Controlled feeding studies may help researchers better understand the effects of diet on the gut microbial structure in association with risk for disease, according to a presentation at The Human Microbiome: Emerging Themes at the Horizon of the 21st Century.
Diet may influence gut microbial metabolism. In particular, dietary constituents can produce compounds that could help reduce disease risk.
Therefore, experimental studies are needed to assess the effects of diet on the gut microbial structure and activity to determine effects on biomarkers and disease.
“We can use these types of studies to develop biomarker dietary exposure and, in many cases, in relation to thinking about biomarkers and bacterial metabolism,” Johanna W. Lampe, PhD, RD, member of the public health sciences division at Fred Hutchinson Cancer Research Center and research professor in University of Washington’s School of Public Health, said during her presentation at the NIH workshop. “We are really looking at several questions. What is the impact of the dietary pattern on the gut microbiome, and how does a diet pattern-microbiome interaction affect disease-risk biomarkers in the host?”
In controlled feeding studies, participants consume diets prepared to exact specifications so researchers can measure the biologic effect of a dietary manipulation.
However, these studies are not designed to evaluate the application of a dietary intervention under real-world conditions, Lampe said.
Controlled feeding studies enable researchers to control intervention and background diet, test dose responses, monitor intermediate biomarkers of effect, and monitor markers of dietary exposure and bacterial metabolism.
However, they may be limited by their short-term intervention and reliance upon intermediate markers. Also, controlled feeding studies cannot evaluate disease as an outcome, Lampe said.
“From a research standpoint, it really helps to offset the limitations of a single nutrient approach, where we know from the standpoint of epidemiologic studies that intakes are often inter-correlated,” she added. “Types of food that are consumed together are often correlated. This also helps to preserve the multidimensional aspects of foods as opposed to feeding specific nutrients.
“We can include all components of the diet, including both nutrients and non-nutrients,” Lampe added. “And we can take different approaches to studying dietary patterns, including cultural comparisons, mechanism-based indices, and comparison to established recommended patterns.”
Lampe and colleagues conducted a study to evaluate the effects of low and high glycemic-load diet patterns in a controlled feeding study with two 4-week periods.
Eighty healthy patients aged 18 to 45 years followed eucaloric diets with similar macronutrient distribution. The low-glycemic diet was higher in fiber (55 g vs. 28 g) than the high-glycemic diet.
Lampe and colleagues found circulating metabolic and inflammation biomarkers were associated with cancer risk.
“We have a strong need for well-annotated metabolomics platforms that really capture the range of endogenous and exogenous compounds in patients’ metabolites,” Lampe said. “Also, as we get to the point of establishing all of the genomes on the various types of bacteria, to actually be able to improve our approach is to characterize the microbial metabolism that involves consortia of bacteria. We often focus on specific microorganisms, but [we need] to find ways to then integrate them in order to get through consortia-based metabolism.” – by Kristie L. Kahl
Lampe JW. Testing Diet-gut microbiome interactions: Use of controlled feeding studies in humans. Presented at: The Human Microbiome: Emerging Themes at the Horizon of the 21st Century; Aug. 16-18, 2017; Bethesda, MD.
Disclosure: HemOnc Today could not confirm Lampe’s relevant financial disclosures at the time of reporting.