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ARS Home » Plains Area » Houston, Texas » Children's Nutrition Research Center » Research » Research Project #436052

Research Project: Nutritional Role of Phytochemicals

Location: Children's Nutrition Research Center

2021 Annual Report

The overall goal of our research is to better understand the impact of specific components of plant-based foods have on nutritional health and dietary outcomes. Research will be undertaken that aims to increase our understanding of the negative impact of dietary oxalic acid on human health and the mechanisms regulating its concentration in plant foods. Additionally we aim to increase our understanding of the role of carotenoids to improve the health and quality of life for mothers and infants. To accomplish this the following objectives will be undertaken: 1) characterize oxalate catabolic activity in low and high oxalate plants of dietary importance such as leafy greens harvested at different stages of development; 2) identify and characterize in a model plant system the genes and encoded proteins responsible for each step in a novel pathway of oxalate catabolism; 3) determine the influence of the newly identified oxalate catabolism pathway on the nutritional composition, phytochemical profile, and production characteristics in plants of dietary importance such as leafy greens grown to different stages of maturity (microgreens to mature greens); 4) to define the effect of pregnancy and lactation on carotenoid and vitamin A status and markers of bioactivity in diverse healthy weight and obese women; 5) to determine the pharmacokinetic basis for why adiposity affects breast milk carotenoid composition; 6) determine the interaction between antinutrients calcium oxalate and phytate in plant foods and the gut microbiome; and to 7)utilize a germ-free murine model to determine the inter-relationships between microbial gut ecology, plant calcium oxalate content or phytate content and host calcium, zinc and iron bioavailability.

These research studies will use various techniques to accomplish the research to be undertaken. We will assess the oxalate catabolic activity in low and high oxalate plants of dietary importance at different stages of development. Various analyses will be utilized (mineral, bioavailability, statistical and microscopic analysis of calcium oxalate crystal deposition) to address these research objectives. Further, carotenoid and vitamin A status of the mother during pregnancy and lactation are important to assure optimal health of the mother and adequate transfer of these components to the fetus and infant, respectively. A quasi-experimental (observational) study of a diverse group of U.S. mothers during pregnancy and early lactation will be conducted to define the key determinants of changes in carotenoid and vitamin A status across pregnancy and to explore the implications of these changes for markers of inflammation and cognitive function. Researchers will also examine the nutritional composition of food and explore how these components regulate metabolism. Mice fed plant diets differing in antinutrient content along with in vitro phenotyping will provide insight into the impact of antinutrients on microbial composition. Mice colonized with microbiomes associated with either an antinutrient replete or antinutrient deficient plant-based diet will be used in feeding studies to address alterations in Ca, Zn, and Fe absorption.

Progress Report
To review the progress made during the year, please refer to the following projects: 3092-51000-061-01S (Project #1), 3092-51000-061-02S (Project #2), and 3092-51000-061-03S (Project #3).

1. Identification of a key enzyme important for oxalate breakdown in plants. Plant scientists have been working to discover new strategies to reduce oxalate in plant foods since it inhibits our ability to absorb calcium present in plant foods and contributes to kidney stone formation (over 75% of all kidney stones contain oxalate). Additionally, there are certain oxalate-secreting fungal pathogens that generate oxalate as a requirement for attacking/infecting plants and causes more than $100 million in crop losses annually. Thus, reducing oxalate can help improve the nutritional quality and production of plant foods. ARS scientists in Houston, Texas, discovered an enzyme, oxalyl-CoA decarboxylase, that is responsible for a critical step in a previously unidentified process of oxalate breakdown in plants. Our research showed that this key enzyme is involved in the important process of converting oxalate into carbon dioxide and that plants lacking that enzyme could not perform this conversion and were more susceptible to oxalate-secreting fungal pathogens which lead to major crop loss. Thus, the identification and isolation of this enzyme (oxalyl-CoA decarboxylase) is an important advancement in our understanding of oxalate development and provides researchers with a new strategic tool to improve the nutritional quality of plant foods and the resistance of plants against infection from certain oxalate-secreting fungal pathogens.

2. Non-invasive measurement of infant carotenoid intake offers new tool for studying early life nutrition. Early life nutrition may be important to an infant's short- and long-term health, however determining what infants consume is challenging since they cannot report on their diet and they often have many caregivers involved in their daily feeding. Carotenoids are an antioxidant and pro-vitamin A, seen in the orange, red, and yellow pigments in some fruits and vegetables. Carotenoid levels in the blood and skin can be used to estimate a person's intake of fruits and vegetables. Researchers in Houston, Texas, determined that a non-invasive optical measurement of the skin, called reflection spectroscopy, could be used to measure skin carotenoids in infants. They found that the skin measurements agreed with both blood carotenoid measurements and diet reports of carotenoid intake for the infants, indicating that this measurement could be a useful tool to monitor infant carotenoid and fruit and vegetable intake non-invasively. Development of precise and accurate non-invasive tools to measure infants' diet will make it easier to study infant nutrition and health and aid in developing evidence-based guidance for infant nutrition.

Review Publications
Foster, J., Cheng, N., Paris, V., Wang, L., Wang, J., Wang, X., Nakata, P.A. 2021. An arabidopsis oxalyl-CoA decarboxylase, AtOXC, is important for oxalate catabolism in plants. International Journal of Molecular Sciences. 22(6):3266.
Engevik, M., Danhof, H., Ruan, W., Engevik, A.C., Chang-Graham, A.L., Engevik, K., Shi, Z., Zhao, Y., Brand, C.K., Krystofiak, E.S., Venable, S., Liu, X., Hirschi, K.D., Hyser, J.M., Spinler, J.K., Britton, R.A., Versalovic, J. 2021. Fusobacterium nucleatum secretes outer membrane vesicles and promotes intestinal inflammation. American Society for Microbiology. 12(2):e02706-e02720.
Cheng, N., Nakata, P.A. 2020. Development of a rapid and efficient protoplast isolation and transfection method for chickpea (Cicer Arietinum). MethodsX. 7:101025.
Hu, Q., Wu, Y., Zhong, L., Ma, N., Zhao, L., Ma, G., Cheng, N., Nakata, P.A., Xu, J. 2020. In vitro digestion and cellular antioxidant activity of beta-carotene-loaded emulsion stabilized by soy protein isolate-Pleurotus eryngii polysaccharide conjugates. Food Hydrocolloids. 112:106340.
McNeill, E.M., Hirschi, K.D. 2020. Roles of regulatory RNAs in nutritional control. Annual Review of Nutrition. 40:77-104.
Cepni, A.B., Taylor, A., Crumbley, C., Thompson, D.J., Moran, N.E., Olvera, N., O'Connor, D.P., Arlinghaus, K.R., Johnston, C.A., Ledoux, T.A. 2021. Feasibility and efficacy of the "FUNPALs Playgroup" intervention to improve toddler dietary and activity behaviors: A pilot randomized controlled trial. International Journal of Environmental Research and Public Health. 18(15):7828.
Cepni, A.B., Taylor, A., Thompson, D.J., Moran, N.E., Olvera, N., O'Connor, D.P., Johnston, C.A., Ledoux, T.A. 2021. Exploring qualities of ethnically diverse parents related to the healthy home environment of toddlers. Appetite. 167:105608.
Cheng, N., Mo, Q., Donelson, J., Wang, L., Breton, G., Rodney, G.G., Wang, J., Hirschi, K.D., Wehrens, X., Nakata, P.A. 2021. Crucial role of mammalian glutaredoxin 3 in cardiac energy metabolism in diet-induced obese mice revealed by transcriptome analysis. International Journal of Biological Sciences. 17(11):2871-2883.