Introduction: A complex relationship between wine and cancer
In a recent study published in the journal Dr Frontiers in nutritionResearchers conducted meta-analytic studies to determine the relationship between wine consumption and cancer.
Cancer is one of the leading causes of morbidity and mortality worldwide. Smoking, alcohol use, tobacco use, and a high body mass index (BMI) are important risk factors in determining the total burden of cancer. Importantly, while alcohol consumption has been associated with an increased risk of developing various cancers (including head, neck, upper gastrointestinal tract, breast, liver, rectum, and colon), moderate wine consumption has shown an antagonistic effect. Current understanding of alcohol consumption and cancer remains controversial, particularly regarding wine consumption, warranting further research.
In the current meta-analysis, researchers investigated whether wine consumption may increase cancer risk.
Study: The relationship between wine consumption and cancer: a systematic review and meta-analysis. Image credit: DALL·E 3
Data pool and inclusion criteria
The Cochrane, Scopus, Web of Science, and MEDLINE (PubMed) databases were searched for relevant records from their inception to December 12, 2022, without publication date restrictions. In addition, the team screened references from previously conducted qualitative (systematic review) and quantitative (meta-analysis) studies. Only longitudinal studies evaluating the link between wine consumption and cancers of the upper gastrointestinal tract, kidney, colon, rectum, skin, pancreas, brain, lung, and gynecological tissues were included.
The team excluded reviews, editorials, environmental studies, case reports, studies not published in Spanish or English, and those lacking documentation of different wine consumption among different alcohol types. Two reviewers performed study selection, risk of bias assessment, data extraction, and resolved discrepancies through discussion or consultation with a third reviewer. Risks of bias were assessed using the Newcastle-Ottawa Scale (NOS).
The team used DerSimonian and Laird methods to determine pooled relative risks (RRs). I2 and τ2 statistics were used to assess heterogeneity and heterogeneity, respectively. A five-year follow-up was determined as the eligibility criteria for included studies for quantitative research to ensure data quality.
The team performed a sensitivity assessment by excluding one study at a time from the primary analysis. In addition, they analyzed subgroups by continent. They also performed random effects-type meta-regressions to assess the effect of participant age, proportion of women, and follow-up duration on the link between wine consumption and cancer risk. Egger’s regression coefficients were assessed to determine publication bias.
What the data reveals
There were 12,651 studies in the literature review; Title and abstract reviews excluded 8,380, and 377 were assessed for eligibility. Finally, 73 studies were included in the systematic review. In total, 31 studies were cohort studies, and 42 were case-control studies.
Study settings of record included are the United States (US), Australia, New Zealand, Greece, Canada, Uruguay, Argentina, the Netherlands, Italy, Denmark, Hawaii, the United Kingdom (UK), Puerto Rico, France, Germany, Spain, Norway, and Sweden. The study’s publication period was from 1986 to 2021, and the study included 4,346,504 individuals aged 18 to 103 years.
NOS scores of included studies ranged from seven to nine, indicating high quality. The pooled relative risks for the effect of wine consumption on the risk of gynecological, colorectal, renal, breast, and ovarian tumors were 1.0, 0.9, 0.9, 1.0, and 1.0, respectively. The variance in the included studies was between 50% and more than 75%.
Publication bias was reported for ovarian and renal tumors. Sensitivity and subgroup analyzes yielded similar results, indicating that the results of the primary analysis were robust. Follow-up duration affects the pooled RR for the association between wine consumption and tumors of the kidney, rectum, and colon. The inverse association between wine consumption and certain cancers may be due to wine components such as phytoestrogens and antioxidants.
The biochemistry behind wine’s effects
It has been established that alcohol is associated with gastric cancer, but the association is claimed to be lower in individuals who drink wine instead of other alcoholic beverages. Wine can increase stomach acidity, which can inhibit the growth of microorganisms such as Helicobacter pylori. Previous investigations have shown neuroprotective benefits of wine when consumed in small amounts.
Wine components, including resveratrol, have anti-mutagenic, anti-inflammatory, and antioxidant effects on carcinogenesis, with anti-inflammatory effects sustained during acute and chronic inflammation stages. Moreover, by suppressing cyclooxygenase 1 (COX1), resveratrol can inhibit the cellular processes of tumor initiation, development, and progression. Other anticarcinogenic components include quercetin, tannins, and anthocyanins, which protect against UV radiation and free radicals and inhibit myeloperoxidase (MPO) and cyclooxygenase-2 (COX-2) enzymatic activity, reducing skin cancer growth.
Overall, the study results showed no link between wine consumption and cancer risk. In contrast, wine consumption showed a protective trend regarding the risk of developing tumors, especially in the brain, lung, skin and pancreas. However, wine consumption was not defined uniformly across studies; The selected studies had different methods and did not document the amount of wine consumed. Considering potential confounders such as diet, lifestyle, and socioeconomic status with less variation, more studies documenting alcohol consumption in similar units are needed to determine the true effect of wine consumption in different populations.