• Katie Floyd

Sorghum: A Gut-Friendly Grain

Updated: Apr 15

According to the CDC, obesity is a serious, costly, and unfortunately common health concern (1). More than one-third (36.5 percent) of adults and 1 in 6 children in the United States are obese (2). Obesity can lead to many other health issues and has been linked to at least 60 chronic diseases, including type 2 diabetes, heart disease, stroke, cancer, and many more (2). More research is being done to determine how gut health relates to body weight.


A study from the academic journal Nutrients evaluated the impact of sorghum on gut microbiota and body weights of normal weight (NW) and overweight/obese (OO) individuals. Their research indicated that “human gut microbiota is a mediator between diet, gut homeostasis, and body weight.” There are hundreds of thousands of microbes living in the human gut. An imbalance in gut microbiota, or dysbiosis, has been implicated in many chronic conditions, specifically obesity (3).

Another recent study showed that non-digestible, complex carbohydrates like resistant starches (starches that are resistant to digestion), are known to have beneficial physiological and biological effects on “weight management, reduction of calorie intake, glucose homeostasis, and lipid metabolism” (4). Some types of resistant starch sources include grains, seeds, legumes, raw potatoes, and unripe bananas (5). Sorghum (Sorghum bicolor L.) is classified as a resistant starch due to its low digestibility of starch, which makes it a promising candidate for weight and obesity management (4). Resistant starch food sources have been the highlight of many recent studies that aim to tackle the increasing issue of metabolic diseases that are directly associated with diet (4).


Resistant starch functions like soluble, fermentable fiber, traveling through the stomach and small intestine undigested and eventually reaching the colon where it can feed the good (or “friendly”) gut bacteria. This is so important because fermentable fibers and resistant starches feed 90% of our cells. Resistant starches have also been shown to possess various health benefits. It has shown to lower blood glucose levels and improve insulin sensitivity by as much as 33-50%. Its effect on insulin sensitivity is extremely important given that having low insulin sensitivity is shown to be a major risk factor for several serious diseases, including metabolic syndrome, type 2 diabetes, and obesity. In addition to the positive effects on blood glucose levels and insulin sensitivity, resistant starches are associated with satiety and reduced calorie intake (5).


Another beneficial compound that is utilized by gut microbiota, and is also found in sorghum, are polyphenols (3). Polyphenols are “biologically active compounds produced by metabolic pathways in plants, with numerous roles including pathogen protection, antimicrobial, and antioxidant activities (3).” The amount and types of polyphenols in sorghum varies depending on its color. Black sorghum varieties are rich in 3-deoxyanthocyanins, including luteolinidin and apigeninidin (3).


The 22 individuals who participated in the study were separated into two groups: 11 normal weight (NW) and 11 overweight/obese (OO). All the study participants received all six treatments using a randomized complete block design. The treatments were as follows:


NC (Negative control)

FOS (Fructooligosaccharides*)

BSE (Black sorghum bran extract)

SSE (Sumac sorghum bran extract)

FOS + BSE (Fructooligosaccharides + Black sorghum bran extract)

FOS + SSE (Fructooligosaccharides + Sumac sorghum bran extract)

* Fructooligosaccharides are a type of carbohydrate that occurs naturally in many plants, including blue agave, garlic, onion, leeks, asparagus, and bananas (6).


The study yielded a number of results, but here are some interesting results specifically related to the sorghum bran extract groups (3):

- In all subjects, BSE resulted in a significantly higher abundance of Bacteroidetes at 24 hours than all other treatments.

- Both BSE and SSE resulted in higher abundance of Bacteroides than FOS.

- Combined sorghum polyphenols and FOS worked to enhance Bifidobacterium, especially Lactobacillus (a probiotic genus that has been difficult to stimulate through prebiotic supplementation).

- Relative abundance of Verrucomicrobia increased in BSE, SSE and FOS + SSE after 24 hours, compared to FOS.

- Differential responses to treatment in NW and OO microbiota for Prevotella, Bifidobacterium, and Roseburia were observed, supporting the theory that gut microbial metabolism is altered in overweight/obese individuals.


Read the full study: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6412247/


References:

(1) Adult Obesity Facts. (2021). Centers for Disease Control and Prevention. www.cdc.gov/obesity/data/adult.html


(2) Obesity Facts. (July 29, 2020). Healthline. www.healthline.com/health/obesity-facts#1.-More-than-one-third-of-adults-in-the-United-States-are-obese.


(3) Ashley, D., Marasini, D., Brownmiller, C., Lee, J. A., Carbonero, F., & Lee, S. O. (2019). Impact of Grain Sorghum Polyphenols on Microbiota of Normal Weight and Overweight/Obese Subjects during In Vitro Fecal Fermentation. Nutrients, 11(2), 217. https://doi.org/10.3390/nu11020217


(4) Pelpolage, S., Nagata, R., Fukuma, N., Shimada, K., Han, K., Hamamoto, T., Hoshizawa, M., Fukushima, M. (2019). In Vivo Colonic Fermentation of Sorghum (Sorghum bicolor L.): Important Correlations Observed among the Physiological Parameters of Cecum, Liver, Adipose Tissue and Fasting Serum Lipid Profile. Journal of Nutritional Science and Vitaminology, 65, 222-227. https://doi.org/10.3177/jnsv.65.S222


(5) Resistant Starch 101 — Everything You Need to Know. (July 3, 2018). Healthline. www.healthline.com/nutrition/resistant-starch-101

(6) Fructooligosaccharides. (December 15, 2017). Healthline. www.healthline.com/health/fructooligosaccharides


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