Location: Children's Nutrition Research Center
2024 Annual Report
Objectives
Objective 1: Determine if antinutrients in plant foods impact the gut microbiome.
Subobjective 1A: Using mice feeding studies, analyze the interaction between antinutrient content in plant-based diets and gut microbiota.
Subobjective 1B: Assess the impact of plant-based antinutrient content on animal and human microbiomes using in vitro systems.
Objective 2: Utilize a germ-free murine model to determine the inter-relationships between microbial gut ecology, plant anti-nutrients and host mineral bioavailability.
Approach
Unique plant diets differing in antinutrient content can be used along with 16S ribosomal RNA sequencing to determine how bacterial populations fluctuate as a function of antinutrients. Calcium (Ca) is often sequestered as an oxalate salt making it an 'antinutrient' and bio-unavailable. Medicago truncatula contains insoluble calcium oxalate crystals making it a poor source of dietary Ca. However, a M. truncatula mutant lacking oxalate crystals in the leaf tissue is an excellent source of Ca and allows the preparation of diets that differ in a single plant mutation to be used to analyze the impact of oxalate on the microbiome. Using primary cell culture models from both humans and mice will provide further insights into the impact of antinutrients on microbial composition. Meanwhile, mice reconstituted with either a microbiome associated with an antinutrient replete or antinutrient deficient diet, but consuming equivalent diets, will be analyzed for differences in calcium, iron, and zinc absorption.
Progress Report
This year, we centered on the role of calcium oxalate in the bioavailability of calcium. We continued work from last year and slightly adjusted our focus and analyzed the spatial distribution of elements using Synchrotron X-Ray Fluorescence (SXRF) and laser-ablation Inductively Coupled Plasma Mass Spectrometry (ICP-MS) at Brookhaven National Laboratories and the Biomedical National Elemental Imaging Laboratory at Dartmouth College. We have shown through visual pictures of both the plant material with and without calcium oxalate that were used in Objective 1, the mouse gut that had been fed diets high in calcium oxalate, Objectives 1A and 1B, showed impacts on the gut of female mice differently than that of male mice.
Understanding the importance of this research requires a closer look at some key concepts and why they matter, not just in a scientific sense but also in our everyday lives. Calcium oxalate is a compound found in many plants, and is a common form of calcium in our diet. However, it’s not easy for our bodies to absorb calcium from calcium oxalate. We have verified this in Objective 1. This is important because calcium is crucial for our bones, teeth, and overall health. By studying how calcium oxalate affects calcium bioavailability such as was done in Sub-objective 1A, scientists can figure out better ways for us to get the calcium we need from our food.
One of the most interesting findings from this research is that calcium oxalate affects male and female mice differently. Our original goal was to use germ-free mice to look at microbiome differences as outlined in Objective 2. However, delays in the research caused a shift in the analysis of how gut architecture was changed. We have shown in Objective 2 that the gut of female mice responds differently to the calcium oxalate in the diet than males. This might mean that the microbiomes have changed. However, there is still more work to be done on Objective 2. This could mean that men and women may also process calcium oxalate differently through changes not related to the microbiome. Understanding these differences is important because it can lead to more personalized nutritional advice. For instance, if scientists discover that women need to consume different types or amounts of calcium than men, this could change dietary recommendations and improve health outcomes for everyone.
Advanced techniques like Synchrotron X-Ray Fluorescence (SXRF) and laser-ablation Inductively Coupled Plasma Mass Spectrometry (ICP-MS) allow scientists to see where elements are distributed within an organism at a very detailed level. The findings from this research have real-world applications that can impact lives. For example, if we can improve how our bodies absorb calcium, it could lead to better dietary supplements and fortified foods. This could be especially important for people at risk of calcium deficiency, like the elderly or those with medical conditions. During the life of this project, this research on calcium oxalate and its impact on calcium bioavailability has proven to be important for several reasons. It helps us understand how our bodies process essential nutrients, highlights the differences between genders in nutrition, uses advanced scientific techniques, and has real-world applications that can improve health.
Accomplishments