Processed Meat Consumption and the Risk of Cancer: A Critical Evaluation of the Constraints of Current Evidence from Epidemiological Studies

Burden of colon and rectum cancer attributable to processed meat consumption in China, 1990-2021

Background

Colon and rectum cancer (CRC) poses a significant public health challenge, and diets high in processed meat have been identified as key risk factors. This study aims to assess the burden of CRC attributable to processed meat consumption in China from 1990 to 2021, focusing on mortality, disability-adjusted life years (DALYs), years lived with disability (YLDs), and years of life lost (YLLs).

Methods

Data were obtained from the Global Burden of Disease (GBD) study for CRC attributable to processed meat consumption in China from 1990 to 2021. The analysis included age-standardized rates for deaths, DALYs, YLDs, and YLLs, alongside age-period-cohort (APC) and decomposition analyses to examine temporal trends and contributing factors. Joinpoint regression was used to detect significant changes in trends.

Results

The burden of CRC attributable to processed meat consumption in China increased significantly between 1990 and 2021. In 2021, males exhibited higher mortality and DALY rates than females, particularly in older age groups. The age-standardized death rate rose from 0.23 to 0.32 per 100,000, and DALYs increased from 5.83 to 8.57 per 100,000. Joinpoint analysis revealed steep rises in DALYs and YLLs, especially during 2007-2011. APC analysis showed that older cohorts consistently exhibited higher death rates, while more recent cohorts displayed lower mortality. Decomposition analysis indicated that population growth and epidemiological changes drove the rise in mortality, with aging contributing to a reduction in deaths. These factors had a more pronounced impact on males.

Conclusion

The study highlights the growing burden of CRC linked to processed meat consumption in China over three decades, with significant gender differences and strong cohort effects. The findings call for targeted interventions to reduce processed meat consumption and mitigate CRC risk.

A Case-Control Study of Dietary Choline Intake and Risk of Colorectal Cancer Modified by Dietary B-Vitamin Intake

BACKGROUND/OBJECTIVES

The incidence of colorectal cancer (CRC) is rising, and Western diets high in red and processed meats may be contributing. It is important to identify dietary nutrients that increase CRC risk and perhaps interventions that may modulate such risk. The relationship between dietary choline intake and CRC is still unclear. We hypothesize that high dietary choline intake is associated with greater CRC risk, and B vitamin supplementation may modify this risk.

METHODS

In this case-control study, we collected demographic and dietary data using the validated National Cancer Institute CRC Risk Assessment Tool and Dietary Health Questionnaire III and analyzed colonoscopy outcomes. Logistic regression and stratified analyses were performed to calculate adjusted odds ratios and evaluate for effect modification.

RESULTS

Of 52 total patients, 21 had a normal colonoscopy result, and 31 were found to either have benign polyps or CRC. The average dietary choline intake was 207 mg/day in the normal group and 297 mg/day in the abnormal outcome group. A doubling in dietary choline intake was significantly associated with increased odds of polyps or CRC (OR 25.32, 95% CI 1.95-327.94). When stratified by vitamin B levels, the effect modification was difficult to confidently quantify due to the limited sample size.

CONCLUSIONS

Our findings suggest that higher dietary choline intake may be associated with an increased risk of CRC and its precursors, such as polyps. Although the potential modifying role of B vitamins was inconclusive, this study underscores the need for larger-scale research to further explore these associations and to assess the potential of dietary interventions in reducing CRC risk.

Dietary consumption trend and its correlation with global cancer burden: A quantitative and comprehensive analysis from 1990 to 2019

OBJECTIVE

The aim of this study was to estimate the effect of dietary consumption on cancer burden and formulate an effective solution.

METHODS

Dietary consumption, number of cancer deaths, disability-adjusted life years, and corresponding age-standardized rates were extracted from the Global Burden of Disease Study 2019. The annual percentage change was used to quantify the temporal trends in cancer burden and dietary consumption. Age, sex, location, and sociodemographic index were stratified to further analyze the discrepancy in cancer burden attributable to dietary intake.

RESULTS

Five cancers (breast, colon and rectal, tracheal, bronchus and lung, esophageal, and stomach) were documented to be associated with dietary consumption in the Global Burden of Disease database. The age-standardized death rate and age-standardized disability-adjusted life years rate in 2019 were 7.56 and 1168.77 per 100 000 population, respectively. For most cancers, the age-standardized death rate and age-standardized disability-adjusted life years rate displayed a decreasing tendency, with annual percentage change varying from -3.60 to -0.29 and from -3.64 to -0.03 from 1990 to 2019, respectively. The age-standardized death rate and age-standardized standardized disability-adjusted life years rate were higher in men than in women (9.68 vs 5.79 and 213.16 vs 129.18, respectively). In addition, the diet-related cancer burden in higher sociodemographic index regions exceeded that in lower sociodemographic index regions.

CONCLUSION

Dietary consumption has a considerable influence on cancer burden, among which colon and rectal cancer burden account for the largest proportion. Increasing the intake of whole grains, milk, fiber, calcium, vegetables, and fruits and reducing the consumption of processed meat and sodium are instrumental in lowering the disease burden of cancer. The quantitative analysis of dietary consumption would provide a more detailed reference for diet-related decision makers and raise awareness of healthy dietary habits in diet management departments, food production enterprises, and the general public.

Processed meat, red meat, white meat, and digestive tract cancers: A two-sample Mendelian randomization study

Background

Previous observational studies suggested inconsistent insights on the associations between meat intake and the risk of digestive tract cancers (DCTs). The causal effect of meat intake on DCTs is unclear.

Methods

Two-sample Mendelian randomization (MR) was performed based on genome-wide association studies (GWAS) summary data from UK Biobank and FinnGen to evaluate the causal effect of meat intake [processed meat, red meat (pork, beef, and lamb), and white meat (poultry)] on DCTs (esophageal, stomach, liver, biliary tract, pancreatic, and colorectal cancers). The causal effects were estimated using a primary analysis that employed inverse-variance weighting (IVW) and complementary analysis that utilized MR-Egger weighted by the median. A sensitivity analysis was conducted using the Cochran Q statistic, a funnel plot, the MR-Egger intercept, and a leave-one-out approach. MR-PRESSO and Radial MR were performed to identify and remove outliers. To demonstrate direct causal effects, multivariable MR (MVMR) was applied. In addition, risk factors were introduced to explore potential mediators of the relationship between exposure and outcome.

Results

The results of the univariable MR analysis indicated that genetically proxied processed meat intake was associated with an increased risk of colorectal cancer [IVW: odds ratio (OR) = 2.12, 95% confidence interval (CI) 1.07-4.19; P = 0.031]. The causal effect is consistent in MVMR (OR = 3.85, 95% CI 1.14-13.04; P = 0.030) after controlling for the influence of other types of exposure. The body mass index and total cholesterol did not mediate the causal effects described above. There was no evidence to support the causal effects of processed meat intake on other cancers, except for colorectal cancer. Similarly, there is no causal association between red meat, white meat intake, and DCTs.

Conclusions

Our study reported that processed meat intake increases the risk of colorectal cancer rather than other DCTs. No causal relationship was observed between red and white meat intake and DCTs.

The whole food beef matrix is more than the sum of its parts

Foods are not simply a delivery vehicle for nutrients; they consist of a matrix in which nutrients and non-nutrient compounds are presented that induce physiologic effects different from isolated nutrients. Dietary guidance is often based on effects of single nutrients that are considered unhealthy, such as saturated fat in beef. The purpose of this paper is to propose a working definition of the whole food beef matrix whose consumption has health effects distinct from those of isolated nutrients. The beef matrix can be defined as: the collective nutritive and non-nutritive components of the beef food structure and their unique chemical and physical interactions that may be important for human health which are distinguishable from those of the single components in isolation. Background information supporting this approach is summarized on multiple components provided by beef, temporal changes in beef consumption, dietary guidance that restricts beef, and how the background diet determines healthfulness rather than a single food. Examples of research are provided on other whole foods that differ from their constitutive nutrients and lay the groundwork for studies of beef as part of a healthy dietary pattern.

The role of prenatal vitamin D on the development of childhood asthma and wheeze: An umbrella review of systematic reviews and meta-analyses

BACKGROUND & OBJECTIVE

It has been suggested that prenatal vitamin D plays a role in the development of childhood asthma and wheeze. Several systematic reviews have been conducted, but the results are inconsistent, and the methodological quality has not been studied. Therefore, the objective of this umbrella review was to assess the internal validity of the evidence base and the evidence for an association between prenatal vitamin D and asthma or wheezing in the offspring.

METHODS

We searched the electronic databases Embase, PubMed, and Cochrane Library for studies on prenatal vitamin D using search words such as vitamin D, 25-hydroxyvitamin D, calcidiol, fetal, and neonatal. The search was conducted in June 2020, and the databases were searched from their date of establishment. We included systematic reviews and/or meta-analyses of experimental and observational studies assessing the association between prenatal vitamin D or asthma and wheeze. We excluded narrative reviews, commentaries, and other umbrella reviews. The methodological quality of systematic reviews was assessed using AMSTAR 2 tool. PROSPERO reg. no. CRD42020151329.

RESULTS

We identified 22 eligible systematic reviews (17 on asthma and 20 on wheeze). Using the AMSTAR 2 quality assessment tool, the methodological quality was rated as critically low in 21 out of 22 systematic reviews, suggesting that previous reviews and meta-analyses did not provide accurate and comprehensive summaries of the included studies and that conclusions reached were potentially flawed. The majority of the included reviews reported that prenatal vitamin D reduces the risk of wheeze in the offspring.

CONCLUSION

Prior to informing public guidelines, high-quality systematic reviews of the current evidence are greatly warranted.

Benefits and Risks Associated with Meat Consumption during Key Life Processes and in Relation to the Risk of Chronic Diseases

Red meat has been an important part of the diet throughout human evolution. Overall, when included as part of a healthy and varied diet, red meat can provide a rich source of bioavailable essential nutrients and high biological value protein. The present paper discusses the dietary role/impact of red and processed meat, with some reference to the relative effect of white meat, in a range of chronic conditions including iron-deficiency anaemia, cardiovascular diseases (CVD), cancer and dementia. The role of red meat in relation to key physiological conditions such as maintaining skeletal muscle and bone health and during pregnancy is also discussed. The inclusion of lean red meat in a healthy, varied diet may be beneficial during these critical conditions. There is however increasing evidence that red meat and especially processed meat are associated with increased risks of CVD, cancer and dementia whereas white meat is neutral or associated with a lower risk. There now seems little doubt that processed and unprocessed meat should have separate public dietary guidance.

The relationship between processed meat, red meat, and risk of types of cancer: A Mendelian randomization study

Background

Observational studies have suggested processed and red meat may increase the risk of cancer. However, the causal effects and direction between them were still unclear. We conducted two-sample Mendelian randomization (MR) analysis to evaluate the causal effect of processed meat and red meat on the risk of nine common types of cancer, namely, lung, ovarian, endometrial, breast, kidney, gastric, prostate, skin, and oropharyngeal cancer.

Methods

Genome-wide association studies (GWAS) for processed meat and red meat (pork, beef, and mutton) were obtained from the UK Biobank. GWAS of types of cancer in this study were extracted from the genetic consortia and the FinnGen consortium. The inverse variance weighted (IVW) was carried out as the main method for two-sample MR analysis. Sensitivity analyses were used to assess the robustness of the results.

Results

Genetically predicted processed meat intake was causally associated with increased risk of lung cancer (OR [odds ratio] = 1.923, 95% CI = 1.084-3.409, P = 0.025). There is no convincing evidence for the associations between genetically determined processed meat, red meat, and the risk of other cancers we studied.

Conclusion

Our results suggested that intake of processed meat may increase the risk of lung cancer. These findings provided no evidence to support that consumption of processed and red meat has a large effect on the risk of other cancers we studied. Further research is needed to clarify the results.