Association of plant-based dietary patterns with the risk of colorectal cancer: a large-scale case-control study

Indices of healthy and unhealthy plant-based diets and the risk of selected digestive cancers

BACKGROUND & AIMS

The relation between various types of plant-based diets and cancer risk is still unclear. We examined the association of the overall plant-based diet index (PDI) and healthy (hPDI) and unhealthy plant-based diet indices (uPDI) with the risk of selected digestive cancers.

METHODS

We used data from a network of hospital-based case-control studies including 942 oral/pharyngeal, 304 esophageal, 230 stomach, 1953 colorectal, and 326 pancreatic cancer cases. We calculated PDI, hPDI, and uPDI from a validated food frequency questionnaire. We used multivariable logistic regression models to estimate the odds ratios (OR) of selected digestive cancers across the three indices (in quintiles, Q, or tertiles, T, and in continuous).

RESULTS

The PDI was significantly inversely associated with oral/pharyngeal (ORQ5 vs Q1=0.63, 95% confidence interval, CI, 0.47-0.84) and esophageal cancer risk (ORT3 vs T1=0.47, 95% CI 0.31-0.72). The inverse associations appeared stronger for the hPDI (oral cavity/pharynx: ORQ5 vs Q1=0.52; 95% CI 0.39-0.70; esophagus: ORT3 vs T1=0.59, 95% CI 0.39-0.91; stomach: ORT3 vs T1=0.42, 95% CI 0.27-0.67; colorectum: ORQ5 vs Q1=0.69; 95% CI 0.57-0.84; pancreas: ORT3 vs T1=0.60; 95% CI 0.41-0.89). In contrast, the uPDI was directly associated with the risk of oral/pharyngeal (ORQ5 vs Q1=1.43, 95% CI 1.06-1.94), colorectal (ORQ5 vs Q1=2.28, 95% CI 1.86-2.81), and pancreatic cancer (ORT3 vs T1=1.74, 95% CI 1.14-2.65). Esophageal and stomach cancer risks were non-significantly increased by 34% and 46% respectively in the highest uPDI quantile.

CONCLUSION

A plant-based diet, especially a healthy plant-based diet, may reduce the risk of various digestive cancers, whereas an unhealthy plant-based diet may increase the risk. The quality of plant-based diets is important for digestive cancer risk evaluation and prevention.

A healthful plant-based diet can reduce the risk of developing colorectal cancer: case-control study

INTRODUCTION

The benefit of adherence to a plant-based diet concerning colorectal cancer (CRC) has not been investigated among Middle Eastern population. This study aimed to investigate how adherence to a plant-based diet influences the risk of CRC in this understudied population.

METHODS

This case-control study was conducted in the CRC surgery departments of general hospitals in Tehran, Iran. A total of 71 individuals with newly diagnosed CRC (cases) and 142 controls subjects free of cancer and acute illness were concurrently recruited from the same hospital. Dietary information was collected using a semi-quantitative 168-item food frequency questionnaire. Dietary patterns were characterized using the plant-based diet index (PDI), unhealthy plant-based diet index (uPDI) and healthy plant-based diet index (hPDI). Multivariate logistic regression was employed to assess the association between these dietary patterns and the risk of CRC.

RESULTS

After adjusting the potential confounders, the risk of CRC was significantly lower in the highest tertile of hPDI compared to the lowest tertile (odds ratio (OR) = 0.21; 95% confidence interval (CI): 0.07-0.56, representing 79% risk reduction). Conversely, the risk of CRC was significantly higher in the highest tertile of uPDI compared to the lowest tertile (OR = 6.76; 95% CI: 2.41-18.94). PDI was no significant associated with the risk of CRC.

CONCLUSIONS

This study found that higher scores on the hPDI was significantly associated with a decrease risk of CRC, while greater adherence to the uPDI contributed to a significantly increase risk.

Healthy dietary patterns, genetic risk, and gastrointestinal cancer incident risk: a large-scale prospective cohort study

BACKGROUND

Dietary patterns have been associated with several cancers, especially gastrointestinal cancer (GIC). However, whether a healthy dietary pattern could modify the risk of GIC among people with different genetic backgrounds is not clear.

OBJECTIVE

The objective of the study was to investigate how dietary patterns and genetic susceptibility contribute to the risk of GIC independently and jointly.

METHODS

This large-scale prospective cohort study included 105,463 participants in UK Biobank who were aged 40-72 y and cancer-free at baseline. Dietary intake (Oxford WebQ) was used to calculate dietary pattern scores including dietary approach to stop hypertension (DASH) score and healthful plant-based diet index (hPDI). Genetic risk was quantified by a polygenic risk score (PRS) comprising 129 known GIC-associated loci. Cox proportional hazards regression was performed to estimate the associations of dietary patterns and PRS with GIC incidence after adjusting for potential confounders.

RESULTS

Over a median follow-up of 11.70 y, 1,661 participants were diagnosed with GIC. DASH and hPDI were associated with 20% and 36% reductions, respectively, in GIC risk. Low PRS was associated with a 30 % decrease in GIC risk (HR: 0.70; 95% CI: 0.62, 0.79). Participants with healthy dietary scores at high-genetic risk had a lower GIC risk with HR of 0.77 (95% CI: 0.60, 0.98) for DASH and 0.66 (95% CI: 0.52, 0.84) for hPDI than those with unhealthy dietary score. Participants with both high-dietary score and low-genetic risk showed the lowest risk of GIC, with HR of 0.58 (95% CI: 0.45, 0.75) for DASH and 0.45 (95% CI: 0.34, 0.58) for hPDI.

CONCLUSIONS

Adherence to DASH and hPDI were associated with a lower risk of some gastrointestinal cancers, and these 2 dietary patterns may partly compensate for genetic predispositions to cancer. Our results advance the development of precision medicine strategies that consider both dietary patterns and genetics to improve gastrointestinal health.

Comparing the Associations of Dietary Patterns Identified through Principal Component Analysis and Cluster Analysis with Colorectal Cancer Risk: A Large Case-Control Study in China

Examining the association between dietary patterns and colorectal cancer (CRC) risk can provide valuable insights beyond the assessment of individual foods or nutrients. However, there is a lack of in-depth analysis of dietary patterns and CRC risk in Chinese populations, and few studies have compared dietary patterns derived from different posteriori methods with the aim of predicting disease risk. The aim of this study was to derive dietary patterns using both principal component analysis (PCA) and cluster analysis (CA) and to assess their respective associations with CRC risk. A large-scale case-control study was conducted in Guangdong Province, China, including 2799 incident colorectal cancer cases and an equal number of frequency-matched controls. Dietary intake information was gathered through the use of a validated food frequency questionnaire. PCA and CA were used to derive dietary patterns. A multivariable logistic regression model was used to calculate the adjusted odds ratio (aOR) and 95% confidence interval (CI). Four major dietary patterns were identified by PCA. CA identified two dietary patterns, referred to as the "Balanced dietary pattern" and the "Refined grain dietary pattern". Notably, there were significant inverse associations between the milk-egg-nut-soy dietary pattern (aOR, 0.51; 95% CI, 0.42, 0.62), the vegetable-fruit dietary pattern (aOR, 0.61; 95%CI, 0.51, 0.74), and the poultry-fish dietary pattern (aOR, 0.81; 95%CI, 0.68, 0.97) and CRC risk. However, the red meat-preserved food dietary pattern was associated with an increased risk of CRC (aOR, 2.99; 95%CI, 2.43, 3.67). When compared with the Refined grain dietary pattern, the Balanced dietary pattern showed a decreased risk of CRC (aOR, 0.59; 95%CI, 0.52, 0.66). The results from the comparison of the two methods indicate that both CA and PCA derived remarkably similar patterns. The combined use of PCA and CA identified consistent underlying patterns, showing comparable associations with CRC risk. These findings suggest that individuals who prefer dietary patterns characterized by a high intake of red meat, preserved food, and refined grains should be cautious about their increased CRC risk. Conversely, dietary patterns rich in fruits, vegetables, and high-quality protein sources are advisable for the prevention of CRC in the Chinese population.

Healthy and Unhealthy Plant-Based Diets and Glioma in the Chinese Population

Plant-based diets have been suggested to help prevent various chronic diseases, including cancer. However, there are few reports on central nervous system tumors, and data on dose-response relationships are lacking. This individual-matched case-control study included 506 cases and 506 controls. The overall plant-based diet index (PDI), the healthy plant-based diet index (hPDI), and the unhealthy plant-based diet index (uPDI) were calculated using dietary information collected through a food frequency questionnaire, with higher scores indicating better adherence. We analyzed the relationship of plant-based diets with glioma. After adequate adjustment for confounders, PDI was associated with a reduced glioma risk (OR = 0.42, 95% CI: 0.24-0.72). Conversely, uPDI was associated with an elevated glioma risk (OR = 8.04, 95% CI: 4.15-15.60). However, hPDI was not significantly associated with glioma risk (OR = 0.83, 95% CI: 0.48-1.45). For subgroups, PDI was not significant in analyzing young age, BMI, or any pathological subtypes. The restricted cubic spline function showed a significant dose-response relationship between PDI (p-nonlinearity< 0.0001) and uPDI (p-nonlinearity= 0.0711) and glioma. Further analysis found that refined grains had the greatest effect on gliomas in the less healthy plant-based food group. Therefore, following a plant-based diet was linked to a lower risk of glioma, especially when consuming fewer unhealthy plant-based foods.

Plant-based dietary patterns, genetic predisposition and risk of colorectal cancer: a prospective study from the UK Biobank

BACKGROUND

Plant-based dietary patterns may affect colorectal cancer (CRC) related outcomes, while risks differ in the quality of plant foods. We aimed to examine the association of plant-based diet quality with risks of CRC incidence and mortality and whether this association was modified by genetic risk.

METHODS

This prospective cohort study included 186,675 participants free of cancer when the last dietary recall was completed. We calculated three plant-based diet indices (PDIs), i.e., the overall plant-based diet index (PDI), the healthful plant-based diet index (hPDI), and the unhealthful plant-based diet index (uPDI) representing adherence to plant-based diets with diverse quality. Genetic risk was characterized using a weighted polygenic risk score (PRS), capturing overall risk variants associated with CRC. Hazard ratios (HR) and 95% confidential intervals (CI) were estimated by the cause-specific Cox proportional hazards model.

RESULTS

Over a follow-up of 9.5 years, 2163 cases and 466 deaths from CRC were documented. The HR of CRC incidence was 0.88 (95% CI, 0.81-0.96) and 0.91 (95% CI, 0.84-0.99) per 10-score increase in PDI and hPDI, respectively. Compared to the lowest quartile, PDI, hPDI, and uPDI in the highest quartile were associated with a 13% decrease, a 15% decrease, and a 14% increase in risk of incident CRC, respectively. We found a joint association of genetic risk and PDIs with incident CRC, with the highest hazard observed in those carrying higher PRS and adhering to lower-quality PDIs. The inverse association of PDI and hPDI with CRC mortality was pronounced in males.

CONCLUSIONS

Our results suggested that better adherence to overall and healthful plant-based diets was associated with a lower risk of CRC, whereas an unhealthful plant-based diet was associated with a higher CRC risk. Consumption of a higher-quality plant-based diet combined with decreased genetic risk conferred less susceptibility to CRC. Our findings highlighted the importance of food quality when adhering to a plant-based dietary pattern for CRC prevention in the general population.

Scoping review of the association of plant-based diet quality with health outcomes

Introduction

The association of plant-based dietary patterns with health outcomes has traditionally been assessed without considering nutritional value. The plant-based dietary index (PDI), first published in 2016, overcomes this limitation with both a healthful PDI (hPDI) and an unhealthful PDI (uPDI), based on the quality of plant foods consumed plus the frequency of animal foods. We sought to summarize the breadth of research using the hPDI and uPDI to gain insight into how the quality of plant-based dietary patterns might be associated with health outcomes.

Methods

Scoping review of studies that used the PDI, hPDI, or uPDI to report associations with health outcomes. Multiple databases were searched from 2010 through April 2023 with 2 authors independently assessing eligibility and extracting data. In addition to assessing the association of the indices to health outcomes, we determined the frequency of concordant or discordant findings for hPDI versus PDI and for hPDI versus uPDI.

Results

We included 95 articles (54% longitudinal, 37% cross-sectional, and 9% case-control) with a median sample size of 3,646. Higher hPDI levels were associated with favorable health outcomes in 36% of comparisons (most often for obesity, mortality, diabetes, cardiovascular disease, and psychiatric disorders), compared to 25% for the PDI and only 2% for the uPDI. Conversely, higher levels of the uPDI were associated with unfavorable health outcomes in 33% of comparisons, in contrast to under 1% for the hPDI and 2% for the PDI. When the hPDI association to an outcome was discordant with the uPDI or PDI, the significance and directionality always favored the hPDI over the uPDI, and nearly always favored the hPDI over the PDI.

Discussion

Dietary indices that account for the quality of plant foods can show health benefits that might be missed by a generic plant-based index. A greater focus on the quality of plant foods could improve nutrition guidelines, raise awareness about the benefits of adding unrefined plant foods to the diet, and empower consumers to make incremental additions of such foods to displace unhealthy foods. We anticipate increasing use of indices that address food quality in future research.

Oxidative balance score and dietary phytochemical index can reduce the risk of colorectal cancer in Iranian population

BACKGROUND

No previous study has assessed the association between oxidative balance score (OBS) and dietary phytochemical index (DPI) with colorectal cancer (CRC) simultaneously. Therefore, this study investigated the association between OBS and DPI with the odds of CRC among the Iranian population.

METHODS

This hospital-based age and sex-matched case-control study was conducted between September 2008 and January 2010 (142 controls and 71 cases were entered for analysis). New diagnosed CRC cases were selected from the Cancer Institute, Imam Khomeini Hospital of Tehran. Dietary intakes were determined by a semi-quantitative food frequency questionnaire (FFQ). Then, dietary indices were calculated by food items and nutrient intake. Logistic regression was utilized for assessing the tertiles of OBS and DPI.

RESULTS

In multivariate analysis, OBS was associated with a 77% reduction in CRC odds in the last tertile than the first tertile (odds ratio (OR) = 0.23, confidence interval (CI): 0.07-0.72, P_trend = 0.017). Also, we found a 64% reduction in CRC odds in the last tertile of DPI compared to the first tertile (OR = 0.36, CI: 0.15-0.86, P_trend = 0.015).

CONCLUSIONS

A diet rich in phytochemicals and anti-oxidants, including fruits and vegetables (citrus fruits, colored berries, and dark-green leafy vegetables) and whole grains, may reduce the CRC odds.

Why Does Obesity as an Inflammatory Condition Predispose to Colorectal Cancer?

Obesity is a complex and multifactorial problem of global importance. Additionally, obesity causes chronic inflammation, upregulates cell growth, disturbs the immune system, and causes genomic instability, increasing the risk of carcinogenesis. Colorectal cancer is one of the most common cancers, and it has become a global problem. In 2018, there were around 1.8 million new cases and around 881,000 deaths worldwide. Another risk factor of colorectal cancer associated with obesity is poor diet. A Western diet, including a high intake of red and processed meat and a low consumption of whole grains, fruits, vegetables, and fiber, may increase the risk of both colorectal cancer and obesity. Moreover, the Western diet is associated with a proinflammatory profile diet, which may also affect chronic low-grade inflammation. In fact, people with obesity often present gut dysbiosis, increased inflammation, and risk of colorectal cancer. In this article, the association between obesity and colorectal cancer is discussed, including the most important mechanisms, such as low-grade chronic inflammation, gut dysbiosis, and poor diet.