generally considered as pure nutritional disorders, only a minority of the vitamin C concentration is determined by food intake. In the presence of transition metals (iron and copper), the antiscorbutic factor shifts from an antioxidant to a pro-oxidant function. Haptoglobin (Hp) is a plasma α-2 glycoprotein characterized by 3 common phenotypes (Hp 1-1, Hp 2-1 and Hp 2-2). Its free hemoglobin (Hb)-binding capacity prevents Hb-driven oxidative damage. When the antioxidant capacity of Hp is insufficient, its role is taken over by hemopexin (heme-binding protein) and by vitamin C (free radical scavenger). The Hp 2-2 phenotype has a lower capacity to inhibit oxidation and vitamin C depletion. In this article, two consequences of this major finding are tackled. The Hp polymorphism is an important non-nutritional modifying factor in the pathogenesis of vitamin C deficiency and scurvy, which may explain the success of long-range human migration by the natural selection of some populations characterized by high Hp 1 allele frequencies. Moreover, we propose tailoring the recommended dietary allowance (RDA) values of vitamin C, taking into consideration the Hp phenotype dependency.

Changing the face of diabetic care with haptoglobin genotype selection and vitamin e

Research over the past 10 years in our laboratory has led to two major findings. The first is that haptoglobin (Hp) genotype can predict the risk of developing vascular complications in individuals with diabetes mellitus (DM), and the second, more far-reaching discovery, is that vitamin E treatment can significantly reduce vascular complications in individuals with DM and the Hp 2-2 genotype. The former finding has been well documented in numerous studies which included over 50,000 patients of diverse geographical and ethnic backgrounds. The latter discovery is more recent and less well accepted by the medical community due to confounding reports over the past 30 years regarding the efficacy of vitamin E treatment for vascular disease. We propose that the benefit of vitamin E treatment was not obvious in earlier studies due to the absence of any genetic basis for patient selection. Our studies dividing DM individuals into vitamin E treatment subgroups based on Hp genotype show a clear benefit for individuals of the Hp 2-2 genotype, while patients carrying the other two Hp genotypes are not affected or may be adversely affected by receiving vitamin E. These findings may explain the overall lack of benefit seen in previous vitamin E studies and emphasize the importance of carefully selecting which patients should receive vitamin E therapy. The pharmacogenomic paradigm discussed in this review potentially could result in a dramatic improvement in the health of millions of individuals worldwide using a treatment that is both accessible and affordable to all.

Haptoglobin genotype modifies the association between dietary vitamin C and serum ascorbic acid deficiency

BACKGROUND

Haptoglobin (which is encoded by the Hp gene) is a hemoglobin-binding protein that has antioxidant properties and a common polymorphism that consists of 2 structurally different alleles: Hp1 and Hp2. The capacity of Hp2 to inhibit oxidation and vitamin C depletion is less than that of Hp1, but the influence on vitamin C requirements remains unknown.

OBJECTIVE

This study aimed to determine whether the Hp polymorphism modifies the association between dietary vitamin C and serum ascorbic acid deficiency (<11 μmol/L).

DESIGN

Nonsmoking men and women (n = 1046) between 20 and 29 y of age participated in the Toronto Nutrigenomics and Health Study. Blood samples were collected after the subjects had fasted overnight to determine serum ascorbic acid concentrations by HPLC and for genotyping. A 196-item food-frequency questionnaire was used to estimate vitamin C intake.

RESULTS

A gene-diet interaction on serum ascorbic acid was observed (P = 0.02). The overall odds ratio (95% CI) for serum ascorbic acid deficiency was 2.84 (1.73, 4.65) for subjects who did not meet the Recommended Dietary Allowance for vitamin C compared with those who did. The corresponding odds ratios were 4.77 (2.36, 9.65) for the Hp2-2 genotype and 1.69 (0.80, 3.63) for carriers of the Hp1 allele.

CONCLUSIONS

Individuals with the Hp2-2 genotype had an increased risk of deficiency if they did not meet the Recommended Dietary Allowance for vitamin C, whereas carriers of the Hp1 allele did not. The findings suggest that the greater antioxidant capacity of Hp1 might spare serum ascorbic acid.

Haptoglobin and sickle cell polymorphisms and risk of active trachoma in Gambian children

Background

Susceptibility and resistance to trachoma, the leading infectious cause of blindness, have been associated with a range of host genetic factors. In vitro studies of the causative organism, Chlamydia trachomatis, demonstrate that iron availability regulates its growth, suggesting that host genes involved in regulating iron status and/or availability may modulate the risk of trachoma. The objective was to investigate whether haptoglobin (Hp) haplotypes constructed from the functional polymorphism (Hp1/Hp2) plus the functional promoter SNPs -61A-C (rs5471) and -101C-G (rs5470), or sickle cell trait (HbAS, rs334) were associated with risk of active trachoma when stratified by age and sex, in rural Gambian children.

Methodology and Principal Findings

In two cross sectional surveys of children aged 6–78 months (n = 836), the prevalence of the clinical signs of active trachoma was 21.4%. Within boys, haplotype E (-101G, -61A, Hp1), containing the variant allele of the -101C-G promoter SNP, was associated with a two-fold increased risk of active trachoma (OR = 2.0 [1.17–3.44]). Within girls, an opposite association was non-significant (OR = 0.58 [0.32–1.04]; P = 0.07) and the interaction by sex was statistically significant (P = 0.001). There was no association between trachoma and HbAS.

Conclusions

These data indicate that genetic variation in Hp may affect susceptibility to active trachoma differentially by sex in The Gambia.

Vitamin C deficiency is an under-diagnosed contributor to degenerative disc disease in the elderly

The human aging process is often accompanied by significant increases in degenerative spine disease. The pathophysiology of intervertebral disc degeneration has been extensively studied, but the etiology of this aging-related problem remains poorly understood. The elderly often have lower daily vitamin C intakes and circulating ascorbic acid values than younger people because of problems with poor dentition or mobility, and also are more likely to have underlying sub-clinical diseases that can reduce plasma ascorbate concentrations. Ascorbate is essential for collagen production, and vitamin C deficiency will result in defective connective tissue, including reductions in collagen synthesis and structural stability. It is hypothesised that vitamin C deficiencies may be a key contributing factor in the development of degenerative disk disease (DDD) in the elderly. Once degenerative disc disease has begun, the tissue inflammation that accompanies DDD may further increase vitamin C requirements in the affected patient, thereby creating a cascade of positive feedbacks that potentially accelerates and contributes to further disc degeneration and low-back pain. Aggressive monitoring of patient ascorbate status, as well as more finely-calibrated RDAs for vitamin C that explicitly take into account the patient's age, may be required if aging-related degenerative disk disease is to be minimised.