If you see weight, you probably know how to avoid sugar and fat foods. But what about preservatives?
Eating a preservative widely used in bread, pastries and cheese can cause metabolic responses that are related to obesity and diabetes, showed an early study.
Gradual increase in body weight
Additive, called propionate, is actually a natural fatty acid produced in the intestine. When used as an additive in processed foods, it helps prevent mold.
But in a new study, the researchers found that feeding mice with low-dose propionate gradually cause weight gain and resistance to insulin to the hormone-which predisposes to type 2 diabetes in humans.
And when researchers gave healthy adults a single dose of propionate, it caused the release of hormones to increase blood sugar – and a subsequent increase in insulin.
None of this proves that foods containing propionate increases the chances of weight gain and diabetes, said senior researcher Dr Gokhan Hotohelmilil, a professor at the Harvard School of Public Health.
"The point is not to say that this supplement is" bad, "he stressed.
Instead, Hootsamilil said his team is interested in understanding the effects – good or bad – of the various "molecules" people consume in their diet.
Host of additives
"There is a lack of scientific evidence of many things that we put in our bodies through food," he said. "The propionate is just one example".
However, Hottomigilil said: the findings do not raise an important question: "Can the long-term consumption of propionate in humans contribute to obesity and diabetes?"
When it comes to processed foods, concern is usually directed to ingredients such as sugar, sodium and trans fats. But there are also many additives that, according to the US Food and Drug Administration, are "generally recognized as safe".
Nevertheless, the status of "GRAS", however, is usually not known for how these food additives can affect metabolism, according to Hotamisligil.
Dr. Emily Gallagher is an assistant professor of endocrinology at the School of Medicine at Mount Sinai Icahn in New York.
She agreed that it is important to dig up the potential metabolic effects of food additives.
Long-term studies are needed
"People can review food labels and think they make a healthy decision," said Gallagher, who was not involved in the study. "But without our knowledge, very small amounts of certain additives in food can cause harmful metabolic effects."
That said, it is premature to point to the finger of the propionate, according to Gallagher.
She called these initial findings "provocative", but says long-term studies are needed to better understand the health effects of the supplement.
For the animal part of the study, the researchers gave mice a propionate in their water. Immediate effects include an increase in three hormones that stimulate the liver to produce glucose (sugar). Over time, chronic exposure to the supplement has caused mice to gain weight and become resistant to insulin to the hormone, which helps lower blood sugar levels.
The human part of the study involved 14 healthy people who received a dose of propionate or placebo with a meal. Compared with a placebo meal, the supplement caused the same hormonal response in mice, plus the rise in insulin in the blood.
It is best to limit processed foods
Whether these effects over time can harm people's health is unknown.
Many factors, including overall diet and exercise, affect the risks of obesity and diabetes, Gallagher said.
For the time being, she said, the findings support the General Council that we need to limit the processed food, in favor of healthier, full-bodied food.
Hodamigilil agreed. "I'm not saying, if you do not eat propionate, you will live forever," he said. "But these are the types of food we need to limit in each case."
The findings were published online Science translational medicine.
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