Medical researchers have discovered that a diet yielding high amounts of the short-chain fatty acids – acetate and butyrate – can impart a beneficial effect on the immune system. This protects an individual against type 1 diabetes.
Type 1 diabetes
The findings relating to the influence of diet on the immune system has come from Monash University’s Biomedicine Discovery Institute, and it relates to autoimmune type 1 diabetes. This type of diabetes occurs when immune cells (autoreactive T cells) attack and destroy the beta cells in the pancreas that produce insulin. Insulin is a hormone that regulates our blood sugar levels. The symptoms of diabetes mellitus type 1 are frequent urination, increased thirst, increased hunger, and weight loss. Additional symptoms can also rise and these include blurry vision, feeling tired, and poor healing.
The cause of type 1 diabetes is unknown, although most medical researchers think it involves a mix of genetic and environmental factors. There is an association with other having family members who have the condition, which relates to the genetic association. Diabetes is diagnosed by testing the level of sugar in the blood, with antibody testing differentiating type 1 diabetes from type 2 diabetes. Diabetes mellitus type 2 is a long term metabolic disorder that is characterized by high blood sugar, insulin resistance, and relative lack of insulin. Type 2 diabetes primarily occurs as a result of obesity and not enough exercise.
Special diet
The new research has looked at whether a specialized diet developed, based on starches (as found in many foods including fruit and vegetables) can be of benefit. The research suggests that some starches can resist digestion and pass through to the colon or large bowel. Here the starches are broken down by the gut microbiome (that is the bacteria that reside in a specific niche, in this case the human gut). The microbial digestion triggers fermentation, and this process produces acetate and butyrate. When these short-chain fatty acids combine they provide complete protection against type 1 diabetes. Short-chain fatty acids are fatty acids with two to six carbon atoms. Short-chain fatty acids are produced when dietary fiber is fermented in the colon.
The research has been based on animal experiments, using mice. Variations with diet showed that feeding mice a combined acetate- and butyrate-yielding diet provided complete protection, which suggested that acetate and butyrate might operate through distinct mechanisms.
Gut microbiome
The research adds to the body of evidence about the importance of the gut microbiome and its links to human health. It also shows who diet affects these microbes. According to the lead researcher, Dr Eliana Mariño: “Our research found that eating a diet which encourages the gut bacteria that produce high levels of acetate or butyrate improves the integrity of the gut lining, which reduces pro-inflammatory factors and promote immune tolerance.” This biochemical change appears to exert a considerable effect on the development of type 1 diabetes.
If the results are shown to be reproducible they could lead to a non-drug based regime for managing type 1 diabetes based on diet. A related application could be with the use of probiotics, designed to raise the numbers of certain gut bacteria. Not only could the approach be used as a treatment for type 1 diabetes it could also form the basis of a preventive treatment.
The important part of the approach would be with the selection of the appropriate foods (what the researchers call ‘medicinal foods’.) Importantly such a diet would be composed of natural foodstuffs. These foods would be the types that can release beneficial metabolites.
Taking the diet approach further, Professor Mackay is investigating the effect of different diets upon obesity and other inflammatory diseases, such as cardiovascular disease, type 2 diabetes, asthma, food allergies and Inflammatory Bowel Disease.
The important research has been published in the journal Nature Immunology under the heading “Gut microbial metabolites limit the frequency of autoimmune T cells and protect against type 1 diabetes.”
Essential Science
This article is part of Digital Journal’s regular Essential Science columns. Each week Tim Sandle explores a topical and important scientific issue. Last week we looked at a new material capable of producing low-cost electricity. The electricity is generated by exposing the material to variations in temperature. The week before weighed in on a new molecule that can be added to corn to prevent crop damaging fungal infections; these fungal infections also pose a risk to human health.
