Dietary fiber intake and risk of renal cell carcinoma: evidence from a meta-analysis

Legume intake and cancer risk in a network of case-control studies

Evidence on the relationship between legume consumption and risk of specific cancer sites is inconclusive. We used data from a series of case-controls studies, conducted in Italy and in the Swiss Canton of Vaud between 1991 and 2009 to quantify the association between legume consumption and several cancer sites including oral cavity, esophagus, larynx, stomach, colorectum, breast, endometrium, ovary, prostate and kidney. Multiple logistic regression models controlled for sex, age, education, smoking, alcohol, body mass index, physical activity, comorbidities, and consumption of fruit, vegetables, processed meat and total calorie intake were used to estimate the odds ratios (OR) for different cancer sites and their corresponding 95% confidence intervals(CI). For female hormone-related cancers, the models also included adjustments for age at menarche, menopausal status and parity. Although most of the estimates were below unity, suggesting a protective effect, only colorectal cancer showed a significant association. Compared to no consumption, the OR for consuming at least one portion of legumes was 0.79 (95% CI: 0.68-0.91), the OR for consuming two or more portions was 0.68 (95% CI: 0.57-0.82) and the estimate for an increment of one portion per week was 0.87 (95% CI: 0.81-0.93). The inverse association between legume consumption and colorectal cancer suggests a possible role of legumes in preventing cancer risk.

Effect of smoking, hypertension and lifestyle factors on kidney cancer - perspectives for prevention and screening programmes

Renal cell carcinoma (RCC) incidence has doubled over the past few decades. However, death rates have remained stable as the number of incidental renal mass diagnoses peaked. RCC has been recognized as a European health care issue, but to date, no screening programmes have been introduced. Well-known modifiable risk factors for RCC are smoking, obesity and hypertension. A direct association between cigarette consumption and increased RCC incidence and RCC-related death has been reported, but the underlying mechanistic pathways for this association are still unclear. Obesity is associated with an increased risk of RCC, but interestingly, improved survival outcomes have been reported in obese patients, a phenomenon known as the obesity paradox. Data on the association between other modifiable risk factors such as diet, dyslipidaemia and physical activity with RCC incidence are conflicting, and potential mechanisms underlying these associations remain to be elucidated.

Association of diabetes risk reduction diet with renal cancer risk in 101,755 participants: a prospective study

BACKGROUND

There is little prospective evidence exists about whether adherence to a diabetes risk reduction diet (DRRD) is related to a significant reduction in renal cancer risk. We sought to clarify whether adherence to DRRD was associated with a reduced risk of renal cancer in a US population.

METHODS

A population-based cohort of 101,755 American adults was identified from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. A DRRD score was calculated to assess adherence to this dietary pattern, where increased scores indicated greater adherence. The relationship between DRRD score and risk of renal cancer was assessed based on the hazard ratios (HRs) and 95% confidence intervals (CIs), which were both calculated using Cox regression. Non-linear association was determined through restricted cubic spline regression. Potential effect modifiers were identified through subgroup analyses.

RESULTS

Over a mean follow-up of 8.8 years, 446 renal cancers were detected. In this analysis, the fully adjusted model depicted a notable 29% reduction in the risk of renal cancer among individuals in the highest quartile of DRRD score in comparison with the lowest quartile individuals (HRQ4 vs. Q1: 0.71; 95% CI = 0.54, 0.94; Ptrend = 0.008). This association remained consistent across a series of sensitivity analyses. A non-linear inverse dose-response association between renal cancer risk with DRRD score was observed (Pnonlinearity = 0.026). Subgroup analyses showed that this favorable link was more prominent in participants with low Healthy Eating Index-2015 (Pinteraction = 0.015). Regarding the individual components of DRRD, a decrease in the risk of renal cancer was linked to increased intake of cereal fiber and whole fruit, and lower sugar-sweetened beverage consumption (all Ptrend < 0.05).

CONCLUSIONS

Our findings indicate that individuals adhering to DRRD are associated with a reduction in the risk of renal cancer.

Food groups and urologic cancers risk: a systematic review and meta-analysis of prospective studies

Background

To assess the association between 12 food groups intake and the risk of urologic cancers.

Methods

We scanned PubMed and Web of Science databases up to April 1st, 2023, and 73 publications met the inclusion criteria in the meta-analysis. We used a random effects model to estimate the summary risk ratios (RRs) and 95% confidence intervals (95% CI).

Results

In the linear dose-response meta-analysis, an inverse association was found between each additional daily 100 g of fruits [RR: 0.89, 95%CI = (0.83, 0.97)], 100 g of vegetables [RR: 0.92, 95%CI = (0.85, 0.99)], 12 g of alcohol [RR: 0.91, 95%CI = (0.88, 0.94)] and 1 cup of coffee [RR: 0.95, 95%CI = (0.83, 0.97)] intake and the risk of renal cell carcinoma. Conversely, each additional daily 100 g of red meat intake was positively associated with renal cell carcinoma [RR: 1.41, 95%CI = (1.03, 2.10)]. Inverse associations were observed between each additional daily 50 g of egg [RR: 0.73, 95%CI = (0.62, 0.87)] and each additional daily 1 cup of tea consumption and bladder cancer risk [RR: 0.97, 95%CI = (0.94, 0.99)]. There were no significant associations for nonlinear dose-response relationships between 12 food groups and urological cancers.

Conclusion

Our meta-analysis strengthens the evidence that appropriate intake of specific food groups, such as fruits, vegetables, alcohol, tea, and coffee, is associated with the risk of renal cell carcinoma or bladder cancer. More studies are required to fill the knowledge gap on the links between various food groups and urologic cancers because the evidence was less credible in this meta-analysis.

Systematic Review Registration

This study was registered on PROSPERO (CRD42022340336).

A major mechanism for immunomodulation: Dietary fibres and acid metabolites

Diet and the gut microbiota have a profound influence on physiology and health, however, mechanisms are still emerging. Here we outline several pathways that gut microbiota products, particularly short-chain fatty acids (SCFAs), use to maintain gut and immune homeostasis. Dietary fibre is fermented by the gut microbiota in the colon, and large quantities of SCFAs such as acetate, propionate, and butyrate are produced. Dietary fibre and SCFAs enhance epithelial integrity and thereby limit systemic endotoxemia. Moreover, SCFAs inhibit histone deacetylases (HDAC), and thereby affect gene transcription. SCFAs also bind to 'metabolite-sensing' G-protein coupled receptors (GPCRs) such as GPR43, which promotes immune homeostasis. The enormous amounts of SCFAs produced in the colon are sufficient to lower pH, which affects the function of proton sensors such as GPR65 expressed on the gut epithelium and immune cells. GPR65 is an anti-inflammatory Gα_s-coupled receptor, which leads to the inhibition of inflammatory cytokines. The importance of GPR65 in inflammatory diseases is underscored by genetics associated with the missense variant I231L (rs3742704), which is associated with human inflammatory bowel disease, atopic dermatitis, and asthma. There is enormous scope to manipulate these pathways using specialized diets that release very high amounts of specific SCFAs in the gut, and we believe that therapies that rely on chemically modified foods is a promising approach. Such an approach includes high SCFA-producing diets, which we have shown to decrease numerous inflammatory western diseases in mouse models. These diets operate at many levels - increased gut integrity, changes to the gut microbiome, and promotion of immune homeostasis, which represents a new and highly promising way to prevent or treat human disease.

Genesis and Mechanism of Some Cancer Types and an Overview on the Role of Diet and Nutrition in Cancer Prevention

Cancer is a major disease with a high mortality rate worldwide. In many countries, cancer is considered to be the second most common cause of death after cardiovascular disease. The clinical management of cancer continues to be a challenge as conventional treatments, such as chemotherapy and radiation therapy, have limitations due to their toxicity profiles. Unhealthy lifestyle and poor dietary habits are the key risk factors for cancer; having a healthy diet and lifestyle may minimize the risk. Epidemiological studies have shown that a high fruit and vegetable intake in our regular diet can effectively reduce the risk of developing certain types of cancers due to the high contents of antioxidants and phytochemicals. In vitro and in vivo studies have shown that phytochemicals exert significant anticancer effects due to their free radical scavenging capacity potential. There has been extensive research on the protective effects of phytochemicals in different types of cancers. This review attempts to give an overview of the etiology of different types of cancers and assesses the role of phytonutrients in the prevention of cancers, which makes the present review distinct from the others available.

The role of diet in renal cell carcinoma incidence: an umbrella review of meta-analyses of observational studies

BACKGROUND

Evidence associating diet with the incidence of renal cell carcinoma (RCC) is inconclusive. We aimed to summarize evidence associating dietary factors with RCC incidence and assess the strength and validity of this evidence.

METHODS

We conducted an umbrella review of systematic reviews or meta-analyses (SRoMAs) that assessed the association between diet and RCC incidence. Through April 2021, PubMed, Web of Science, Embase, The Cochrane Library, Scopus, and WCRF were searched. Two independent reviewers selected studies, extracted data, and appraised the quality of SRoMAs. According to credibility assessment criteria, evidence can be divided into five categories: convincing (class I), highly suggestive (class II), suggestive (class III), weak (class IV), and nonsignificant (class V).

RESULTS

Twenty-nine meta-analyses were obtained after screening. After excluding 7 overlapping meta-analyses, 22 meta-analyses including 502 individual studies and 64 summary hazard ratios for RCC incidence were included: dietary patterns or dietary quality indices (n = 6), foods (n = 13), beverages (n = 4), alcohol (n = 7), macronutrients (n =15), and micronutrients (n =19). No meta-analyses had high methodological quality. Five meta-analyses exhibited small study effects; one meta-analysis showed evidence of excess significance bias. No dietary factors showed convincing or highly suggestive evidence of association with RCC in the overall analysis. Two protective factors had suggestive evidence (vegetables (0.74, 95% confidence interval 0.63 to 0.86) and vitamin C (0.77, 0.66 to 0.90)) in overall analysis. One protective factor had convincing evidence (moderate drinking (0.77, 0.70 to 0.84)) in Europe and North America and one protective factor had highly suggestive evidence (cruciferous vegetables (0.78, 0.70 to 0.86)) in North America.

CONCLUSIONS

Although many meta-analyses have assessed associations between dietary factors and RCC, no high-quality evidence exists (classes I and II) in the overall analysis. Increased intake of vegetables and vitamin C is negatively associated with RCC risk. Moderate drinking might be beneficial for Europeans and North Americans, and cruciferous vegetables might be beneficial to North Americans, but the results should be interpreted with caution. More researches are needed in the future.

TRIAL REGISTRATION

PROSPERO CRD42021246619.

Whole Grains, Refined Grains, and Cancer Risk: A Systematic Review of Meta-Analyses of Observational Studies

PubMed, Web of Science, and the Cochrane Database of Systematic Reviews were searched for meta-analyses that provided risk estimates (±95% confidence intervals) for associations between intakes of whole and refined grains and risk of total and site-specific cancer. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were followed. Only meta-analyses that included whole grains and refined grains as separate food groups, and not as part of dietary patterns, were included. A total of 17 publications were identified that met inclusion criteria. Within these, results from a total of 54 distinct meta-analyses were reported for whole grains and 5 meta-analyses for refined grains. For total cancer mortality, 7 meta-analyses of cohort studies indicated that whole grain intake was associated with 6% to 12% lower risk in comparison of highest vs. lowest intake groups, and 3% to 20% lower risk for doses ranging from 15 to 90 g/day. For site-specific cancers, meta-analyses indicated that whole grain intake was consistently associated with lower risks of colorectal, colon, gastric, pancreatic, and esophageal cancers. Limited data were available for refined grains, with only 4 publications providing risk estimates, and only 1 of the meta-analyses included more than 3 studies. High intake of refined grains was associated with increased risk of colon and gastric cancer. By contrast, in the only dose-response meta-analysis, each 90 g/day consumption of refined grains was associated with a 6% lower risk of total cancer. In addition to the limited number of published meta-analyses on refined grains, results were also weakened due to the fact that refined grains were frequently defined to include both staple grain foods and indulgent grain foods, and the majority of studies included in the meta-analyses provided no specific definition of refined grains. Overall, meta-analyses of cohort and case-control studies consistently demonstrate that whole grain intake is associated with lower risk of total and site-specific cancer, and support current dietary recommendations to increase whole grain consumption. By contrast, the relationship between refined grain intake and cancer risk is inconclusive.

Association of Processed Meats and Alcohol Consumption with Renal Cell Carcinoma: A Worldwide Population-Based Study

The link between diet and renal cell carcinoma (RCC) is still unclear. The purpose of this study was to evaluate the association of diet with RCC's incidence and mortality rates worldwide. We conducted an ecological study including 170 countries, whose data on age-standardized (AS) incidence and mortality rates of RCC, dietary factors, and potentially confounding factors such as obesity, insufficient physical activity, tobacco smoking, hypertension, diabetes, and human development index (HDI) were collected and available on May 2020 from the Global Cancer Observatory, the Global Dietary Database, the Global Health Observatory data repository, the Diabetes Atlas 9th edition and the Human Development Report 2019. Univariable and multivariable linear regression analyses were performed to determine the association of dietary factors with incidence and mortality rates of RCC adjusted for the effects of population age and potentially confounding factors. Intake of processed meats and consumption of alcohol were both positively associated with AS incidence rates of RCC (β = 0.11, P < 0.001 and β = 0.1, P = 0.044, respectively). We suggest that high consumption of processed meats and/or alcohol is a risk factor for RCC. However, they were not associated with mortality. Further research is needed at an individual level.Supplemental data for this article is available online at https://doi.org/10.1080/01635581.2020.1856388.

Diabetes and kidney cancer risk among post-menopausal women: The Iowa women's health study

BACKGROUND

Many studies have reported a positive association between diabetes and kidney cancer. However, it is unclear whether diabetes is a risk factor for kidney cancer independent of other risk factors, such as obesity and hypertension. We comprehensively examined the association of diabetes and its duration with incident kidney cancer in the prospective cohort Iowa Women's Health Study (1986-2011).

METHODS

Diabetes status was self-reported at baseline (1986) and on five follow-up questionnaires. Cox proportional hazards regression was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations of baseline and time-dependent diabetes with the risk of incident kidney cancer.

RESULTS

During the 25 years of follow-up, 245 cases of kidney cancer occurred among 36,975 post-menopausal women. In an age-adjusted model, there was a significant association between time-dependent diabetes and the risk of kidney cancer [HR (95% CI) = 1.76 (1.26, 1.45)]; the association was attenuated after multivariable adjustment for age, body mass index (BMI), waist-to-hip ratio (WHR), hypertension, physical activity, diuretic use, pack-years of smoking, alcohol intake, and total caloric intake [HR = 1.35 (0.94, 1.94)]. However, among non-obese women or women with a waist circumference less than 34.6 in., diabetes was significantly associated with kidney cancer risk: for time-dependent diabetes, HRs (95% CIs) were 1.82 (1.10, 3.00) among those with BMI < 30 kg/m² and 2.18 (1.08, 4.38) among those with a waist circumference <34.6 in..

CONCLUSIONS

Our results suggest that diabetes is associated with kidney cancer risk among non-obese post-menopausal women.

Lifestyle in urology: Cancer

The opportunity to prevent, to improve their prognosis, or even to cure uro-oncological diseases by modifying the lifestyle habits is a very modern topical subject and represents a great and fascinating challenge for the future. A PubMed and Web of Science databases search has been performed to review the published knowledge on most important lifestyle habits, such as smoking, physical activity, nutrition, sexual activity, and personal hygiene, highlighting modifiable factors influencing development and progression of urological cancers. Cigarette smoking has been historically established as risk factors for urothelial cancer, and an association with risk of renal cell carcinoma and worse prognosis of prostate cancer has been sufficiently demonstrated. Poor genital hygiene is a recognized risk factor for penile cancer. Furthermore, a convincing evidence has been found on the association between physical activity and both risk and prognosis of bladder and prostate cancer. Obesity is strongly associated with increased risk of developing lethal prostate cancer. An unequivocal evidence of a direct relationship between most of the other lifestyle habits and development of the uro-oncological diseases has not been found.

Dietary fiber, glycemic index, glycemic load and renal cell carcinoma risk

Several epidemiological studies have investigated the potential association between dietary fiber, glycemic index (GI) or glycemic load (GL), and renal cell carcinoma (RCC) risk with inconsistent results. The aim of this study was to systematically evaluate this issue with a meta-analysis approach. A comprehensive literature search up to March 2018 was performed in PubMed and Web of Science databases. Summary relative risks (RRs) and 95% confidence intervals (CIs) were estimated with a random-effects model. Twelve studies were finally included in this study (eight for fiber analysis, five for GI and five for GL). A significant positive association was observed between GI and the risk of RCC (summary RR 1.16, 95% CI 1.02-1.32), and no significant heterogeneity was detected among studies (I2 = 22.8%, P = 0.262). A significant inverse association was found between fiber intake and the risk of RCC (summary RR 0.82, 95% CI 0.72-0.92), and no significant heterogeneity was observed across studies (I2 = 27.6%, P = 0.218). GL was not significantly associated with RCC risk (summary RR 1.14, 95% CI 0.81-1.60), and significant heterogeneity was found across studies (I2 = 78.6%, P < 0.001). In conclusion, this systematic review and meta-analysis suggests that dietary GI and fiber may be associated with the risk of RCC. Further large prospective cohort studies are still warranted to confirm our preliminary findings.

Ureteropelvic junction obstruction caused by metastatic cholangiocarcinoma

We describe the rare case of a 61-year-old female with right ureteropelvic junction (UPJ) obstruction caused by metastatic cholangiocarcinoma. Her past medical history was notable for cholangiocarcinoma treated with neoadjuvant chemoradiation and two orthotopic liver transplants six years earlier. Urology was consulted when she presented with flank pain and urinary tract infection. Diagnostic workup demonstrated right UPJ obstruction. She was managed acutely with percutaneous nephrostomy. She subsequently underwent robotic pyeloplasty and intrinsic obstruction of the UPJ was discovered. Histological examination revealed adenocarcinoma, consistent with systemic recurrence of the patient's known cholangiocarcinoma.

Dietary Fiber and Gut Microbiota in Renal Diets

Nutrition is crucial for the management of patients affected by chronic kidney disease (CKD) to slow down disease progression and to correct symptoms. The mainstay of the nutritional approach to renal patients is protein restriction coupled with adequate energy supply to prevent malnutrition. However, other aspects of renal diets, including fiber content, can be beneficial. This paper summarizes the latest literature on the role of different types of dietary fiber in CKD, with special attention to gut microbiota and the potential protective role of renal diets. Fibers have been identified based on aqueous solubility, but other features, such as viscosity, fermentability, and bulking effect in the colon should be considered. A proper amount of fiber should be recommended not only in the general population but also in CKD patients, to achieve an adequate composition and metabolism of gut microbiota and to reduce the risks connected with obesity, diabetes, and dyslipidemia.

Obesity and cancer risk: Emerging biological mechanisms and perspectives

Continuously rising trends in obesity-related malignancies render this disease spectrum a public health priority. Worldwide, the burden of cancer attributable to obesity, expressed as population attributable fraction, is 11.9% in men and 13.1% in women. There is convincing evidence that excess body weight is associated with an increased risk for cancer of at least 13 anatomic sites, including endometrial, esophageal, renal and pancreatic adenocarcinomas; hepatocellular carcinoma; gastric cardia cancer; meningioma; multiple myeloma; colorectal, postmenopausal breast, ovarian, gallbladder and thyroid cancers. We first synopsize current epidemiologic evidence; the obesity paradox in cancer risk and mortality; the role of weight gain and weight loss in the modulation of cancer risk; reliable somatometric indicators for obesity and cancer research; and gender differences in obesity related cancers. We critically summarize emerging biological mechanisms linking obesity to cancer encompassing insulin resistance and abnormalities of the IGF-I system and signaling; sex hormones biosynthesis and pathway; subclinical chronic low-grade inflammation and oxidative stress; alterations in adipokine pathophysiology; factors deriving from ectopic fat deposition; microenvironment and cellular perturbations including vascular perturbations, epithelial-mesenchymal transition, endoplasmic reticulum stress and migrating adipose progenitor cells; disruption of circadian rhythms; dietary nutrients; factors with potential significance such as the altered intestinal microbiome; and mechanic factors in obesity and cancer. Future perspectives regarding prevention, diagnosis and therapeutics are discussed. The aim of this review is to investigate how the interplay of these main potential mechanisms and risk factors, exerts their effects on target tissues provoking them to acquire a cancerous phenotype.

Association between dietary fiber intake and risk of ovarian cancer: a meta-analysis of observational studies

Objective

To evaluate the associations between dietary fiber intake and ovarian cancer risk.

Methods

A literature survey was conducted by searching the PubMed, Web of Science, and Wanfang Med Online databases up to March 1st, 2018. The effect of dietary fiber intake on ovarian cancer risk was evaluated by calculating relative risks with 95% confidence intervals (95%CI) using Stata 12.0 software.

Results

A total of 17 articles with 149,177 participants including 7609 ovarian cancer patients were included in this analysis. The summarized relative risk for ovarian cancer in participants with the highest compared with the lowest fiber intake was 0.760 (95%CI=0.702–0.823), with no significant between-study heterogeneity (I²=12.4%). Subgroup analysis according to study design demonstrated positive associations in both cohort studies and case-control studies. Moreover, the results were consistent among populations from America, Europe, and Asia. No publication bias was found by Egger’s test or funnel plots.

Conclusion

This meta-analysis concluded that a high intake of dietary fiber could significantly reduce the risk of ovarian cancer compared with a low fiber intake.

The Benefits of Dietary Fiber Intake on Reducing the Risk of Cancer: An Umbrella Review of Meta-analyses

Objective

The purpose of this study was to review previously published meta-analyses on the effectiveness of dietary fiber on reducing the incidence of cancer.

Methods

An umbrella review of all published meta-analyses was performed. A PubMed search from January 1, 1980 to June 30, 2017 was conducted using the following search strategy: (fiber OR fibre) AND (meta-analysis OR systematic review) AND (cancer OR carcinoma). Only English-language publications that provided quantitative statistical analysis on cancer were retrieved.

Results

Nineteen meta-analyses comparing highest vs lowest dietary fiber intake were retrieved for inclusion in this umbrella review. There was a statistically significant reduction in the relative risk (RR) of colorectal, esophageal, gastric, and pancreatic cancer (RR = 0.52-0.88); however, statistically significant heterogeneity was observed in the meta-analyses on esophageal, gastric, and pancreatic cancer. There was a statistically significant reduction in the RR of breast cancer (RR = 0.85-0.93).

Conclusion

This review suggests that those consuming the highest amounts of dietary fiber may benefit from a reduction in the incidence of developing colorectal cancer, and there also appears to be a small reduction in the incidence of breast cancer.

Dietary fiber and health outcomes: an umbrella review of systematic reviews and meta-analyses

Background

Several studies have suggested that higher consumption of dietary fiber is beneficial for a variety of health outcomes. However, many results have been inconclusive and, to our knowledge, there has been no attempt to systematically capture the breadth of outcomes associated with dietary fiber intake or to systematically assess the quality and the strength of the evidence on the associations of dietary fiber intake and different health outcomes or medical conditions.

Objective

The aim of this study was to describe the diverse health outcomes convincingly associated with dietary fiber consumption.

Design

This was an umbrella review of systematic reviews with meta-analysis of observational studies. For each association, random-effects summary effect size, 95% CIs, and 95% prediction intervals were estimated. We also assessed heterogeneity, evidence for small-study effect, and evidence for excess significance bias. We used these metrics to evaluate the credibility of the identified evidence.

Results

Our literature search identified 1351 abstracts. Of these, 18 meta-analyses including a total of 298 prospective observational studies and 21 outcomes were included. Outcomes studied included cancer and precancer lesions (n = 12), cardiovascular diseases (CVDs; n = 3), all-cause and specific-cause mortality (n = 4), type 2 diabetes (n = 1), and Crohn disease (n = 1). Overall, 6 (29%) of the 21 eligible outcomes reported highly significant summary results (P < 1 × 10-6); these included CVD and CVD mortality, coronary artery disease, pancreatic cancer, and gastric cancer. Overall, 3 of 21 (14%) outcomes presented convincing evidence (pancreatic cancer, CVD mortality, and all-cause mortality), but only CVD and all-cause mortality were based on prospective studies. Two other outcomes (10%), CVD and coronary artery disease, presented highly suggestive evidence based on prospective studies.

Conclusion

Our results support dietary recommendations that promote higher fiber intake as part of a healthy diet.

Dietary fibre intake in relation to the risk of incident chronic kidney disease

The purpose of this study was primarily to evaluate the association of total fibre intake with the risk of incident chronic kidney disease (CKD). We also evaluated the association of dietary fibre from fruits, vegetables, cereals and legumes with the incidence of CKD in a population-based prospective study. We followed up 1630 participants of the Tehran Lipid and Glucose Study for 6·1 years, who were initially free of CKD. Baseline diet was assessed by a valid and reliable FFQ. Estimated glomerular filtration rate (eGFR) was calculated, using the Modification of Diet in Renal Disease Study equation, and CKD was defined as eGFR <60 ml/min per 1·73 m2. OR using multivariable logistic regression was reported for the association of incident CKD with tertiles of dietary fibre intake. After adjustment for age, sex, smoking, total energy intake, physical activity, diabetes and using angiotensin-converting-enzyme inhibitor, the OR for subjects in the highest compared with the lowest tertile of total fibre intake was 0·47 (95 % CI 0·27, 0·86). In addition, for every 5 g/d increase in total fibre intake, the risk of incident CKD decreased by 11 %. After adjusting for potential confounders, OR for participants in the highest compared with the lowest tertile of fibre from vegetables was 0·63 (95 % CI 0·43, 0·93) and from legumes it was 0·68 (95 % CI 0·47, 0·98). We observed inverse associations between total fibre intake and risk of incident CKD, which demonstrate that high fibre intake, mainly from legumes and vegetables, may reduce the occurrence of CKD.

Glycemic index, glycemic load and carbohydrate intake in association with risk of renal cell carcinoma

Carbohydrate intake affects postprandial glucose levels and insulin response, which plays a role in carcinogenesis. The relationship between carbohydrate intake, dietary glycemic index (GI) and glycemic load (GL), and risk of renal cell carcinoma (RCC) remains unclear. We conducted a case-control study including 854 patients with newly diagnosed RCC (cases) and 1255 healthy participants (controls) recruited since 2002. GI, GL and carbohydrate intake were obtained via a validated food frequency questionnaire. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using multivariable logistic regression, adjusting for potential confounders. We found that higher GI was significantly associated with RCC risk with an OR of 1.32 (95% CI, 0.99-1.74; Ptrend = 0.026) (the highest versus the lowest quartiles). We also observed an inverse association between fiber intake and RCC risk with OR of 0.70 (95% CI = 0.50-0.99) as well as between starch intake and risk of RCC with OR of 0.65 (95% CI = 0.49-0.87). Individuals with a high-GI diet and hypertension or high body mass index (BMI) had a 2.7 times (OR = 2.67, 95% CI = 1.96-3.64) and two times (OR = 1.95, 95% CI = 1.29-2.92) higher RCC risk, respectively, than those without these factors. Our findings suggest that a high-GI diet is associated with an increased risk of RCC, whereas increased fiber and starch intakes appear to be associated with a decreased risk of RCC. We found that reducing GI levels and increasing fiber intake could be a dietary strategy to decrease RCC risk, especially for individuals with hypertension or high BMI.

Dietary Inflammatory Index and Renal Cell Carcinoma Risk in an Italian Case-Control Study

BACKGROUND

The relation between diet-related inflammation and renal cell carcinoma (RCC) has not been investigated.

METHODS

In this study, we explored the association between the dietary inflammatory index (DII) and RCC in an Italian case-control study conducted between 1992 and 2004. Cases were 767 patients with incident, histologically confirmed RCC. Controls were 1534 subjects admitted to the same hospitals as cases for various acute, nonneoplastic conditions. The DII was computed based on dietary intake assessed using a reproducible and valid 78-item food frequency questionnaire. Odds ratios (ORs) were estimated through logistic regression models conditioned on age, sex, and center, and adjusted for recognized confounding factors, including total energy intake.

RESULTS

Subjects in the highest quartile of DII scores (i.e., with the most proinflammatory diets) had a higher risk of RCC compared to subjects in the lowest quartile [OR 1.41, 95% confidence interval (CI) 1.02, 1.97; p-trend = 0.04)]. Apparently stronger associations were observed among females (OR 1.68, 95% CI 0.93, 3.03), subjects aged <60 yr (OR 1.77, 95% CI 1.05, 2.98), body mass index ≥25 kg/m2 (OR 1.64, 95% CI 1.07, 2.51), and ever smokers (OR 1.66, 95% CI 1.08, 2.57), in the absence of significant heterogeneity.

CONCLUSION

A proinflammatory diet is associated with increased RCC risk.

Dietary fibre in Europe: current state of knowledge on definitions, sources, recommendations, intakes and relationships to health

Research into the analysis, physical properties and health effects of dietary fibre has continued steadily over the last 40–50 years. From the knowledge gained, countries have developed guidelines for their populations on the optimal amount of fibre to be consumed each day. Food composition tables from many countries now contain values for the dietary fibre content of foods, and, from these, combined with dietary surveys, population intakes have been determined. The present review assessed the uniformity of the analytical methods used, health claims permitted, recommendations and intakes, particularly from national surveys across Europe and around the world. It also assessed current knowledge on health effects of dietary fibre and related the impact of different fibre types on health. The overall intent was to be able to provide more detailed guidance on the types of fibre which should be consumed for good health, rather than simply a total intake figure, the current situation. Analysis of data indicated a fair degree of uniformity in the definition of dietary fibre, the method used for analysis, the recommended amount to be consumed and a growing literature on effects on digestive health and disease risk. However, national dietary survey data showed that intakes do not reach recommendations and very few countries provide guidance on the types of fibre that are preferable to achieve recommended intakes. Research gaps were identified and ideas suggested to provide information for more detailed advice to the public about specific food sources that should be consumed to achieve health benefits.

Dietary inflammatory index and risk of renal cancer in the Iowa Women's Health Study

BACKGROUND

The association between inflammatory potential of diet and renal cancer risk has not been investigated.

METHODS

In this study, we explored the association between the dietary inflammatory index (DII) and risk of renal cancer in the Iowa Women's Health Study. From 1986 to 2011, 33,817 women initially recruited at 55-69 years of age were followed for incident renal cancers (n = 263). The DII was computed based on dietary intake assessed using a reproducible and valid 121-item food frequency questionnaire. Cox proportional hazards regression was used to estimate hazard ratios (HR) adjusting for age, body mass index, energy intake, smoking status, education, pack years of smoking, hypertension, and hormone replacement therapy.

RESULTS

Multivariable analyses revealed positive association between higher DII scores and renal cancer risk (HR for DII_continuous: 1.07 per unit increase in DII (corresponding to 10% change in the DII range in the current study); 95% CI 1.00, 1.15; HR for DII_tertile3vs1 = 1.52; 95% CI 1.09, 2.13). Stratified analyses produced slightly stronger associations between DII and renal cancer risk among women with BMI <30 kg/m² (HR_Tertile3vs1 = 1.57; 95% CI = 1.04, 2.36) and ever smokers (HR_tertile3vs1 = 2.35; 95% CI = 1.22, 4.55), although the corresponding interaction p values were not significant.

CONCLUSION

Pro-inflammatory diet, as indicated by higher DII scores, was associated with increased renal cancer risk.

Renal cell carcinoma: links and risks

This review provides an overview of the incidence of renal cell carcinoma (RCC) and a summary of the most commonly associated risk factors. A literature review was performed with a focus on recent studies with a high level of evidence (large prospective cohort studies and meta-analyses). The incidence rate of RCC varies globally, with the rate rising rapidly in more developed regions, demonstrating the effects of increased use of diagnostic imaging and prevalence of modifiable risk factors. Based on the current evidence, cigarette smoking, obesity, and hypertension are the most well-established risk factors for sporadic RCC worldwide. Acquired cystic kidney disease is also a significant risk factor, specifically in dialysis patients. There is increasing evidence for an inverse association between RCC risk and moderate alcohol consumption. Certain analgesics and occupational exposure have been linked to an increased risk of RCC, although data are limited. Diets rich in fruits and vegetables may provide a protective effect.