Dietary vitamin A and risk of cancer in the Western Electric study

Unraveling the Effects of Carotenoids Accumulation in Human Papillary Thyroid Carcinoma

Among the thyroid cancers, papillary thyroid cancer (PTC) accounts for 90% of the cases. In addition to the necessity to identify new targets for PTC treatment, early diagnosis and management are highly demanded. Previous data indicated that the multivariate statistical analysis of the Raman spectra allows the discrimination of healthy tissues from PTC ones; this is characterized by bands typical of carotenoids. Here, we dissected the molecular effects of carotenoid accumulation in PTC patients by analyzing whether they were required to provide increased retinoic acid (RA) synthesis and signaling and/or to sustain antioxidant functions. HPLC analysis revealed the lack of a significant difference in the overall content of carotenoids. For this reason, we wondered whether the carotenoid accumulation in PTC patients could be related to vitamin A derivative retinoic acid (RA) biosynthesis and, consequently, the RA-related pathway activation. The transcriptomic analysis performed using a dedicated PCR array revealed a significant downregulation of RA-related pathways in PTCs, suggesting that the carotenoid accumulation in PTC could be related to a lower metabolic conversion into RA compared to that of healthy tissues. In addition, the gene expression profile of 474 PTC cases previously published in the framework of the Cancer Genome Atlas (TGCA) project was examined by hierarchical clustering and heatmap analyses. This metanalysis study indicated that the RA-related pathways resulted in being significantly downregulated in PTCs and being associated with the follicular variant of PTC (FV-PTC). To assess whether the possible fate of the carotenoids accumulated in PTCs is associated with the oxidative stress response, the expression of enzymes involved in ROS scavenging was checked. An increased oxidative stress status and a reduced antioxidant defense response were observed in PTCs compared to matched healthy thyroids; this was possibly associated with the prooxidant effects of high levels of carotenoids. Finally, the DepMap datasets were used to profile the levels of 225 metabolites in 12 thyroid cancer cell lines. The results obtained suggested that the high carotenoid content in PTCs correlates with tryptophan metabolism. This pilot provided novel possible markers and possible therapeutic targets for PTC diagnosis and therapy. For the future, a larger study including a higher number of PTC patients will be necessary to further validate the molecular data reported here.

Population health science as a unifying foundation for translational clinical and public health research

Separated both in academics and practice since the Rockefeller Foundation effort to "liberate" public health from perceived subservience to clinical medicine a century ago, research in public health and clinical medicine have evolved separately. Today, translational research in population health science offers a means of fostering their convergence, with potentially great benefit to both domains. Although evidence that the two fields need not and should not be entirely distinct in their methods and goals has been accumulating for over a decade, the prodigious efforts of biomedical and social sciences over the past year to address the COVID-19 pandemic has placed this unifying approach to translational research in both fields in a new light. Specifically, the coalescence of clinical and population-level strategies to control disease and novel uses of population-level data and tools in research relating to the pandemic have illuminated a promising future for translational research. We exploit this unique window to re-examine how translational research is conducted and where it may be going. We first discuss the transformation that has transpired in the research firmament over the past two decades and the opportunities these changes afford. Next, we present some of the challenges-technical, cultural, legal, and ethical- that need attention if these opportunities are to be successfully exploited. Finally, we present some recommendations for addressing these challenges.

Empirico-inductive and/or hypothetico-deductive methods in food science and nutrition research: which one to favor for a better global health?

Scientific research generally follows two main methods: empirico-inductive (EI), gathering scattered, real-world qualitative/quantitative data to elaborate holistic theories, and the hypothetico-deductive (HD) approach, testing the validity of hypothesized theory in specific conditions, generally according to reductionist methodologies or designs, with the risk of over simplifying the initial complexity empirically perceived in its holistic view. However, in current food and nutrition research, new hypotheses are often elaborated from reductionist data obtained with the HD approach, and aggregated to form (ultra)reductionist theories, with no application of EI observations, limiting the applicability of these hypotheses in real life. This trend and the application of the EI method are illustrated as regards with the global health issue through the examples of food classifications/scoring, clinical studies, the definition of a sustainable diet, the "matrix effect"-related hypothesis, the concept of healthy core metabolism, and obesity prevention within the perspective of social sciences. To be efficient for producing food and nutritional data appropriable by the society, it finally appears that not only both approaches are necessary, starting with the EI method then the HD one, but also a back and forth between the two, this being not always realized, potentially leading to confusion and misunderstanding in society.

Higher Fruits and Vegetables Consumption Is not Associated with Risk of Breast Cancer in Iranian Women

We aimed to investigate the association of fruits and vegetables (FVs) and their all subgroups intakes with breast cancer (BC) risk in Iranian women.

The present case-control study conducted on 150 age-matched women with newly diagnosed BC and apparently healthy controls. Anthropometric measures were collected and eventually, the mean intakes of total FVs and each subgroup were obtained from a validated 147-item food frequency questionnaire. Multivariate regression analysis was used to estimate odds ratios (OR) with 95% confidence intervals (CI).

Our findings revealed that the intake of only dark yellow vegetable was significantly higher in BC patients (P = 0.03) after controlling for covariates. OR of BC across tertiles of FVs intake, showed that there was not any statistical association of total FVs (OR: 1.83, CI: 0.54-6.24, P-trend = 0.3) and their subgroups intakes with BC risk. Except for berry fruits intake which was adversely associated with BC risk (OR: 0.36, CI: 0.09-1.37, P-trend = 0.02).

Our findings did not support the hypothesis that higher total FVs and their subgroups intakes reduce BC risk and suggested that only higher berry fruits intake may have an association with lower BC risk.

Citrus fruit intake and lung cancer risk: A meta-analysis of observational studies

OBJECTIVE

To explore the hypothesis that Citrus intake may reduce the risk of lung cancer.

DESIGN

Meta-analyses of Dichotomy and dose-response relationship.

DATA SOURCES

We searched online literature databases including PubMed, Embase, and Cochrane Library to screen relevant articles available up to 27 July 2020. Search terms included (i) Citrus, Fruit, Diet, Dietary; (ii) cancer, neoplasm, tumor (iii)lung; (iv)case-control, cohort, prospective.

STUDY SELECTION

The selection of studies and the meta-analysis were carried out by following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The following inclusion criteria were chosen: (i) epidemiological studies with case-control or cohort design; (ii) human participants; (iii) studies investigated the relationship between Citrus fruit intake and lung cancer risk; (iv) if data were duplicated in more than two studies, we brought the most recent or all-sided study into this analysis. We collected all full-text articles that met the inclusion criteria. We applied the following exclusion criteria to the full-text articles, including possible articles listed by manual search: (i) there was no represented odds ratio (OR) or relative risk (RR) estimate and its corresponding 95 % confidence interval (95 % CI) (or data to calculate them) for the highest versus lowest levels of Citrus fruit consumption (ii) reviews, systematic reviews and meta-analyses; (iii) there was no data of Citrus fruit intake at the individual level.

DATA EXTRACTION

Two reviewers independently performed the extraction of data from eligible studies.

STATISTICAL METHODS

Adjusted odds ratios (ORs) and 95 % CIs were combined and weighted by the method of "Dersimonian and Laird" to produce pooled ORs using a random-effects model. Moreover, we utilized the method reported by "Longnecker and Greenland" to evaluate linear trends and 95 % CIs by the ORs' natural logs and corresponding CIs from categories of Citrus intake. Finally, we evaluated the risk of publication bias and selection bias by inspecting for asymmetry in the pre-specified funnel plots of the study OR against the standard error of the OR's logarithm and by "Egger's test".

RESULTS

We included twenty-one studies in the final review. Pooled analyses suggested that those with the highest Citrus fruit intake compared to the lowest intake had a 9% reduction in lung cancer risk [OR 0.91 (95 % CI 0.84-0.98)]. We found a nonlinear association between Citrus intake and lung cancer risk in the dose-response analysis (p = 0.0054) and that the risk reached the minimum (OR = 0.91) around 60 g/d. However, no obvious dose-response association was observed with intakes above 80 g/d.

CONCLUSION

We found that Citrus fruit intake was negatively associated with the risk of lung cancer. Besides, there was a nonlinear dose-response relationship between Citrus intake and lung cancer risk within a certain range.

The Benefits and Risks of Certain Dietary Carotenoids that Exhibit both Anti- and Pro-Oxidative Mechanisms-A Comprehensive Review

Carotenoid pigments, particularly β-carotene and lycopene, are consumed in human foodstuffs and play a vital role in maintaining health. β-carotene is known to quench singlet oxygen and can have strong antioxidant activity. As such, it was proposed that β-carotene might reduce the risk of cancer. Epidemiological studies found inverse relationships between cancer risk and β-carotene intake or blood levels. However, clinical trials failed to support those findings and β-carotene supplementation actually increased lung cancer incidence in male smokers. Early experimental animal studies found dietary β-carotene inhibited UV-induced skin cancers. Later studies found that β-carotene supplementation exacerbated UV-carcinogenic expression. The discrepancies of these results were related to the type of diet the animals consumed. Lycopene has been associated with reduced risk of lethal stage prostate cancer. Other carotenoids, e.g., lutein and zeaxanthin, play a vital role in visual health. Numerous studies of molecular mechanisms to explain the carotenoids' mode of action have centered on singlet oxygen, as well as radical reactions. In cellular systems, singlet oxygen quenching by carotenoids has been reported but is more complex than in organic solvents. In dietary β-carotene supplement studies, damaging pro-oxidant reactivity can also arise. Reasons for this switch are likely due to the properties of the carotenoid radicals themselves. Understanding singlet oxygen reactions and the anti-/pro-oxidant roles of carotenoids are of importance to photosynthesis, vision and cancer.

Spirulina platensis ameliorates arsenic-mediated uterine damage and ovarian steroidogenic disorder

Novel, non-invasive, painless oral therapeutic agents are needed to replace the painful conventional treatment of arsenic-associated health hazards with metal chelators. Our aim was to examine the effect of spirulina ( Spirulina platensis ( Geitler, 1925 )) on arsenic-mediated uterine toxicity. Female Wistar rats were divided equally into four experimental treatment groups: control group, sodium arsenite group (1.0 mg/100 g body mass), spirulina placebo group (20 mg/100 g body mass), and sodium arsenite + spirulina group. In contrast with the control group, spectrophotometric and electrozymographic evaluation revealed that rats that ingested arsenic for 8 d showed significant diminution of the activities of superoxide dismutase, catalase, and peroxidase ( p < 0.001). Mutagenic uterine DNA breakage and tissue damage were prominent following arsenic consumption by the rats. Oral delivery of spirulina resulted in a significant amelioration of arsenic-induced adverse oxidative stress and genotoxic state of rats. A significant low-signaling ( p < 0.001) of gonadotropins and estradiol was also noted in the arsenic-treated rats, which was terminated by spirulina; this arsenic-primed adverse effect was significant ( p < 0.05, p < 0.01). The spirulina treatment mechanism could be associated with augmentation of the antioxidant defense system that protects the arsenic-mediated pathological state of the uterus.

Mitochondrial dysfunction contribute to diabetic neurotoxicity induced by streptozocin in mice: protective effect of Urtica dioica and pioglitazone

INTRODUCTION

Uncontrolled chronic hyperglycemia in diabetic patients could result in various complications, including neurotoxicity. Urtica dioica L. (UD) is known for its hypoglycemic and antioxidant effects. In this study, we evaluated the efficacy of UD and pioglitazone (PIO) in reduction of neurotoxicity and oxidative stress in streptozocin-induced diabetic mice.

MATERIALS AND METHODS

Male mice were divided into seven groups: control, diabetic, dimethyl sulfoxide-treated control, PIO-treated, UD-treated, UD-PIO-treated, and vitamin E-treated. For induction of diabetes, streptozocin was injected in a single dose (65 mg/kg, i.p.). All treatments were performed for 5 weeks. Neurotoxicity was evaluated through hot plate and formalin test. Then, animals were killed, brain tissue was separated and the mitochondrial fraction was isolated with different centrifuge technique. Also, oxidative stress markers (reactive oxygen species, lipid peroxidation, protein carbonyl, glutathione) were measured in brain. Mitochondrial function was evaluated by MTT test in brain isolated mitochondria.

RESULTS

Elevation of oxidative stress markers and mitochondrial damage were observed in diabetic mice compared to control group. Administration of PIO and UD ameliorated the oxidative stress and mitochondrial damage (p < 0.05) in diabetic mice. Also increase in pain score was shown in diabetic mice that treatment with UD and PIO diminished elevation of pain score in diabetic mice. Interestingly, simultaneous administration of PIO and UD showed synergism effect in attenuation of oxidative stress and hyperglycemia.

CONCLUSION

UD showed a therapeutic potential for the attenuation of oxidative stress and diabetes-induced hyperglycemia that can be considered as co-treatment in treatment of diabetic neurotoxicity.

Identification and Evaluation of Cytotoxicity of Peptide Liposome Incorporated Citron Extracts in an in Vitro System

Abstract: Citrons have been widely used for medicinal purposes for a long time, but the application of citron in the food industry is still restricted. The extensive advantages of nanotechnology in the food industry have greatly broadened the application of foods. In this study, by employing nanotechnology, we prepared citron-extract nanoparticle with an average size of 174.11 ± 3.89 nm, containing protein peptide and/or liposome. In order to evaluate the toxicity of nanoparticles and to ensure food safety, biological cytotoxicity at the cell and genomic levels was also identified to examine the toxicity of citron extracts by using an in vitro system. Our results demonstrated that the cytotoxicity of citron_liposome was dependent on cell type in high concentrations (1 and 5 mg/mL), selectively against primary human cardiac progenitor cells (hCPCs), and human endothelial progenitor cells (hEPCs) in MTT and lactate dehydrogenase (LDH) assays. Interestingly, for the NIH-3T3 and H9C2 cell lines, cell cytotoxicity was observed with slight genotoxicity, especially from citron_peptide extract for both cell lines. Taken together, our study provides cytotoxicity data on nanoengineered citron extracts according to different cell type as is crucial for further applications.

Benzo(a)pyrene induced lung cancer: Role of dietary phytochemicals in chemoprevention

Lung cancer is the major cause of overall cancer deaths, and chemoprevention is a promising strategy to control this disease. Benzo(a)pyrene [B(a)P], a polycyclic aromatic hydrocarbon, is one among the principal constituents of tobacco smoke that plays a key role in lung carcinogenesis. The B(a)P induced lung cancer in mice offers a relevant model to study the effect of natural products and has been widely used by many researchers and found considerable success in ameliorating the pathophysiological changes of lung cancer. Currently available synthetic drugs that constitute the pharmacological armamentarium are themselves effective in managing the condition but not without setbacks. These hunches have accelerated the requisite for natural products, which may be used as dietary supplement to prevent the progress of lung cancer. Besides, these agents also supplement the conventional treatment and offer better management of the condition with less side effects. In the context of soaring interest toward dietary phytochemicals as newer pharmacological interventions for lung cancer, in the present review, we are attempting to give a silhouette of mechanisms of B(a)P induced lung carcinogenesis and the role of dietary phytochemicals in chemoprevention.

Citrus fruit intake and breast cancer risk: a quantitative systematic review

PURPOSE

We investigated the association between dietary intake of citrus fruits and breast cancer risk.

METHODS

The PubMed and EMBASE were searched for relevant articles on diet and breast cancer up to January 2012. All of the epidemiological studies that assessed dietary intake of citrus fruits and presented risk estimates of the association between citrus fruits intake and risk of breast cancer were reviewed. Multivariable-adjusted odds ratios (OR) and associated 95% confidence intervals (CI) for highest versus lowest intake of dietary citrus fruits level were extracted. Overall summary OR was calculated by using a fixed-effect meta-analysis.

RESULTS

Six case-control studies out of five articles were eligible. Overall summary OR showed a 10% reduction in risk of breast cancer associated with high intake of citrus fruits (summary OR, 0.90; 95% CI, 0.85-0.96; p<0.001); results were consistent across the studies (I (2)=0). Visual inspection of the results did not suggest a publication bias.

CONCLUSION

Pooled results from observational studies showed an inverse association between citrus fruits intake and the risk of breast cancer.

Food synergy: the key to a healthy diet

Food synergy is the concept that the non-random mixture of food constituents operates in concert for the life of the organism eaten and presumably for the life of the eater. Isolated nutrients have been extensively studied in well-designed, long-term, large randomised clinical trials, typically with null and sometimes with harmful effects. Therefore, although nutrient deficiency is a known phenomenon, serious for the sufferer, and curable by taking the isolated nutrient, the effect of isolated nutrients or other chemicals derived from food on chronic disease, when that chemical is not deficient, may not have the same beneficial effect. It appears that the focus on nutrients rather than foods is in many ways counterproductive. This observation is the basis for the argument that nutrition research should focus more strongly on foods and on dietary patterns. Unlike many dietary phenomena in nutritional epidemiology, diet pattern appears to be highly correlated over time within person. A consistent and robust conclusion is that certain types of beneficial diet patterns, notably described with words such as 'Mediterranean' and 'prudent', or adverse patterns, often described by the word 'Western', predict chronic disease. Food is much more complex than drugs, but essentially uninvestigated as food or pattern. The concept of food synergy leads to new thinking in nutrition science and can help to forge rational nutrition policy-making and to determine future nutrition research strategies.

Cancer chemoprevention: successes and failures

BACKGROUND

Cancer has traditionally been considered a single disease, but it is now known to be far more complex, with an unfolding etiology. In less than 2 centuries, hundreds--if not thousands--of drugs for the treatment of cancer and for palliative care have been developed and tested, with 143 having achieved approval by the US Food and Drug Administration (MediLexicon International; "Cancer Drugs & Oncology Drugs," http://www.medilexicon.com/drugs-list/cancer.php). Just 13 agents have been approved, however, for treating precancerous lesions or for reducing risk.

CONTENT

Nonsteroidal antiinflammatory drugs, vitamins, food constituents and spice components, antidiabetic drugs, ω-3 fatty acids, and fiber are just a few of the many classes of compounds that have been tested for their cancer-preventive potential. We highlight some of the agents that have been scrutinized by way of randomized clinical trials in humans for their cancer prevention potential. We summarize the major definitive cancer chemoprevention studies that (a) were successful in demonstrating efficacy and ultimately received regulatory approval; (b) were not successful in demonstrating efficacy or had unacceptable toxicities, but from which the field has learned important lessons; and (c) showed compelling efficacy against surrogate end points but failed to achieve regulatory approval because of a lack of consensus regarding the relevance of those end points to clinical benefit.

SUMMARY

Chemopreventive studies have provided new insights into early disease pathogenesis, stimulated new risk assessments and models, fostered important research in end point biomarkers, and led to 13 approved agents. The development of safe and effective chemopreventive agents holds tremendous potential for reducing the burden of cancer.

Lung cancer: epidemiology, etiology, and prevention

Lung cancer is the leading cause of cancer death in the United States and around the world. A vast majority of lung cancer deaths are attributable to cigarette smoking, and curbing the rates of cigarette smoking is imperative. Understanding the epidemiology and causal factors of lung cancer can provide additional foundation for disease prevention. This article focuses on modifiable risk factors, including tobacco smoking, occupational carcinogens, diet, and ionizing radiation. It also discusses briefly the molecular and genetic aspects of lung carcinogenesis.

Lung cancer: epidemiology, etiology, and prevention

Lung cancer is the leading cause of cancer death in the United States and around the world. A vast majority of lung cancer deaths are attributable to cigarette smoking, and curbing the rates of cigarette smoking is imperative. Understanding the epidemiology and causal factors of lung cancer can provide additional foundation for disease prevention. This article focuses on modifiable risk factors, including tobacco smoking, occupational carcinogens, diet, and ionizing radiation. It also discusses briefly the molecular and genetic aspects of lung carcinogenesis.

Longitudinal association between animal and vegetable protein intake and obesity among men in the United States: the Chicago Western Electric Study

BACKGROUND

Literature on the association of protein intake with body weight is inconsistent. Little is known about the relation of long-term protein intake to obesity.

OBJECTIVE

This study aimed to determine the association between protein intake and obesity.

DESIGN

A cohort of 1,730 employed white men aged 40 to 55 years from the Chicago Western Electric Study was followed from 1958 to 1966. Diet was assessed twice with Burke's comprehensive diet history method at two baseline examinations; height, weight, and other covariates were measured annually by trained interviewers. Generalized estimating equation was used to examine the relation of baseline total, animal, and vegetable protein intake to likelihood of being overweight or obese at sequential annual examinations.

RESULTS

Dietary animal protein was positively related to overweight and obesity across 7 years of follow up. With adjustment for potential confounders (age, education, cigarette smoking, alcohol intake, energy, carbohydrate and saturated fat intake, and history of diabetes or other chronic disease), the odds ratios (95% confidence intervals) for obesity were 4.62 (2.68 to 7.98) (P for trend <0.01) for participants in the highest compared to the lowest quartile of animal protein and 0.58 (0.36, 0.95) (P for trend = 0.053) for those in the highest quartile of vegetable protein intake. A statistically significant, positive association was seen between animal protein intake and obesity; those in higher quartiles of vegetable protein intake had lower odds of being obese.

CONCLUSIONS

These results indicate that animal and vegetable protein may relate differently to occurrence of obesity in the long run.

Chemoprevention--history and general principles

Our current understanding of tumourigenesis suggests that cancer develops as a series of cumulative genetic and epigenetic derangements across time culminating in a clone of cells differing from its population of origin in terms of cellular identity, growth control, and its contextual relationship to its environment. Our increasing knowledge of the timing, sequence, frequency, and specific implications of these changes provides unique opportunities for earlier identification of aberrations and preventive interventions. Here we discuss the fundamentals of cancer prevention including the targets, cohorts, agents, endpoints, mechanistic biomarkers, designs, and strategies employed in preventive drug development. There have been many notable successes in this field such as the identification and development of tamoxifen and raloxifene for breast cancer risk reduction, instillational BCG and valrubicin for treatment of preinvasive bladder cancer, and a variety of topical and systemic agents that effectively treat preinvasive neoplastic lesions of the skin. A variety of null or negative developmental endeavours have occurred as well, including trials of beta-carotene for lung cancer prevention, nutritional modifications for colorectal adenoma prevention, and most recently, selenium and alpha-tocopherol for prostate cancer prevention. A third category of prevention trials can be summarized as investigationally successful, but not achieving regulatory success. The development of finasteride and dutasteride for prostate cancer prevention, and celecoxib for colorectal neoplasia prevention fall into this category. In less than four decades, cancer chemoprevention has transformed from a concept to an achievable reality.

Tomato lycopene and lung cancer prevention: from experimental to human studies

Increasing evidence suggests that tomato lycopene may be preventive against the formation and the development of lung cancer. Experimental studies demonstrated that lycopene may inhibit the growth of several cultured lung cancer cells and prevent lung tumorigenesis in animal models through various mechanisms, including a modulation of redox status, cell cycle arrest and/or apoptosis induction, a regulation of growth factor signaling, changes in cell growth-related enzymes, an enhancement of gap junction communication and a prevention of smoke-induced inflammation. In addition, lycopene also inhibited cell invasion, angiogenesis, and metastasis. Several lycopene metabolites have been identified, raising the question as to whether the preventive effects of lycopene on cancer risk is, at least in part, due to its metabolites. Despite these promising reports, it is difficult at the moment to directly relate available experimental data to human pathophysiology. More well controlled clinical intervention trials are needed to further clarify the exact role of lycopene in the prevention of lung cancer cell growth. Such studies should take into consideration subject selection, specific markers of analysis, the levels of carotenoids being tested, metabolism and isomerization of lycopene, interaction with other bioactive food components. This article reviews data on the cancer preventive activities of lycopene, possible mechanisms involved, and the relationship between lycopene consumption and human cancer risk.

How strong is the evidence that solar ultraviolet B and vitamin D reduce the risk of cancer?: An examination using Hill's criteria for causality

The ultraviolet-B (UVB)-vitamin D-cancer hypothesis was proposed in 1980. Since then, several ecological and observational studies have examined the hypothesis, in addition to one good randomized, controlled trial. Also, the mechanisms whereby vitamin D reduces the risk of cancer have been elucidated. This report aims to examine the evidence to date with respect to the criteria for causality in a biological system first proposed by Robert Koch and later systematized by A. Bradford Hill. The criteria of most relevance are strength of association, consistency, biological gradient, plausibility/mechanisms and experimental verification. Results for several cancers generally satisfy these criteria. Results for breast and colorectal cancer satisfy the criteria best, but there is also good evidence that other cancers do as well, including bladder, esophageal, gallbladder, gastric, ovarian, rectal, renal and uterine corpus cancer, as well as Hodgkin's and non-Hodgkin's lymphoma. Several cancers have mixed findings with respect to UVB and/or vitamin D, including pancreatic and prostate cancer and melanoma. Even for these, the benefit of vitamin D seems reasonably strong. Although ecological and observational studies are not generally regarded as able to provide convincing evidence of causality, the fact that humanity has always existed with vitamin D from solar UVB irradiance means that there is a wealth of evidence to be harvested using the ecological and observational approaches. Nonetheless, additional randomized, controlled trials are warranted to further examine the link between vitamin D and cancer incidence, survival and mortality.

Carotenoids and the risk of developing lung cancer: a systematic review

BACKGROUND

Carotenoids are thought to have anti-cancer properties, but findings from population-based research have been inconsistent.

OBJECTIVE

We aimed to conduct a systematic review of the associations between carotenoids and lung cancer.

DESIGN

We searched electronic databases for articles published through September 2007. Six randomized clinical trials examining the efficacy of beta-carotene supplements and 25 prospective observational studies assessing the associations between carotenoids and lung cancer were analyzed by using random-effects meta-analysis.

RESULTS

The pooled relative risk (RR) for the studies comparing beta-carotene supplements with placebo was 1.10 (95% confidence limits: 0.89, 1.36; P = 0.39). Among the observational studies that adjusted for smoking, the pooled RRs comparing highest and lowest categories of total carotenoid intake and of total carotenoid serum concentrations were 0.79 (0.71, 0.87; P < 0.001) and 0.70 (0.44, 1.11; P = 0.14), respectively. For beta-carotene, highest compared with lowest pooled RRs were 0.92 (0.83, 1.01; P = 0.09) for dietary intake and 0.84 (0.66, 1.07; P = 0.15) for serum concentrations. For other carotenoids, the RRs comparing highest and lowest categories of intake ranged from 0.80 for beta-cryptoxanthin to 0.89 for alpha-carotene and lutein-zeaxanthin; for serum concentrations, the RRs ranged from 0.71 for lycopene to 0.95 for lutein-zeaxanthin.

CONCLUSIONS

beta-Carotene supplementation is not associated with a decrease in the risk of developing lung cancer. Findings from prospective cohort studies suggest inverse associations between carotenoids and lung cancer; however, the decreases in risk are generally small and not statistically significant. These inverse associations may be the result of carotenoid measurements' function as a marker of a healthier lifestyle (higher fruit and vegetable consumption) or of residual confounding by smoking.

Vitamin A deficiency causes metaplasia in vocal fold epithelium: a rat study

OBJECTIVES

The roles of vitamin A in the vocal fold epithelium are not well documented, although vitamin A has been used as a conservative treatment for laryngeal leukoplakia. The purpose of this study was to analyze the roles of vitamin A in vocal fold epithelial differentiation.

METHODS

Vitamin A-deficient (VAD) rats were generated, and the abnormality of their vocal fold epithelium was examined by hematoxylin and eosin staining and immunohistochemical analysis for keratin 10 and transglutaminase (TGase) 1.

RESULTS

The VAD experimental rats exhibited orthokeratosis of the vocal fold epithelium. Keratin 10 and TGase 1 were up-regulated in the epithelium of the VAD rats.

CONCLUSIONS

It is suggested that vitamin A suppresses TGase 1 expression in normal vocal folds to inhibit keratinization, and that the TGase 1 up-regulation caused by vitamin A deficiency may be related to the formation of metaplasia in the laryngeal epithelium.

Development, implementation, and evaluation of a computerized self-administered diet history questionnaire for use in studies of American Indian and Alaskan native people

Collection of dietary intake in epidemiologic studies involves using methods that are comprehensive yet appropriate for the population being studied. Here we describe a diet history questionnaire (DHQ) that was developed using an audio self-administered computer-assisted interview technique. The DHQ was developed for use in a cohort of American Indians and Alaskan Natives with tribal input and area-specific modules to incorporate local food availability. The DHQ includes 54 main food group questions, specific food items within the main food group, and food preparation and general eating practice questions. The questionnaire was programmed to be self-administered using a computer with a touch screen. The average time for the first 6,604 participants to complete the questionnaire was 36 minutes. Almost 100% of participants had complete DHQ data and the average number of food items selected was 70. The methods developed for collection of dietary data appear to be appropriate for the targeted population and may have usefulness for other populations where collecting dietary data in a self-administered format is desirable.

Food, not nutrients, is the fundamental unit in nutrition

The identification of nutrients and the study of their bioactivity were significant developments in the evolution of contemporary nutrition science. This review argues for shifting the focus towards food in order to better understand the nutrition-health interface. It begins by introducing the concept of food synergy (a perspective that more information can be obtained by looking at foods than at single food components) to denote the action of the food matrix (the composite of naturally occurring food components) on human biological systems. A proposal is then made for the means by which food-focused research might build the knowledge base for etiologic discovery and appropriate dietary advice. The diet-heart disease dilemma is put forward as an example of where a nutrient-based approach has limitations, and a summary of studies targeting food composition strengthens the case for a food-based approach. Finally, the argument is made that evidence from interventions points back to the central position of food in the relationship between nutrition and health, a position that begs for more whole food-based research.

Combination of physical activity, nutrition, or other metabolic factors and vaccine response

A number of lifestyle factors that reduce cancer risk in the primary prevention setting may be potential new targets for use in combination with cancer vaccines. This review discusses the modulation of energy balance (physical activity, calorie restriction, and obesity prevention), and the supplementation with natural and synthetic analogs of vitamins A and E, as potential interventions for use in combination with cancer vaccines. Additionally, the pharmacologic manipulation of nutrient metabolism in the tumor microenvironment (e.g., arachidonic acid, arginine, tryptophan, and glucose metabolism) is discussed. This review includes a brief overview of the role of each agent in primary cancer prevention; outlines the effects of these agents on immune function, specifically adaptive and/or anti-tumor immune mechanisms, when known; and discusses the potential use of these interventions in combination with therapeutic cancer vaccines. Modulation of energy balance through exercise and strategies targeting nutrient metabolism in the tumor microenvironment represent the most promising interventions to partner with therapeutic cancer vaccines. Additionally, the use of vitamin E succinate and the retinoid X receptor-directed rexinoids in combination with cancer vaccines offer promise. In summary, a number of energy balance- and nutrition-related interventions are viable candidates for further study in combination with cancer vaccines.

Monitoring micronutrients in cigarette smokers

Smoking is associated with oxidative stress and increased risks of many chronic diseases that both shorten life and impair its quality. Low concentrations of several micronutrients, especially the antioxidants vitamin C and beta-carotene, are also associated with smoking, and there has been much interest in determining whether deficiencies in micronutrients are involved etiologically in smoking-related diseases. The objective of this review was to bring together reports on dietary intakes, biochemical indicators of micronutrient status, and results of some intervention studies on micronutrients where authors had compared outcomes in smokers and non-smokers. The micronutrients discussed are vitamins A, E, and C; the carotenoids; some of the B-vitamin group; and the minerals selenium, zinc, copper, and iron. The data were then examined to determine whether effects on the biochemical markers of micronutrient status were due to differences in dietary intakes between smokers and non-smokers or to the consequences of inflammatory changes caused by the oxidative stress of smoking. It was concluded that although smoking is associated with reduced dietary intake of vitamin C and carotenoid-containing foods, inflammatory changes increase turnover of these micronutrients so that blood concentrations are still lower in smokers than non-smokers even when there is control for dietary differences. In the case of vitamin E, there is some evidence for increased turnover of this nutrient in smokers, but this has little to no influence on blood concentrations, and there are no differences in dietary intake of vitamin E between smokers and non-smokers. Serum concentrations of vitamin A, folate, and vitamin B12 and B6 markers do not appear to be influenced by smoking, although there is some influence of dietary intake on concentrations of these nutrients in the body. In the case of the minerals examined, the main effects on biochemical markers of mineral status were attributed to inflammation and were therefore greater in heavy or long-term smokers. Serum concentrations of selenium and erythrocyte GPx activity were lower in smokers. Erythrocyte CuZn-SOD activity and serum ceruloplasmin concentrations were elevated, while serum zinc concentrations were depressed only in heavy smokers. Lastly, smoking appears to affect iron homeostasis mainly by changing hemoglobin concentrations, which were in general increased. Serum iron, TfR, and ferritin were mostly unaffected by smoking, except in pregnancy where there is evidence of increased erythropoiesis causing lower saturation of plasma transferrin and some evidence of lowering of iron stores.

Carotenoid actions and their relation to health and disease

Based on extensive epidemiological observation, fruits and vegetables that are a rich source of carotenoids are thought to provide health benefits by decreasing the risk of various diseases, particularly certain cancers and eye diseases. The carotenoids that have been most studied in this regard are beta-carotene, lycopene, lutein and zeaxanthin. In part, the beneficial effects of carotenoids are thought to be due to their role as antioxidants. beta-Carotene may have added benefits due its ability to be converted to vitamin A. Additionally, lutein and zeaxanthin may be protective in eye disease because they absorb damaging blue light that enters the eye. Food sources of these compounds include a variety of fruits and vegetables, although the primary sources of lycopene are tomato and tomato products. Additionally, egg yolk is a highly bioavailable source of lutein and zeaxanthin. These carotenoids are available in supplement form. However, intervention trials with large doses of beta-carotene found an adverse effect on the incidence of lung cancer in smokers and workers exposed to asbestos. Until the efficacy and safety of taking supplements containing these nutrients can be determined, current dietary recommendations of diets high in fruits and vegetables are advised.

The effect of exercise and nettle supplementation on oxidative stress markers in the rat brain

Chronic swimming training and phytotherapeutic supplementation are assumed to alleviate oxidative damage, and support cell survival in the brain. The effect of forced, chronic swimming training, and enriched lab chow containing 1% (w/w) dried nettle (Urtica dioica) leaf were investigated for oxidative stress, inflammation and neurotrophic markers in Wistar rat brains. The rats were divided into groups subjected to swimming training (6 weeks) or to nettle supplementation (8 weeks) or to a combination of these two treatments. The level of oxidative stress was measured by electron spin resonance (EPR), and by the concentration of carbonylated proteins. Nettle supplementation resulted in a decreased concentration of free radicals in both cerebellum and frontal lobe. Swimming, however, did not influence significantly the oxidative damage nor was it reflected in the carbonyl content. The protein content of nerve growth factor (NGF), and brain-derived neurotrophic factors (BDNF) was evaluated by E-Max ImmunoAssay in the cerebellum. No changes occurred either with exercise or nettle diet treatments. On the other hand, nuclear factor kappa B (NF-kappaB) binding activity to DNA increased with the combined effect of swimming training and nettle diet, while the activator protein1 (AP-1) DNA binding activity showed a more profound elevation in the nettle treated animals. The amount of c-Jun decreased by swimming training. In conclusion, the results suggest that both exercise and nettle influenced physiological brain functions. Nettle supplementation reduces the free radical concentration and increases the DNA binding of AP-1 in the brain. Nettle was found to be an effective antioxidant and possible antiapoptotic supplement promoting cell survival in the brain. Exercise, as a downregulator of c-Jun and in combined group as an upregulator of NF-kappaB, may play also a role in antiapoptotic processes, which is important after brain injury.

Effects of age and dietary beta-carotene on immunological variables in dogs

beta-Carotene is a naturally occurring carotenoid reported to have health-promoting effects in several species. Advancing age is known to have a negative impact on various immune variables in several species. This study was conducted in order to assess the effect of age on immune response in dogs and to determine whether beta-carotene is able to reverse this age-associated decline. To test this hypothesis, young and old dogs (n = 36) were fed either a control diet or experimental diets containing supplemental beta-carotene for 2-month periods. Age significantly (P < .05) lowered CD4+ T cell populations (47.2% versus 33.7%; young-control versus old-control, respectively) and beta-carotene restored percent distributions in old dogs to nonsignificance versus younger controls (41.0%). T cell proliferation was lower in old dogs (30,254 +/- 2,248 versus 14,811 +/- 2,497 cCPM; young-control versus old-control, respectively; P < .05), and beta-carotene supplementation significantly improved responses in this age group (21,329 +/- 2,275 cCPM). Although B cell proliferation was depressed with age (17,967 +/- 1,384 versus 7,535 +/- 1,469 cCPM; young-control versus old-control, respectively; P < .05), beta-carotene supplementation improved B cell proliferation in young dogs (23,500 +/- 1,339 cCPM). Old dogs displayed lower delayed-type hypersensitivity test (DTH) responses versus younger controls to both phytohemagglutinin-P (PHA; 11.1 +/- 0.95 versus 7.57 +/- 1.15 mm; young-control versus old-control, respectively; P < .05) and sheep red blood cell (RBC; 9.12 +/- 0.62 versus 8.08 +/- 0.75 mm; young-control versus old-control, respectively; P < .10). beta-Carotene improved these responses, mostly within the first 24-48 hours after injection. In summary, older dogs have lower immunological responses compared with younger controls. beta-Carotene supplementation significantly restored immune responses in older dogs when compared with their age-matched controls and younger counterparts.

Epidemiology, etiology, and prevention of lung cancer

Over the past century, lung cancer has gone from an obscure disease to the leading cause of cancer death worldwide. Initially an epidemic disease among men in industrialized nations, lung cancer now has become the leading cancer killer in both sexes in the United States and an increasingly common disease of both sexes in developing countries. Lung cancer incidence largely mirrors smoking prevalence, with a latency period of several decades. Other important risk factors for the development of lung cancer include environmental exposure to tobacco smoke, radon, occupational carcinogens, and pre-existing nonmalignant lung disease. Studies in molecular biology have elucidated the role that genetic factors play in modifying an individual's risk for lung cancer. Although chemopreventive agents may be developed to prevent lung cancer, prevention of smoking initiation and promotion of smoking cessation are currently the best weapons to fight lung cancer. No other malignancy has been shown to have such a strong epidemiologic relation between a preventable behavior and incidence of disease. Despite this knowledge, more than 20% of all Americans smoke, and tobacco use is exploding in developing countries. Based on current and projected smoking patterns, it is anticipated that lung cancer will remain the leading cause of cancer death in the world for decades to come.

UV light, beta-carotene and human skin--beneficial and potentially harmful effects

Solar radiation is one of the most important environmental stress agents for human skin, causing sunburn, premature skin aging, and skin cancer. Beta-carotene is discussed to protect against photooxidative stress and thus prevent skin damage. Though beta-carotene has been successfully used against photosensitivity in patients with erythropoietic protoporphyria, its beneficial potential in normal skin is still uncertain. A number of experimental studies indicate protective effects of beta-carotene against acute and chronic manifestations of skin photodamage. However, most clinical studies have failed to convincingly demonstrate its beneficial effects so far. Nevertheless, intake of oral beta-carotene supplements before sun exposure has been recommended on a population-wide basis. Recent studies on skin cells in culture have revealed that beta-carotene acts not only as an antioxidant but also has unexpected prooxidant properties. At present, there is an ongoing debate on the protective or potentially harmful role of beta-carotene in human skin.

The epidemiology of lung cancer

Lung cancer continues to be the leader in cancer deaths in the United States. The incidence of lung cancer in men has slowly decreased since the late 1980s, but has just now begun to plateau in women at the end of this decade. Despite modest advances in chemotherapy for treating lung cancer, it remains a deadly disease with overall 5-yr survival rates having not increased significantly over the last 25 years, remaining at approximately 14%. Tobacco smoking causes approximately 85-90% of bronchogenic carcinoma. Environmental tobacco exposure or a second-hand smoke also may cause lung cancer in life-long non-smokers. Certain occupational agents such as arsenic, asbestos, chromium, nickel and vinyl chloride increase the relative risk for lung cancer. Smoking has an additive or multiplicative effect with some of these agents. Familial predisposition for lung cancer is an area with advancing research. Developments in molecular biology have led to growing interest in investigation of biological markers, which may increase predisposition to smoking-related carcinogenesis. Hopefully, in the future we will be able to screen for lung cancer by using specific biomarkers. Finally, dietary factors have also been proposed as potential risk modulators, with vitamins A, C and E proposed as having a protective effect. Despite the slow decline of smoking in the United States, lung cancer will likely continue its devastation for years to come.

Vegetarian diet: panacea for modern lifestyle diseases?

We review the beneficial and adverse effects of vegetarian diets in various medical conditions. Soybean-protein diet, legumes, nuts and soluble fibre significantly decrease total cholesterol, low-density lipoprotein cholesterol and triglycerides. Diets rich in fibre and complex carbohydrate, and restricted in fat, improve control of blood glucose concentration, lower insulin requirement and aid in weight control in diabetic patients. An inverse association has been reported between nut, fruit, vegetable and fibre consumption, and the risk of coronary heart disease. Patients eating a vegetarian diet, with comprehensive lifestyle changes, have had reduced frequency, duration and severity of angina as well as regression of coronary atherosclerosis and improved coronary perfusion. An inverse association between fruit and vegetable consumption and stroke has been suggested. Consumption of fruits and vegetables, especially spinach and collard green, was associated with a lower risk of age-related ocular macular degeneration. There is an inverse association between dietary fibre intake and incidence of colon and breast cancer as well as prevalence of colonic diverticula and gallstones. A decreased breast cancer risk has been associated with high intake of soy bean products. The beneficial effects could be due to the diet (monounsaturated and polyunsaturated fatty acids, minerals, fibre, complex carbohydrate, antioxidant vitamins, flavanoids, folic acid and phytoestrogens) as well as the associated healthy lifestyle in vegetarians. There are few adverse effects, mainly increased intestinal gas production and a small risk of vitamin B12 deficiency.

Vitamin A toxicity secondary to excessive intake of yellow-green vegetables, liver and laver

We report a case of sudden onset of vitamin A poisoning. A 20-year-old Japanese woman had been eating pumpkin and only a very limited amount of other foods on a daily basis for 2 years. She was overly concerned about weight reduction. Aurantiasis cutis and abnormal liver function tests were noted by her family doctor in 1995 when she was 18 years old. At that time, she stopped eating pumpkin. However, she secretly continued an excessive intake of other beta-carotene-rich vegetables, liver and laver for about 2 years. Two and one-half years after being seen by her family physician, she experienced sudden onset of low-grade fever, limb edema, cheilitis, dry skin, and headache. These symptoms worsened daily. A liver needle biopsy was performed, and it showed a normal portal tract along with fat-laden Ito cells in the space of Disse. A final diagnosis of vitamin A poisoning and hepatic injury secondary to an eating disorder was made. Her symptoms and serum beta-carotene levels returned to normal with successful adjustment of her diet.

Beta-carotene and lung cancer: a case study

The conflicting evidence of the relation between beta-carotene and lung cancer in humans serves as a poignant case study with respect to what types of evidence are sufficient to support or change a nutrition recommendation. This article is a review of the available evidence of the relation between beta-carotene and lung cancer, including data regarding beta-carotene intake (from diet and supplements), beta-carotene biochemical status, and vegetable and fruit consumption, and a discussion of the role of this evidence in making nutrition recommendations. More than 30 case-control and cohort studies were conducted over many years in various populations and indicated that people who eat more vegetables and fruit, foods rich in carotenoids, and carotenoids (beta-carotene in particular), as well as those with higher blood beta-carotene concentrations, have a lower risk of lung cancer than those who eat fewer such foods or have lower beta-carotene concentrations. In contrast, the intervention results from large, controlled trials of beta-carotene supplementation do not support the observed beneficial associations or a role for supplemental beta-carotene in lung cancer prevention; instead, they provide striking evidence for adverse effects (ie, excess lung cancer incidence and overall mortality) in smokers. The findings require that caution be exercised in recommending supplemental beta-carotene, particularly for smokers, and argue against changing the vegetable-fruit recommendations in the direction of greater nutrient specificity. This case study of beta-carotene and lung cancer stresses the importance of having results from at least one, and preferably more, large, randomized intervention trial before public health recommendations concerning micronutrient supplementation are considered.

Toward a new recommended dietary allowance for vitamin C based on antioxidant and health effects in humans

The current recommended dietary allowance (RDA) for vitamin C for adult nonsmoking men and women is 60 mg/d, which is based on a mean requirement of 46 mg/d to prevent the deficiency disease scurvy. However, recent scientific evidence indicates that an increased intake of vitamin C is associated with a reduced risk of chronic diseases such as cancer, cardiovascular disease, and cataract, probably through antioxidant mechanisms. It is likely that the amount of vitamin C required to prevent scurvy is not sufficient to optimally protect against these diseases. Because the RDA is defined as "the average daily dietary intake level that is sufficient to meet the nutrient requirement of nearly all healthy individuals in a group," it is appropriate to reevaluate the RDA for vitamin C. Therefore, we reviewed the biochemical, clinical, and epidemiologic evidence to date for a role of vitamin C in chronic disease prevention. The totality of the reviewed data suggests that an intake of 90-100 mg vitamin C/d is required for optimum reduction of chronic disease risk in nonsmoking men and women. This amount is about twice the amount on which the current RDA for vitamin C is based, suggesting a new RDA of 120 mg vitamin C/d.