Proprionate is often added to baked goods, artificial flavoring, and cheese. But it also naturally occurs inside the digestive system, where it's produced by gut bacteria when it breaks down fiber. Earlier studies have suggested that propionate, as well as other fatty acids, is beneficial when made by the latter. However, the researchers noted that the effects of propionate when consumed as a food additive are unclear.
For this study, the research team first evaluated the effects of propionate in vivo. They found that mice treated with propionate had elevated levels of metabolism-related hormones, including:
The researchers observed that the mice had increased blood sugar levels after receiving propionate. After 20 weeks, the mice also exhibited weight gain and insulin resistance – a typical characteristic found among individuals with Type 2 diabetes.
Afterward, the researchers enrolled 14 healthy, lean participants who were not diagnosed with diabetes for a clinical trial. Divided into two groups, the participants fasted for eight hours before eating meals which either contained one gram of propionate or a placebo. This was repeated one week later, where the participants who received propionate were given placebo and vice-versa. In both sessions, researchers took blood samples taken before eating and at regular intervals for four hours after meals.
The participants who were treated with propionate exhibited an increase in hormone levels that were disconcertingly similar to those seen in the in vivo models. They also had significantly higher levels of insulin and insulin resistance. The researches also observed that all participants had higher blood sugar levels after eating, but it took longer for those who ingested propionate to return to normal blood sugar levels.
The researchers concluded that propionate – when consumed as a food additive – contributed to insulin resistance and high blood sugar levels. This could potentially lead to more serious diseases such as diabetes and cardiovascular disease. (Related: High Blood Sugar and Insulin Levels Linked to Heart Disease.)
The study showed that ingesting propionate as a food additive has negative health effects. However, this preservative is used in a wide array of foods that are consumed multiple times a day. Fortunately, its effects can be avoided by simple changes to a person’s diet. Here are some of the foods which have the opposite effects of propionate:
Learn more about other potentially harmful substances in everyday foods and how to avoid them at Health.news.