Valerie Stull begins her mornings with a breakfast shake. She blends peanut butter, cocoa powder, banana, soymilk and flax seeds into it. She also sweetens it with honey and stirs in a little extra protein. That last ingredient is a powder made from ground crickets. Her research has shown that these bugs can be good for the gut.
Stull works at the Global Health Institute. It’s based at the University of Wisconsin in Madison. There she studies the overlap between agriculture, the environment and health. She’s part of an emerging group of researchers who study the impacts of eating insects. There’s a formal name for dining on bugs: entomophagy (En-tuh-MAH-fuh-jee).
About two billion people regularly eat insects. That’s almost one in every four. Most North Americans and Europeans tend to find the idea of entomophagy revolting. Yet even in their parts of the world, bug eating is starting to catch on. That’s especially true when the bugs are downed, as Stull’s are, in a form that doesn’t show their eyes, wings and feet.
Some scientists view edible insects as “mini-livestock.” (Livestock refers to animals that can be farmed.) Compared to raising cattle and more traditional livestock, insects need far less land and water. Bugs also are nutritious. They’re packed with protein, vitamins and minerals. Plus, their outer shells contain chitin (KY-tin) — a source of fiber.
High-fiber diets help guard against diabetes, heart disease and some types of cancer. Fruits, leafy greens and whole-grain foods all contain fiber. But the human body cannot digest fiber. Instead, fiber’s health benefits come from serving as a food for the beneficial microbes that live in our gut. Those gut germs make up our microbiome (My-kroh-BY-ohm). They include bacteria that can make us ill and others that boost our health.
The helpful crew breaks fiber into small molecules. These compounds can then boost the immune system, control body weight and even influence mood and emotions. Scientists refer to fiber and other parts of the microbes’ diet as prebiotics. That means they feed good gut bacteria.
It’s easy to confuse the terms prebiotic and probiotic. Probiotics are microbes that are good for you. Yogurt and sauerkraut are examples of foods that contain probiotics. Prebiotics, in contrast, are foods that fuel the growth of helpful gut microbes.
Stull wondered if chitin and other fibers in insects might offer health benefits similar to other fibers found in a typical American diet. To find out, she teamed up with Tiffany Weir. She’s a microbiome scientist at Colorado State University in Fort Collins. Breakfasts enriched with crickets changed the ratio of different microbes in the gut, the two now report. And those changes were in a direction that should boost a diner’s health.
The researchers described the results July 17 in Scientific Reports.
The cricket advantage
Stull and Weir recruited 20 healthy adults for a six-week study. Each morning for the first two weeks, the volunteers dined on chocolate shakes and pumpkin muffins. For half of the group, these foods contained a bonus: 25 grams of cricket powder. For the next two weeks, the volunteers ate whatever they wanted. In the final two weeks, each of the two groups ate what the others had during the first two weeks of the trial.
Before the study started, and again after each two-week period, each volunteer gave blood and provided a fecal sample. The recruits also took a survey that asked about bloating, constipation or feeling some type discomfort after meals.
Back in the lab, the researchers pulled out DNA from each person’s poop. They used a technique known as PCR to look for evidence of bacteria in those feces. The researchers then “read” the DNA sequences and looked for any matches to those for known gut bacteria.
Of 147 bacterial species analyzed, 15 changed after the cricket diet. One of those that changed is Bifidobacterium animalis (BIFF-idd-oh-bak-TEER-ee-um Aa-nih-MAL-is). It prevents diarrhea and other illnesses. Its abundance in poop increased 5.7-fold in the group consuming shakes and muffins with crickets. In contrast, levels of several harmful microbes fell.
These findings suggest that crickets work as prebiotics, says Melissa Agnello. “It’s evidence warranting further study of this novel food source,” she says. Agnello works at uBiome in San Francisco, Calif. This company creates technologies to study the microbiome.
Scientists think prebiotics, which fuel the growth of helpful gut microbes, have longer and larger benefits than probiotics do, Stull says. Probiotics exist in your gut, and you can also add them to your diet, notes Stull. But, she explains, “when you take probiotics, you’re infusing a whole bunch of good bacteria. But if you don’t feed those good bacteria, they’re not going to stick around very long.”
Since cricket was a new food, Agnello says, the participants might have lacked some gut microbes that digest chitin. She suspects the effect would have been larger if the participants’ microbiomes were better equipped from the start to break chitin down into beneficial molecules.
It’s also possible that crickets confer larger benefits to people who eat them regularly. In a future study Stull’s team would like to test that idea. These scientists will begin by looking at the microbiome of people from different parts of the world who have been lifelong insect eaters.
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agriculture The growth of plants, animals or fungi for human needs, including food, fuel, chemicals and medicine.
bacteria (singular: bacterium) Single-celled organisms. These dwell nearly everywhere on Earth, from the bottom of the sea to inside other living organisms (such as plants and animals).
bug The slang term for an insect. Sometimes it’s even used to refer to a germ.
cancer Any of more than 100 different diseases, each characterized by the rapid, uncontrolled growth of abnormal cells. The development and growth of cancers, also known as malignancies, can lead to tumors, pain and death.
cattle Also known as bovines (because they’re members of the subfamily known as Bovinae), these are breeds of livestock raised as a source of milk and meat. Although the adult females are known as cows and the males as bulls, many people refer to them all, generally, as cows.
chitin A tough, semi-transparent substance that is the main component of the exoskeletons of arthropods (such as insects). A carbohydrate, chitin also is found in the cell walls of some fungi and algae.
cocoa A powder derived from the solids (not the fats) in beans that grow on the Theobroma cacao plant, also known as the cocoa tree. Cocoa is also the name of a hot beverage made from cocoa powder (and sometimes other materials) mixed with water or milk.
compound (often used as a synonym for chemical) A compound is a substance formed when two or more chemical elements unite (bond) in fixed proportions. For example, water is a compound made of two hydrogen atoms bonded to one oxygen atom. Its chemical symbol is H2O.
diabetes A disease where the body either makes too little of the hormone insulin (known as type 1 disease) or ignores the presence of too much insulin when it is present (known as type 2 diabetes).
diarrhea (adj. diarrheal) Loose, watery stool (feces) that can be a symptom of many types of microbial infections affecting the gut.
diet The foods and liquids ingested by an animal to provide the nutrition it needs to grow and maintain health. (verb) To adopt a specific food-intake plan for the purpose of controlling body weight.
digest (noun: digestion) To break down food into simple compounds that the body can absorb and use for growth. Some sewage-treatment plants harness microbes to digest — or degrade — wastes so that the breakdown products can be recycled for use elsewhere in the environment.
DNA (short for deoxyribonucleic acid) A long, double-stranded and spiral-shaped molecule inside most living cells that carries genetic instructions. It is built on a backbone of phosphorus, oxygen, and carbon atoms. In all living things, from plants and animals to microbes, these instructions tell cells which molecules to make.
edible Something that can be eaten safely.
entomophagy A term for the human practice of eating insects.
environment The sum of all of the things that exist around some organism or the process and the condition those things create. Environment may refer to the weather and ecosystem in which some animal lives, or, perhaps, the temperature and humidity (or even the placement of components in some electronics system or product).
feces A body's solid waste, made up of undigested food, bacteria and water. The feces of larger animals are sometimes also called dung.
fiber Something whose shape resembles a thread or filament. (in nutrition) Components of many fibrous plant-based foods. These so-called non-digestible fibers tend to come from cellulose, lignin, and pectin — all plant constituents that resist breakdown by the body’s digestive enzymes.
fruit A seed-containing reproductive organ in a plant.
fuel Any material that will release energy during a controlled chemical or nuclear reaction.
germ Any one-celled microorganism, such as a bacterium or fungal species, or a virus particle. Some germs cause disease. Others can promote the health of more complex organisms, including birds and mammals. The health effects of most germs, however, remain unknown.
gut An informal term for the gastrointestinal tract, especially the intestines.
honey A viscous (gooey) material that honeybees store in their honeycombs. The bees make it from nectar. Foraging bees visit flowers in search of that sugary liquid. Back at the hive, honeybees will add some enzymes to the nectar, then deposit the amber colored liquid into the hive’s combs. As worker bees use their wings to fan the cells containing this liquid, the goo heats up and some of its water will evaporate to form honey.
immune system The collection of cells and their responses that help the body fight off infections and deal with foreign substances that may provoke allergies.
insect A type of arthropod that as an adult will have six segmented legs and three body parts: a head, thorax and abdomen. There are hundreds of thousands of insects, which include bees, beetles, flies and moths.
livestock Animals raised for meat or dairy products, including cattle, sheep, goats, pigs, chickens and geese.
microbe Short for microorganism. A living thing that is too small to see with the unaided eye, including bacteria, some fungi and many other organisms such as amoebas. Most consist of a single cell.
microbiome The scientific term for the entirety of the microorganisms — bacteria, viruses, fungi and more — that take up permanent residence within the body of a human or other animal.
mineral Crystal-forming substances that make up rock, such as quartz, apatite or various carbonates. Most rocks contain several different minerals mish-mashed together. A mineral usually is solid and stable at room temperatures and has a specific formula, or recipe (with atoms occurring in certain proportions) and a specific crystalline structure (meaning that its atoms are organized in regular three-dimensional patterns). (in physiology) The same chemicals that are needed by the body to make and feed tissues to maintain health.
molecule An electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in the air is made of two oxygen atoms (O2), but water is made of two hydrogen atoms and one oxygen atom (H2O).
novel Something that is clever or unusual and new, as in never seen before.
PCR Short for polymerase chain reaction. A biochemical process that repeatedly copies a particular sequence of DNA. A related, but somewhat different technique, copies genes expressed by the DNA in a cell. This technique is called reverse transcriptase PCR. Like regular PCR, it copies genetic material so that other techniques can identify aspects of the genes or match them to known genes.
peanut Not a true nut (which grow on trees), these protein-rich seeds are actually legumes. They’re in the pea and bean family of plants and grow in pods underground.
prebiotic An adjective that describes something that existed prior to living things. (in nutrition) A food or nutrient that promotes the growth of beneficial microbes in the gut.
probiotic A beneficial bacterium that is found in food or can be added to the diet. It can fight bad germs in the body or perform functions, such as producing vitamins that support human health.
protein A compound made from one or more long chains of amino acids. Proteins are an essential part of all living organisms. They form the basis of living cells, muscle and tissues; they also do the work inside of cells. Among the better-known, stand-alone proteins are the hemoglobin (in blood) and the antibodies (also in blood) that attempt to fight infections. Medicines frequently work by latching onto proteins.
ratio The relationship between two numbers or amounts. When written out, the numbers usually are separated by a colon, such as a 50:50. That would mean that for every 50 units of one thing (on the left) there would also be 50 units of another thing (represented by the number on the right).
recruit (noun) New member of a group or human trial. (verb) To enroll a new member into a research trial. Some may receive money or other compensation for their participation, particularly if they enter the trial healthy.
species A group of similar organisms capable of producing offspring that can survive and reproduce.
survey (v.) To ask questions that glean data on the opinions, practices (such as dining or sleeping habits), knowledge or skills of a broad range of people. Researchers select the number and types of people questioned in hopes that the answers these individuals give will be representative of others who are their age, belong to the same ethnic group or live in the same region. (n.) The list of questions that will be offered to glean those data.
vitamin Any of a group of chemicals that are essential for normal growth and nutrition and are required in small quantities in the diet because either they cannot be made by the body or the body cannot easily make them in sufficient amounts to support health.
Journal: V.J. Stull et al. Impact of edible cricket consumption on gut microbiota in healthy adults, a double-blind, randomized crossover trial. Scientific Reports. Vol. 8, July 17, 2018. doi: 10.1038/s41598-018-29032-2.