The Challenge of Reproducibility and Accuracy in Nutrition Research: Resources and Pitfalls

Policy Actions Required to Improve Nutrition for Brain Health

Brain health is a pressing global concern. Poor diet quality is a recognized major environmental risk factor for brain disorders and one of the few that is modifiable. There is substantial evidence that nutrition impacts brain development and brain health across the life course. So why then is the full potential of nutrition not utilized to improve brain function? This commentary, which is based on discussions of the European Brain Research Area BRAINFOOD cluster, aims to highlight the most urgent research priorities concerning the evidence base in the area of nutrition and brain health and identifies 3 major issues that need to be addressed: (1) increase causal and mechanistic evidence on the link between nutrition and brain health, (2) produce effective messages/education concerning the role of food for brain health, and (3) provide funding to support collaborative working across diverse stakeholders.

Building an open-source community to enhance autonomic nervous system signal analysis: DBDP-autonomic

Smartphones and wearable sensors offer an unprecedented ability to collect peripheral psychophysiological signals across diverse timescales, settings, populations, and modalities. However, open-source software development has yet to keep pace with rapid advancements in hardware technology and availability, creating an analytical barrier that limits the scientific usefulness of acquired data. We propose a community-driven, open-source peripheral psychophysiological signal pre-processing and analysis software framework that could advance biobehavioral health by enabling more robust, transparent, and reproducible inferences involving autonomic nervous system data.

Reporting completeness of nutrition and diet-related randomised controlled trials protocols

BACKGROUND AND AIMS

There is a need to consolidate reporting guidance for nutrition randomised controlled trial (RCT) protocols. The reporting completeness in nutrition RCT protocols and study characteristics associated with adherence to SPIRIT and TIDieR reporting guidelines are unknown. We, therefore, assessed reporting completeness and its potential predictors in a random sample of published nutrition and diet-related RCT protocols.

METHODS

We conducted a meta-research study of 200 nutrition and diet-related RCT protocols published in 2019 and 2021 (aiming to consider periods before and after the start of the COVID pandemic). Data extraction included bibliometric information, general study characteristics, compliance with 122 questions corresponding to items and subitems in the SPIRIT and TIDieR checklists combined, and mention to these reporting guidelines in the publications. We calculated the proportion of protocols reporting each item and the frequency of items reported for each protocol. We investigated associations between selected publication aspects and reporting completeness using linear regression analysis.

RESULTS

The majority of protocols included adults and elderly as their study population (n = 73; 36.5%), supplementation as intervention (n = 96; 48.0%), placebo as comparator (n = 89; 44.5%), and evaluated clinical status as the outcome (n = 80; 40.0%). Most protocols described a parallel RCT (n = 188; 94.0%) with a superiority framework (n = 141; 70.5%). Overall reporting completeness was 52.0% (SD = 10.8%). Adherence to SPIRIT items ranged from 0% (n = 0) (data collection methods) to 98.5% (n = 197) (eligibility criteria). Adherence to TIDieR items ranged from 5.5% (n = 11) (materials used in the intervention) to 98.5% (n = 197) (description of the intervention). The multivariable regression analysis suggests that a higher number of authors [β = 0.53 (95%CI: 0.28-0.78)], most recent published protocols [β = 3.19 (95%CI: 0.24-6.14)], request of reporting guideline checklist during the submission process by the journal [β = 6.50 (95%CI: 2.56-10.43)] and mention of SPIRIT by the authors [β = 5.15 (95%CI: 2.44-7.86)] are related to higher reporting completeness scores.

CONCLUSIONS

Reporting completeness in a random sample of 200 diet or nutrition-related RCT protocols was low. Number of authors, year of publication, self-reported adherence to SPIRIT, and journals' endorsement of reporting guidelines seem to be positively associated with reporting completeness in nutrition and diet-related RCT protocols.

A call to action in review of the Australian Dietary Guidelines: Impacts of conflicting nutrition information: A mixed methods study

ISSUES ADDRESSED

The overabundance of conflicting nutrition information (CNI) and accompanying confusion and backlash are a public health concern; however, the complexity of responses to CNI has yet to be explored. The following mixed methods study brings depth to the perceptions and behavioural responses to CNI among Australian millennials to better inform successful nutrition guidelines.

METHODS

An explanatory sequential mixed methods design explored the cognitive and behavioural responses to CNI in Australian millennials. Cross-sectional data (n = 204) on CNI exposure, confusion, and backlash was analysed via multivariate ordinal logistic regression. The qualitative phase thematically analysed 18 semi-structured interviews on experiences with and responses to CNI.

RESULTS

Exposure to CNI via social media was positively associated with confusion. Nutrition confusion was positively associated with backlash. Qualitative analysis confirmed social media as a frequent, yet sometimes trusted, source of CNI. In addition, participants revealed using various methods to alleviate backlash while also relying heavily on traditional nutrition information (TNI) to inform dietary choices.

CONCLUSIONS

The methods to alleviate nutrition backlash provide new and innovative ways to tailor nutrition messages for maximum impact. Nutrition promotion initiatives and dietary guidelines should consider the complexity of responses to CNI and modernise interventions across mediums, including social media, with clear and attractive dietary recommendations. SO WHAT?: Results can inform the drafting of the new Australian Dietary Guidelines in 2023 and how they are promoted to the community on an ongoing basis.

Development of a Comprehensive Food Data Citation Standard: A Surprising Gap in the Nutrition Research Literature

Currently, there is no standard for the citation of food composition data. This leads to the questions: how are food and nutrient data cited in research papers, and are they presented in a way that allows studies to be reproduced? To answer these questions, we performed a review of the literature and quantified the accuracy and completeness of data citations from publications (January to December 2020) in the top 5 nutrition journals as ranked by the Scimago Journal Rankings. We then performed a review of citation guidelines currently in place in other disciplines. Similar to the requirement of completing the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist for systematic reviews, we have developed a comprehensive data citation checklist, the Comprehensive Food Data Citation (CFDC) checklist. The CFDC checklist was developed through a benchmarking assessment against established data citation standards. Its purpose is to establish a standardized, best-practice approach for reporting food composition data. The CFDC checklist has been designed to cater to both publishers and authors, ensuring consistency and accuracy in food composition data reporting. The CFDC checklist is also available as an interactive citation generator to facilitate the adoption of consistent and comprehensive citation of food composition data and is available at https://www.nutrientinstitute.org/cfdc. Despite general agreement that accurate data citation is paramount, this is the first citation standard specifically developed to capture food composition data. Because food composition data are the foundation of nutrition research, our proposed guidelines aim to provide the field with a much-needed foundation for acknowledging and sharing data in a way that fosters reproducibility.

Optimizing clinical nutrition research: the role of adaptive and pragmatic trials

Evidence-based nutritional recommendations address the health impact of suboptimal nutritional status. Efficacy randomized controlled trials (RCTs) have traditionally been the preferred method for determining the effects of nutritional interventions on health outcomes. Nevertheless, obtaining a holistic understanding of intervention efficacy and effectiveness in real-world settings is stymied by inherent constraints of efficacy RCTs. These limitations are further compounded by the complexity of nutritional interventions and the intricacies of the clinical context. Herein, we explore the advantages and limitations of alternative study designs (e.g., adaptive and pragmatic trials), which can be incorporated into RCTs to optimize the efficacy or effectiveness of interventions in clinical nutrition research. Efficacy RCTs often lack external validity due to their fixed design and restrictive eligibility criteria, leading to efficacy-effectiveness and evidence-practice gaps. Adaptive trials improve the evaluation of nutritional intervention efficacy through planned study modifications, such as recalculating sample sizes or discontinuing a study arm. Pragmatic trials are embedded within clinical practice or conducted in settings that resemble standard of care, enabling a more comprehensive assessment of intervention effectiveness. Pragmatic trials often rely on patient-oriented primary outcomes, acquire outcome data from electronic health records, and employ broader eligibility criteria. Consequently, adaptive and pragmatic trials facilitate the prompt implementation of evidence-based nutritional recommendations into clinical practice. Recognizing the limitations of efficacy RCTs and the potential advantages of alternative trial designs is essential for bridging efficacy-effectiveness and evidence-practice gaps. Ultimately, this awareness will lead to a greater number of patients benefiting from evidence-based nutritional recommendations.

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.

Interactions between Medical Plant-Derived Bioactive Compounds: Focus on Antimicrobial Combination Effects

It is accepted that the medicinal use of complex mixtures of plant-derived bioactive compounds is more effective than purified bioactive compounds due to beneficial combination interactions. However, synergy and antagonism are very difficult to study in a meticulous fashion since most established methods were designed to reduce the complexity of mixtures and identify single bioactive compounds. This study represents a critical review of the current scientific literature on the combined effects of plant-derived extracts/bioactive compounds. A particular emphasis is provided on the identification of antimicrobial synergistic or antagonistic combinations using recent metabolomics methods and elucidation of approaches identifying potential mechanisms that underlie their interactions. Proven examples of synergistic/antagonistic antimicrobial activity of bioactive compounds are also discussed. The focus is also put on the current challenges, difficulties, and problems that need to be overcome and future perspectives surrounding combination effects. The utilization of bioactive compounds from medicinal plant extracts as appropriate antimicrobials is important and needs to be facilitated by means of new metabolomics technologies to discover the most effective combinations among them. Understanding the nature of the interactions between medicinal plant-derived bioactive compounds will result in the development of new combination antimicrobial therapies.

Pharmacokinetics and Pharmacodynamics of Key Components of a Standardized Centella asiatica Product in Cognitively Impaired Older Adults: A Phase 1, Double-Blind, Randomized Clinical Trial

Centella asiatica is reputed in Eastern medicine to improve cognitive function in humans. Preclinical studies have demonstrated that aqueous extracts of C. asiatica improve cognition in mouse models of aging and Alzheimer's disease (AD) through the modulation of mitochondrial biogenesis and nuclear factor-erythroid-2-related factor 2 (Nrf2)-dependent antioxidant response genes. This randomized, double-blind, crossover Phase I trial explored the oral bioavailability and pharmacokinetics of key compounds from two doses (2 g and 4 g) of a standardized C. asiatica aqueous extract product (CAP), over 10 h, in four mildly demented older adults on cholinesterase inhibitor therapy. The analysis focused on triterpenes (TTs) and caffeoylquinic acids (CQAs), which are known to contribute to C. asiatica's neurological activity. The acute safety of CAP and the effects on NRF2 gene expression in peripheral blood mononuclear cells were evaluated. Single administration of 2 g or 4 g of CAP was safe and well-tolerated. The TT aglycones, asiatic acid and madecassic acid, were identified in plasma and urine, while the parent glycosides, asiaticoside and madecassoside, although abundant in CAP, were absent in plasma and had limited renal excretion. Similarly, mono- and di-CQAs showed delayed absorption and limited presence in plasma or urine, while the putative metabolites of these compounds showed detectable plasma pharmacokinetic profiles and urinary excretion. CAP elicited a temporal change in NRF2 gene expression, mirroring the TT aglycone's pharmacokinetic curve in a paradoxical dose-dependent manner. The oral bioavailability of active compounds or their metabolites, NRF2 target engagement, and the acute safety and tolerability of CAP support the validity of using CAP in future clinical studies.

Developing a Rational, Optimized Product of Centella asiatica for Examination in Clinical Trials: Real World Challenges

Botanical products are frequently sold as dietary supplements and their use by the public is increasing in popularity. However, scientific evaluation of their medicinal benefits presents unique challenges due to their chemical complexity, inherent variability, and the involvement of multiple active components and biological targets. Translation away from preclinical models, and developing an optimized, reproducible botanical product for use in clinical trials, presents particular challenges for phytotherapeutic agents compared to single chemical entities. Common deficiencies noted in clinical trials of botanical products include limited characterization of the product tested, inadequate placebo control, and lack of rationale for the type of product tested, dose used, outcome measures or even the study population. Our group has focused on the botanical Centella asiatica due to its reputation for enhancing cognition in Eastern traditional medicine systems. Our preclinical studies on a Centella asiatica water extract (CAW) and its bioactive components strongly support its potential as a phytotherapeutic agent for cognitive decline in aging and Alzheimer's disease through influences on antioxidant response, mitochondrial activity, and synaptic density. Here we describe our robust, scientific approach toward developing a rational phytotherapeutic product based on Centella asiatica for human investigation, addressing multiple factors to optimize its valid clinical evaluation. Specific aspects covered include approaches to identifying an optimal dose range for clinical assessment, design and composition of a dosage form and matching placebo, sourcing appropriate botanical raw material for product manufacture (including the evaluation of active compounds and contaminants), and up-scaling of laboratory extraction methods to available current Good Manufacturing Practice (cGMP) certified industrial facilities. We also address the process of obtaining regulatory approvals to proceed with clinical trials. Our study highlights the complexity of translational research on botanicals and the importance of identifying active compounds and developing sound analytical and bioanalytical methods for their determination in botanical materials and biological samples. Recent Phase I pharmacokinetic studies of our Centella asiatica product in humans (NCT03929250, NCT03937908) have highlighted additional challenges associated with designing botanical bioavailability studies, including specific dietary considerations that need to be considered.

A guide for authors and readers of the American Society for Nutrition Journals on the proper use of P values and strategies that promote transparency and improve research reproducibility

Two questions regarding the scientific literature have become grist for public discussion: 1) what place should P values have in reporting the results of studies? 2) How should the perceived difficulty in replicating the results reported in published studies be addressed? We consider these questions to be 2 sides of the same coin; failing to address them can lead to an incomplete or incorrect message being sent to the reader. If P values (which are derived from the estimate of the effect size and a measure of the precision of the estimate of the effect) are used improperly, for example reporting only significant findings, or reporting P values without account for multiple comparisons, or failing to indicate the number of tests performed, the scientific record can be biased. Moreover, if there is a lack of transparency in the conduct of a study and reporting of study results, it will not be possible to repeat a study in a manner that allows inferences from the original study to be reproduced or to design and conduct a different experiment whose aim is to confirm the original study's findings. The goal of this article is to discuss how P values can be used in a manner that is consistent with the scientific method, and to increase transparency and reproducibility in the conduct and analysis of nutrition research.

Date Palm Fruit (Phoenix dactylifera): Effects on Vascular Health and Future Research Directions

Cardiovascular disease is a leading cause of death globally, presenting an immense public and economic burden. Studies on cardioprotective foods and their bioactive components are needed to address both personal and public health needs. Date fruit is rich in polyphenols, particularly flavonoids, certain micronutrients, and dietary fiber, which can impact vascular health, and have the potential to attenuate vascular disease in humans. Data from in vitro and animal studies report that consumption of date fruit or extracts can modulate select markers of vascular health, particularly plasma lipid levels including triglycerides and cholesterol, indices of oxidative stress and inflammation, but human data is scant. More investigation is needed to better characterize date polyphenols and unique bioactive compounds or fractions, establish safe and effective levels of intake, and delineate underlying mechanisms of action. Implementing scientific rigor in clinical trials and assessment of functional markers of vascular disease, such as flow-mediated dilation and peripheral arterial tonometry, along with gut microbiome profiles would provide useful information with respect to human health. Emerging data supports the notion that intake of date fruit and extracts can be a useful component of a healthy lifestyle for those seeking beneficial effects on vascular health.

Ketogenic and low-sugar diets for patients with cancer: perceptions and practices of medical oncologists in Canada

PURPOSE

Many patients with cancer are interested in complementary therapies, including strategies such as reduced carbohydrate diets. Guidelines regarding the use of these diets during cancer treatment are lacking; therefore, we aimed to explore the perceptions and practices of medical oncologists in Canada regarding low-sugar and ketogenic diets.

METHOD

A cross-sectional, online multiple-choice survey was distributed to 206 Canadian medical oncologists. Questions explored frequency of patient interactions, oncologist perceptions of efficacy, advice given to patients, and concerns about side effects related to reduced carbohydrate diets.

RESULTS

Responses were received from 57 medical oncologists in seven of thirteen provinces and territories, with an overall response rate of 28%. Forty-nine percent of respondents were asked at least weekly about a low-sugar diet, and 9% about the ketogenic diet. Eighty-five percent supported the use of a low-added sugar diet in patients with diabetes or hyperglycemia, while conversely 87% did not support the use of a ketogenic diet for any of their patients undergoing active cancer treatment. Respondents felt either that a ketogenic diet was not effective (31%) or that the effect on cancer outcomes was unknown (69%). Ninety-six percent of respondents had concerns about a ketogenic diet for patients receiving active cancer treatment.

CONCLUSION

The role of reduced carbohydrate diets during cancer treatment is topical. Canadian oncologists are particularly reluctant to support a ketogenic diet for patients on active cancer treatment, with concerns about side effects and unknown efficacy. There may be a role for continuing medical education and institutional guidelines to inform these discussions with patients.

Nutrition and the ageing brain: Moving towards clinical applications

The global increases in life expectancy and population have resulted in a growing ageing population and with it a growing number of people living with age-related neurodegenerative conditions and dementia, shifting focus towards methods of prevention, with lifestyle approaches such as nutrition representing a promising avenue for further development. This overview summarises the main themes discussed during the 3^rd Symposium on "Nutrition for the Ageing Brain: Moving Towards Clinical Applications" held in Madrid in August 2018, enlarged with the current state of knowledge on how nutrition influences healthy ageing and gives recommendations regarding how the critical field of nutrition and neurodegeneration research should move forward into the future. Specific nutrients are discussed as well as the impact of multi-nutrient and whole diet approaches, showing particular promise to combatting the growing burden of age-related cognitive decline. The emergence of new avenues for exploring the role of diet in healthy ageing, such as the impact of the gut microbiome and development of new techniques (imaging measures of brain metabolism, metabolomics, biomarkers) are enabling researchers to approach finding answers to these questions. But the translation of these findings into clinical and public health contexts remains an obstacle due to significant shortcomings in nutrition research or pressure on the scientific community to communicate recommendations to the general public in a convincing and accessible way. Some promising programs exist but further investigation to improve our understanding of the mechanisms by which nutrition can improve brain health across the human lifespan is still required.

Prospective clinical trial examining the impact of genetic variation in FADS1 on the metabolism of linoleic acid- and ɣ-linolenic acid-containing botanical oils

BACKGROUND

Unexplained heterogeneity in clinical trials has resulted in questions regarding the effectiveness of ɣ-linolenic acid (GLA)-containing botanical oil supplements. This heterogeneity may be explained by genetic variation within the fatty acid desaturase (FADS) gene cluster that is associated with circulating and tissue concentrations of arachidonic acid (ARA) and dihomo-ɣ-linolenic acid (DGLA), both of which may be synthesized from GLA and result in proinflammatory and anti-inflammatory metabolites, respectively.

OBJECTIVES

The objective of this study was to prospectively compare the capacity of a non-Hispanic white cohort, stratified by FADS genotype at the key single-nucleotide polymorphism (SNP) rs174537, to metabolize 18-carbon omega-6 (n-6) PUFAs in borage oil (BO) and soybean oil (SO) to GLA, DGLA, and ARA.

METHODS

Healthy adults (n = 64) participated in a randomized, double-blind, crossover intervention. Individuals received encapsulated BO (Borago officinalis L.; 37% LA and 23% GLA) or SO [Glycine max (L.) Merr.; 50% LA and 0% GLA] for 4 wk, followed by an 8-wk washout period, before consuming the opposite oil for 4 wk. Serum lipids and markers of inflammation (C-reactive protein) were assessed for both oil types at baseline and during weeks 2 and 4 of the intervention.

RESULTS

SO supplementation failed to alter circulating concentrations of any n-6 long-chain PUFAs. In contrast, a modest daily dose of BO elevated serum concentrations of GLA and DGLA in an rs174537 genotype-dependent manner. In particular, DGLA increased by 57% (95% CI: 0.38, 0.79) in GG genotype individuals, but by 141% (95% CI: 1.03, 2.85) in TT individuals. For ARA, baseline concentrations varied substantially by genotype and increased modestly with BO supplementation, suggesting a key role for FADS variation in the balance of DGLA and ARA.

CONCLUSIONS

The results of this study clearly suggest that personalized and population-based approaches considering FADS genetic variation may be necessary to optimize the design of future clinical studies with GLA-containing oils. This trial was registered at clinicaltrials.gov as NCT02337231.

Improving natural product research translation: From source to clinical trial

While great interest in health effects of natural product (NP) including dietary supplements and foods persists, promising preclinical NP research is not consistently translating into actionable clinical trial (CT) outcomes. Generally considered the gold standard for assessing safety and efficacy, CTs, especially phase III CTs, are costly and require rigorous planning to optimize the value of the information obtained. More effective bridging from NP research to CT was the goal of a September, 2018 transdisciplinary workshop. Participants emphasized that replicability and likelihood of successful translation depend on rigor in experimental design, interpretation, and reporting across the continuum of NP research. Discussions spanned good practices for NP characterization and quality control; use and interpretation of models (computational through in vivo) with strong clinical predictive validity; controls for experimental artefacts, especially for in vitro interrogation of bioactivity and mechanisms of action; rigorous assessment and interpretation of prior research; transparency in all reporting; and prioritization of research questions. Natural product clinical trials prioritized based on rigorous, convergent supporting data and current public health needs are most likely to be informative and ultimately affect public health. Thoughtful, coordinated implementation of these practices should enhance the knowledge gained from future NP research.

Current regulatory guidelines and resources to support research of dietary supplements in the United States

The U.S. Dietary Supplement Health and Education Act (DSHEA) established the regulatory framework for dietary supplements as foods through the Food and Drug Administration (FDA). DSHEA outlined the legal definition, labeling requirements, and process for adverse event reporting for dietary supplements. FDA also issued formal guidance on current Good Manufacturing Practice to ensure that processes for preparation, packaging, labeling, and storage of supplements and ingredients are documented and meet specifications to ensure purity, composition, and strength. However, efficacy of dietary supplements is not required under U.S. law. Despite regulations to improve the marketplace, many challenges remain; as a result, the quality and safety of products available can be highly variable, especially for botanical and herbal products. The ability of regulators to successfully carry out their mission is hampered by the sheer number of products and manufacturing facilities and a lack of analytical methods for all ingredients and products in the marketplace, this is especially difficult for herbal and botanical dietary supplements. Safety issues continue to exist such as adulteration and contamination, especially with specific product types (i.e. body building, sexual enhancement). Thus, a need remains for continued efforts and improved techniques to assess the quality of dietary supplements, especially with regard to purity, bioavailability, and safety. This review will highlight the existing American regulatory framework for dietary supplements and will describe the remaining regulatory barriers to ensuring that safe and high-quality dietary supplements are offered in the marketplace.

Dietary Flavanols: A Review of Select Effects on Vascular Function, Blood Pressure, and Exercise Performance

An individual's diet affects numerous physiological functions and can play an important role in reducing the risk of cardiovascular disease. Epidemiological and clinical studies suggest that dietary flavanols can be an important modulator of vascular risk. Diets and plant extracts rich in flavanols have been reported to lower blood pressure, especially in prehypertensive and hypertensive individuals. Flavanols may act in part through signaling pathways that affect vascular function, nitric oxide availability, and the release of endothelial-derived relaxing and constricting factors. During exercise, flavanols have been reported to modulate metabolism and respiration (e.g., maximal oxygen uptake, O₂ cost of exercise, and energy expenditure), and reduce oxidative stress and inflammation, resulting in increased skeletal muscle efficiency and endurance capacity. Flavanol-induced reductions in blood pressure during exercise may decrease the work of the heart. Collectively, these effects suggest that flavanols can act as an ergogenic aid to help delay the onset of fatigue. More research is needed to better clarify the effects of flavanols on vascular function, blood pressure regulation, and exercise performance and establish safe and effective levels of intake. Flavanol-rich foods and food products can be useful components of a healthy diet and lifestyle program for those seeking to better control their blood pressure or to enhance their physical activity. Key teaching points • Epidemiological and clinical studies indicate that dietary flavanols can reduce the risk of vascular disease. • Diets and plant extracts rich in flavanols have been reported to lower blood pressure and improve exercise performance in humans. • Mechanisms by which flavanols may reduce blood pressure function include alterations in signaling pathways that affect vascular function, nitric oxide availability, and the release of endothelial-derived relaxation and constriction factors. • Mechanisms by which flavanols may enhance exercise performance include modulation of metabolism and respiration (e.g., maximal oxygen uptake, O₂ cost of exercise, and energy expenditure) and reduction of oxidative stress and inflammation. These effects can result in increased skeletal muscle efficiency and endurance capacity. • Further research is needed to clarify the amount, timing, and frequency of flavanol intake for blood pressure regulation and exercise performance.

Nutrition and Cancer Research: Resources for the Nutrition and Dietetics Practitioner

This issue of the Journal focuses on issues in the intersection of nutritional science and cancer prevention research. In this commentary, we provide a high-level orientation for the reader to nutrition and cancer. We begin by reviewing the burden of cancer which has necessitated public policy recommending improvements to diet for the prevention of cancer in the U.S., although this is true of many other countries as well. These policy recommendations are based on the critical review of scientific evidence linking diet and cancer. We then discuss the inconsistencies in the nutrition-cancer scientific literature and the subsequent issues Registered Dietitian Nutritionists (RDNs) face when translating this literature in the clinic. We conclude with some resources for practitioners and general guidance.

Comparative Medicine: An Inclusive Crossover Discipline

Comparative Medicine is typically defined as a discipline which relates and leverages the biological similarities and differences among animal species to better understand the mechanism of human and animal disease. It has also been defined as a field of study concentrating on similarities and differences between human and veterinary medicine and is increasingly associated with animal models of human disease, including the critical role veterinarians, animal resource centers, and Institutional Animal Care and Use Committees play in facilitating and ensuring humane and reproducible laboratory animal care and use. To this end, comparative medicine plays a pivotal role in reduction, refinement, and replacement in animals in biomedical research. On many levels, comparative medicine facilitates the translation of basic science knowledge into clinical applications; applying comparative medicine concepts throughout the translation process is critical for success. In addition to the supportive role of comparative medicine in the research enterprise, its role as a distinct and independent scientific discipline should not be lost. Although comparative medicine's research "niche" is not one particular discipline or disease process, rather, it is the investigative mindset that seeks to reveal common threads that weave different pathophysiologic processes into translatable approaches and outcomes using various models.

The role of the IACUC in ensuring research reproducibility

There is a "village" of people impacting research reproducibility, such as funding panels, the IACUC and its support staff, institutional leaders, investigators, veterinarians, animal facilities, and professional journals. IACUCs can contribute to research reproducibility by ensuring that reviews of animal use requests, program self-assessments and post-approval monitoring programs are sufficiently thorough, the animal model is appropriate for testing the hypothesis, animal care and use is conducted in a manner that is compliant with external and institutional requirements, and extraneous variables are minimized. The persons comprising the village also must have a shared vision that guards against reproducibility problems while simultaneously avoids being viewed as a burden to research. This review analyzes and discusses aspects of the IACUC's "must do" and "can do" activities that impact the ability of a study to be reproduced. We believe that the IACUC, with support from and when working synergistically with other entities in the village, can contribute to minimizing unintended research variables and strengthen research reproducibility.