Peppers and capsaicin — spicy pain or a potent remedy?

Aim of the study: The lipid-lowering effects of capsaicin, capsinoids, and pepper-derived products have shown inconsistent results in previous research. This systematic review and meta-analysis aimed to assess their impact on lipid profiles in overweight or obese individuals.

Results: The meta-analysis showed significant reductions in triglycerides (WMD: -14.29 mg/dL; 95 % CI: -27.01 to -1.58; p = 0.028) and total cholesterol (WMD: -9.97 mg/dL; 95 % CI: -17.41 to -2.52; p = 0.009). However, no significant effects were observed on low-density lipoprotein cholesterol (LDL-C) or high-density lipoprotein cholesterol (HDL-C) levels. Subgroup analyses indicated stronger effects with higher daily doses (≥10 mg), longer intervention periods (≥12 weeks), and among individuals with elevated baseline lipid levels. In conclusion, capsaicin, capsinoids, and pepper-based products significantly reduce total cholesterol and triglyceride levels in overweight or obese individuals, especially when used at higher doses and for extended durations, or in those with initially elevated lipid profiles.

Aim of the study: The outcomes of the earlier trials are controversial concerning the effect of Capsaicinoids/Capsinoids on thermogenesis. We carried out this systematic review and meta-analysis to examine the effect of Capsaicinoids/Capsinoids on thermogenesis indices including resting metabolic rate (RMR) and respiratory quotient (RQ) in healthy adults.

Results: It also significantly lessened RQ (WMD: -0.01, 95% CI: -0.02, -0.01; I2 : 5.4%, p = .39) and carbohydrate oxidation. Moreover, intervention in capsule form for longer duration had a more considerable influence on RMR than comparative groups. We observed moderate improvement in RMR, RQ, and fat oxidation following supplementation with Capsaicinoids/Capsinoids. However, further high-quality studies are required to clarify the thermogenic properties of Capsaicinoids/Capsinoids.

Aim of the study: Rhinitis is a multifactorial disease characterized by symptoms of sneezing, rhinorrhea, postnasal drip, and nasal congestion. Non-allergic rhinitis is characterized by rhinitis symptoms without systemic sensitization of infectious etiology.

Results: Patients with idiopathic rhinitis benefit from intranasal treatment with capsaicin. Expression of TRPV1 is reduced in patients with idiopathic rhinitis after capsaicin treatment. Recently, in a Cochrane review, the effectiveness of capsaicin in the management of idiopathic rhinitis was evaluated and the authors concluded that given that many other options do not work well in non-allergic rhinitis, capsaicin is a reasonable option to try under physician supervision. Capsaicin has not been shown to be effective in allergic rhinitis nor in other forms of non-allergic rhinitis like the inflammatory endotypes or other neurogenic endotypes like rhinitis of the elderly or smoking induced rhinitis.

Aim of the study: Bioactive ingredients have been shown to reduce appetite and energy intake. The magnitude of these effects might depend on energy balance why it was investigated how capsaicin, green tea, CH-19 sweet pepper as well as green tea and capsaicin affect appetite and energy intake during respectively negative and positive energy balance.

Results: CH-19 sweet pepper and a combination of capsaicin and green tea reduced energy intake during positive energy balance. Capsaicin and green tea suppressed hunger and increased satiety more during negative than during positive energy balance. Bioactive ingredients had energy intake reducing effects when used in combinations and in positive energy balance. Energy balance did not affect possible treatment induced energy intake, but did affect appetite by supporting negative energy balance. Bioactive ingredients may therefore be helpful in reducing energy intake and might support weight loss periods by relatively sustaining satiety and suppressing hunger.

Aim of the study: Chili is the most heavily and frequently consumed spice, either as a flavouring or colouring agent, and it is also a major source of pro-vitamin A, vitamin E and C. The main capsinoidcapsaicinoid found in chili peppers is capsaicin. It has been demonstrated that capsaicin acts as a cancer-suppressing agent through its antioxidant and anti-inflammatory effects, by blocking several signal transduction pathways.

Results: allAll the studies confirm that capsaicin is a chemopreventive agent that prevents the development of oral cancer, through inhibition of malignant cell proliferation and increase of apoptosis. More human studies are needed in order to clarify the real link between consumption of chili (capsaicin) and the prevalence of oral cancer.

Aim of the study: Alzheimer's Disease (AD) is a progressive neurodegenerative disorder characterised by cognitive impairment, and amyloid-β plaques and neurofibrillary tau tangles at neuropathology. Capsaicin is a spicy-tasting compound found in chili peppers, with anti-inflammatory, antioxidant, and possible neuroprotective properties.

Results: A systematic analysis was conducted on the effect of capsaicin on AD-associated molecular changes, cognitive and behaviour resulting in 11 studies employing rodents and/or cell cultures, which were appraised with the Cochrane Risk of Bias tool. Ten studies showed capsaicin attenuated tau deposition, apoptosis, and synaptic dysfunction; was only weakly effective on oxidative stress; and had conflicting effects on amyloid processing. Eight studies demonstrated improved spatial and working memory, learning, and emotional behaviours in rodents following capsaicin treatment. Overall, capsaicin showed promise in improving AD-associated molecular, cognitive, and behavioural changes in cellular and animal models, and further investigations are recommended to test the readily available bioactive, capsaicin, to treat AD.

Aim of the study: Marine biofouling imposes significant operational and ecological costs for the maritime industry, including increased hydrodynamic drag, material degradation, and the spread of non-native species.

Results: Notably, bare space - perhaps the most relevant indicator of antifouling efficacy - was significantly greater in the 2% capsaicin treatment than in the copper treatments, indicating enhanced antifouling performance with incorporation of capsaicin. Largest differences were also seen between 1% and 2% capsaicin treatments, particularly in total mean taxa abundance and percent detritus. Overall, capsaicin enhanced antifouling performance in a concentration-dependent manner, particularly against soft-bodied taxa and increasing bare space, suggesting this approach has potential as an environmentally benign antifouling option. Our results provide preliminary in-situ research-based evidence for this low-technology and cost-effective approach to reduce marine biofouling on infrastructure and recreational vessels.

Aim of the study: Capsaicin, the pungent vanilloid of chili pepper, is a widely consumed dietary constituent that exerts pleiotropic actions on physiological and pathophysiological processes, including anti-inflammatory, antioxidant, antiproliferative, metabolic and cardioprotective effects.

Results: Its principal molecular target, transient receptor potential vanilloid 1 (TRPV1), is upregulated in the inflamed colonic mucosa of patients with inflammatory bowel disease (IBD), a chronic relapsing disorder in which current therapies remain limited by incomplete efficacy, loss of response and cumulative toxicity. Because capsaicin activates TRPV1 on capsaicin-sensitive sensory neurons and can thereby evoke burning pain and neurogenic inflammation, its potential relevance to IBD was long overlooked. In recent years, however, a growing body of preclinical evidence has shown that capsaicin can attenuate experimental colitis through multiple pathways, including anti-inflammatory action, mucosal protection, microbiota regulation and microcirculation regulation, whereas higher doses, certain routes of administration and an already-inflamed mucosa favour adverse effects-consistent with the bell-shaped dose-response relationship reported for capsaicin.

Aim of the study: Hot red pepper (HRP) has emerged as a phytogenic feed additive with the potential to enhance laying performance in laying hens by improving gut health and mitigating oxidative stress.

Results: Regarding gut environment, dietary inclusion of 0.5%-0.75% HRP decreased caecal pH, whereas 0.75% HRP reduced colon pH (P < 0.05). For antioxidant status, HRP at 0.25-0.5% enhanced hepatic superoxide dismutase activity (P < 0.05), while all inclusion levels (0.5-0.75%) lowered malondialdehyde concentrations (P < 0.05). Histopathological evaluation confirmed reduced liver inflammation and cellular degeneration. Overall, dietary HRP improves productive performance, physiological status, gut function, and liver health in laying hens under tropical conditions, with 0.5% providing the most consistent benefits, supporting its application as an effective phytogenic feed additive in poultry production.

Aim of the study: Pepper fruits are globally consumed vegetables and spices that may serve as potential vectors for the dissemination of antibiotic resistance genes (ARGs) into the human food chain. This study investigated the associations of endogenous capsaicin and exogenous heavy metals with the resistome dynamics of peppers across successive harvest stages.

Results: Exposure to 50 mg/L of Cu2+ increased the abundance of CopR by 11.63-fold, while 0.6 mg/L Cd2+ exposure increased the abundances of baeR and mdtB by 8.51- and 7.89-fold, respectively. Furthermore, heavy metal stress substantially enhanced horizontal gene transfer, with Cd exposure increasing conjugation frequencies by 2.57-fold. These findings demonstrate that the pepper microenvironment represents a dynamic ecological niche in which plant-derived chemical defenses and abiotic contaminants jointly influence ARG dissemination. This study provides new insights into the multifactorial mechanisms driving ARG migration in soil-pepper systems and offers a scientific basis for reducing antibiotic resistance risks in agricultural production.