A systematic review of food composition tools used for determining dietary polyphenol intake in estimated intake studies

Interaction of high amylose corn starch with polyphenols: Modulating the stability of polyphenols with different structure against thermal processing

Polyphenols are known to undergo thermal degradation and their bioactivity is reduced. In this study, the thermal degradation of polyphenols was modulated by the complexation between polyphenols and high amylose corn starch (HACS). The inclusion complex between ferulic acid with hydrophobic group methoxy and HACS had the highest encapsulation efficiency (EE = 26.15 %), loading efficiency (LE = 2.38 %) and thermal stability (DPPH radical scavenging activity was reduced by only 5.99 % after baking). After complexing with HACS, protocatechuic acid with ortho-position hydroxyl group had a higher encapsulation rate and thermal stability than 3, 5-dihydroxybenzoic acid with meta-position hydroxyl. In addition, soy isoflavone with the higher logarithmic value of octanol-water partition coefficient (Log P = 3.66) resulted in higher encapsulation rate and thermal stability than naringenin (Log P = 2.11). The results suggest that the complexation between polyphenols and starch protects the bioactivity of polyphenols and improves the processing suitability of polyphenols.

Systematic Review of the Literature to Inform the Development of a South African Dietary Polyphenol Composition Database

Comprehensively compiled dietary polyphenol data is required to compare polyphenol content between foods, calculate polyphenol intake and study its association with health and disease. The purpose of this review was to identify data on the presence and content of polyphenolic components in South African foods, with the aim of compiling the data into a database. An electronic literature search was conducted up until January 2020 using multiple databases. Additional literature was sourced from South African university repositories. A total of 7051 potentially eligible references were identified, of which 384 met the inclusion criteria. These studies provided information on food item name, geographical distribution, polyphenol type, quantity, and quantification method. Data for 1070 foods were identified, amounting to 4994 polyphenols. Spectrophotometry was the main method used for quantification of gross phenolic content in various assays such as total phenolic content (Folin-Ciocalteu assay), total flavonoid content (AlCl₃ assay) and condensed tannin content (vanillin-HCl assay). Phenolic acids and flavonoids were the main polyphenol classes identified. This review highlights that South Africa has abundant information on the polyphenol content of foods, which could be utilised within a food composition database for the estimation of polyphenol intake for South Africa.

Descriptive analysis of dietary (poly)phenol intake in the subcohort MAX from DCH-NG: "Diet, Cancer and Health-Next Generations cohort"

PURPOSE

(Poly)phenols are bioactive compounds widely distributed in plant-based foods. Currently, limited data exist on the intake distribution of (poly)phenols across meals. This study aimed to estimate dietary intakes of all individual (poly)phenols and total intake per class and subclass by meal event, and to identify their main food sources in the subcohort MAX from the Diet, Cancer and Health-Next Generations cohort (DCH-NG).

METHODS

Dietary data were collected using three web-based 24-h dietary recalls over 1 year. In total, 676 participants completed at least one recall. The dietary data were linked to Phenol-Explorer database using standardized procedures and an in-house software. We categorized foods/drinks into five options of meal events selected by the participant: 'Breakfast', 'Lunch', 'Evening', 'Snack', and 'Drink'.

RESULTS

Adjusted total (poly)phenols mean intake by meal was the highest in the drink event (563 mg/day in men and 423 mg/day in women) and the lowest in the evening event (146 mg/day in men and 137 mg/day in women). The main overall (poly)phenol class contributor was phenolic acids (55.7-79.0%), except for evening and snack events where it was flavonoids (45.5-60%). The most consumed (poly)phenol subclasses were hydroxycinnamic acids and proanthocyanidins. Nonalcoholic beverages (coffee accounted for 66.4%), cocoa products, and cereals were the main food sources of total (poly)phenols.

CONCLUSION

This study provides data on the variability in the intake of classes and subclasses of (poly)phenols and their main food sources by meal event according to lifestyle data, age, and gender in a Danish population.

The Role of Dietary Polyphenols in Pregnancy and Pregnancy-Related Disorders

Polyphenols are a group of phytochemicals with extensive biological functions and health-promoting potential. These compounds are present in most foods of plant origin and their increased widespread availability through the intake of nutritional supplements, fortified foods, and beverages, has also led to increased exposure throughout gestation. In this narrative review, we focus on the role of polyphenols in both healthy and pathological pregnancy. General information related to their classification and function is followed by an overview of their known effects in early-pregnancy events, including the current insights into molecular mechanisms involved. Further, we provide an overview of their involvement in some of the most common pregnancy-associated pathological conditions, such as preeclampsia and gestational diabetes mellitus. Additionally, we also discuss the estimated possible risk of polyphenol consumption on pregnancy outcomes. The consumption of dietary polyphenols during pregnancy needs particular attention considering the possible effects of polyphenols on the mechanisms involved in maternal adaptation and fetal development. Further studies are strongly needed to unravel the in vivo effects of polyphenol metabolites during pregnancy, as well as their role on advanced maternal age, prenatal nutrition, and metabolic risk of the offspring.

Total urinary polyphenols and ideal cardiovascular health metrics in Spanish adolescents enrolled in the SI Program: a cross-sectional study

To study the relationship between urinary total polyphenol excretion (TPE) in adolescents and ideal cardiovascular (CVH) metrics. 1151 adolescents aged 12.04 (0.46) years participating in the SI! Program for Secondary Schools were selected based on the availability of urine samples and information required to assess CVH metrics. Data on health behaviours (smoking status, body mass index, physical activity, and healthy diet) and health factors (blood pressure, total cholesterol, and blood glucose) were used to calculate the CVH metrics. TPE in urine was analysed by a Folin-Ciocalteu method after solid-phase extraction. Associations between TPE (categorized into tertiles) and CVH metrics (total and separate scores) were assessed using multilevel mixed-effect regression models. Higher TPE levels were associated with higher (healthier) CVH scores and ideal smoking status (OR 1.54, 95% CI 1.10; 1.87, p value = 0.007), physical activity (OR 1.12, 95% CI 1.02; 1.23, p value = 0.022) and total cholesterol (OR 1.78, 95% CI 1.16; 2.73, p value = 0.009) after multivariate adjustment. An association between TPE and total CVH scores was observed only in boys. Girls with higher TPE had higher rates of ideal total cholesterol and blood pressure. According to our findings, higher urinary TPE is related to better CVH scores, with relevant differences in this association by gender.

Antioxidant Effects of a Polyphenol-Rich Dietary Supplement Incorporating Pinus massoniana Bark Extract in Healthy Older Adults: A Two-Arm, Parallel Group, Randomized Placebo-Controlled Trial

Oxidative stress is a key physiological phenomenon underpinning the ageing process and plays a major developmental role in age-associated chronic diseases. This study investigated the antioxidant effects of a polyphenol-rich dietary supplement containing Pinus massoniana bark extract (PMBE) in healthy older adults. In a double-blinded, placebo-controlled clinical trial, participants were randomised (in a 1:1 ratio) to receive a 50 mL/day dietary supplement containing placebo (0 mg PMBE) or PMBE (1322 mg PMBE) for 12 weeks. The primary outcome was fasting plasma malondialdehyde (MDA) concentrations and secondary outcomes were plasma inflammatory markers. MDA concentrations significantly reduced following PMBE for 6 weeks (−1.19 nmol/mL, 95%CI −1.62, −0.75, p < 0.001) and 12 weeks (−1.35 nmol/mL, 95%CI −1.74, −0.96, p < 0.001) compared to baseline. MDA did not significantly change after the placebo. MDA levels at 6 and 12 weeks were significantly lower following PMBE compared to placebo (p < 0.001). At 12 weeks in the PMBE group, fibrinogen concentrations significantly reduced (−0.25 g/L, 95%CI −0.39, −0.11; p < 0.0001) and interleukin-6 significantly increased compared to placebo (0.30 pg/mL, 95%CI 0.02, 0.59; p < 0.05). PMBE in a polyphenol-rich dietary supplement reduced oxidative stress in healthy older adults. Further studies are warranted to investigate the antioxidant capacity of PMBE in conditions with heightened oxidative stress, such as osteoarthritis, hypertension, type 2 diabetes, or other lifestyle related diseases.

Oxidative stress, aging, antioxidant supplementation and their impact on human health: An overview

Aging is characterized by a progressive loss of tissue and organ function due to genetic and environmental factors, nutrition, and lifestyle. Oxidative stress is one the most important mechanisms of cellular senescence and increased frailty, resulting in several age-linked, noncommunicable diseases. Contributing events include genomic instability, telomere shortening, epigenetic mechanisms, reduced proteome homeostasis, altered stem-cell function, defective intercellular communication, progressive deregulation of nutrient sensing, mitochondrial dysfunction, and metabolic unbalance. These complex events and their interplay can be modulated by dietary habits and the ageing process, acting as potential measures of primary and secondary prevention. Promising nutritional approaches include the Mediterranean diet, the intake of dietary antioxidants, and the restriction of caloric intake. A comprehensive understanding of the ageing processes should promote new biomarkers of risk or diagnosis, but also beneficial treatments oriented to increase lifespan.

Comparison of Flavonoid Intake Assessment Methods Using USDA and Phenol Explorer Databases: Subcohort Diet, Cancer and Health-Next Generations-MAX Study

Flavonoids are bioactive plant compounds that are widely present in the human diet. Estimating flavonoid intake with a high degree of certainty is challenging due to the inherent limitations of dietary questionnaires and food composition databases. This study aimed to evaluate the degree of reliability among flavonoid intakes estimated using four different approaches based on the two most comprehensive flavonoid databases, namely, United States Department of Agriculture (USDA) and Phenol Explorer (PE). In 678 individuals from the MAX study, a subcohort of the Diet, Cancer and Health-Next Generations cohort, dietary data were collected using three 24-h diet recalls over 1 year. Estimates of flavonoid intake were compared using flavonoid food content from PE as (1) aglycones (chromatography with hydrolysis), (2) aglycones transformed (converted from glycosides by chromatography without hydrolysis), (3) as they are in nature (glycosides, aglycones, and esters), and 4) using flavonoid content from USDA as aglycones (converted). Spearman's intra-class correlation (ICC) coefficient and weighted kappa (K) coefficient were calculated for the reliability analysis. When comparing PE total aglycones to USDA total aglycones, there was a moderate reliability when a continuous variable was used [ICC: 0.73, 95% confidence interval (CI): 0.70–0.76] and an excellent reliability when flavonoid intake was modeled as a categorical variable (K: 0.89, 95% CI: 0.88–0.90). The degree of reliability among all methods of estimated flavonoid intakes was very similar, especially between database pairs, for the flavanol subclass, while larger differences were observed for flavone, flavonol, and isoflavone subclasses. Our findings indicate that caution should be taken when comparing the results of the associations between flavonoid intakes and health outcomes from studies, when flavonoid intakes were estimated using different methods, particularly for some subclasses.

A useful and simple tool to evaluate and compare the intake of total dietary polyphenols in different populations

OBJECTIVE

Polyphenols are antioxidant compounds with an impact on different health factors. Thus, it is important to have precise tools to estimate the intake of polyphenols. This study focuses on the development of an intuitive tool to estimating the intake of dietary total polyphenols.

DESIGN

The tool was developed in a spreadsheet to improve accessibility and use. It is divided into six different meals for each of the 7 d with a similar format to 24-h diet recalls. The total polyphenol values of 302 foods were included and the possibility of own values.

SETTING

Framework of the European project Stance4Health, Granada, Spain.

PARTICIPANTS

This tool was tested on 90 participants in different stages of life (girls, women and pregnant women). Ages ranged from 10 to 35 years.

RESULTS

The total polyphenol intake obtained was of 1790 ± 629 mg polyphenols/d. The highest consumption of polyphenols was observed in pregnant women (2064 mg/d). Polyphenols intake during the weekend was lower for the three groups compared to the days of the week. The results were comparable with those of other studies.

CONCLUSIONS

The current tool allows the estimation of the total intake of polyphenols in the diet in a fast and easy way. The tool will be used as a basis for a future mobile application.

Dietary Assessment Methods to Estimate (Poly)phenol Intake in Epidemiological Studies: A Systematic Review

Nutritional epidemiological studies have frequently reported associations between higher (poly)phenol intake and a decrease in the risk or incidence of noncommunicable diseases. However, the assessment methods that have been used to quantify the intakes of these compounds in large-population samples are highly variable. This systematic review aims to characterize the methods used to assess dietary (poly)phenol intake in observational studies, report the validation status of the methods, and give recommendations on method selection and data reporting. Three databases were searched for publications that have used dietary assessment methods to measure (poly)phenol intake and 549 eligible full texts were identified. Food-frequency questionnaires were found to be the most commonly used tool to assess dietary (poly)phenol intake (73%). Published data from peer-reviewed journals were the major source of (poly)phenol content data (25%). An increasing number of studies used open-access databases such as Phenol-Explorer and USDA databases on flavonoid content since their inception, which accounted for 11% and 23% of the data sources, respectively. Only 16% of the studies reported a method that had been validated for measuring the target (poly)phenols. For future research we recommend: 1) selecting a validated dietary assessment tool according to the target compounds and target period of measurement; 2) applying and combining comprehensive (poly)phenol content databases such as USDA and Phenol-Explorer; 3) detailing the methods used to assess (poly)phenol intake, including dietary assessment method, (poly)phenol content data source; 4) follow the Strengthening the Reporting of Observational Studies in Epidemiology-Nutritional Epidemiology (STROBE-nut) framework; and 5) complementing dietary intake assessment based on questionnaires with measurement of (poly)phenols in biofluids using appropriate and validated analytical methods.

Nanoselenium foliar application enhances biosynthesis of tea leaves in metabolic cycles and associated responsive pathways

An emerging stress of pesticides in plant and soil is closely watched as it affects crop antioxidant systems, nutritional quality, and flavor. Although selenium (Se) can enhance the resistance of plants, the protective mechanism of nanoselenium is still not known under the long-term pesticide stress in tea trees. In this study, we investigated the potential effects of foliar application of nanoselenium for a two-year field experiment on tea plants under pesticide-induced oxidative stress. Compared to control, nano-Se (10 mg/L) markedly enhanced the protein, soluble sugar, carotenoid, tea polyphenols, and catechins contents. High levels of theanine, glutamic acid, proline, and arginine were found to be induced most likely by adjusting the GS-GOGAT cycle. Se-supplementation may promote tea leaves' secondary metabolism, thus increasing the accumulation of total phenols and flavonoids (apigenin, kaempferol, quercetin, myricetin, and rutin). It also minimized the accumulation of malondialdehyde, hydrogen peroxide, and superoxide anion by activating the antioxidants enzymes including in the AsA-GSH cycle. Selenium-rich tea also showed better fragrance and flavor. In summary, nano-Se can ameliorate the nutrients quality and abiotic stresses resistance of crops.

The Relationship between Dietary Polyphenol Intakes and Urinary Polyphenol Concentrations in Adults Prescribed a High Vegetable and Fruit Diet

Urinary polyphenol metabolites are potential biomarkers of dietary polyphenol intake. The current study aims to evaluate associations between total diet, vegetable and fruit polyphenol intakes with urinary polyphenol metabolite concentrations in a sample of adults prescribed a diet rich in vegetables and fruit. Thirty-four participants completed a 10-week pre-post study. Participants were asked to consume Australian recommended daily vegetable and fruit serves and attend measurement sessions at baseline and at weeks 2 and 10. Two 24-h diet recalls were collected at each time-point and polyphenol intakes were calculated using the Phenol-Explorer database. Spot urine samples, collected at each time-point, were analyzed for 15 polyphenol metabolites using liquid chromatography-mass spectroscopy. Spearman’s correlation analyzes assessed the strength of relationships between urinary and dietary polyphenols. Linear mixed models were used to investigate relationships between polyphenol excretion and intake. Total urinary polyphenols were significantly correlated with total polyphenol intakes at week 10 (r_s = 0.47) and fruit polyphenols at week 2 (r_s = 0.38). Hippuric acid was significantly correlated with vegetable polyphenols at baseline (r_s = 0.39). Relationships were identified between individual polyphenol metabolites and vegetable and fruit polyphenols. Linear mixed model analyzes identified that for every 1 mg increase in polyphenol intakes, urinary polyphenol excretion increased by 16.3 nmol/g creatinine. Although the majority of relationships were not sufficiently strong or consistent at different time-points, promising relationships were observed between total urinary polyphenols and total polyphenol intakes, and hippuric acid and vegetable polyphenols.

Association between flavonoid intake and risk of hypertension in two cohorts of Australian women: a longitudinal study

PURPOSE

Epidemiological evidence suggests higher dietary flavonoid intake is associated with lower risk of several chronic diseases. This study aimed to investigate the association between intake of flavonoids and their subclasses, and incidence of hypertension among Australian women in two age cohorts.

METHODS

This population-based study included 6599 middle-aged (52.5 ± 1.5 years) and 6099 reproductive-aged (27.5 ± 1.5 years) women from the Australian Longitudinal Study on Women's Health. Food frequency questionnaires were used to quantify intake of flavonoids by cross-referencing with the Phenol-Explorer food composition database. Generalised Estimating Equation analyses investigated associations with incident hypertension, adjusting for demographic and dietary variables and hypertension risk factors.

RESULTS

There were 1645 cases (24.9%) of hypertension during 15 years follow-up in the middle-aged cohort and 336 cases (5.5%) during 12 years follow-up in the reproductive-aged cohort. Higher intakes of flavones [adjusted relative risk (ARR) for quintile 5 vs. 1: 0.82, 95% CI 0.70-0.97], isoflavones (0.86, 0.75-0.99) and flavanones (0.83, 0.69-1.00) were associated with a lower risk of hypertension in the middle-aged cohort. In the reproductive-aged cohort, higher intakes of flavanols (0.70, 0.49-0.99) were associated with a lower risk of hypertension. Key foods that provided these flavonoids were oranges, orange juice, apples, red wine and soy milk.

CONCLUSION

Higher intakes of total flavonoids and subclasses were associated with a lower risk of hypertension in Australian women. These findings can be used in nutrition messaging and policies for improved cardiovascular health of women.

Potential health benefits of (poly)phenols derived from fruit and 100% fruit juice

(Poly)phenol-rich diets have been associated with reduced risk of various diseases. Coffee and tea are typically identified as dietary sources of chlorogenic acid and flavan-3-ols; however, 100% fruit juice greatly contributes to anthocyanin, flavonol, flavan-3-ols, and flavanone intake, making them complementary sources of dietary (poly)phenols. Thus, the aim of this narrative review was to provide an overview of fruit (poly)phenols and their potential health benefits. Fruit (poly)phenols have been associated with several health benefits (eg, reduced risk of cardiovascular disease and neurocognitive benefits). Although perspectives on 100% fruit juice consumption are controversial due to the perception of sugar content, growing evidence supports the role of fruit in whole and 100% juice forms to provide consumer benefits in alignment with dietary guidance. However, differences in (poly)phenol profiles and bioavailability likely exist between whole fruit and 100% fruit juice due to processing and the presence/absence of fiber. Ongoing studies are better defining similarities and differences between whole fruit and 100% fruit juice to elucidate protective mechanisms and align with processing and consumer products.

A Review on Flavonoid Apigenin: Dietary Intake, ADME, Antimicrobial Effects, and Interactions with Human Gut Microbiota

Apigenin is a flavonoid of low toxicity and multiple beneficial bioactivities. Published reviews all focused on the findings using eukaryotic cells, animal models, or epidemiological studies covering the pharmacokinetics, cancer chemoprevention, and drug interactions of apigenin; however, no review is available on the antimicrobial effects of apigenin. Research proves that dietary apigenin passes through the upper gastrointestinal tract and reaches the colon after consumption. For that reason, it is worthwhile to study the potential interactions between apigenin and human gut microbiota. This review summarizes studies on antimicrobial effects of apigenin as well as what has been reported on apigenin and human gut microbiota. Various levels of effectiveness have been reported on apigenin's antibacterial, antifungal, and antiparasitic capability. It has been shown that apigenin or its glycosides are degraded into smaller metabolites by certain gut bacteria which can regulate the human body after absorption. How apigenin contributes to the structural and functional changes in human gut microbiota as well as the bioactivities of apigenin bacterial metabolites are worth further investigation.

Usual dietary anthocyanin intake, sources and their association with blood pressure in a representative sample of Australian adults

BACKGROUND

Anthocyanins represent an important subgroup of non-nutritive components of food as evidence continues to build related to their beneficial bioactive effects. Using a recently developed Australian anthocyanin database, the present study aimed to estimate the intake of both total anthocyanins and their subclasses, identify food sources of anthocyanins, and determine associations between anthocyanin intake and measured blood pressure (BP).

METHODS

The present study comprised a secondary analysis of the 2011-12 National Nutrition and Physical Activity component of the Australian Health Survey. Anthocyanin intake was estimated using an Australian anthocyanin database. Usual anthocyanin intake, as estimated from 24-h diet recall data, was computed using multiple source methods, whereas food sources were determined by calculating contribution of food groups to total anthocyanin intake. Regression analysis, adjusted for covariates (age, gender, body mass index, high BP diagnosis, smoking status and physical activity) assessed the relationship between anthocyanin intake and BP in adults aged ≥50 years.

RESULTS

Mean anthocyanin intake was 24.17 ± 0.32 mg day^-1 . Across age groups, berries were the top sources: blackberry (5-65%), cherry (2-24%), blueberry (2-13%) and raspberry (3-12%). There was a significant inverse association between anthocyanin intake and systolic BP (β = -0.04, F = 16.8, d.f. = 6, r²  = 0.05, P < 0.01) and diastolic BP (β = 0.01, F = 5.35, d.f. = 6, R²  = 0.013, P < 0.01), in models that adjusted for covariates.

CONCLUSIONS

In comparison with the world composite database, anthocyanin intake in the Australian population was above average [mean (SD): 24.17 (0.32) mg day^-1 versus 18.05 (21.14) mg day^-1 ]. Berries were the primary source of anthocyanins. Anthocyanin intake in older adults aged ≥50 years was inversely associated with BP.

Dietary Patterns and Cardiovascular Disease: Insights and Challenges for Considering Food Groups and Nutrient Sources

PURPOSE OF REVIEW

The relationship between dietary patterns and cardiovascular disease has been the subject of much research, but an important methodological consideration is the interdependence between the nutrient composition of foods and the recognition of healthy dietary patterns. This review considers some of the challenges in researching dietary patterns with implications for translation to public health promotions.

RECENT FINDINGS

A number of statistical methods have emerged for analysing dietary patterns using population dietary data. There are limitations in the assumptions underpinning food categorisation, but this research is able to consistently identify foods and dietary patterns that are positively related to health. Aligned to this activity is the ongoing development of food composition databases which has its own limitations such as keeping up to date with changing foods and newly identified components, sampling of foods, and developments in chemical analytical methods. Finally, dietary patterns form the basis for current dietary guidelines and related public health-oriented programs, but the issues raised for research (e.g. food categorisation and cuisine influences on dietary patterns) can also translate to these settings. The study of dietary patterns in cardiovascular disease prevention presents with a number of methodological challenges relating to the way food groups are formed and the limitations of food composition databases. Added to this are new considerations for the environmental impact of recommended dietary patterns. Future research across the entire knowledge chain should target more accurate methods in a number of analytical areas.

A systematic review of osteoarthritis prevention and management with dietary phytochemicals from foods

Osteoarthritis is the most prevalent chronic inflammatory joint disease affecting mobility in humans, as well as in companion and captive animals. Understanding the effect of dietary phytochemical intake from foods on osteoarthritis and its long-term outcomes may inform public health strategies for osteoarthritis prevention and management, reducing healthcare costs globally. The aim of this systematic review was to examine the effects of dietary phytochemical intake from foods on osteoarthritis in adult populations. A literature search was performed using Scopus, Web of Science, MEDLINE, PubMed and the Cochrane Library for human studies to identify randomised controlled trials (RCTs) and observational studies focused on osteoarthritis up to May 2018. From 5879 articles, five RCTs and four cross-sectional studies were identified. Dietary carotenoids were examined in the observational studies, while dietary intakes of polyphenols from foods were assessed in the RCTs. Dietary polyphenol intake from foods (e.g., freeze-dried strawberries and tart cherry juice) may slow the progression of osteoarthritis via decreased inflammation and reduced cartilage degradation. However, there were relatively few studies and a lack of uniformity in the biomarkers used and the measurements of pain, quality of life and physical activity relating to osteoarthritis. The heterogeneity among the studies suggests that there is insufficient evidence related to phytochemical intake from foods. High-quality epidemiological studies and controlled trials are therefore required. Nevertheless, exploring dietary phytochemical intake from foods may complement current dietary strategies for the management of osteoarthritis and help in the formulation of more economical and manageable strategies for osteoarthritis.

Relationship between Mediterranean Dietary Polyphenol Intake and Obesity

Obesity is a multifactorial and complex disease defined by excess of adipose mass and constitutes a serious health problem. Adipose tissue acts as an endocrine organ secreting a wide range of inflammatory adipocytokines, which leads to systemic inflammation, insulin resistance, and metabolic disorders. The traditional Mediterranean diet is characterized by a high phenolic-rich foods intake, including extra-virgin olive oil, nuts, red wine, vegetables, fruits, legumes, and whole-grain cereals. Evidence for polyphenols’ effect on obesity and weight control in humans is inconsistent and the health effects of polyphenols depend on the amount consumed and their bioavailability. The mechanisms involved in weight loss in which polyphenols may have a role are: activating β-oxidation; a prebiotic effect for gut microbiota; inducing satiety; stimulating energy expenditure by inducing thermogenesis in brown adipose tissue; modulating adipose tissue inhibiting adipocyte differentiation; promoting adipocyte apoptosis and increasing lipolysis. Even though the intake of some specific polyphenols has been associated with body weight changes, there is still no evidence for the effects of total polyphenols or some polyphenol subclasses in humans on adiposity.

Dietary flavonoid intake in older adults: how many days of dietary assessment are required and what is the impact of seasonality?

BACKGROUND

Within- and between-person variation in nutrient intake is well established, but little is known about variability in dietary flavonoid intake, including the effect of seasonality.

METHODS

Within- and between-individual variability of flavonoid intake, and intake of flavonoid subclasses was examined in older adults (n = 79; mean age 70.1 y (range: 60y-80y)), using three separate 4-day weighed food records (WFR) collected approximately 4 months apart. The effects of seasonality were also examined. Mixed-effects linear regression models were used to estimate within- and between-individual variance components for flavonoids and subclasses. The number of days of dietary assessment required for a high level of hypothetical accuracy was calculated from variance ratios.

RESULTS

Within- and between-individual variability was high for flavonoid intake, and intake of flavonoid subclasses, with variance ratios > 1. It was calculated that six days of WFR data are required for total flavonoid intake, and between 6 and 10 days was required for flavonoid subclasses. There was no effect of seasonality for total flavonoid intake or intake of flavonoid subclasses, with the exception that flavan-3-ol and flavanone intakes which were relatively low in summer, and in summer and winter, respectively.

CONCLUSION

While the effects of seasonality on total flavonoid intake may be small, within- and between-individual variation associated with flavonoid intake assessment appears to be substantial across 12 days of WFR data in older adults. It is recommended that a minimum of 6 days of weighed food records are collected to minimise the impact of within- and between-individual variability on total flavonoid intake assessments in this population.

Dietary phytochemical intake from foods and health outcomes: a systematic review protocol and preliminary scoping

INTRODUCTION

Dietary phytochemicals are found in plant-based foods such as fruits, vegetables and grains and may be categorised in a nested hierarchical manner with many hundred individual phytochemicals identified to date. To associate phytochemical intakes with positive health outcomes, a fundamental step is to accurately estimate the dietary phytochemical intake from foods reported. The purpose of this systematic review protocol is to describe the process to be undertaken to summarise the evidence for food-based dietary phytochemical intakes and health outcomes for adults.

METHODS AND ANALYSIS

The review will be undertaken following the PRISMA guidelines and the Cochrane Handbook for Systematic Reviews of Interventions using the Review Manager software. Phytochemical subclasses (phenolic acids, flavanols, etc) will be used to search for relevant studies using the Web of Science and Scopus scientific databases. The retrieved studies will be screened based on inclusion of natural whole food items and health outcomes. Phytochemical studies related to cardiovascular disease, cancer, overweight, glucose tolerance, digestive, reproductive, macular and bone health and mental disorders, fatigue and immunity will be examined based on prior scoping. The evidence will be aggregated by the food types and health outcomes. Comparison of differences in the outcomes for randomised controlled trials and observational studies will be undertaken. The strength of the review lies in its focus on whole food items and health conditions rather than one type of phytochemical related to one single health condition. Subgroup and sensitivity analyses will be conducted where an adequate number of publications are found per phytochemical subclass.

DISSEMINATION

By comparing the outcomes from experimental and observational studies, the review will determine whether the overall conclusions related to the phytochemical subclasses are the same between study types for the identified health conditions. This is useful to public health policymakers and health professionals alike.

TRIAL REGISTRATION NUMBER

#CRD42014015610.