Lincoln, Neb. —New research on waxy starch in sorghum by University of Nebraska-Lincoln researchers shows that waxy starches can have undesirable effects on the human gut microbiome. The gut microbiome is an ecosystem of microorganisms living in the gastrointestinal tract.
The Nebraska Food for Health research project focused on sorghum starch content, and its findings, were recently published in the journal “Gut Microbes”: “The waxy mutation in sorghum and other cereal grains reshapes the gut microbiome by reducing levels of multiple beneficial species.”
While starch is part of a healthy diet, it's important to note that not all starches are created equal. Typically, native starch comprises 20 to 25% amylose and 75 to 80% amylopectin, while waxy starches contain no amylose and are composed almost entirely of amylopectin molecules due to a naturally occurring mutation in starch synthesis genes. Normal starches often have physicochemical properties that are undesirable for food processing, while waxy starches are known for their high digestibility, desirable viscous properties in food processing, and unique organoleptic characteristics, such as sticky rice.
We know little about the health effects of consuming waxy starch compared to normal starch, particularly in context of a whole grain. Our gut contains trillions of microbes, which are influenced by our diet and impact our health through host-microbiome interaction. Could waxy vs normal starch have different effects on our gut microbiome and our health?
Using plant genetics and advanced research platforms, scientists at Nebraska Food for Health Center studied the in vitro fermentation of six pairs of near-isogenic sorghum lines. These lines were created through years of breeding and only differed in starch characteristics.
“It’s a gold mine!” exclaimed Dr. Qinnan Yang, lead researcher, discussing the exceptional plant materials studied. Analyzing fermentation profiles across diverse human microbiomes, they discovered that grain from parental lines of sorghum stimulate growth of many species of gut microbes that are known to be beneficial to our health whereas grain from waxy derivatives lacks this capacity. Thus, there is a trade-off effect between the desirable characteristics of waxy starch for food processing and an undesirable effect on the human gut microbiome.
Waxy starch lacks amylose, a component more resistant to human digestion, which can reach the colon and fuel beneficial gut microbes to produce short chain fatty acids. The amylose content of normal starches drives growth of beneficial microbes and their desirable metabolites whereas waxy starch does not. Adding extracted normal sorghum starch to waxy sorghum restores the beneficial microbiome changes, demonstrating the causal effect of amylose on the gut microbiome. Their work also showed that this effect also applies to waxy derivatives of other commonly consumed grains like corn, wheat, rice, and millet.
They also showed that humanized gnotobiotic mice fed waxy sorghum have different microbiome composition and gain more weight than those on a normal sorghum diet.
The conclusion drawn is that while waxy starches offer benefits in terms of food functionality, they can also have unintended consequences on both the gut microbiome and host physiology. This could be especially relevant in human populations in parts of Asia that consume significant quantities of waxy grains (e.g. sticky rice).
This study marks the third major discovery from the Nebraska Food for Health Center demonstrating the substantial impact that naturally occurring genetic variation in food crops can have on the human gut microbiome.
This growing list of food crop components identified by these genetic analyses now includes levels of amylose in wildtype vs. waxy starch (https://www.tandfonline.com/doi/full/10.1080/19490976.2023.2178799), levels of condensed tannins influenced by major tannin regulatory loci in sorghum (https://www.nature.com/articles/s41467-022-33419-1), and the effects of mutations in the opaque-2 locus on seed protein composition in maize (https://www.frontiersin.org/articles/10.3389/fmicb.2022.921456/full).
“Collectively, these findings point toward the importance of plant breeding and genetics in human health-associated traits and should open the door for breeding programs to consider incorporating human health traits into crop improvement strategies,” said Dr. Andrew Benson, director of the Nebraska Food for Health Center.
FAQs
Waxy starch lacks amylose, a component more resistant to human digestion, which can reach the colon and fuel beneficial gut microbes to produce short chain fatty acids. The amylose content of normal starches drives growth of beneficial microbes and their desirable metabolites whereas waxy starch does not.
Is starch bad for the microbiome? ›
Resistant starch is important for supporting a healthy gut microbiome. Starch escaping the small bowel acts as a source of food for the 'good bacteria' in the large bowel, fuelling their growth and activity, leading to favourable changes within the large bowel.
What are two things that can hurt the gut microbiome? ›
How can you get healthy gut bacteria? Start by eating a nutritious diet high in fiber-rich foods, like fruits, vegetables, and whole grains. A “western” diet that's high in fat and sugar and low in fiber can kill certain types of gut bacteria, making your microbiota less diverse.
What has the biggest impact on gut microbiome? ›
Prior research on the gut microbiome has shown that diet affects both gut diversity and mood, typically within 24 hours. Studies on neurological diseases such as epilepsy have shown particular diets, like the ketogenic diet, improve the symptoms of the disease.
What are the negative effects of the gut microbiome? ›
What are common signs or symptoms of a problem with my gut microbiome?
- Gas and gas pain.
- Bloated stomach.
- Poor digestion.
- Lower abdominal pain.
- Diarrhea.
- Constipation.
Analyzing fermentation profiles across diverse human microbiomes, they discovered that grain from parental lines of sorghum stimulate growth of many species of gut microbes that are known to be beneficial to our health whereas grain from waxy derivatives lacks this capacity.
What three foods does a gut doctor say to avoid? ›
Foods to Avoid
Refined carbohydrates, like white bread and pasta. Glutinous grains, like barley, rye, and oats. White sugar found in candy, baked goods, or cereal. Dairy products, including milk, ice cream, and some cheeses.
Are eggs bad for gut health? ›
More recently there has been a trend to reduce them for gut health or symptom management. But despite what you might hear, generally speaking, eggs are not inflammatory or 'bad' for the gut! Eggs are more commonly known to be an allergy vs an intolerance.
What food kills bacteria in the stomach? ›
Extra virgin olive oil, rapeseed oil, sunflower oil; Fatty fish: Mackerel, salmon, tuna; Nutritional nuts: Chia seeds, walnuts, almonds, sunflower seeds, etc. The above foods have the effect of eliminating HP bacteria, restoring the lining of the stomach and reducing the risk of stomach ulcers.
What is the best food for microbiome? ›
Probiotic foods contain beneficial live microbiota that may further alter one's microbiome. These include fermented foods like kefir, yogurt with live active cultures, pickled vegetables, tempeh, kombucha tea, kimchi, miso, and sauerkraut.
Gut resets aim to restore the balance of the microbiome by:
- removing foods that feed harmful bacteria and cause inflammation.
- introducing plenty of prebiotic foods, which feed beneficial bacteria.
- encouraging healthful practices, such as getting enough sleep and exercise and staying hydrated.
Eat plenty of fiber-rich foods.
When you think about your diet, consider the number of plant-based foods, grains, legumes and beans you're eating. Foods high in fiber, especially prebiotic fiber, balance your gut increasing good bacteria and starving bad bacteria.
Is coffee bad for your gut? ›
While there is no definite answer as to whether coffee is good or bad for digestion, it certainly affects the digestive system. Various research studies have indicated that coffee can contribute to: Heartburn and indigestion. Stimulation of movement in the intestines, leading to loose stools and/or diarrhea.
What kills bad bacteria in the gut? ›
By definition, antibiotics and antimicrobials kill bacteria and reduce the diversity that is key to a healthy microbiome (Source: NCBI).
Does starch irritate the gut? ›
Resistant starches are really good for our gut health and for preventing symptoms. Large intakes of resistant starches MAY increase some IBS symptoms, including gas, pain, and bloating. It is still a good idea to include resistant starches in the diet if you have IBS.
Why should we avoid starch? ›
Diets high in refined starches are linked to a higher risk of diabetes, heart disease and weight gain. In addition, they can cause blood sugar to spike rapidly and then fall sharply. This is especially important for people with diabetes and prediabetes, since their bodies can't efficiently remove sugar from the blood.
What is the best resistant starch for microbiome? ›
The results of this study by Mary Riwes and colleagues demonstrate that an easy-to-consume and inexpensive, low-tech, nonproprietary form of resistant starch, specifically Bob's Red Mill potato starch, is capable of shifting gut microbiome populations enough to significantly increase butyrate production, a response ...
