Blood concentrations of carotenoids and retinol and lung cancer risk: an update of the WCRF-AICR systematic review of published prospective studies

The Efficacy of Dietary Intake, Supplementation, and Blood Concentrations of Carotenoids in Cancer Prevention: Insights from an Umbrella Meta-Analysis

Previous meta-analyses of multiple studies have suggested that dietary intake and blood concentrations of carotenoids, as well as dietary supplement of certain carotenoids, play a role in reducing the risk of cancer. However, the conclusions of these studies have been subject to controversy. We conducted an umbrella review of meta-analyses to comprehensively analyze and evaluate the evidence pertaining the association between carotenoids and cancer outcomes. We searched PubMed, Web of Science, Embase, and Cochrane Library databases of meta-analyses and systematic reviews up to June 2023. Our selection criteria encompassed meta-analyses of cohort and case-control studies, as well as randomized controlled clinical trials, which investigated the associations between carotenoids and cancer risk. We also determined the levels of evidence for these associations with AMSTAR 2 criteria. We included 51 eligible articles, including 198 meta-analyses for qualitative synthesis in the umbrella review. Despite the presence of moderate to high heterogeneity among the studies, dietary intake, supplementation, and blood concentrations of carotenoids were inversely associated with the risk of total cancer, and certain specific cancers of lung, digestive system, prostate, breast, head and neck, and others. Subgroup analysis also showed that individual carotenoids (α-carotene, β-carotene, β-cryptoxanthin, lutein, zeaxanthin, and lycopene) offer certain protection against specific types of cancers. However, high doses of carotenoid supplements, especially β-carotene, significantly increased the risk of total cancer, lung cancer, and bladder cancer. Our umbrella meta-analysis supported that high intake of dietary carotenoids as a whole food approach could be more beneficial in reducing cancer risk. Concurrently, the findings suggest that the efficacy of single-carotenoid supplementation in cancer prevention remains a subject of controversy.

Recent Advances in Lycopene for Food Preservation and Shelf-Life Extension

In recent years, there has been increasing concern about the safety of additives used to extend the shelf-life of food products. As a result, lycopene, a natural phytochemical compound, has attracted attention, as it has been demonstrated to be a potential alternative to traditional artificial antioxidants, with significant health benefits when applied to food preservation. Based on this, this review introduces the specific forms of lycopene currently used as an antioxidant in foods, both in its naturally occurring forms in fruits and vegetables and in artificially added forms involving technologies such as composite coating, active film packaging, emulsion, and microcapsules. In addition, it also provides a comprehensive summary of the effects and progress of lycopene in the preservation of different types of food products, such as meat, seafood, oil, dairy products, fruits, and vegetables, in the last decade. At last, it also points out the limitations of lycopene, including its insolubility in water, dark color, and high sensitivity to heat or light, as well as the potential solutions to load lycopene on suitable carriers, such as combining lycopene with antimicrobial substances or other actives, in order to broaden its applications as an antioxidant in future foods.

Retinol Saturase Mediates Retinoid Metabolism to Impair a Ferroptosis Defense System in Cancer Cells

Ferroptosis is an iron-dependent form of regulated cell death induced by the lethal overload of lipid peroxides in cellular membranes. In recent years, modulating ferroptosis has gained attention as a potential therapeutic approach for tumor suppression. In the current study, retinol saturase (RETSAT) was identified as a significant ferroptosis mediator using a publicly accessible CRISPR/Cas9 screening dataset. RETSAT depletion protected tumor cells from lipid peroxidation and subsequent cell death triggered by various ferroptosis inducers. Furthermore, exogenous supplementation with retinoids, including retinol (the substrate of RETSAT) and its derivatives retinal and retinoic acid, also suppressed ferroptosis, whereas the product of RETSAT, 13, 14-dihydroretinol, failed to do so. As effective radical-trapping antioxidant, retinoids protected the lipid membrane from autoxidation and subsequent fragmentation, thus terminating the cascade of ferroptosis. Pseudotargeted lipidomic analysis identified an association between retinoid regulation of ferroptosis and lipid metabolism. Retinoic acid, but not 13, 14-dihydroretinoic acid, interacted with its nuclear receptor and activated transcription of stearoyl-CoA desaturase, which introduces the first double bond into saturated fatty acid and thus catalyzes the generation of monounsaturated fatty acid, a known ferroptosis suppressor. Therefore, RETSAT promotes ferroptosis by transforming retinol to 13, 14-dihydroretinol, thereby turning a strong anti-ferroptosis regulator into a relatively weak one.

SIGNIFICANCE

Retinoids have ferroptosis-protective properties and can be metabolized by RETSAT to promote ferroptosis, suggesting the possibility of targeting retinoid metabolism in cancer as a treatment strategy to trigger ferroptosis.

Interaction between retinol intake and ISX rs5755368 polymorphism in colorectal cancer risk: a case-control study in a Korean population

This study aimed to examine whether the ISX rs5755368 genotypes are associated with the effect of dietary retinol consumption on CRC risk. We recruited 923 CRC patients and 1846 controls to identify the association between dietary retinol and CRC risk. Dietary retinol intake was assessed using a semiquantitative food frequency questionnaire. Genotype data were available for 1419 patients (600 cases and 819 controls) of the total study population. Genotyping was performed using an Illumina MEGA Expanded Array. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using unconditional logistic regression models. Retinol intake was inversely associated with CRC (OR = 0.49; 95% CI = 0.37-0.63). Participants with AA genotype showed lower CRC risk than subjects carrying the G allele (AG + GG) (OR = 0.76; 95% CI = 0.58-0.99). A 68% reduced risk of CRC was related to subjects who had the highest retinol intake and carrying AA genotype compared to the risk of participants consumed the lowest retinol intake and carrying the G allele (OR = 0.32; 95% CI = 0.20-0.53; P interaction = 0.026). Retinol intake could be a protective factor for CRC risk while this association could be strengthened among individuals carrying the homozygous AA genotype.

Lycopene destabilizes preformed Aβ fibrils: Mechanistic insights from all-atom molecular dynamics simulation

The therapeutic strategy employing destabilization of the preformed Aβ fibril by various natural compounds, as studied by experimental and computational methods, has been reported significant in curing Alzheimer's disease (AD). However, lycopene (a carotenoid), from terpenes family, needs investigation for its destabilization potential of Aβ fibril. The highest antioxidant potential and ability to cross blood brain barrier makes lycopene a preferred choice as drug lead for treating AD. The current study focuses on investigating the destabilization potential and underpinning mechanism of lycopene on different polymorphic forms of Aβ fibril via Molecular Dynamics (MD) simulation. The key findings highlight binding of lycopene to the outer surface of the chain F of the fibril (2NAO). Herein G9, K16 and V18 residues were found to be involved in van der Waals with the methyl groups of the lycopene. Additionally, Y10 and F20 residues were observed to interact via π-π interactions with CC bonds of the lycopene. The surface mediated binding of lycopene to the fibril is attributed to the large size and structural rigidity of lycopene along with the bulky size of 2NAO and narrow space of fibrillar cavity. The destabilization of the fibril is evident by breakage of inherent H-bonds and hydrophobic interactions in the presence of one lycopene molecule. The lesser β-sheet content explains disorganization of the fibril and bars the higher order aggregation curbing neurotoxicity of the fibril. The higher concentration of the lycopene is not found to be linearly correlated with the extent of destabilization of the fibril. Lycopene is also observed to destabilize the other polymorphic form of Aβ fibril (2BEG), by accessing the fibrillar cavity and lowering the β-sheet content. The destabilization observed by lycopene on two major polymorphs of Aβ fibril explains its potency towards developing an effective therapeutic approach in treating AD.

Phytochemicals in Cancer Treatment and Cancer Prevention-Review on Epidemiological Data and Clinical Trials

Phytochemicals are a non-nutritive substances that are present in plants and contribute significantly to their flavor and color. These biologically active compounds are classified into five major groups, namely phenolics, carotenoids, organosulfur compounds, nitrogen-containing compounds, and alkaloids, and are known for their potential health benefits in the prevention of various diseases, including cancer. The purpose of this review article is to explore the potential therapeutic benefits of the dietary phytochemicals, such as flavonoids, phenolic acids, phytosterols, carotenoids, and stilbenes, in cancer treatment and prevention based on the epidemiological studies and clinical trials. Although the majority of epidemiological studies report a significant advantage of the heightened phytochemical consumption and increased serum levels of these compounds, linking increased exposure with a lower cancer risk across most cancer types, these effects could not be replicated in the most available clinical trials. In fact, many of these trials were withdrawn early due to a lack of evidence and/or risk of harm. Despite the strong anticancer effect of phytochemicals, as well as their proven efficacy in multiple epidemiological studies, there is still a great need for human studies and clinical trials, with great caution regarding the safety measures. This review article provides an overview of the epidemiological and clinical evidence supporting the potential chemopreventive and anticancer properties of phytochemicals, with a focus on the need for further research in this area.

Carrot and carotene and multiple health outcomes: an umbrella review of the evidence

In recent years, the benefits of carrots and carotene in different areas of health have been examined. The purpose of this umbrella review was to identify the associations between carrots and carotene and multiple health outcomes. The review considered evidence from meta-analyses of interventional and observational studies of carrots and carotene and any health outcome. We comprehensively searched Web of Science, PubMed, and Embase. For each association, we estimated the summary effect size using random and fixed effects models and the 95% confidence interval. A total of 1329 studies were searched, and 30 meta-analyses with 26 health outcomes were identified that met the eligibility criteria. Carrot intake was associated with a lower risk of multiple cancer outcomes including breast cancer, lung cancer, pancreatic cancer, gastric cancer, urothelial cancer, and prostate cancer. Carotene intake was associated with a lower risk of fracture, age-related cataract, sunburn, Alzheimer's disease, breast cancer, lung cancer, pancreatic cancer, gastric cancer, esophageal cancer, prostate cancer, and head and neck cancer (HNC). Serum carotene was inversely associated with all-cause mortality, breast cancer, and lung cancer. Our study revealed that carrot or carotene intake could reduce the risk of various negative health outcomes. © 2023 Society of Chemical Industry.

Potential Role of Natural Antioxidant Products in Oncological Diseases

Nutrition has a significant effect and a crucial role in disease prevention. Low consumption of fruit and vegetables and a sedentary lifestyle are closely related with the onset and development of many types of cancer. Recently, nutraceuticals have gained much attention in cancer research due to their pleiotropic effects and relatively non-toxic behavior. In fact, although in the past there have been conflicting results on the role of some antioxidant compounds as allies against cancer, numerous recent clinical studies highlight the efficacy of dietary phytochemicals in the prevention and treatment of cancer. However, further investigation is necessary to gain a deeper understanding of the potential anticancer capacities of dietary phytochemicals as well as the mechanisms of their action. Therefore, this review examined the current literature on the key properties of the bioactive components present in the diet, such as carotenoids, polyphenols, and antioxidant compounds, as well as their use in cancer therapy. The review focused on potential chemopreventive properties, evaluating their synergistic effects with anticancer drugs and, consequently, the side effects associated with current cancer treatments.

Japanese carotenoid database with α- and β-carotene, β-cryptoxanthin, lutein, zeaxanthin, lycopene, and fucoxanthin and intake in adult women

Carotenoid intake is associated with low mortality and cancer risks; data on non-provitamin carotenoid intake is limited especially in Asians. We aimed to estimate carotenoid intake in Japanese adult women. Carotenoid content database comprises 196 food items, including 39 fruits, 87 vegetables and mushrooms, and 11 seaweeds, and was established using data from the literature and analyses of foods available in Japan. We surveyed the intake of these foods in Japanese women aged 21-56 years (n=109). Total intake of 7 carotenoids (mean±SD [range]) was 7,450±3,840 (1,160-21,300) μg/day; α-carotene, β-carotene, β-cryptoxanthin, lutein, zeaxanthin, lycopene, and fucoxanthin represented 4.3%, 23%, 3.4%, 15%, 2.0%, 39%, and 13% of total intake, respectively. Lutein intake was 1,132±686 (294-3,490) μg/day; its best sources were spinach, cucumber, chicken egg, green onion, and Chinese chives, representing 51% of total intake. Lutein can be obtained from a variety of sources. Thus, lutein intake levels did not vary widely among individuals and very few individuals consumed insufficient levels of lutein. Intake of zeaxanthin, lycopene, and fucoxanthin was 149±93 (2-479), 2,890±2,970 (0-17,100), and 980±1,230 (0-5,660) μg/day, respectively. Their intake required rich sources including chicken egg for zeaxanthin (52%); tomato products for lycopene (98%), and wakame seaweed for fucoxanthin (76%). The carotenoid content database including all food items consumed in Japan will be helpful for further investigations on carotenoid intake and its health benefits.

Investigating Causal Associations of Circulating Micronutrients Concentrations with the Risk of Lung Cancer: A Mendelian Randomization Study

Previous observational studies have suggested that the effect of diet-derived circulating micronutrient concentrations on lung cancer (LC) risk is controversial. We conducted a two-sample Mendelian randomization (MR) analysis to investigate the causal relationship between circulating micronutrient concentrations and the overall risk of LC and three LC subtypes (namely lung adenocarcinoma (LA), squamous cell lung cancer (SqCLC), and small cell lung cancer (SCLC)). The instrumental variables (IVs) of 11 micronutrients (beta-carotene, calcium, copper, folate, lycopene, magnesium, phosphorus, retinol, selenium, zinc, and vitamin B6) were screened from the published genome-wide association studies (GWAS). Summary statistics related to LC and its subtypes came from the largest meta-analysis, including 29,266 cases and 56,450 controls. Inverse-variance weighted (IVW) method is used as the main MR analysis, and the sensitivity analysis is carried out to ensure the MR assumptions. This MR study found suggestive evidence that genetically predicted 6 circulating micronutrient concentrations was correlated with the risk of overall LC (odds ratio (OR): 1.394, 95% confidence interval (CI): 1.041–1.868, p = 0.026, phosphorus), LA (OR: 0.794, 95% CI: 0.634–0.995, p = 0.045, beta-carotene; OR: 0.687, 95%CI: 0.494–0.957, p = 0.026, calcium), SqCLC (OR: 0.354, 95% CI: 0.145–0.865, p = 0.023, retinol), and SCLC (OR: 1.267, 95% CI: 1.040–1.543, p = 0.019, copper; OR: 0.801, 95% CI: 0.679–0.944, p = 0.008, zinc). We found no evidence that other micronutrients are associated with the risk of overall LC or its subtypes. Our study suggested that the increase in circulating beta-carotene, calcium, retinol, and zinc concentration may reduce the risk of LC; the increase in circulating copper and phosphorus concentration may be related to the increased risk of LC. In the future, larger replication samples of LC genetic data and larger micronutrient-related GWAS will be needed to verify our findings.

The Protective Anticancer Effect of Natural Lycopene Supercritical CO2 Watermelon Extracts in Adenocarcinoma Lung Cancer Cells

Carotenoids may have different effects on cancer and its progression. The safety of carotenoid supplements was evaluated in vitro on human non-small cell lung cancer (NSCLC) adenocarcinoma A549 cells by the administration of three different oleoresins containing lycopene and other lipophilic phytochemicals, such as tocochromanols. The oleoresins, obtained by the supercritical CO₂ green extraction technology from watermelon (Lyc W), gấc(Lyc G) and tomato (Lyc T) and chlatrated in α-cyclodextrins, were tested in comparison to synthetic lycopene (Lyc S), by cell cycle, Annexin V-FITC/PI, clonogenic test, Mytosox, intracellular ROS, Western Blot for NF-kB and RT-PCR and ELISA for IL-8. The extracts administered at the same lycopene concentration (10 µM) showed conflicting behaviors: Lyc W, with the highest lycopene/tocochromanols ratio, significantly increased cell apoptosis, mitochondrial stress, intracellular ROS, NF-kB and IL-8 expression and significantly decreased cell proliferation, whereas Lyc G and Lyc T significantly increased only cell proliferation. Lyc S treatment was ineffective. The highest amount of lycopene in Lyc W was able to counteract and revert the cell survival effect of tocochromanols supporting the importance of evaluating the lycopene bio-availability and the real effect of antioxidant tocochromanols' supplementation which may not only have no anticancer benefits but may even increase cancer aggressivity.

Antitumor Potential of Immunomodulatory Natural Products

Cancer is one of the leading causes of death globally. Anticancer drugs aim to block tumor growth by killing cancerous cells in order to prevent tumor progression and metastasis. Efficient anticancer drugs should also minimize general toxicity towards organs and healthy cells. Tumor growth can also be successfully restrained by targeting and modulating immune response. Cancer immunotherapy is assuming a growing relevance in the fight against cancer and has recently aroused much interest for its wider safety and the capability to complement conventional chemotherapeutic approaches. Natural products are a traditional source of molecules with relevant potential in the pharmacological field. The huge structural diversity of metabolites with low molecular weight (small molecules) from terrestrial and marine organisms has provided lead compounds for the discovery of many modern anticancer drugs. Many natural products combine chemo-protective and immunomodulant activity, thus offering the potential to be used alone or in association with conventional cancer therapy. In this review, we report the natural products known to possess antitumor properties by interaction with immune system, as well as discuss the possible immunomodulatory mechanisms of these molecules.

Exploring the Role of Metabolites in Cancer and the Associated Nerve Crosstalk

Since Otto Warburg's first report on the increased uptake of glucose and lactate release by cancer cells, dysregulated metabolism has been acknowledged as a hallmark of cancer that promotes proliferation and metastasis. Over the last century, studies have shown that cancer metabolism is complex, and by-products of glucose and glutamine catabolism induce a cascade of both pro- and antitumorigenic processes. Some vitamins, which have traditionally been praised for preventing and inhibiting the proliferation of cancer cells, have also been proven to cause cancer progression in a dose-dependent manner. Importantly, recent findings have shown that the nervous system is a key player in tumor growth and metastasis via perineural invasion and tumor innervation. However, the link between cancer-nerve crosstalk and tumor metabolism remains unclear. Here, we discuss the roles of relatively underappreciated metabolites in cancer-nerve crosstalk, including lactate, vitamins, and amino acids, and propose the investigation of nutrients in cancer-nerve crosstalk based on their tumorigenicity and neuroregulatory capabilities. Continued research into the metabolic regulation of cancer-nerve crosstalk will provide a more comprehensive understanding of tumor mechanisms and may lead to the identification of potential targets for future cancer therapies.

Aloe emodin 3-O-glucoside inhibits cell growth and migration and induces apoptosis of non-small-cell lung cancer cells via suppressing MEK/ERK and Akt signalling pathways

AIMS

Non-small-cell lung cancer (NSCLC) is the most frequent type of lung cancer with a high mortality rate. Glycosylation of phenolic compounds may increase water-solubility and pharmacological activities and reduce the toxicity of aglycones. This study aimed to evaluate and compare the anticancer effect of aloe emodin 3-O-glucoside (AE3G) and its aglycone, aloe emodin (AE), against NSCLC.

MAIN METHOD

A human adenocarcinoma cell line (A549) and BALB/c nu/nu xenograft mice harboring A549 cells were used as the NSCLC models. Inhibition of cell migration, disruption of mitochondrial membrane potential (MMP), DNA fragmentation, and expression levels of apoptotic proteins were measured by western blot, wound healing assay, JC-1 staining, or TUNEL staining. Histopathological changes in tumour tissues were observed by H&E and TUNEL staining.

RESULTS

With no significant cytotoxicity against noncancerous cells (Vero cells), AE3G (5-50 μM) significantly and more effectively inhibited the growth, attachment, migration, Bcl-2 expression, and activation of MEK/ERK and Akt signalling proteins and induced cytochrome c release and Bax expression in A549 cells than AE. AE3G augmented the collapse of MMP, cleavage of caspases (caspase 9, 8, and 3) and PARP, and DNA fragmentation. Intraperitoneal injection of AE3G (13 and 26 mg/kg/day) reduced the tumour volume and weight and induced apoptotic cell death in tumour tissues of xenograft NSCLC mice.

SIGNIFICANCE

The present study demonstrated that AE3G significantly and more effectively diminished human NSCLC cell growth and migration by triggering mitochondria-dependent intrinsic apoptosis than AE, providing AE3G as a new potent candidate to prevent or treat human NSCLC.

Bacterial Carotenoids: Extraction, Characterization, and Applications

Natural carotenoids are secondary metabolites that exhibit antioxidant, anti-inflammatory, and anti-cancer properties. These types of compounds are highly demanded by pharmaceutical, cosmetic, nutraceutical, and food industries, leading to the search for new natural sources of carotenoids. In recent years, the production of carotenoids from bacteria has become of great interest for industrial applications. In addition to carotenoids with C40-skeletons, some bacteria have the ability to synthesize characteristic carotenoids with C30-skeletons. In this regard, a great variety of methodologies for the extraction and identification of bacterial carotenoids has been reported and this is the first review that condenses most of this information. To understand the diversity of carotenoids from bacteria, we present their biosynthetic origin in order to focus on the methodologies employed in their extraction and characterization. Special emphasis has been made on high-performance liquid chromatography-mass spectrometry (HPLC-MS) for the analysis and identification of bacterial carotenoids. We end up this review showing their potential commercial use. This review is proposed as a guide for the identification of these metabolites, which are frequently reported in new bacteria strains.

Redox regulation by carotenoids: Evidence and conflicts for their application in cancer

Carotenoids have been constantly investigated since the early fifty for their chemical, biochemical and biological properties being presence in foods. Among the more than 1100 carotenoids synthesized by plants and microorganisms, approximately 50 are present in the human diet, and about 20 can be detected in human blood and tissues. Review articles that discuss the anticancer and cancer preventing activity of phytochemicals have often in common the difficulty to find a coherency between the results deriving from experimental studies and the controversial or weak clinical indications arising from epidemiological and interventional studies. In this scenario, the class of carotenoids does not represent an exception. In fact, according with World Cancer Research Fund, strong evidence exists that high-dose supplementation of β-carotene increases the risk of lung cancer, while for other types of cancer, the protective or harmful effects of food-containing carotenoids or carotenoid supplements have been considered limited, suggestive or unlikely. The analysis of the mechanistic evidence is complicated by the double nature of carotenoids being molecules acting either as antioxidant or pro-oxidant compounds. The present review analyzes the ambiguity and the unexpected results deriving from the epidemiological and interventional studies and discusses how the effects of carotenoids on cancer risk can be explained by understanding their capacity to modulate the cellular antioxidant response, depending on the concentration applied and the cellular metabolism. In the final part, a new global approach is proposed to study the contribution of carotenoids, but also of other phytochemicals, to disease prevention, including cancer.

Blood plasma resonance Raman spectroscopy combined with multivariate analysis for esophageal cancer detection

We herein report a novel, reliable and inexpensive method for detecting esophageal cancer using blood plasma resonance Raman spectroscopy combined with multivariate analysis methods. The blood plasma samples were divided into late stage cancer group (n = 164), early stage cancer group (n = 35) and normal group (n = 135) based on clinical pathological diagnosis. Using a specially designed quartz capillary tube as sample holder, we obtained higher quality resonance Raman spectra of blood plasma than existing method. The study demonstrated that the carotenoids levels in blood plasma were reduced in esophageal cancer patients. The area under the receiver operating characteristic curve (and 95% confidence interval) calculated by wavenumber selection and principal component analysis combined with linear discriminant analysis (PC-LDA) algorithm were 0.894 (0.858-0.929), 0.901 (0.841-0.960) and 0.871 (0.799-0.942) for differentiating late cancer from normal, late cancer from early cancer, and early cancer from normal respectively. The contribution from the two carotenoids wavenumber regions of 1155 and 1515 cm^-1 were more than 84.2%. The results show that the plasma carotenoids could be a potential biomarker for screening esophageal cancer using resonance Raman spectroscopy combined with wavenumber selection and PC-LDA algorithms.

Fruits and Vegetables and Lung Cancer Risk in Never Smokers. A Multicentric and Pooled Case-Control Study

BACKGROUND

The etiology of lung cancer in never smokers is partly unknown. We aimed to assess the effect of fruits and vegetables consumption on lung cancer risk in never smokers.

METHODS

We pooled five multicenter case-control studies performed in Northwestern Spain. Cases and controls were all never smokers. All lung cancer cases had anatomopathological confirmed diagnoses. We performed a multivariate logistic regression to analyze the effect of different types of fruits and vegetables consumption on lung cancer risk.

RESULTS

A total of 438 cases and 781 controls were included. We observed that a consumption from one to six times per week shows a negative association with lung cancer risk for: kiwis (OR 0.67; 95%CI 0.46-0.95), oranges (OR 0.55; 95%CI 0.37-0.80), turnip tops (OR 0.48; 95%CI 0.34-0.66), "berza gallega" (OR 0.70; 95%CI 0.51-0.97) and broccoli (OR 0.55; 95%CI 0.35-0.83) compared to less than once a week consumption. On the other hand, we found an increased risk for lung cancer with a daily consumption of tomatoes, carrots and potatoes.

CONCLUSIONS

Oranges, kiwis, turnip tops, berza gallega and broccoli may play a protective role on lung cancer development in never smokers while tomatoes, carrots and potatoes might have some association with this disease.

SERS liquid biopsy: An emerging tool for medical diagnosis

Surface-enhanced Raman scattering (SERS) is emerging as a novel strategy for biofluid analysis. In this review, we delineate four experimental SERS protocols that are frequently used for the profiling of biofluids: 1) liquid SERS for the detection of purine metabolites; 2) iodide-modified liquid SERS for the detection of proteins; 3) dried SERS for the detection of both purine metabolites and proteins; 4) resonant Raman for the detection of carotenoids. To explain the selectivity of each experimental SERS protocol, we introduce a heuristic model for the chemisorption of analytes mediated by adsorbed ions (adions) onto the SERS substrate. Next, we show that the promising results of SERS liquid biopsy stem from the fact that the concentration levels of purine metabolites, proteins and carotenoids are informative of the cellular turnover rate, inflammation, and oxidative stress, respectively. These processes are perturbed in virtually every disease, from cancer to autoimmune maladies. Finally, we review recent SERS liquid biopsy studies and discuss future steps that are required for translating SERS in the clinical setting.

[Nutritional problems in smokers and passive smokers]

OBJECTIVE

active or passive tobacco use affects a high percentage of individuals and is associated with various health risks. The aim of this review was to look more closely at the nutritional problems that are specific of smokers, which may harm their health.

METHODS

a bibliographic search related to the topic.

RESULTS

smokers consume lower amounts of various foods, especially fruits, vegetables, cereals and dairy. As a result, their intake of vitamins, minerals, and phytochemicals is lower than that observed in non-smokers. Their consumption of meat, caffeine and alcohol is usually higher, and their activity lower than those of non-smokers, coexisting in smokers unhealthy behaviors that contribute to harming their health and quality of life. Oxidative stress and metabolic changes render the needs for some nutrients higher in smokers to achieve the same biochemical situation as in non-smokers. Recommended intakes of vitamin C have increased, but it will probably be necessary to also increase the intakes of other nutrients. In general, smokers suffer from deficiencies more frequently (vitamins C, E, β-carotene, B1, B2, B12, folic acid, calcium, magnesium, iron, iodine, etc.) than non-smokers. Passive smokers are also affected in their eating habits and nutritional status.

CONCLUSIONS

the worse nutritional status of smokers can contribute to the appearance/worsening of various diseases associated with smoking (cardiovascular, cancer, cataracts, osteoporosis, etc.); therefore, nutritional surveillance and correction of nutritional deficiencies could represents health benefits for smokers and passive smokers, which should be considered in the future.

New Insights into Molecular Mechanism behind Anti-Cancer Activities of Lycopene

Lycopene is a well-known compound found commonly in tomatoes which brings wide range of health benefits against cardiovascular diseases and cancers. From an anti-cancer perspective, lycopene is often associated with reduced risk of prostate cancer and people often look for it as a dietary supplement which may help to prevent cancer. Previous scientific evidence exhibited that the anti-cancer activity of lycopene relies on its ability to suppress oncogene expressions and induce proapoptotic pathways. To further explore the real potential of lycopene in cancer prevention, this review discusses the new insights and perspectives on the anti-cancer activities of lycopene which could help to drive new direction for research. The relationship between inflammation and cancer is being highlighted, whereby lycopene suppresses cancer via resolution of inflammation are also discussed herein. The immune system was found to be a part of the anti-cancer system of lycopene as it modulates immune cells to suppress tumor growth and progression. Lycopene, which is under the family of carotenoids, was found to play special role in suppressing lung cancer.

Recent Progress in Discovering the Role of Carotenoids and Their Metabolites in Prostatic Physiology and Pathology with a Focus on Prostate Cancer-A Review-Part I: Molecular Mechanisms of Carotenoid Action

Among the vast variety of plant-derived phytochemicals, the group of carotenoids has continuously been investigated in order to optimize their potential application in the area of dietary intervention and medicine. One organ which has been especially targeted in many of these studies and clinical trials is the human prostate. Without doubt, carotenoids (and their endogenous derivatives—retinoids and other apo-carotenoids) are involved in intra- and intercellular signaling, cell growth and differentiation of prostate tissue. Due to the accumulation of new data on the role of different carotenoids such as lycopene (LC) and β-carotene (BC) in prostatic physiology and pathology, the present review aims to cover the past ten years of research in this area. Data from experimental studies are presented in the first part of the review, while epidemiological studies are disclosed and discussed in the second part. The objective of this compilation is to emphasize the present state of knowledge regarding the most potent molecular targets of carotenoids and their main metabolites, as well as to propose promising carotenoid agents for the prevention and treatment of prostatic diseases.

Lycopene: A Critical Review of Digestion, Absorption, Metabolism, and Excretion

Lycopene is a non-provitamin A carotenoid that exhibits several health benefits. Epidemiological data support a correlation between lycopene intake and the attenuation of several chronic diseases, including certain types of cancers and cardiovascular diseases. It is currently unknown whether the beneficial effects are from the native structure of lycopene or its metabolic derivatives: lycopenals, lycopenols, and lycopenoic acids. This literature review focuses on the current research on lycopene digestion, absorption, metabolism, and excretion. This review primarily focuses on in vivo studies because of the labile nature and difficulty of studying carotenoids within in vitro experimental models. The studies presented address tissue accumulation of lycopene, the modification of bioavailability due to genetic and dietary factors, and lycopene cleavage by the enzymes ß-carotene oxygenase 1 (BCO1) and ß-carotene oxygenase 2 (BCO2). The current literature suggests that the majority of lycopene is cleaved eccentrically by BCO2, yet further research is needed to probe the enzymatic cleavage activity at the tissue level. Additionally, results indicate that single nucleotide polymorphisms and dietary fat influence lycopene absorption and thus modify its health effects. Further research exploring the metabolism of lycopene, the mechanisms related to its health benefits, and optimal diet composition to increase the bioavailability is required.

Adherence to Prudent and Mediterranean Dietary Patterns Is Inversely Associated with Lung Cancer in Moderate But Not Heavy Male Polish Smokers: A Case-Control Study

Lung cancer is the most commonly diagnosed cancer in men worldwide. Studies regarding dietary patterns (DPs) and lung cancer are limited, with results remaining inconclusive, and the association of DPs with lung cancer in smokers is unclear. This study analyzed the associations between DPs, including the Polish-adapted Mediterranean diet (Polish-aMED) score, and lung cancer risk in Polish adult male smokers. This case-control study involved 439 men aged 45–80 years from northeastern Poland, including 187 newly diagnosed lung cancer cases. Dietary data was collected with a 62-item food frequency questionnaire (FFQ-6). Two approaches were applied to identify dietary patterns. The Polish-aMED score was calculated (hypothesis-driven approach) and a principal component analysis (PCA) was used to identify PCA-driven DPs (data-driven approach). A logistic regression analysis was performed to estimate the odds ratio (OR) and 95% confidence interval (95% CI) of the lung cancer risk associated with the adherence to DPs overall as well as for moderate (2.5–11 pack-years) and heavy (>11 pack-years) smokers. Among moderate smokers, the risk of lung cancer was lower by 41% (OR: 0.59; 95% CI: 0.39–0.90; p < 0.05; adjusted model) in the higher adherence to the prudent DP when compared to the lower adherence, and by 66% (OR: 0.34; 95% CI: 0.15–0.76; p < 0.05; adjusted model) in the high adherence (7–9 points) to the Polish-aMED score when compared to the low adherence (0–3 points). No significant association between the westernized traditional DP or the sweet dairy DP and lung cancer was revealed. In conclusion, the current study suggests that pro-healthy dietary patterns, including the Mediterranean pattern, may favour lower risk of lung cancer in moderate smokers, although it was not confirmed in heavy smokers.

Serum Retinol and Risk of Overall and Site-Specific Cancer in the ATBC Study

Retinol, the most biologically active form of vitamin A, might influence cancer-related biological pathways. However, results from observational studies of serum retinol and cancer risk have been mixed. We prospectively examined serum retinol and risk of overall and site-specific cancer in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study (n = 29,104 men), conducted in 1985-1993, with follow-up through 2012. Serum retinol concentration was measured using reverse-phase high-performance liquid chromatography. Cox proportional hazards models estimated the association between baseline serum retinol quintile and overall and site-specific cancer risk in 10,789 cases. After multivariable adjustment, higher serum retinol was not associated with overall cancer risk (highest vs. lowest quintile: hazard ratio (HR) = 0.97, 95% confidence interval (CI): 0.91, 1.03; P for trend = 0.43). Higher retinol concentrations were, however, associated with increased risk of prostate cancer (highest vs. lowest quintile: HR = 1.28, 95% CI: 1.13, 1.45; P for trend < 0.0001) and lower risk of both liver and lung cancers (highest vs. lowest quintile: for liver, HR = 0.62, 95% CI: 0.42, 0.91; P for trend = 0.004; and for lung, HR = 0.80, 95% CI: 0.72, 0.88; P for trend < 0.0001). No associations with other cancers were observed. Understanding the mechanisms that underlie these associations might provide insight into the role of vitamin A in cancer etiology.

Dietary carotenoids in cancer chemoprevention and chemotherapy: A review of emerging evidence

In recent years, natural products have reemerged as biotherapeutic options, with several dietary carotenoids, viz. astaxanthin, fucoxanthin, siphonaxanthin, β-cryptoxanthin, α-carotene, β-carotene, and lycopene, developing as potential candidates for chemoprevention and chemotherapeutics of breast, colorectal, lung, and prostate cancers. The potent cytotoxic and antiproliferative effects of carotenoids against various cancer cells are mediated by a wide range of molecular mechanisms modulating oxidative stress and redox balance, mitogen-activated protein kinases (MAPK) and other cellular signaling proteins, transcription factors, caspase cascade pathways of apoptosis, cell cycle progression and proliferation, angiogenesis, metastasis, gap junction intercellular communication (GJIC), and multidrug resistance (MDR). This review discusses recent evidence demonstrating the crucial roles of carotenoids in these cellular and molecular events of cancer cell cytotoxicity. In addition, recent case-control and cohort studies are discussed to support the potential role of carotenoids in cancer prevention and therapy.

Mechanistic understanding of β-cryptoxanthin and lycopene in cancer prevention in animal models

To better understand the potential function of carotenoids in the chemoprevention of cancers, mechanistic understanding of carotenoid action on genetic and epigenetic signaling pathways is critically needed for human studies. The use of appropriate animal models is the most justifiable approach to resolve mechanistic issues regarding protective effects of carotenoids at specific organs and tissue sites. While the initial impetus for studying the benefits of carotenoids in cancer prevention was their antioxidant capacity and pro-vitamin A activity, significant advances have been made in the understanding of the action of carotenoids with regards to other mechanisms. This review will focus on two common carotenoids, provitamin A carotenoid β-cryptoxanthin and non-provitamin A carotenoid lycopene, as promising chemopreventive agents or chemotherapeutic compounds against cancer development and progression. We reviewed animal studies demonstrating that β-cryptoxanthin and lycopene effectively prevent the development or progression of various cancers and the potential mechanisms involved. We highlight recent research that the biological functions of β-cryptoxanthin and lycopene are mediated, partially via their oxidative metabolites, through their effects on key molecular targeting events, such as NF-κB signaling pathway, RAR/PPARs signaling, SIRT1 signaling pathway, and p53 tumor suppressor pathways. The molecular targets by β-cryptoxanthin and lycopene, offer new opportunities to further our understanding of common and distinct mechanisms that involve carotenoids in cancer prevention. This article is part of a Special Issue entitled Carotenoids recent advances in cell and molecular biology edited by Johannes von Lintig and Loredana Quadro.

Carotenoids and their role in cancer prevention

Approximately two of every five people will develop cancer in their lifetime. Dietary modifications are one of the most promising lifestyle changes that can adjust the risk of developing cancer by nearly 40%. Carotenoids are a diverse group of natural pigments and are present in many fruits and vegetables. The data surrounding carotenoids and their potential roles in carcinogenesis have been rapidly growing over the past two decades. This review summarizes the literature surrounding the associations between the most six common carotenoids in the diet and ten of the most commonly diagnosed cancers. In this study, preclinical, epidemiological, and toxicology data were reviewed. Data from these studies suggest that several carotenoids might provide a beneficial impact on reducing carcinogenesis. Further studies are needed to determine the causal relationships between individual carotenoids and cancer incidence and progression. This article is part of a Special Issue entitled Carotenoids recent advances in cell and molecular biology edited by Johannes von Lintig and Loredana Quadro.

SERS-based differential diagnosis between multiple solid malignancies: breast, colorectal, lung, ovarian and oral cancer

Purpose

Surface-enhanced Raman scattering (SERS) spectroscopy on serum and other biofluids for cancer diagnosis represents an emerging field, which has shown promising preliminary results in several types of malignancies. The purpose of this study was to demonstrate that SERS spectroscopy on serum can be employed for the differential diagnosis between five of the leading malignancies, ie, breast, colorectal, lung, ovarian and oral cancer.

Patients and methods

Serum samples were acquired from healthy volunteers (n=39) and from patients diagnosed with breast (n=42), colorectal (n=109), lung (n=33), oral (n=17), and ovarian cancer (n=13), comprising n=253 samples in total. SERS spectra were acquired using a 532 nm laser line as excitation source, while the SERS substrates were represented by Ag nanoparticles synthesized by reduction with hydroxylamine. The classification accuracy yielded by SERS was assessed by principal component analysis–linear discriminant analysis (PCA-LDA).

Results

The sensitivity and specificity in discriminating between cancer patients and controls was 98% and 91%, respectively. Cancer samples were correctly assigned to their corresponding cancer types with an accuracy of 88% for oral cancer, 86% for colorectal cancer, 80% for ovarian cancer, 76% for breast cancer and 59% for lung cancer.

Conclusion

SERS on serum represents a promising strategy of diagnosing cancer which can discriminate between cancer patients and controls, as well as between cancer types such as breast, colorectal, lung ovarian and oral cancer.

Do We Utilize Our Knowledge of the Skin Protective Effects of Carotenoids Enough?

Due to their potential health-promoting effects, carotenoids have drawn both scientific and public attention in recent years. The primary source of carotenoids in the human skin is diet, mainly fruits, vegetables, and marine product, but they may originate from supplementation and topical application, too. In the skin, they accumulate mostly in the epidermis and act as a protective barrier to various environmental influences. Namely, the skin is exposed to numerous environmental factors, including ultraviolet radiation (UVR), air pollution, and smoking, that cause oxidative stress within the skin with consequent premature (extrinsic) aging. UVR, as the most prominent environmental factor, may cause additional detrimental skin effects, such as sunburn, DNA damage, and skin cancer. Therefore, photoprotection is the first line intervention in the prevention of premature aging and skin cancer. Numerous studies have demonstrated that carotenoids, particularly β-carotene, lycopene, lutein, and astaxanthin, have photoprotective effects, not only through direct light-absorbing properties, but also through their antioxidant effects (scavenging reactive oxygen species), as well as by regulation of UV light-induced gene expression, modulation of stress-dependent signaling, and/or suppression of cellular and tissue responses like inflammation. Interventional studies in humans with carotenoid-rich diet have shown its photoprotective effects on the skin (mostly by decreasing the sensitivity to UVR-induced erythema) and its beneficial effects in prevention and improvement of skin aging (improved skin elasticity and hydration, skin texture, wrinkles, and age spots). Furthermore, carotenoids may be helpful in the prevention and treatment of some photodermatoses, including erythropoietic protoporphyria (EPP), porphyria cutanea tarda (PCT) and polymorphous light eruption (PMLE). Although UVR is recognized as the main etiopathogenetic factor in the development of non-melanoma skin cancer (NMSC) and melanoma, and the photoprotective effects of carotenoids are certain, available studies still could not undoubtedly confirm the protective role of carotenoids in skin photocarcinogenesis.

Lycopene improves the efficiency of anti-PD-1 therapy via activating IFN signaling of lung cancer cells

Background

Monoclonal antibodies targeting programmed death-1 receptor (PD-1) and its ligand (PD-L1) have been developed to treat cancers including lung cancer. In this study, we aimed to investigate whether lycopene could promote the effect of anti-PD-1 treatment on lung cancer.

Methods

Tumor formation assay was conducted. Immune reactions were assessed by detecting several cytokine levels using enzyme-like immunosorbent assay. T cell activity was analyzed using cytometry. The mechanism of lycopene action was investigated using Western blot, quantitative real-time polymerase chain reaction and bisulfite sequencing analysis.

Results

After the mice injected with Lewis lung carcinoma (LLC) cells were sacrificed, we found that combined lycopene and anti-PD-1 reduced the tumor volume and weight compared to control treatment. Cell apoptosis in the tumor tissues was significantly enhanced in mice with combined lycopene and anti-PD-1 treatment in comparison with those of either lycopene or anti-PD-1 alone. Furthermore, lycopene could assist anti-PD-1 to elevate the levels of interleukin (IL)-1 and interferon (IFN) γ while reduce the levels of IL-4 and IL-10 in the spleen of mice injected with LLC cells. Lycopene treatment increased the CD4+/CD8+ ratio in the spleen and promoted IFNγ-expressing CD8+ T cells in tumor tissues. Upon IFNγ stimulation, lycopene diminished PD-L1 expression via activating JAK and repressing phosphorylation of AKT.

Conclusion

Our results have demonstrated that lycopene could be used as a potential adjuvant drug to synergistically improve the efficiency of anti-PD-1 therapy.

Electronic supplementary material

The online version of this article (10.1186/s12935-019-0789-y) contains supplementary material, which is available to authorized users.

Let food be your medicine: nutraceutical properties of lycopene

In this review, we highlight research and clinical trials involving lycopene and its impact on human health.

Intrinsic and Extrinsic Factors Impacting Absorption, Metabolism, and Health Effects of Dietary Carotenoids

Carotenoids are orange, yellow, and red lipophilic pigments present in many fruit and vegetables, as well as other food groups. Some carotenoids contribute to vitamin A requirements. The consumption and blood concentrations of specific carotenoids have been associated with reduced risks of a number of chronic conditions. However, the interpretation of large, population-based observational and prospective clinical trials is often complicated by the many extrinsic and intrinsic factors that affect the physiologic response to carotenoids. Extrinsic factors affecting carotenoid bioavailability include food-based factors, such as co-consumed lipid, food processing, and molecular structure, as well as environmental factors, such as interactions with prescription drugs, smoking, or alcohol consumption. Intrinsic, physiologic factors associated with blood and tissue carotenoid concentrations include age, body composition, hormonal fluctuations, and variation in genes associated with carotenoid absorption and metabolism. To most effectively investigate carotenoid bioactivity and to utilize blood or tissue carotenoid concentrations as biomarkers of intake, investigators should either experimentally or statistically control for confounding variables affecting the bioavailability, tissue distribution, and metabolism of carotene and xanthophyll species. Although much remains to be investigated, recent advances have highlighted that lipid co-consumption, baseline vitamin A status, smoking, body mass and body fat distribution, and genetics are relevant covariates for interpreting blood serum or plasma carotenoid responses. These and other intrinsic and extrinsic factors are discussed, highlighting remaining gaps in knowledge and opportunities for future research. To provide context, we review the state of knowledge with regard to the prominent health effects of carotenoids.

Association with Monoclonal Antibody Promotes Intracellular Delivery of Lycopene

Incubation of B10.MLM cells, a cell line of alveolar macrophages, with lycopene, a carotenoid, leads to an increase of lycopene content in their microsomal fraction. That increase was higher and developed faster when the cells were incubated with immune complexes formed by lycopene and mAb 6B9 (L-6B9 mAb), a monoclonal hapten-specific antibody raised against lycopene, as compared with dimethyl sulfoxide (DMSO)-dissolved lycopene (DMSO-L). Moreover, incubation of B10.MLM cells with L-6B9 mAb complexes was accompanied by more efficient accumulation of lipid droplets in the cultured cells and more significant inhibition of mRNA for 3-hydroxy-3-methylglutaryl-coenzyme (HMG-CoA) reductase, a rate-limiting enzyme of cholesterol biosynthesis known to be targeted by lycopene. Additionally, there was a better inhibition of Chlamydia trachomatis infection in B10.MLM cells infected with the pathogen and incubated thereafter with L-6B9 mAb complexes as compared with DMSO-L. Altogether, the results suggest that association with monoclonal antibody promotes intracellular delivery of lycopene in cultured cells possibly through Fc-receptor mediated uptake.

Pollution and respiratory disease: can diet or supplements help? A review

Pollution is known to cause and exacerbate a number of chronic respiratory diseases. The World Health Organisation has placed air pollution as the world's largest environmental health risk factor. There has been recent publicity about the role for diet and anti-oxidants in mitigating the effects of pollution, and this review assesses the evidence for alterations in diet, including vitamin supplementation in abrogating the effects of pollution on asthma and other chronic respiratory diseases. We found evidence to suggest that carotenoids, vitamin D and vitamin E help protect against pollution damage which can trigger asthma, COPD and lung cancer initiation. Vitamin C, curcumin, choline and omega-3 fatty acids may also play a role. The Mediterranean diet appears to be of benefit in patients with airways disease and there appears to be a beneficial effect in smokers however there is no direct evidence regarding protecting against air pollution. More studies investigating the effects of nutrition on rapidly rising air pollution are urgently required. However it is very difficult to design such studies due to the confounding factors of diet, obesity, co-morbid illness, medication and environmental exposure.

Metastasis-associated protein 2 promotes the metastasis of non-small cell lung carcinoma by regulating the ERK/AKT and VEGF signaling pathways

Non-small cell lung carcinoma (NSCLC) is the most common cause of cancer‑associated mortality in the world and accounts for ~85% of human lung cancers. Metastasis‑associated protein 2 (MTA2) is a component of the histone deacetylase complex and serves a role in tumor progression; however, the mechanism through which MTA2 is involved in the progression of NSCLC remains unclear. The aim of the present study was to investigate the expression and function of MTA2 and the MTA2‑mediated signaling pathway in NSCLC cells. Expression of MTA2 and its target genes was analyzed in MTA2‑overexpressing and anti‑MTA2 antibody (AbMTA2)‑treated NSCLC cells, as well as growth, migration, invasion and apoptotic‑resistance. The inhibitory effects on tumor formation were analyzed using AbMTA2‑treated NSCLC cells and in a mouse model. Histological assessment was conducted to analyze the expressions levels of extracellular signal‑regulated kinase (ERK), RAC‑α serine/threonine protein kinase (AKT) and vascular endothelial growth factor (VEGF) in experimental tumors. Results of the present study demonstrated that MTA2 was overexpressed in NSCLC cells. The growth, migration and invasion of NSCLC cells were markedly inhibited by AbMTA2. In addition, it was observed that the ERK/AKT and VEGF signaling pathways were both upregulated in MTA2‑overexpressing NSCLC cells, and downregulated following silencing of MTA2 activation. ERK and AKT phosphorylation levels were downregulated in NSCLC cells and tumors following MTA2 silencing. The in vivo study demonstrated that tumor growth was markedly inhibited following siRNA‑MTA2 treatment. In conclusion, the results of the present study suggested that MTA2 silencing may significantly inhibit the growth and aggressiveness of NSCLC cells. Results from the present study indicated that the mechanism underlying the MTA2‑mediated invasive potential of NSCLC cells involved the ERK/AKT and VEGF signaling pathways, which may be a potential therapeutic target for the treatment of NSCLC.

Dietary consumption of antioxidant vitamins and subsequent lung cancer risk: The Japan Public Health Center-based prospective study

While many epidemiological studies have studied the association between lung cancer risk and fruits and vegetable consumption (the major sources of antioxidant vitamins), only a few have investigated the direct association with antioxidants in consideration of cancer subtypes and smoking status. Here, we examined the association between consumption of antioxidant vitamins and lung cancer risk in one of the largest prospective cohort studies in Japan. We investigated the association of dietary antioxidant vitamins intake, namely retinol, vitamin C, vitamin E, α-carotene, and β-carotene and subsequent incidence of lung cancer among 38,207 men and 41,498 women in the Japan Public Health Center-based prospective study. Cox proportional hazard regression was performed with adjustment for potential confounders and by strata of cancer subtypes and smoking status. Antioxidant and other dietary intakes were assessed using a food frequency questionnaire (FFQ). During 1,233,096 person-years of follow-up between 1995 and 2013, a total of 1,690 lung cancer cases were newly diagnosed. In a multivariate regression model, while higher retinol intake was positively associated with overall lung cancer risk in men (HR 1.26; 95% CI 1.05-1.51; p_trend  = 0.003), the estimates were more evident with small cell carcinoma (HR 1.92; 95% CI 1.13-3.24; p_trend  < 0.001). Null associations were observed for other antioxidant vitamins. Our prospective study suggests that higher consumption of retinol may be associated with an increased risk of lung cancer in men, especially with small cell carcinoma, although confirmation is required.

Principles of pharmacological research of nutraceuticals

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

Lifetime report of perceived stress at work and cancer among men: A case-control study in Montreal, Canada

BACKGROUND

The association between perceived workplace psychological stress, over the entire work career, and cancer among men has never been assessed. This was explored in the context of a population-based case-control study conducted in Montreal, Canada.

METHODS

3103 incident cancer cases (11 types) diagnosed in 1979-1985 and 512 population controls were interviewed. Subjects described in detail each job held during their lifetime, including the occurrence of stress, and its reason. Logistic regression estimated odds ratios (OR) and 95% confidence intervals (CI) for the association between perceived workplace stress and its duration, and each cancer site, adjusting for lifestyle and occupational factors.

RESULTS

Employment in at least one stressful job was associated with increased odds of cancers of the lung (OR=1.33, 95% CI: 1.01-1.75), colon (OR=1.51, 95% CI: 1.15-1.98), bladder (OR=1.37, 95% CI: 1.03-1.81), rectal (OR=1.52, 95% CI: 1.10-2.10), and stomach (OR=1.53, 95% CI: 1.08-2.15). A duration-response trend was found for cancers of the lung, colon, rectum, stomach, and for NHL. Subjects reported changes in stress level over their career. Perceived stress was ascribed to several sources, including high demand and time pressure, financial issues, job insecurity, and hazardous conditions.

CONCLUSION

Prolonged exposure to perceived stress at work was associated with greater odds of cancer at 5 out of 11 sites. While over reporting of stress by cases cannot be fully ruled out, these associations, if substantiated, would bear important public health significance. Prospective studies building on detailed stress assessment protocols considering all sources and changes over the career are necessary.

Blood concentrations of carotenoids and retinol and lung cancer risk: an update of the WCRF-AICR systematic review of published prospective studies

Carotenoids and retinol are considered biomarkers of fruits and vegetables intake, and are of much interest because of their anti‐inflammatory and antioxidant properties; however, there is inconsistent evidence regarding their protective effects against lung cancer. We conducted a meta‐analysis of prospective studies of blood concentrations of carotenoids and retinol, and lung cancer risk. We identified relevant prospective studies published up to December 2014 by searching the PubMed and several other databases. We calculated summary estimates of lung cancer risk for the highest compared with lowest carotenoid and retinol concentrations and dose–response meta‐analyses using random effects models. We used fractional polynomial models to assess potential nonlinear relationships. Seventeen prospective studies (18 publications) including 3603 cases and 458,434 participants were included in the meta‐analysis. Blood concentrations of α‐carotene, β‐carotene, total carotenoids, and retinol were significantly inversely associated with lung cancer risk or mortality. The summary relative risk were 0.66 (95% confidence interval [CI]: 0.55–0.80) per 5 μg/100 mL of α‐carotene (studies [n] = 5), 0.84 (95% CI: 0.76–0.94) per 20 μg/100 mL of β‐carotene (n = 9), 0.66 (95% CI: 0.54–0.81) per 100 μg/100 mL of total carotenoids (n = 4), and 0.81 (95% CI: 0.73–0.90) per 70 μg/100 mL of retinol (n = 8). In stratified analysis by sex, the significant inverse associations for β‐carotene and retinol were observed only in men and not in women. Nonlinear associations were observed for β‐carotene, β‐cryptoxanthin, and lycopene, with stronger associations observed at lower concentrations. There were not enough data to conduct stratified analyses by smoking. In conclusion, higher blood concentrations of several carotenoids and retinol are associated with reduced lung cancer risk. Further studies in never and former smokers are needed to rule out confounding by smoking.