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Study procedures, methods, and best practices

Developing a scientifically sound set of methods for a dietary intervention that could result in replicable, causally valid results took investigators five years of intensive effort.

That was a necessary first step because no such standards, protocols, methods or best practices existed. That absence required investigators to develop those standards and protocols de novo in order to move dietary intervention studies closer to replicability and credible conclusions of causality.

Establishing principles for replicability

The University of California, San Francisco IRB/Commitee on Human Research approved the n=20 study & on Nov. 14, 2014.

Once approved, the investigators began an intense effort to scrutinize every aspect of the study. That resulted in the recognition that no such effort at using basic laboratory practices and data recording had ever been made. This realization came from an examination of five dietary intervention studies. A sixth study, which was published in 2019, should be add to that list:

At that point, investigators determined the following principle: A kitchen must be subject to the same established practices as a laboratory. Consequently, the following three implementation strategies were created:

  1. Food, water, spices and all consumables must be treated as reagents whose sources, provenance, treatment, handling, measurement, and usage must be fully disclosed.
  2. Cookware, dishes, appliances, utensils and all other items involved in the preparation, cooking, serving and consumption must be treated as laboratory devices and apparatus.
  3. Recipes must be treated as protocols with scientifically accurate and complete conditions, materials, procedures, and timing recorded.

Researching and developing specific implementations of the revised protocols took four years, As a result, the UCSF-IRB/CHR Approved a revised study protocol and a one-year extension on Nov. 14 2018.

A further extension was granted due to delays — including planned and actual power outages — caused by wildfires in the San Francisco Bay area.

The PM2.5 particles in wildfire smoke can cause many adverse health effects including inflammation. (See also). This situation was a serious concern because our study’s primary indicator was hsCRP — a potent measure of inflammation.

Sourcing the Menu – Sources & Provenance

The primary goal of this strategy was to define Plastic-Derived Chemical contamination sources for specific menu items.

This work — described in a lengthy appendix to the revised protocol — determined the principles of which foods could be used for the uncontaminated  intervention leg and which PDC-contaminated analogs would be used for the initial leg.

The following guiding principles would later cause numerous difficult decisions as investigators applied the principles to the acquisition and treatment of specific foods from specific sources.

Decisions were made on the basis of whether the foods were typical of An American diet (according to the USDA) and which could be readily obtained in the United States by investigators who wished to replicate the study.

Accommodating the ideal with the realistic

As the trial grew near in 2019, investigators refined and tightened strategies 2 and 3/ They also reconciled their  ideal measures of menu item purity with the practical need need to execute of a trial which could be conducted without going to hysterical lengths which were proving to be un-necessary, expensive and time-consuming.

Items in progress

Actual selection choices, their rationale, and concordance with the revised protocol will be noted as an update at the top each of the sourcing links, above.

Choices will also be described in a detailed list of final ingredients that is analogous to a list of reagents and their sources.

A separate methods section will detail preparation and all recipes.

Best Practices

Following the UCSF/CHR approval of the revised study protocol, investigators also began developing a set of best laboratory practices to implement the study. Note that the following is a partial presentation of a much larger number of links.