Sprouted Grains as a functional food -Part 2

Welcome back! In my first post on sprouted grains, I identified some of the changes that occur by sprouting grains and the nutritional advantages that result, including greater antioxidant capacity, the accumulation of resistant starches and the significant reduction of anti-nutrients. In this second post of the series, I will consider the longer-term impact of sprouted grain consumption on human gastrointestinal function and microbiome colonization versus traditional, un-sprouted whole grain diet. 

First, it is important to define and recall some important terms to contextualize the impacts of sprouted grains. The first term is intestinal permeability. This refers to a complex anatomical and functional regulation of the mucosal barrier to ensure the proper passage of essential nutrients and fluids and the exclusion of toxins and pathogens. Having high intestinal permeability is increasingly associated with a myriad of adverse health conditions, including inflammatory bowel disorders like Crohn’s and celiac diseases, obesity, and metabolic and autoimmune diseases (Bischoff et al., 2014; Di Palo et al., 2020). Second, as I noted before in this blog series, arabinoxylan is a non-digestible prebiotic fiber that is substantially increased from germination and is also responsible for improving various functional components of the intestinal barrier (Chen et al., 2015).  

To restore the intestinal wall, arabinoxylan triggers expression of genes controlling tight-junction (TJ)  related proteins (Salden et al., 2018). TJs are the intercellular strands between the epithelial cells that line our internal organs like the intestines. The “tighter” these strands are, the less likely we are to experience the so-called “leaky” gut symptoms of an inflammatory bowel. Improvement in this mucosal barrier function was shown in rats fed a high-fat diet supplemented with arabinoxylan (Li et al., 2019). Just before the pandemic, in 2019, I set out to conduct a novel self-experimental model with my research partner in which we rigorously examined the impact of regular, daily consumption of sprouted grains in a non-diseased human (not rodent) state.

Our experiment was quite simple. I had a healthy human male subject consume a daily diet of  two, four-ounce servings of commercially sprouted grains and beans for four weeks. We were not interested in the type of grain or bean, only that they were sprouted. I used a measure called the lactulose to mannitol ratio (LMR) obtained from urine to examine intestinal permeability both before beginning any dietary change and immediately at the conclusion of the experiment. A LMR value of 0 indicates that no lactulose or mannitol sugars pass through the intestinal wall. Lactulose is a larger sugar molecule that is only passed in-tact between cells in the small intestine, to be later metabolized by bacteria in the large intestine. It passes through the wall of the small intestine very easily when the TJ proteins are “loose.” This would therefore likely increase the LMR reading. Mannitol, on the other hand, is a smaller sugar alcohol that passes both between and through cells in the small intestine to also be fermented by gut bacteria in the large intestine. Hence, its absorption is somewhat less sensitive to TJ disruptions. The selected subject had never before regularly consumed sprouted grains prior to the experiment. 

I noted that this dietary change did yield a substantial decrease in intestinal permeability (Fluegge & Fluegge, 2020). More specifically, the pre-intervention LMR reading was 0.8 as compared to a post-intervention reading of 0.5, representing a 38% decline in the LMR, which suggests a notable improvement of the TJ integrity. This result contrasts with that of a recent randomized-controlled trial showing that an 8-week diet of whole grains did not produce any alterations in either LMR or fecal microbial composition (Roager et al., 2019).

I mentioned longer-term impacts before. Granted, our self-experimental model lasted only a month, hardly a long-term perspective. It is quite possible, even likely, that the positive effect on LMR was only scratching the surface of what can be achieved via consistent sprouted grain consumption. For example, Bifidobacterium, bacteroides, and lachnospiracceae species in the gut are all capable of fermenting arabinoxylan (Rivière et al., 2014; Yasuma et al., 2021) to produce short-chain fatty acids and antioxidants like ferulic acid, which are themselves capable of restoring intestinal wall impermeability (Hwang et al., 2022). To date, these species’ notable beneficial impact on TJ regulation is widely considered remarkable and more than likely related to their fermenting capabilities (Abdulqadir, Engers, & Al-Sadi, 2023), despite the molecular mechanisms behind their influences being poorly understood and explained.

In my third and final blog post of the series, I will highlight the issues of Western food production processes that often affect the sprouting potential of many commercially available products. These processes include the application of toxic pesticides & herbicides (including the well-known glyphosate herbicide), heavy metal contamination (e.g., lead), other anthropogenic environmental conditions that have impacted climate change, and the prevalent use of genetically modified inputs.

Kyle Fluegge, PhD MPH

Director of Public Health Research and Evaluation
Institute of Health and Environmental Research
USA

References:

Abdulqadir, R., Engers, J., & Al-Sadi, R. (2023). Role of Bifidobacterium in modulating the intestinal epithelial tight junction barrier: Current knowledge and perspectives. Current Developments in Nutrition, 102026.

Bischoff, S. C., Barbara, G., Buurman, W., Ockhuizen, T., Schulzke, J. D., Serino, M., … & Wells, J. M. (2014). Intestinal permeability–a new target for disease prevention and therapy. BMC gastroenterology, 14, 1-25.

Chen, H., Wang, W., Degroote, J., Possemiers, S., Chen, D., De Smet, S., & Michiels, J. (2015).  Arabinoxylan in wheat is more responsible than cellulose for promoting intestinal barrier function in weaned male piglets. Journal of Nutrition, 145, 51-58. https://doi.org/10.3945/jn.114.201772 

Di Palo, D. M., Garruti, G., Di Ciaula, A., Molina-Molina, E., Shanmugam, H., De Angelis, M., & Portincasa, P. (2020). Increased Colonic Permeability and Lifestyles as Contributing Factors to Obesity and Liver Steatosis. Nutrients, 12(2), 564. https://doi.org/10.3390/nu12020564

Fluegge, Keith & Fluegge, Kyle. (2020). Influence of a Short-Term, Sprouted Grain Intervention Diet on Intestinal Permeability: A Model of Self-Experimentation. MedSurg Nursing. 29 (3), 201-2014. 

Hwang, H. J., Lee, S. R., Yoon, J. G., Moon, H. R., Zhang, J., Park, E., … & Cho, J. A. (2022). Ferulic acid as a protective antioxidant of human intestinal epithelial cells. Antioxidants, 11(8), 1448.

Li, S., Sun, Y., Hu, X., Qin, W., Li, C., Liu, Y., … & Chen, H. (2019). Effect of arabinoxylan on colonic bacterial metabolites and mucosal barrier in high‐fat diet‐induced rats. Food Science & Nutrition, 7(9), 3052-3061.

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