Starch beats juvenile diabetes in mice
Can diet alone completely prevent type 1 diabetes? Quite possibly. Andrew Masterson reports.
The phrase “extreme superfood” sounds like the sort of hyperbole you might expect from a self-appointed diet guru with a fondness for quinoa and a dislike of evidence, but when it’s used by a senior immunologist at one of the world’s leading universities it might be worth pulling back on the skepticism.
Charles Mackay from the Biomedicine Discovery Institute at Monash University in Australia uses the term to characterise a diet formulation he and colleagues have discovered retards the development of type 1 diabetes – at least in mice.
A paper describing the results of the research has been published in Nature Immunology.
The work of Mackay's team concentrates on the matter of “resistant starch” (RS) – starch that escapes digestion in the gut and contributes to lower intestinal health. Long championed by researchers at CSIRO, RS has been firmly associated with numerous health benefits, including reduced risk of obesity and colorectal cancer.
A paper published in early 2017 established, again in a mice model, that consumption of RS improves insulin resistance, with implications for the management of type 2 diabetes.
The latest work potentially extends the benefits of RS, finding that in rodents it protects against type 1 or juvenile diabetes. After it passes undamaged through the small intestine, the RS is deposited in the colon, where it is fermented by resident bacteria (known collectively as the microbiome). This process liberates large amounts of short-chain fatty acids called butyrate and acetate, and it is these in combination that provided the protection.
Indeed, in the paper, the researchers conclude that “that key features of disease correlated inversely with blood and fecal concentrations” of the two compounds. A diet high in RS, they add, “provided a high degree of protection from diabetes”.
Butyrate and acetate, the study discovered, act to reregulate the body’s autoreactive T-cells – immune cells that malfunction and attack insulin-producing cells, thus producing diabetes.
Acetate, in particular, was found to markedly decrease T-cell populations, and the two compounds combined greatly improved gut functioning to a level, the researchers say, that provides “complete protection” against type 1 diabetes.
"The findings illustrate the dawn of a new era in treating human disease with medicinal foods," says Mackay.
"The materials we used are something you can digest that is comprised of natural products - resistant starches are a normal part of our diet. The diets we used are highly efficient at releasing beneficial metabolites. I would describe them as an extreme superfood."
RS is found in a wide variety of commonly available foods, including bran, oats, brown rice, legumes, leafy greens and milk fat. And while a diet containing lots of these elements is unquestionably healthy (assuming the absence of confounding conditions) that alone will not mitigate against the development of juvenile diabetes.
Mackay and colleagues are looking to create special foods and medicines based on their findings – and suggest that any diet derived therefrom will require input from nutritionists, clinicians and dietitians.