In recent years, scientists have been wary of the warned of subtle damage Certain food additives can cause in humans. A new study released Wednesday suggests that the common propionate for food preservation could be one of those additives to worry about. In experiments on mice and humans, it was found that eating propionate can adversely affect metabolism, including increasing insulin resistance.
Propionate or Propionic Acid is an omnipresent part of our world. It is naturally produced by many bacteria, including those that live in our intestines and our skin. It is added to animal feed and foods such as cheese, baked goods and artificial flavors as a preservative. Although propionate is one of many additives on the GRAS list (Food and Drug Administration), there is research to suggest that propionate in the body is not completely harmless.
"But here it was It almost causes the body to believe that it has to produce glucose, if it does not. For example, in animals, it is believed that propionate can raise blood sugar levels through the liver, converting glucose from carbohydrate-free sources into fuel.
This ability is even used by herbivorous ruminants such as cows to regulate healthy blood sugar levels . In humans, the relationship with propionate is more mysterious. Some studies have shown that propionate and other short-chain fatty acids naturally produced by the intestinal bacteria in the body can actually help maintain a healthy metabolism, suppress appetite and reduce the risk of obesity. However, other studies indicate that individuals with more propionate in their system are more obese.
To better control the short-term effects of food-borne propionate, the authors of this latest study in Science Translational Medicine published feeding experiments with mice and humans. The human part of the study was a randomized, placebo-controlled, double-blind study of 14 healthy volunteers.
"We have confirmed that this causes an increase in blood sugar in mice. The most interesting thing we found in these experiments, however, is that a single dose of propionate can increase the hormones in the body that are supposed to stimulate glucose production from the liver, "said Gökhan S. Hotamışlıgil, director of the Sabri Ülker Center for Nutrition. Genetic and Metabolic Research at Harvard's TH Chan School of Public Health, Gizmodo said. "There are times when this is necessary, such as starving or having dangerously low blood sugar. But here, the body was almost tempted to believe that it has to produce glucose, if that's not the case. "
And in humans, these higher hormone levels also seemed to cause insulin resistance, meaning that their bodies did not respond too to signal insulin, lowering blood sugar. Over time, chronic insulin resistance contributes to type 2 diabetes and other metabolic disorders such as obesity.
In mouse experiments, mice receiving prolonged low doses of propionate also gradually gained more weight than mice, consuming no propionate. But Hotamışlıgil and his team do not claim that their results should immediately lead one to avoid cheese and bread.
"We are currently reluctant to make huge demands and recommendations," he said. "This is a proof-of-principle study that only shows that we can actually identify these molecules and study their biology, which then stimulates further work."
Hotamışlıgil added that it needs to be further explored how exactly this is understood Propionate could cause these metabolic changes. In humans, for example, they found evidence that propionate effects on the brain and nervous system occur through the production of adrenaline rather than by directly affecting the digestive system or the liver. This research must include human studies with many more volunteers from different laboratories.
Regardless of what Hotamışlıgil and other scientists discover at the end of Propionate, in studies like this one, he sees a silvery background trying to pronounce the more nuanced nutritional effects of food.
"I think in the 21st century we can look at diet and nutrition from a different perspective than a century ago. Now we have tools that allow us to study not only the harmful things in detail at the molecular level – because people are usually interested in the harmful things, but in the useful things in our food, "he said. "We can then easily remove some of these harmful things from our food preparation or reduce our exposure, and that could have a huge impact on our health."