Perspective: Framework for Developing Recommended Intakes of Bioactive Dietary Substances

Precision Nutrition: The Hype Is Exceeding the Science and Evidentiary Standards Needed to Inform Public Health Recommendations for Prevention of Chronic Disease

As dietary guidance for populations shifts from preventing deficiency disorders to chronic disease risk reduction, the biology supporting such guidance becomes more complex due to the multifactorial risk profile of disease and inherent population heterogeneity in the diet-disease relationship. Diet is a primary driver of chronic disease risk, and population-based guidance should account for individual responses. Cascading effects on evidentiary standards for population-based guidance are not straightforward. Precision remains a consideration for dietary guidance to prevent deficiency through the identification of population subgroups with unique nutritional needs. Reducing chronic disease through diet requires greater precision in (a) establishing essential nutrient needs throughout the life cycle in both health and disease; (b) considering effects of nutrients and other food substances on metabolic, immunological, inflammatory, and other physiological responses supporting healthy aging; and (c) considering healthy eating behaviors. Herein we provide a template for guiding population-based eating recommendations for reducing chronic diseases in heterogenous populations.

Potential roles of dietary zeaxanthin and lutein in macular health and function

Lutein, zeaxanthin, and meso-zeaxanthin are three xanthophyll carotenoid pigments that selectively concentrate in the center of the retina. Humans cannot synthesize lutein and zeaxanthin, so these compounds must be obtained from the diet or supplements, with meso-zeaxanthin being converted from lutein in the macula. Xanthophylls are major components of macular pigments that protect the retina through the provision of oxidant defense and filtering of blue light. The accumulation of these three xanthophylls in the central macula can be quantified with non-invasive methods, such as macular pigment optical density (MPOD). MPOD serves as a useful tool for assessing risk for, and progression of, age-related macular degeneration, the third leading cause of blindness worldwide. Dietary surveys suggest that the dietary intakes of lutein and zeaxanthin are decreasing. In addition to low dietary intake, pregnancy and lactation may compromise the lutein and zeaxanthin status of both the mother and infant. Lutein is found in modest amounts in some orange- and yellow-colored vegetables, yellow corn products, and in egg yolks, but rich sources of zeaxanthin are not commonly consumed. Goji berries contain the highest known levels of zeaxanthin of any food, and regular intake of these bright red berries may help protect against the development of age-related macular degeneration through an increase in MPOD. The purpose of this review is to summarize the protective function of macular xanthophylls in the eye, speculate on the compounds' role in maternal and infant health, suggest the establishment of recommended dietary values for lutein and zeaxanthin, and introduce goji berries as a rich food source of zeaxanthin.

Perspectives on the application of CONSORT guidelines to randomised controlled trials in nutrition

PURPOSE

Reporting guidelines facilitate quality and completeness in research reporting. The CONsolidated Standards Of Reporting Trials (CONSORT) statement is widely applied to dietary and nutrition trials but has no extension specific to nutrition. Evidence suggests poor reporting in nutrition research. The Federation of European Nutrition Societies led an initiative to make recommendations for a nutrition extension to the CONSORT statement towards a more robust reporting of the evidence base.

METHODS

An international working group was formed of nutrition researchers from 14 institutions in 12 different countries and on five continents. Using meetings over a period of one year, we interrogated the CONSORT statement specifically for its application to report nutrition trials.

RESULTS

We provide a total of 28 new nutrition-specific recommendations or emphasised recommendations for the reporting of the introduction (three), methods (twelve), results (five) and discussion (eight). We also added two additional recommendations that were not allocated under the standard CONSORT headings.

CONCLUSION

We identify a need to provide guidance in addition to CONSORT to improve the quality and consistency of the reporting and propose key considerations for further development of formal guidelines for the reporting of nutrition trials. Readers are encouraged to engage in this process, provide comments and conduct specific studies to inform further work on the development of reporting guidelines for nutrition trials.

Have safety and efficacy assessments of bioactives come of age?

This article describes why the safety and efficacy assessment of non-nutrient bioactives for reducing chronic disease risk is so complicated, especially for dietary supplements and traditional medicines. Scientists, regulators, and the public have different and sometimes opposing perspectives about bioactives. Drug, food, and traditional medicine models used for bioactive safety assessment are based on different assumptions and use different processes. Efficacy assessment is seldom based on clinical trials of boactives' effects in reducing chronic disease risk. It usually consists of application of quality assurance measures and evaluation of label claims and commercial speech about ingredients or products to ensure conformity to regulations. Harmonization of safety and efficacy assessment on a global basis is difficult because of differences within and between regulatory systems. The recommendations provided may open the way for bioactives to play a larger health role in the future, fill gaps in data needed for crafting authoritative dietary guidance on intakes, and speed harmonization of global standards.

Health and nutrition beyond essential nutrients: The evolution of the bioactives concept for human health

Our food supply contains a range of essential and non-essential food components. There are substantial epidemiologic findings and additional clinical data to support the health benefits for some non-essential food components - these compounds are often referred to as bioactives. While there is a well-established process in place to make science-based dietary recommendations for essential nutrients, this is not the case for bioactive food components. This manuscript reviews the evolution of the RDAs and the transition to a DRI framework for establishing requirements for essential nutrients. Then, the potential of development of public health recommendations for bioactives will be explored and the benefits and challenges of making recommendations will be presented. The scientific support for case studies for lutein and flavan-3-ols, will be made. Finally, suggestions for frameworks that might be considered by authoritative policy-making bodies when evaluating the efficacy and safely of proposed bioactives will be discussed.

Estimated polyphenol intake and major food sources of the Brazilian population: changes between 2008–2009 and 2017–2018

Assessing the dietary intake of polyphenols and their major food sources is the first step towards documenting the associations with health outcomes. Considering recent changes in dietary patterns of the Brazilian population, continuous monitoring of polyphenol intake is important. Thus, the present study was conducted to estimate the polyphenol intake and major food sources in the diet of the Brazilian population using data from the most recent National Dietary Survey (NDS, 2017–2018), to characterise the intake changes according to demographic characteristics and to compare the intake over the past decade in Brazil. Data from two cross-sectional population-based surveys were analyzed in the study. Trends in polyphenol intake and major food sources were estimated using food consumption data from NDS 2008–2009 (n 34 003) and 2017–2018 (n 46 164). The median (25–75th percentiles) of energy-adjusted polyphenol intake in 2017–2018 was 216·3 mg (125·3–495·2 mg) per 1000 kcal/d (4184 kJ/d), representing an increase of 12·3 mg/d from 2008–2009. However, unadjusted polyphenol intakes were similar between the surveys (medians: 364·3 mg/d in 2008–2009 and 366·9 mg/d in 2017–2018). The main food sources of total and polyphenol intake classes presented some variations between 2008–2009 and 2017–2018, with greater contribution of beans preparations, salads and tea to polyphenol intake, and decrease of orange contribution. Our study provided an updated information on polyphenol intake and its major food sources. The median intake remains lower than the reported by other populations. Furthermore, the results may contribute to future studies investigating temporal trends in polyphenol intake and disease risk.

Flavan-3-ols and Cardiometabolic Health: First Ever Dietary Bioactive Guideline

Guideline recommendation for a plant bioactive such as flavan-3-ols is a departure from previous recommendations because it is not based on deficiencies but rather improvement in health outcomes. Nevertheless, there is a rapidly growing body of clinical data reflecting benefits of flavan-3-ol intake that outweigh potential harms. Thus, the objective of the Expert Panel was to develop an intake recommendation for flavan-3-ols and cardiometabolic outcomes to inform multiple stakeholders including clinicians, policymakers, public health entities, and consumers. Guideline development followed the process set forth by the Academy of Nutrition and Dietetics, which includes use of the Evidence to Decision Framework. Studies informing this guideline (157 randomized controlled trials and 15 cohort studies) were previously reviewed in a recently published systematic review and meta-analysis. Quality and strength-of-evidence along with risk-of-bias in reporting was reviewed. In drafting the guideline, data assessments and opinions by authoritative scientific bodies providing guidance on the safety of flavan-3-ols were considered. Moderate evidence supporting cardiometabolic protection resulting from flavan-3-ol intake in the range of 400-600 mg/d was supported in the literature. Further, increasing consumption of dietary flavan-3-ols can help improve blood pressure, cholesterol concentrations, and blood sugar. Strength of evidence was strongest for some biomarkers (i.e., systolic blood pressure, total cholesterol, HDL cholesterol, and insulin/glucose dynamics). It should be noted that this is a food-based guideline and not a recommendation for flavan-3-ol supplements. This guideline was based on beneficial effects observed across a range of disease biomarkers and endpoints. Although a comprehensive assessment of available data has been reviewed, evidence gaps identified herein can inform scientists in guiding future randomized clinical trials.

Dietary Supplements Use among Serbian Undergraduate Students of Different Academic Fields

The rising popularity of dietary supplements as a part of self-care practice increases interest in monitoring their usage in the general and specific population groups. This study investigated the prevalence and patterns of dietary supplement use among Belgrade University undergraduate students and its variations across different academic study fields. Of the 914 online survey students, 55.7% used dietary supplements during the past year. Female gender, eating behavior, and academic field were significant predictors of dietary supplement use. For all students, the most commonly used dietary supplements were vitamins and minerals, alone or in combination. Magnesium, vitamin C, and B vitamins were the most frequently supplemented micronutrients. The reasons for using, place of purchase, and source of information regarding dietary supplements significantly varied among students of different fields of study. Adverse effects related to dietary supplement use, including gastrointestinal symptoms, skin flushing, dizziness, and heart palpitation, were reported in 4.5% of students. Insufficient knowledge about these products was self-reported by 16.5% of users, more common among non-medical students. Thus, public health interventions are needed to improve students' knowledge regarding rational and safe dietary supplement use.

Plasma metabolomic analysis indicates flavonoids and sorbic acid are associated with incident diabetes: A nested case-control study among Women's Interagency HIV Study participants

INTRODUCTION

Lifestyle improvements are key modifiable risk factors for Type 2 diabetes mellitus (DM) however specific influences of biologically active dietary metabolites remain unclear. Our objective was to compare non-targeted plasma metabolomic profiles of women with versus without confirmed incident DM. We focused on three lipid classes (fatty acyls, prenol lipids, polyketides).

MATERIALS AND METHODS

Fifty DM cases and 100 individually matched control participants (80% with human immunodeficiency virus [HIV]) were enrolled in a case-control study nested within the Women's Interagency HIV Study. Stored blood samples (1-2 years prior to DM diagnosis among cases; at the corresponding timepoint among matched controls) were assayed in triplicate for metabolomics. Time-of-flight liquid chromatography mass spectrometry with dual electrospray ionization modes was utilized. We considered 743 metabolomic features in a two-stage feature selection approach with conditional logistic regression models that accounted for matching strata.

RESULTS

Seven features differed by DM case status (all false discovery rate-adjusted q<0.05). Three flavonoids (two flavanones, one isoflavone) were respectively associated with lower odds of DM (all q<0.05), and sorbic acid was associated with greater odds of DM (all q<0.05).

CONCLUSION

Flavonoids were associated with lower odds of incident DM while sorbic acid was associated with greater odds of incident DM.

Bioactives in the Food Supply: Effects on CVD Health

PURPOSE OF REVIEW

Interest in preventing atherosclerosis and cardiovascular disease extends beyond essential nutrients and dietary patterns. This article reviews the potential for bioactive compounds to play a role in prevention and the recent process in guidance for developing policy for bioactives.

RECENT FINDINGS

A framework for developing recommended intakes of bioactives dietary substances was recently developed and the first guideline expected is for a bioactive targeted for cardiometabolic health. Bioactives target endothelial health, the gut microbiome, serum lipids, blood pressure, inflammation, and oxidative stress. The evidence base is growing and will be enhanced further with the discovery of good biomarkers of exposure and health outcomes. A robust evidence base is essential to develop policy and influence clinical practice for bioactives, an exciting and growing area of research.

Usual Intake of Flavonoids Is Inversely Associated with Metabolic Syndrome in African American and White Males but Not Females in Baltimore City, Maryland, USA

Despite research that suggests flavonoids protect against metabolic syndrome (MetS) and evidence that intake of these compounds differs by race, knowledge about whether flavonoid-MetS associations vary among racial groups is limited. This study sought to estimate usual total flavonoid intake in African American and White adults and assess its sex- and sex/race-specific associations with MetS and its risk factors. Analysis of cross-sectional data from 1837 adults participating in the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) study were analyzed. Usual total flavonoid intake was estimated using the NCI Method, and logistic regression measured its linkages with health outcomes. Among males overall and when stratified by race, odds of MetS and its risk factors low high-density lipoprotein cholesterol (HDL-C) and elevated glucose were lower at the 75th percentile of usual total flavonoid intake than at the 25th percentile (OR for MetS = 0.62; 95% CI = 0.53, 0.71). However, low HDL-C and elevated glucose were positively associated with usual flavonoid intake among females. The comparable associations by race within sex imply that the relationships between flavonoid and health outcomes may be evident across an array of intakes.

Designing, Conducting, and Documenting Human Nutrition Plant-Derived Intervention Trials

Best practices for designing, conducting, documenting, and reporting human nutrition randomized controlled trials were developed and published in Advances in Nutrition. Through an example of the randomized clinical trial on blueberries and bone health funded by the National Institutes of Health, this paper will illustrate the elements of those best practices that apply specifically to plant-based intervention clinical trials. Unique study design considerations for human feeding interventions with bioactive plant compounds include the difficulty of blinding the intervention, background nutritional status of participants, carry-over effects of the intervention, benefits of a run-in period, lack of safety/tolerability data, and nutrition-specific regulatory policies. Human nutrition randomized controlled trials are the gold standard for establishing causal relations between an intervention and health outcome measures. Rigorous studies and documentation define the quality of the evidence-base to inform public health guidelines and to establish personalized dietary recommendations for the health-promoting plant components.