Challenges in the design, interpretation, and reporting of randomized controlled clinical studies on the health effects of whole foods (original) (raw)
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Common Limitations and Challenges of Dietary Clinical Trials for Translation into Clinical Practices
International Journal of Endocrinology and Metabolism, 2021
The progressive development of clinical and public health nutrition has long relied on dietary clinical trials (DCTs), investigating the causal relationship between diet and multiple risk factors of non-communicable and chronic diseases. DCTs are also hallmarks for establishing dietary requirements and promoting overall nutritional health among the population. Despite their critical importance in translation into public health strategies and practices, DCTs have several limitations and challenges for study design, implementation and finding interpretation. The complex nature of nutrition interventions, collinearity between diet components, multi-target effects of the interventions, diverse dietary behaviors, and food culture are the most challenging issues. Furthermore, baseline exposure and dietary status, appropriate control groups, blinding, randomization, and poor adherence undermine the effectiveness of DCTs in translation into practices. Disruptive factors will be minimized if researchers are committed to following good clinical practice (GCP) standards available for common designs of clinical trials. Planning DCTs, however, needs careful considerations for hypothesis generation, study design development, the definition of primary and secondary outcome measures, and target population.
Methodological Aspects in Randomized Clinical Trials of Nutritional Interventions
Nutrients
Nutrition is an essential component when promoting human health. Without a doubt, improving the quality of one’s diet can improve one’s quality of life as a whole and help postpone the onset or control of many chronic diseases. The volume of publications in this field has increased in recent years, in line with increased awareness of the importance of nutrition in health; however, the quality of the evidence on which most nutritional guidelines are based remains low, due to errors in conducting nutritional interventions or because the information is primarily derived from observational studies. To enhance the evidence supporting clinical guidelines in nutrition, the quality of randomized clinical trials (RCT) based on nutritional interventions must be improved; nevertheless, due to their heterogeneous nature and a lack of specific guidelines for designing, performing, documenting, and reporting on this type of intervention, conducting a nutritional intervention is a real challenge. ...
The Journal of Nutrition
The Nutrition Evidence Systematic Review (NESR) team conducts nutrition- and public health-related systematic reviews and is within the U.S. Department of Agriculture's (USDA) Center for Nutrition Policy and Promotion (CNPP). NESR has collaborated with scientific experts to conduct systematic reviews on nutrition and public health topics for more than a decade and is uniquely positioned to share recommendations with the research community to strengthen research quality and impact, especially the evidence base that supports public health nutrition guidance, including future editions of the Dietary Guidelines for Americans. Leveraging the expertise of NESR and its systematic review process resulted in the following recommendations for the research community: a) use the strongest study design feasible with sufficient sample size(s); b) enroll study participants who reflect the diversity of the population of interest and report participant characteristics; c) use valid and reliable ...
An assessment of clinical trials used in functional food science
Functional Foods in Health and Disease, 2023
Abstract: The emergence of chronic diseases with nutritional origin has rendered the wide use of clinical trials and intervention strategies necessary. Clinical trials have become a “gold standard” for testing the health impacts of different dietary changes; however, they also pose a potential risk to participants. Particularly with clinical trials used in food studies, there is an added complexity of food chemistry and food behavior as well as unique ethical issues related to clinical nutrition trials such as a potential violation of the right to be fed, disruption of food culture, and the need for food security. Thus, it becomes imperative to have a basic understanding of the key principles and methodology of different clinical trials to enable researchers to determine the best type of clinical trial for their functional food nutrition study. The progression of clinical nutrition trials is promising, but there is an increased importance of reviewing different models to determine the best method of performing nutrition-based research that minimizes the potential risk to participants while increasing current food knowledge. In this article, we aim to achieve two major goals: the first is analyzing various types of clinical trials and the second is using this analysis to figure out which type of clinical trial is ideally suited for research related to food and nutrition. Conclusion: We conclude that randomized trials are the most effective type of clinical trial used in functional food studies. Randomized cluster trials and randomized parallel-group trials are particularly effective in diminishing the challenges in functional food studies that are outlined in this paper as they reduce the effects one intervention has on another intervention. Keywords: Clinical trials, Functional Food Science, Clinical research, Functional Food, Food, Nutrition
Cureus, 2021
Randomized controlled trials (RCTs) provide the best quality evidence to steer patient care in the field of clinical nutrition. However, designing and conducting an RCT, analyzing data, interpreting and reporting its findings is rather complex for young researchers working in the field of clinical nutrition. This review article attempts to educate early researchers by offering a simple step by step guide on planning the key aspects (randomization, allocation concealment, blinding, outcome measures) of a trial, and highlighting the practical considerations (ethical clearance, trial registry, patient recruitment, trial monitoring) to be kept in mind while conducting a trial contextualised to clinical nutrition settings.
Advances in Nutrition, 2021
The USDA's Nutrition Evidence Systematic Review (NESR) team conducts food- and nutrition-related systematic reviews used to inform US Federal guidelines and programs, including the Dietary Guidelines for Americans. NESR's systematic review methodology includes a step to grade the strength of the evidence underlying conclusion statements, which is critical for ensuring that end users understand the level of certainty in conclusions when using them to make decisions. Over time, NESR has ensured its grading process not only remains state of the art but is also designed specifically for systematic reviews that inform Federal guidelines and programs on nutrition and public health. The NESR grading process used by the 2020 Dietary Guidelines Advisory Committee included 5 grading elements: risk of bias, consistency, directness, precision, and generalizability. Evidence was grouped by study design and assessed against these elements, and the grade assigned to the entire body of evid...
Long-term dietary intervention trials: critical issues and challenges
Trials, 2012
Background: There are many challenges involved in running randomised controlled dietary intervention trials that investigate health outcomes. The aim of this paper was to evaluate the recruitment process, retention of participants and challenges faced in our dairy intervention trial, and to provide strategies to combat the difficulties of running long-term dietary intervention trials. Methods: A 12-month, randomised, two-way crossover study was conducted in overweight adults with habitually low dairy food consumption to assess the effects of a high dairy intake (4 servings of reduced-fat dairy per day) compared with a low dairy intake (1 serving of reduced-fat dairy per day) on measures of cardiometabolic and cognitive health. On completion of the high dairy intake phase, each participant was interviewed about their experience in the trial and responses were used to evaluate the key issues for study participants. Results: Although the recruitment target was achieved, high rates of attrition (49.3%) and difficulties maintaining participant compliance (reported by 37.8% of participants) were major threats to the viability of the study. Factors that contributed to the high attrition included inability to comply with the dietary requirements of the study protocol (27.0%), health problems or medication changes (24.3%) and time commitment (10.8%).
Advances in Nutrition
Studies on the relation between health and nutrition are often inconclusive. There are concerns about the validity of many research findings, and methods that can deliver high-quality evidence-such as the randomized controlled trial (RCT) method-have been embraced by nutritional researchers. Unfortunately, many nutritional RCTs also yield ambiguous results. It has been argued that RCTs are ill-suited for certain settings, including nutritional research. In this perspective, we investigate whether there are fundamental limitations of the RCT method in nutritional research. To this end, and to limit the scope, we use probiotic studies as an example. We use an epistemological approach and evaluate the presuppositions that underlie the RCT method. Three general presuppositions are identified and discussed. We evaluate whether these presuppositions can be considered true in probiotic RCTs, which appears not always to be the case. This perspective concludes by exploring several alternative study methods that may be considered for future probiotic or nutritional intervention trials.