Medical doctors have employed insects not just as an alternate source to animal and plant proteins, but to aid digestion and weight loss because of their high dietary fibre value.
According to a report first published by Medical News Today (MNT), one lesser-known rich source of dietary fibre called chitin can be found in the exoskeletons of crustaceans and insects, as well as in mushrooms and other fungi.
Via a mouse model, researchers from the Washington University School of Medicine in St. Louis have found evidence that consuming chitin can help enhance digestion, lower body fat, and promote weight loss.
Several studies have shown that eating foods rich in fibre forms part of a healthy diet. This is because fiber helps the body in various ways, including improving digestion, maintaining a healthy weight, and helping solid waste move through the body more easily.
Past studies also show that dietary fibre can help lower cholesterol levels, improve blood sugar levels, and lower the risk of colorectal cancer.
While most people may be aware that dietary fibre can be found in fruits, vegetables, legumes, and whole grains, there are some lesser-known great sources of fibre, such as the exoskeletons of crustaceans and insects, as well as mushrooms and other fungi.
This form of fibre is known as chitin, and researchers from the Washington University School of Medicine in St. Louis have found evidence, via a mouse model, that consuming chitin can help enhance digestion, lower body fat, and promote weight loss.
This study was recently published in the journal Science.
What is chitin? Chitin is a naturally occurring biopolymer found in the exoskeletons of crustaceans such as shrimp and lobster and in the cell walls of mushrooms and other fungi.
Chitin acts a bit like the protein keratin found in human nails. The chitin in insects and crustaceans helps make their hard, protective outer shell.
Chitosan is a form of chitin normally used as a food additive and in supplements.
As a type of insoluble fibre, chitin does not dissolve in water, and it aids digestion by helping to move materials through the gastrointestinal system.
Additionally, previous research shows chitin provides other benefits to the body, including: acting as a prebiotic in the gut microbiome, reducing inflammation, preventing constipation, promoting weight loss, and offering skin protection.
According to Dr. Steven Van Dyken, an assistant professor of pathology and immunology at the Washington University School of Medicine in St. Louis and lead author of this study, his research team was interested in understanding immune responses to different types of foods and has been studying how the body responds to chitin, which is abundant in these types of foods.
“Dietary fibre intake is associated with healthy metabolism but much more needs to be learned about the different ways that different fibers are broken down after they are eaten,” he explained to Medical News Today.
During the study, scientists found an immune system response during chitin digestion. This is because after consuming chitin, stomach distention occurs.
This automatically triggers an immune response, telling stomach cells to ramp up the production of enzymes called chitinases to break down chitin.
“We studied how chitin is broken down or digested by the body’s own chitinases,” Dr. Van Dyken continued. “This happens after eating chitin, and the digestive process is enhanced by activating cells of the immune system that also affect obesity and metabolism. We think that intervening in this pathway might be a way to improve metabolic health.”
During this study, Dr. Van Dyken and his team found the mice who consumed chitin, so it activated their immune system, but their body did not digest it, saw the greatest impact on obesity.
Researchers used a mouse model that was fed a high-fat diet. Some of the mice were then given chitin.
According to researchers, some mice could not produce chitinases to break down the chitin. Because of that inability, these particular mice gained the least weight, had the lowest body fat measurements, and resisted obesity, compared to the mice that either did not receive chitin or did receive it but were able to break it down.
Dr. Van Dyken said they anticipated these results from previous studies showing that eating dietary fibers that are not digested very efficiently improves metabolic health.
“Activation of type 2 immunity is also associated with the lean state and metabolic health, so it made sense that the mice that did the best in terms of resisting obesity showed both reduced chitin digestion and an enhanced type 2 immune response,” he continued.
MNT also spoke with Monique Richard, a registered dietitian nutritionist, owner of Nutrition-In-Sight, and national media spokesperson for the Academy of Nutrition and Dietetics, about this study. Richard was not involved in this research.
Richard said her initial reaction to the study was to recognise that it is based on animal models, not humans.
Yet Richard also suggested it is important for human health to take advantage of all the foods rich in insoluble fiber and many other beneficial nutrients: “Eating a variety of fiber-rich foods that contain both soluble — turns into gel with liquid — and insoluble fiber such as beans, whole grains like oatmeal, fruits with their pulp and/or skins, most vegetables especially mushrooms, celery, cauliflower, green beans, and leafy greens.”
Also, a systematic review of human studies published in Nutrients reveals that insect proteins are as good as other protein sources in providing essential amino acids and other health benefits.
The study is titled, “Effects of Insect Consumption on Human Health: A Systematic Review of Human Studies.”
Edible insects are considered highly nutritious food in many countries, including Africa, Asia, Australia, Oceania, and Latin America. Humans consume more than 2,000 insect species; of them, beetles, caterpillars, bees, wasps, ants, grasshoppers, locusts, crickets, true bugs, dragonflies, termites, flies, and cockroaches are the most commonly consumed insects worldwide.
Insects require less feed, water, and land use for survival. They also emit lower amounts of greenhouse gases than conventional animal protein sources. Because of these factors, insects are considered a sustainable and nutritious food source. In some countries, insects are considered a nutraceutical food source because of their medicinal properties, including antioxidant, anti-inflammatory, immune-modulatory, anti-microbial, and gastrointestinal protection.
In this systematic review, scientists analysed the results of randomised controlled trials and allergenicity assessment studies investigating insect consumption’s health impact on human adults.
Scientists searched various scientific databases to identify in vivo human studies published between 2012 and 2022. From an initial screening of 1063 studies, they selected nine randomized controlled trials and five allergenicity assessment studies.
The primary outcomes of selected trials were iron absorption, amino acid absorption and muscle protein synthesis, amino acid synthesis and appetite regulation, microbiota, and disease treatment. Insect-based products tested in these trials included protein or flour derived from crickets, lesser mealworms, and silkworms.
The analysis of trial findings revealed differences in iron absorption between high-phytate and low-phytate meals. Phytate acts as the main inhibitor of iron absorption.
In trials where low-phytate meals were consumed, significantly lower iron absorption was noticed for insect-based test meals compared to placebo meals. In contrast, no significant difference in iron absorption was observed between insect-based and placebo meals for high-phytate meals. Notably, comparable plasma hemoglobin and ferritin levels were observed for insect and placebo meals, irrespective of the meal phytate content.
Post-prandial amino acid level was assessed after insect protein-based or conventional animal protein-based products were consumed. An induction in amino acid level was observed, irrespective of protein sources.
The comparison of insect protein sources with other protein sources revealed no significant differences in post-prandial essential amino acid levels. However, ingestion of insect proteins appeared to be associated with lower and delayed peaks of amino acids, including leucine, branched-chain amino acids, essential amino acids, non-essential amino acids, and total amino acids.
A comparable blood glucose level was observed after ingestion of insect proteins and other animal proteins. In contrast, a lower insulin level was observed after insect protein consumption than after consuming soy, whey, and beef protein.
Regarding pro-inflammatory mediators, a significantly lower level of tumor necrosis factor was observed after insect-based meal consumption compared to placebo meal consumption.
Overall, insect-based food products had no significant impact on appetite regulation. A sensation of indigestion after insect meal consumption was reported in one study. Another study reported lower hunger sensation after consuming high quantities of cricket and lesser worms.
Only one study reported decreased levels of Lactobacillus spp. and increased levels of Bifidobacterium after consumption of insect-based meal. A reduction in acetate and propionate short-chain fatty acid synthesis by gut microbiota after ingestion of insect meal was also reported in this study.
One study assessed the therapeutic efficacy of Caoshi silkworm granules supplemented for three months with routine medication in chronic obstructive pulmonary disease (COPD) patients.
The findings revealed no significant difference in pulmonary functions between granule-supplemented and placebo-supplemented patients. However, improvements in respiratory symptoms and activity were observed following granule supplementation.
A case study of a 31-year-old man allergic to house dust mites revealed severe food anaphylaxis after ingestion of mealworm. Tenebrio Molitor proteins were identified as the main allergy-inducing agents structurally similar to house dust mite proteins.
Epidemiological findings indicated that allergens from mopane worms, a popular indigenous edible insect, can induce respiratory symptoms in a vulnerable rural community occupationally involved in mopane worm harvesting. About 50 per cent of participants from this community were found to be sensitive to this worm.
Cross-reactivity studies revealed that cricket allergens can cross-react with shrimp allergens. A high molecular weight tropomyosin was identified as the major cross-reactive allergen between both species. Similar cross-reactivity was detected between yellow mealworm allergens, shrimp, and house dust mite allergens.
Different thermal treatments, including boiling and frying, partially reduced the cross-reactivity between shrimp, house dust mites, and insect allergens.
This systematic review of existing literature indicates that insect proteins are a valuable nutritional source with many health benefits. Future studies are needed to fully understand the safety and benefits of edible insects so that they can be introduced into regular human diets.
