Mediterranean diet and olive oil, microbiota, and obesity-related cancers. From mechanisms to prevention.

Olive oil (OO) is the main source of added fat in the Mediterranean diet (MD). It is a mix of bioactive compounds, including monounsaturated fatty acids, phytosterols, simple phenols, secoiridoids, flavonoids, and terpenoids. There is a growing body of evidence that MD and OO improve obesity-related factors. In addition, obesity has been associated with an increased risk for several cancers: endometrial, oesophageal adenocarcinoma, renal, pancreatic, hepatocellular, gastric cardia, meningioma, multiple myeloma, colorectal, postmenopausal breast, ovarian, gallbladder, and thyroid cancer. However, the epidemiological evidence linking MD and OO with these obesity-related cancers, and their potential mechanisms of action, especially those involving the gut microbiota, are not clearly described or understood. The goals of this review are 1) to update the current epidemiological knowledge on the associations between MD and OO consumption and obesity-related cancers, 2) to identify the gut microbiota mechanisms involved in obesity-related cancers, and 3) to report the effects of MD and OO on these mechanisms.

Plasma Concentration of 36 (Poly)phenols and Prospective Body Weight Change in Participants from the EPIC Cohort.

INTRODUCTION: Dietary intake of (poly)phenols has been linked to reduced adiposity and body weight (BW) in several epidemiological studies. However, epidemiological evidence on (poly)phenol biomarkers, particularly plasma concentrations, is scarce. We aimed to investigate the associations between plasma (poly)phenols and prospective BW change in participants from the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. METHODS: This study included 761 participants with data on BW at baseline and after 5 years of follow-up. Plasma concentrations of 36 (poly)phenols were measured at baseline using liquid chromatography-tandem mass spectrometry. Associations were assessed through general linear mixed models and multinomial logistic regression models, using change in BW as a continuous or as a categorical variable (BW loss, maintenance, gain), respectively. Plasma (poly)phenols were assessed as log2-transformed continuous variables. The false discovery rate (FDR) was used to control for multiple comparisons. RESULTS: Doubling plasma (poly)phenol concentrations showed a borderline trend towards a positive association with BW loss. Plasma vanillic acid showed the strongest association (-0.53 kg/5 years; 95% confidence interval [CI]: -0.99, -0.07). Similar results were observed for plasma naringenin comparing BW loss versus BW maintenance (odds ratio: 1.1; 95% CI: 1.0, 1.2). These results did not remain significant after FDR correction. CONCLUSION: Higher concentrations of plasma (poly)phenols suggested a tendency towards 5-year BW maintenance or loss. While certain associations seemed promising, they did not withstand FDR correction, indicating the need for caution in interpreting these results. Further studies using (poly)phenol biomarkers are needed to confirm these suggestive protective trends.

Association between classes and subclasses of polyphenol intake and 5-year body weight changes in the EPIC-PANACEA study.

OBJECTIVE: The aim of this study was to evaluate the associations among the intake of total polyphenols, polyphenol classes, and polyphenol subclasses and body weight change over 5 years. METHODS: A total of 349,165 men and women aged 25 to 70 years were recruited in the Physical Activity, Nutrition, Alcohol, Cessation of Smoking, Eating Out of Home and Obesity (PANACEA) project of the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort from nine European countries. Body weight was measured at baseline and at follow-up after a median time of 5 years. Polyphenol intake, including four main polyphenol classes and eighteen subclasses, was estimated using validated dietary questionnaires and Phenol-Explorer. Multilevel mixed linear regression models were used to estimate the associations. RESULTS: Participants gained, on average, 2.6 kg (±5.0 kg) over 5 years. Total flavonoids intake was inversely associated with body weight change (-0.195 kg/5 years, 95% CI: -0.262 to -0.128). However, the intake of total polyphenols (0.205 kg/5 years, 95% CI: 0.138 to 0.272) and intake of hydroxycinnamic acids (0.324 kg/5 years, 95% CI: 0.267 to 0.381) were positively associated with body weight gain. In analyses stratified by coffee consumption, hydroxycinnamic acid intake was positively associated with body weight gain in coffee consumers (0.379 kg/5 years, 95% CI: 0.319 to 0.440), but not in coffee nonconsumers (-0.179 kg/5 years, 95% CI: -0.490 to 0.133). CONCLUSIONS: Higher intakes of flavonoids and their subclasses are inversely associated with a modest body weight change. Results regarding hydroxycinnamic acids in coffee consumers require further investigation.

Effects of a (poly)phenol-rich supplement on anthropometric, biochemical, and inflammatory parameters in participants with morbid obesity: Study protocol for a randomised controlled trial.

Background: Morbid obesity (body mass index ≥40 kg/m2) represents a severe health risk and implies the need of urgent therapeutic action. (Poly)phenols may play a relevant role in the management of this disease modulating physiological and molecular pathways involved in energy metabolism and adiposity. The purpose of this double-blinded, placebo-controlled, randomised trial is to determine if (poly)phenol supplementation, in combination with a dietary intervention, can improve anthropometric and cardiometabolic parameters in participants with morbid obesity. Methods: Adults (n = 40) with morbid obesity, bariatric surgery candidates, will be recruited from the Bellvitge University Hospital, Spain, and randomly assigned (stratified by sex) to intervention (poly)phenol-rich supplement 1,200 mg/day + hypocaloric diet) or control group (placebo + hypocaloric diet) for 12 weeks. The primary outcome is body weight. Secondary outcomes are: other anthropometric markers and body composition measured through standardized methods and a bioimpedance analysis, cardiometabolic and inflammatory biomarkers, metabolic pathways, and gut microbiota diversity. Anthropometric parameters, dietary, physical activity and lifestyle questionnaires, blood pressure, and blood and urine samples will be collected at baseline, 6 weeks, and 12 weeks. Faecal samples will be collected at baseline and at 12 weeks. Informed consent of participants will be obtained before the start of the study. Discussion: The present study is expected to provide evidence on the effects of a combination of (poly)phenols on several well-established obesity and cardiometabolic markers, and to unravel possible underlying mechanisms by metabolomic analyses. Gut microbiota diversity will be considered as a potential future endpoint. The study will contribute to future strategies for prevention or treatment of obesity and related conditions.

Dietary Intake of 91 Individual Polyphenols and 5-Year Body Weight Change in the EPIC-PANACEA Cohort.

Polyphenols are bioactive compounds from plants with antioxidant properties that may have a protective role against body weight gain, with adipose tissue and systemic oxidative stress as potential targets. We aimed to investigate the dietary intake of individual polyphenols and their association with 5-year body weight change in a sub-cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC). This study included 349,165 adult participants from nine European countries. Polyphenol intake was estimated through country-specific validated dietary questionnaires and the Phenol-Explorer database. Body weight was obtained at recruitment and after a mean follow-up time of 5 years. Associations were estimated using multilevel mixed linear regression models. From 91 polyphenols included, the majority (n = 67) were inversely associated with 5-year body weight change after FDR-correction (q < 0.05). The greatest inverse associations were observed for quercetin 3-O-rhamnoside (change in weight for doubling in intake: −0.071 (95% CI: −0.085; −0.056) kg/5 years). Only 13 polyphenols showed positive associations with body weight gain, mainly from the subclass hydroxycinnamic acids (HCAs) with coffee as the main dietary source, such as 4-caffeoylquinic acid (0.029 (95% CI: 0.021; 0.038) kg/5 years). Individual polyphenols with fruit, tea, cocoa and whole grain cereals as the main dietary sources may contribute to body weight maintenance in adults. Individual HCAs may have different roles in body weight change depending on their dietary source.

Consumption of Sweet Beverages and Cancer Risk. A Systematic Review and Meta-Analysis of Observational Studies.

The consumption of sweet beverages, including sugar-sweetened beverages (SSB), artificial-sweetened beverages (ASB) and fruit juices (FJ), is associated with the risk of different cardiometabolic diseases. It may also be linked to the development of certain types of tumors. We carried out a systematic review and meta-analysis of observational studies aimed at examining the association between sweet beverage intake and cancer risk. Suitable articles published up to June 2020 were sourced through PubMed, Web of Science and SCOPUS databases. Overall, 64 studies were identified, of which 27 were selected for the meta-analysis. This was performed by analyzing the multivariable-adjusted OR, RR or HR of the highest sweet beverage intake categories compared to the lowest one. Random effects showed significant positive association between SSB intake and breast (RR: 1.14, 95% CI: 1.01-1.30) and prostate cancer risk (RR: 1.18, 95% CI: 1.10-1.27) and also between FJs and prostate cancer risk (RR: 1.03, 95% CI: 1.01-1.05). Although the statistically significant threshold was not reached, there tended to be positive associations for the following: SSBs and colorectal and pancreatic cancer risk; FJs and breast, colorectal and pancreatic cancer risk; and ASBs and pancreatic cancer risk. This study recommends limiting sweet beverage consumption. Furthermore, we propose to establish a homogeneous classification of beverages and investigate them separately, to better understand their role in carcinogenesis.