Guidance from an NIH Workshop on Designing, Implementing, and Reporting Clinical Studies of Soy Interventions

Abstract

The NIH sponsored a scientific workshop, “Soy Protein/Isoflavone Research: Challenges in Designing and Evaluating Intervention Studies,” July 28–29, 2009. The workshop goal was to provide guidance for the next generation of soy protein/isoflavone human research. Session topics included population exposure to soy; the variability of the human response to soy; product composition; methods, tools, and resources available to estimate exposure and protocol adherence; and analytical methods to assess soy in foods and supplements and analytes in biologic fluids and other tissues. The intent of the workshop was to address the quality of soy studies, not the efficacy or safety of soy. Prior NIH workshops and an evidence-based review questioned the quality of data from human soy studies. If clinical studies are pursued, investigators need to ensure that the experimental designs are optimal and the studies properly executed. The workshop participants identified methodological issues that may confound study results and interpretation. Scientifically sound and useful options for dealing with these issues were discussed. The resulting guidance is presented in this document with a brief rationale. The guidance is specific to soy clinical research and does not address nonsoy-related factors that should also be considered in designing and reporting clinical studies. This guidance may be used by investigators, journal editors, study sponsors, and protocol reviewers for a variety of purposes, including designing and implementing trials, reporting results, and interpreting published epidemiological and clinical studies.

Documentation of Functional and Clinical Effects of Infant Nutrition: Setting the Scene for COMMENT

“…These guidelines were developed for drug trials, but several papers have provided guidance on designing clinical trials for specific functional food ingredients [16,17,18]. Consensus guidelines have recently been collated for designing, conducting and reporting human intervention studies to evaluate the health benefits of foods [19].…”

Quantification of soy isoflavones and their conjugative metabolites in plasma and urine: an automated and validated UHPLC-MS/MS method for use in large-scale studies

“…Whereas the estrogen agonist activity of S-equol was found to be higher compared with daidzein, O-desmethylangolensin showed reduced estrogenic properties [3]. It has been pointed out that the ability to metabolize DAI to S-equol might be crucial for the health effects of soy isoflavones [2]. Next to microbial metabolism, phase II metabolism to glucuronide and sulfate conjugates may substantially alter the biological properties of IF.…”

“…Among several reasons, human inter-individual variability in the bioavailability and metabolism of IF are believed to be most important [2]. In general, metabolism alters the chemical structure of a parent compound and can thereby tremendously modify its biological activity.…”

Long-term soy isoflavone supplementation and cognition in women

“…Soybeans have biologically active constituents other than genistin, daidzin, and glycitin, 37,38 which individually or in aggregate could modify the cognitive effects of isoflavones. Our trial did not assess phytoestrogens more abundant in nonsoy food products (e.g., flavones, coumestans, and lignans), and results cannot be generalized to these compounds.…”