The impact of capsaicin intake on risk of developing gastric cancers: a meta-analysis

Capsaicinoids and Their Effects on Cancer: The "Double-Edged Sword" Postulate from the Molecular Scale

Capsaicinoids are a unique chemical species resulting from a particular biosynthesis pathway of hot chilies (Capsicum spp.) that gives rise to 22 analogous compounds, all of which are TRPV1 agonists and, therefore, responsible for the pungency of Capsicum fruits. In addition to their human consumption, numerous ethnopharmacological uses of chili have emerged throughout history. Today, more than 25 years of basic research accredit a multifaceted bioactivity mainly to capsaicin, highlighting its antitumor properties mediated by cytotoxicity and immunological adjuvancy against at least 74 varieties of cancer, while non-cancer cells tend to have greater tolerance. However, despite the progress regarding the understanding of its mechanisms of action, the benefit and safety of capsaicinoids' pharmacological use remain subjects of discussion, since CAP also promotes epithelial-mesenchymal transition, in an ambivalence that has been referred to as "the double-edge sword". Here, we update the comparative discussion of relevant reports about capsaicinoids' bioactivity in a plethora of experimental models of cancer in terms of selectivity, efficacy, and safety. Through an integration of the underlying mechanisms, as well as inherent aspects of cancer biology, we propose mechanistic models regarding the dichotomy of their effects. Finally, we discuss a selection of in vivo evidence concerning capsaicinoids' immunomodulatory properties against cancer.

High spicy food intake may increase the risk of esophageal cancer: A meta-analysis and systematic review

Spicy food is popular with people around the world and reports on the association between spicy food intake and esophageal cancer (EC) risk have been controversial. Therefore, we conducted a meta-analysis of 25 studies to provide the latest evidence for this uncertainty. We hypothesized that high spicy food intake is associated with an increased risk of EC. A database was searched to identify case-control or cohort studies of spicy food intake associated with EC through March 2022. Combined odds ratios (ORs) and their 95% CIs were used to estimate the effect of spicy food intake on EC. Subgroup analyses and sensitivity analyses were also performed. All data were analyzed using STATA 15.1 software. Twenty-five studies from 22 articles met the inclusion criteria for the meta-analysis (7810 patients with EC and 515,397 controls). Despite significant heterogeneity (P < .001), the comparison of highest versus lowest spicy food intake in each study showed a significant OR of 1.70 (95% CI, 1.30-2.22). In subgroup analyses, this positive association was found among the Chinese population, different sample sizes of EC, different sources of the control group, and different quality of articles. However, for India, as well as for other countries, esophageal squamous cell carcinoma and esophageal adenocarcinoma showed no statistically significant association. This meta-analysis suggests that high levels of spicy food intake may be associated with an increased risk of EC, although 1 prospective study found an inverse association. Additional studies are necessary to confirm the relationship between spicy food and EC risk.

Dietary Supplements for Weight Management: A Narrative Review of Safety and Metabolic Health Benefits

Dietary supplements for weight management include myriad ingredients with thermogenic, lipotropic, satiety, and other metabolic effects. Recently, the safety of this product category has been questioned. In this review, we summarize the safety evidence as well as relevant clinical findings on weight management and metabolic effects of six representative dietary supplement ingredients: caffeine, green tea extract (GTE), green coffee bean extract (GCBE), choline, glucomannan, and capsaicinoids and capsinoids. Of these, caffeine, GTE (specifically epigallocatechin gallate [EGCG]), and choline have recommended intake limits, which appear not to be exceeded when used according to manufacturers’ instructions. Serious adverse events from supplements with these ingredients are rare and typically involve unusually high intakes. As with any dietary component, the potential for gastrointestinal intolerance, as well as possible interactions with concomitant medications/supplements exist, and the health status of the consumer should be considered when consuming these components. Most of the ingredients reviewed also improved markers of metabolic health, such as glucose, lipids, and blood pressure, although the data are limited for some. In summary, weight management supplements containing caffeine, GTE, GCBE, choline, glucomannan, and capsaicinoids and capsinoids are generally safe when taken as directed and demonstrate metabolic health benefits for overweight and obese people.

Diet and Risk of Gastric Cancer: An Umbrella Review

Several dietary exposures have been associated with gastric cancer (GC), but the associations are often heterogenous and may be afflicted by inherent biases. In the context of an Umbrella Review (UR), we provide an overview and a critical evaluation of the strength and quality, and evidence classification of the associations of diet-related exposures in relation to the risk of GC. We searched PubMed and Scopus for eligible meta-analyses of observational studies published in English from inception to 12 December 2021, and for any identified association, we applied robust epidemiological validity evaluation criteria and individual study quality assessment using AMSTAR. We screened 3846 titles/abstracts and assessed 501 full articles for eligibility, of which 49 were included in the analysis, investigating 147 unique exposures in relation to GC, cardia (GCC) or non-cardia (GNCC) cancer. Supported by suggestive evidence, positive associations were found comparing the highest vs. lowest categories for: heavy (>42 g/day) alcohol consumption (Relative Risk (RR) = 1.42, 95% Confidence Interval (CI): 1.20−1.67), salted fish consumption (RR = 1.56, 95% CI:1.30−1.87) and waist circumference (RR = 1.48, 95% CI:1.24−1.78) and an inverse association for the healthy lifestyle index (RR = 0.60, 95% CI:0.48−0.74) in relation to GC. Additionally, a positive association was found comparing obese individuals (Body Mass Index (BMI) ≥ 30) to normal-weight individuals (BMI: 18.5−25) (RR = 1.82, 95% CI:1.32−2.49) in relation to GCC. Most of the meta-analyses were of medium-to-high quality (median items: 7.0, interquartile range: 6−9). Maintaining a normal body weight and adopting healthy dietary choices, in particular, limiting the consumption of salt-preserved foods and alcohol, can reduce the risk of gastric cancer.

Estimation of Dietary Capsaicinoid Exposure in Korea and Assessment of Its Health Effects

The consumption of capsaicinoids, the active components in chili peppers, has been associated with both positive and negative health effects, and the level of capsaicinoid exposure may be an important determinant. Dietary capsaicinoid exposure was estimated using a previously developed database for capsaicinoid content and a 24-h dietary recall dataset obtained from the Korea National Health and Nutrition Examination Survey. The estimated consumption level was evaluated to determine its potential effects on weight reduction and gastrointestinal distress. The estimated daily mean capsaicinoid intake was 3.25 mg (2.17 mg capsaicin), and most Koreans consumed 1–30 mg of capsaicinoids (0.67–20 mg capsaicin) in a day. No adverse effect of capsaicin consumption was reported other than abdominal pain. For long-term repeated consumption, 30 mg may be the maximum tolerable dose. However, the effects on body weight or energy balance were inconsistent in 4–12 week clinical studies conducted with various capsaicin doses (2–135 mg), which was likely due to the complex interplay between capsaicin dose, study length, and participant characteristics. Therefore, the capsaicin consumption of most Koreans was below the levels that may cause adverse effects. However, more long-term studies for the dose range of 2–20 mg are required to further characterize capsaicin’s health benefits in Koreans.

Capsaicin lacks tumor-promoting effects during colon carcinogenesis in a rat model induced by 1,2-dimethylhydrazine

Capsaicin (CPS, 8-methyl-N-vanillyl-trans-6-nonenamide), a pungent alkaloid from chili peppers, has contradictory effects in both experimental and human carcinogenesis. Thus, we evaluated the modifying effects of chronic CPS during the promotion and progression stages of rat colon carcinogenesis induced by 1,2-dimethylhydrazine (DMH). Male Wistar rats were given four subcutaneous injections of DMH (40 mg/body weight (b.w.)) twice a week, for 2 weeks. After DMH-induced tumor initiation, the animals were treated with CPS at 5 or 50 mg/kg b.w. by gavage for 24 weeks (three times a week). High-dose CPS reduced both cell proliferation in adjacent "normal-appearing" colonic crypts and the total number of preneoplastic aberrant crypt foci (ACF) but did not change the number of dysplastic ACF or ACF multiplicity. Although the proportion of adenomas was increased, and tubular adenocarcinomas decreased in high-dose CPS, both CPS interventions exerted no effects on total tumor incidence, volume, multiplicity, cell proliferation (Ki-67), and apoptosis (caspase-3). In accordance, high-dose CPS treatment had discrete effects on gene expression in colon tumors, as only 3/94 (3.19%) genes were significantly modified (downregulation of Cebpd and Fasl, and upregulation of Jag1). The findings of the present study show that CPS does not impact on the promotion/progression stages of rat colon carcinogenesis. Therefore, CPS at a high-dose intervention showed to be a safe food ingredient.

The Effects of Capsaicin on Gastrointestinal Cancers

Gastrointestinal (GI) cancers are a group of diseases with very high positions in the ranking of cancer incidence and mortality. While they show common features regarding the molecular mechanisms involved in cancer development, organ-specific pathophysiological processes may trigger distinct signaling pathways and intricate interactions with inflammatory cells from the tumoral milieu and mediators involved in tumorigenesis. The treatment of GI cancers is a topic of increasing interest due to the severity of these diseases, their impact on the patients' survivability and quality of life, and the burden they set on the healthcare system. As the efficiency of existing drugs is hindered by chemoresistance and adverse reactions when administered in high doses, new therapies are sought, and emerging drugs, formulations, and substance synergies are the focus of a growing number of studies. A class of chemicals with great potential through anti-inflammatory, anti-oxidant, and anti-tumoral effects is phytochemicals, and capsaicin in particular is the subject of intensive research looking to validate its position in complementing cancer treatment. Our paper thoroughly reviews the available scientific evidence concerning the effects of capsaicin on major GI cancers and its interactions with the molecular pathways involved in the course of these diseases.

Development of a database of capsaicinoid contents in foods commonly consumed in Korea

Chili peppers (Capsicum annuum L.) are widely consumed worldwide, and the health benefits of capsaicinoids (the active compounds in chili peppers) have been suggested. However, the link between capsaicinoid consumption and the risk of certain cancers remains controversial. Capsaicinoid consumption level is an important determinant of its potential health effects. This study sought to construct a database of capsaicinoid contents in foods commonly consumed in Korea (CAPKO) to enable a more reliable estimation of capsaicinoid intake. Capsaicinoid-containing foods were identified from the Korea National Health and Nutrition Examination Survey datasets and divided into eight categories: chili peppers, red pepper powder, hot sauce, kimchi, salted seafood, red pepper paste, instant noodles, and convenience foods other than instant noodles. The capsaicinoid contents of primary capsaicinoid sources (chili peppers, red pepper powder, and hot sauce) were estimated from the literature. For the remaining food categories, the contents of primary capsaicinoid sources were identified from standardized recipes (kimchi) or food labels (salted seafood, red pepper paste, and convenience foods other than instant noodles). Then, capsaicinoid contents were estimated by calculation using the identified capsaicinoid source contents and the estimated capsaicinoid content in these sources. This information was unavailable for instant noodles, and capsaicinoid content was measured by HPLC analyses. This study developed the CAPKO database, which includes a variety of foods with varying levels of spiciness, which can be used in combination with dietary surveys to estimate capsaicinoid intakes. Therefore, this study established a framework for future database development for other compounds with potential health effects.

The Mexican consensus on the detection and treatment of early gastric cancer

Gastric cancer is one of the most frequent neoplasias in the digestive tract and is the result of premalignant lesion progression in the majority of cases. Opportune detection of those lesions is relevant, given that timely treatment offers the possibility of cure. There is no consensus in Mexico on the early detection of gastric cancer, and therefore, the Asociación Mexicana de Gastroenterología brought together a group of experts and produced the "Mexican consensus on the detection and treatment of early gastric cancer" to establish useful recommendations for the medical community. The Delphi methodology was employed, and 38 recommendations related to early gastric cancer were formulated. The consensus defines early gastric cancer as that which at diagnosis is limited to the mucosa and submucosa, irrespective of lymph node metástasis. In Mexico, as in other parts of the world, factors associated with early gastric cancer include Helicobacter pylori infection, a family history of the disease, smoking, and diet. Chromoendoscopy, magnification endoscopy, and equipment-based image-enhanced endoscopy are recommended for making the diagnosis, and accurate histopathologic diagnosis is invaluable for making therapeutic decisions. The endoscopic treatment of early gastric cancer, whether dissection or resection of the mucosa, should be preferred to surgical management, when similar oncologic cure results can be obtained. Endoscopic surveillance should be individualized.

A Review of Gastric Cancer Research in Malaysia

Incidence rates of gastric cancer in Malaysia has declined by 48% among males and 31% among females in the latest reporting period of 13 years. Malays used to have age-standardized-rates only a fifth of those in Chinese and Indians, but the incidence among them is slightly rising even as the rates drop in the other races. Besides ethnicity, a low level of education, high intake of salted fish and vegetables, H pylori infection and smoking are risk factors. Consumption of fresh fruit and vegetable is protective. Variation in the strains of H pylori infection affect gastric cancer risk, with hspEAsia isolates among Chinese appearing linked to a high incidence than with hpAsia2 or hpEurope strains among Indians and Malays. It was reported in the 1980s that only about 3% of patients presented with early gastric cancer, but more encouraging rates reaching 27% with Stage 1 and 2 disease have been reported in the twenty-first century from leading centres. More tumours occur in the distal stomach except in Kelantan, where the incidence is low and main site is the cardia. Prompt endoscopy is advocated and open access, with direct referrals, to such services using a weighted scoring system should be more utilized. In view of the high rate of late disease laparoscopic staging unnecessary laparotomy needs to be avoided. Late presentation of gastric cancer however, is still predominant and the mortality to incidence ratio is relatively high. Besides seeking to reduce risk factors and achieve early detection, implementation of improved care for patients with late disease must be promoted in Malaysia.

Potential Phytopharmacy and Food Applications of Capsicum spp.: A Comprehensive Review

Capsicum genus (Solanaceae) is native to the Americas. Today, it is an important agricultural crop cultivated around the world, not only due to its economic importance, but also for the nutritional value of the fruits. Among their phytochemical constituents, capsaicinoids are characteristic and responsible of the pungency of sharp-tasting cultivars. Moreover, Capsicum and capsaicinoids (mainly, capsaicin) have been largely studied because of their health benefits. Thus, this study reviews the scientific knowledge about Capsicum spp. and their phytochemicals against cancer, diabetes, gastrointestinal diseases, pain, and metabolic syndrome, as well as their antioxidant and antimicrobial activity. These bioactivities can be the basis of the formulation of functional ingredients and natural preservatives containing Capsicum extracts or isolated compounds.

High Spicy Food Intake and Risk of Cancer: A Meta-analysis of Case-control Studies

Background:

Studies on the association between spicy food intake and cancer risk have reported inconsistent results. We quantitatively assessed this association by conducting a meta-analysis based on evidence from case–control studies.

Methods:

PubMed, EMBASE, and the Cochrane Library were searched for eligible publications. Combined odds ratios (ORs) with their 95% confidence interval (CI) were calculated using a random- or fixed-effects model. The methodological quality of the included articles was assessed using the Newcastle–Ottawa scale (NOS). All data were analyzed using STATA 11.0 software (version 11.0; StataCorp., College Station, TX, USA). Subgroup analyses were also performed with stratification by region, sex, number of cases, cancer subtype, source of the control group, and NOS score.

Results:

A total 39 studies from 28 articles fulfilled the inclusion criteria for the meta-analysis (7884 patients with cancer and 10,142 controls). Comparison of the highest versus lowest exposure category in each study revealed a significant OR of 1.76 (95% CI = 1.35–2.29) in spite of significant heterogeneity (P < 0.001). In the subgroup analyses, this positive correlation was still found for gastric cancer, different regions, different numbers of cases, different sources of the control group, and high-quality articles (NOS score of ≥ 7). However, no statistically significant association was observed for women, esophageal cancer, gallbladder cancer, or low-quality articles (NOS score of <7). No evidence of publication bias was found.

Conclusions:

Evidence from case–control studies suggested that a higher level of spicy food intake may be associated with an increased incidence of cancer despite significant heterogeneity. More studies are warranted to clarify our understanding of the association between high spicy food intake and the risk of cancer.

Phytochemistry and gastrointestinal benefits of the medicinal spice, Capsicum annuum L. (Chilli): a review

Dietary spices and their active constituents provide various beneficial effects on the gastrointestinal system by variety of mechanisms such as influence of gastric emptying, stimulation of gastrointestinal defense and absorption, stimulation of salivary, intestinal, hepatic, and pancreatic secretions. Capsicum annuum (Solanaceae), commonly known as chilli, is a medicinal spice used in various Indian traditional systems of medicine and it has been acknowledged to treat various health ailments. Therapeutic potential of chilli and capsaicin were well documented; however, they act as double-edged sword in many physiological circumstances. In traditional medicine chilli has been used against various gastrointestinal complains such as dyspepsia, loss of appetite, gastroesophageal reflux disease, gastric ulcer, and so on. In chilli, more than 200 constituents have been identified and some of its active constituents play numerous beneficial roles in various gastrointestinal disorders such as stimulation of digestion and gastromucosal defense, reduction of gastroesophageal reflux disease (GERD) symptoms, inhibition of gastrointestinal pathogens, ulceration and cancers, regulation of gastrointestinal secretions and absorptions. However, further studies are warranted to determine the dose ceiling limit of chilli and its active constituents for their utilization as gastroprotective agents. This review summarizes the phytochemistry and various gastrointestinal benefits of chilli and its various active constituents.

Gingerol Reverses the Cancer-Promoting Effect of Capsaicin by Increased TRPV1 Level in a Urethane-Induced Lung Carcinogenic Model

Both gingerol and capsaicin are agonists of TRPV1, which can negatively control tumor progression. This study observed the long-term effects of oral administration of 6-gingerol alone or in combination with capsaicin for 20 weeks in a urethane-induced lung carcinogenic model. We showed that lung carcinoma incidence and multiplicity were 70% and 21.2 ± 3.6, respectively, in the control versus 100% and 35.6 ± 5.2 in the capsaicin group (P < 0.01) and 50% and 10.8 ± 3.1 in the 6-gingerol group (P < 0.01). The combination of 6-gingerol and capsaicin reversed the cancer-promoting effect of capsaicin (carcinoma incidence of 100% versus 20% and multiplicity of 35.6 ± 5.2 versus 4.7 ± 2.3; P < 0.001). The cancer-promoting effect of capsaicin was due to increased epidermal growth-factor receptor (EGFR) level by decreased transient receptor potential vanilloid type-1 (TRPV1) level (P < 0.01) . The capsaicin-decreased EGFR level subsequently reduced levels of nuclear factor-κB (NF-κB) and cyclin D1 that favored enhanced lung epithelial proliferation and epithelial-mesenchymal transition (EMT) during lung carcinogenesis (P < 0.01). In contrast, 6-gingerol promoted TRPV1 level and drastically decreased the levels of EGFR, NF-κB, and cyclin D1 that favored reduced lung epithelial proliferation and EMT (P < 0.01). This study provides valuable information for the long-term consumption of chili-pepper-rich diets to decrease the risk of cancer development.

Capsaicin may have important potential for promoting vascular and metabolic health

Capsaicin, the phytochemical responsible for the spiciness of peppers, has the potential to modulate metabolism via activation of transient receptor potential vanilloid 1 (TRPV1) receptors, which are found not only on nociceptive sensory neurons, but also in a range of other tissues. TRPV1 activation induces calcium influx, and in certain tissues this is associated with increased activation or expression of key proteins such as endothelial nitric oxide synthase (eNOS), uncoupling protein 2 (UCP2), KLF2, PPARdelta, PPARgamma, and LXRα. The calcium influx triggered by TRPV1 activation in endothelial cells mimics the impact of shear stress in this regard, activating and increasing the expression of eNOS-but also increasing expression of cox-2, thrombomodulin, and nrf2-responsive antioxidant enzymes, while decreasing expression of proinflammatory proteins. Hence, dietary capsaicin has favourably impacted endothelium-dependent vasodilation in rodents. TRPV1-mediated induction of LXRα in foam cells promotes cholesterol export, antagonising plaque formation. Capsaicin-mediated activation of TRPV1-expressing neurons in the gastrointestinal tract promotes sympathetically mediated stimulation of brown fat, raising metabolic rate. The increased expression of UCP2 induced by TRPV1 activation exerts a protective antioxidant effect on the liver in non-alcoholic fatty liver disease, and on vascular endothelium in the context of hyperglycaemia. In rodent studies, capsaicin-rich diets have shown favourable effects on atherosclerosis, metabolic syndrome, diabetes, obesity, non-alcoholic fatty liver, cardiac hypertrophy, hypertension and stroke risk. Clinically, ingestion of capsaicin-or its less stable non-pungent analogue capsiate-has been shown to boost metabolic rate modestly. Topical application of capsaicin via patch was found to increase exercise time to ischaemic threshold in patients with angina. Further clinical studies with capsaicin administered in food, capsules, or via patch, are needed to establish protocols that are tolerable for most patients, and to evaluate the potential of capsaicin for promoting vascular and metabolic health.