Location: Diet, Microbiome and Immunity Research
2021 Annual Report
Accomplishments
1. Stool consistency is related to diet and stress. ARS researchers in Davis, California, sought to understand how diet, physical activity, and stress influence whether stool produced by healthy people is normal, hard, or soft by examining dietary records, blood tests, physical activity data, and stool samples. Dietary factors which influenced stool form included moisture, saturated fat, dairy, sodium, vegetables, fruit, and alcohol. Stool was less likely to be normal with a high physiological stress load, particularly influenced by the stress hormones norepinephrine and cortisol. These results suggest that manipulation of diet and/or stress could help improve stool consistency, even in healthy adults.
2. Dietary fiber-enriched wheat promotes health. Growing evidence indicates a connection between the gut microbiome and development of obesity. Consumption of dietary fiber can shift the microbiome composition and increase the production of Short Chain Fatty Acids (SCFA) in the gut, which may reduce the inflammation associated with negative health impacts of obesity. ARS researchers in Davis, California, administered baked rolls made with regular wheat or wheat enriched for the dietary fiber, resistant starch type 2 (RS2), to healthy adults for one week each. Consumption of the RS2-enriched rolls increased the abundance of bacterial taxa known to produce the SCFA butyrate, increased bacterial fermentation and reduced postprandial glycemia relative to the regular wheat rolls. This research indicates that replacement of dietary fiber enriched wheat for regular wheat in commonly consumed products in the American diet could help alter the gut microbiome and reduce glycemia to decrease the risk of developing type II diabetes.
3. Vitamin A (VA) supplementation improves immune function in infants. Vitamin A (VA) protects against respiratory and intestinal infections, but the mechanism is not fully known. In animals, VA increases the expression of a protein, chemokine receptor 9 (CCR9), that allows immune cells to migrate to mucosal immune sites where they protect against pathogenic microorganisms. However, this has not been shown in humans. ARS Researchers in Davis, California, working with colleagues at the International Centre for Diarrhoeal Disease Research (icddr,b), Bangladesh, conducted a randomized, controlled trial of VA supplementation in 306 Bangladeshi newborns and found that VA increased CCR9 expression by T regulatory (Treg) cells in early infancy relative to the placebo treatment. Since Treg cells play a central role in regulating immunity at mucosal surfaces, these results suggest that increased CCR9 expression by Treg cells may be one mechanism by which VA supplementation during infancy decreases the risk of death from common childhood infections in populations at risk of deficiency.
Review Publications
Stephensen, C.B. 2020. Primer on immune response and interface with malnutrition. In: Humphries D.L., Scott M.E., Vermund S.H., editors. Nutrition and Infectious Diseases. Nutrition and Health. Cham, Switzerland: Humana. p. 83-110. https://doi.org/10.1007/978-3-030-56913-6_3.
Stephensen, C.B., Liets, G. 2021. Vitamin A in resistance to and recovery from infection: relevance to SARS-CoV2. British Journal of Nutrition. 1-10. https://doi.org/10.1017/S0007114521000246.
Lemay, D.G., Baldiviez, L.M., Chin, E.L., Spearman, S., Cervantes, E., Woodhouse, L.R., Keim, N.L., Stephensen, C.B., Laugero, K.D. 2021. Technician-scored stool consistency spans the full range of the Bristol scale in a healthy US population and differs by diet and chronic stress load. Journal of Nutrition. 151(6):1443-1452. https://doi.org/10.1093/jn/nxab019.
Hughes, R.L., Horn, W.F., Finnegan, P., Newman, J.W., Marco, M.L., Keim, N.L., Kable, M.E. 2021. Resistant starch type 2 from wheat reduces postprandial glycemic response with concurrent alterations in gut microbiota composition. Nutrients. 13(2):645. https://doi.org/10.3390/nu13020645.
Joslin, S.E., Durbin-Johnson, B.P., Britton, M.T., Settles, M.L., Korf, I., Lemay, D.G. 2020. Association of the lactase persistence haplotype block with disease risk in populations of European descent. Frontiers in Genetics. 11. Article: 558762. https://doi.org/10.3389/fgene.2020.558762.
Ehrlich, A.M., Pacheco, A.R., Henrick, B.M., Taft, D., Xe, G., Huda, N.M., Mishchuk, D., Goodson, M., Slupsky, C., Barile, D., Lebrilla, C.B., Stephensen, C.B., Mills, D.A., Raybould, H.E. 2020. Indole-3-lactic acid associated with Bifidobacterium-dominated microbiota significantly decreases inflammation in intestinal epithelial cells. Gut Microbes. 20:357. https://doi.org/10.1186/s12866-020-02023-y.
Xue, Z., Brooks, J.T., Quart, Z., Stevens, E.T., Kable, M.E., Heidenriech, J., McLeod, J., Marco, M.L. 2021. Microbiota assessments for the identification and confirmation of slit defect-causing bacteria in milk and cheddar cheese. mSystems. 6(1). Article e01114-20. https://doi.org/10.1128/mSystems.01114-20.
Kable, M.E., Riazati, N., Kirschke, C.P., Zhao, J., Tepaamorndech, S., Huang, L. 2020. The Znt7-null mutation has sex dependent effects on the gut microbiota and goblet cell population in the mouse colon. PLoS ONE. 15(9). Article e0239681. https://doi.org/10.1371/journal.pone.0239681.
Ahmad, S.M., Hudaa, N.M., Raqib, R., Qadri, F., Peerson, J., Tanumihardjo, S., Stephensen, C.B. 2020. High-dose vitamin A supplementation at birth increases the percentage of CCR9+ treg cells in infants with lower birthweight in early infancy and decreases plasma sCD14 and prevalence of vitamin A deficiency at two years. Journal of Nutrition. 150(11):3005-3012. https://doi.org/10.1093/jn/nxaa260.
Parr, C.J, Lemay, D.G., Owen, C.L., Woodward Greene, M.J., Sun, J. 2021. Multimodal AI to improve agriculture. IEEE IT Professional. 23(3):53-57. https://doi.org/10.1109/MITP.2020.2986122.