A common preservative added to breakfast cereals increases appetite and promotes obesity, a study in human stem cells has found.

The preservative butylhydroxytoluene (BHT) is included in processed foods such as breakfast cereals to stop fats in the food from turning rancid. But it is also a suspected endocrine disruptor – a class of chemicals that interferes with human hormones.

Finding out the effects of endocrine disruptors in humans is ethically difficult, as conducting a systematic test of these substances on people could well do them harm. Scientists at the Cedars-Sinai Medical Centre in Los Angeles invented a method using gut tissues grown from human stem cells to measure exposure to several likely endocrine disruptors.

As well as BHT, the researchers tested perfluorooctanoic acid (PFOA), which is used in non-stick pots and pans, and tributyltin (TBT) ,which is found in paints that often leak into waterways and accumulates in seafood. The scientists added these chemicals to the gut tissues to see what effect they had.

All three of them were found to interfere with the hormone production of the stem-cell-derived tissues. The disruption is thought to affect the nerve signals that the gut sends to the brain to signal when to stop eating.

"We discovered that each of these chemicals damaged hormones that communicate between the gut and the brain," said study author Dhruv Sareen, director of the Induced Pluripotent Stem Cell Core Facility at the Cedars-Sinai Board of Governors Regenerative Medicine Institute, in a statement. "When we tested the three together, the combined stress was more robust."

BHT, the cereal preservative, had the strongest effect. When the gut tissue was exposed to all three together, the effects were cumulative.

The chemicals damaged the tissue by disrupting the cell's machinery to create and transport hormones out of the cell. They also damaged the cells' mitochondria, the powerhouses of the cell responsible for energy generation from food.

"This is a landmark study that substantially improves our understanding of how endocrine disruptors may damage human hormonal systems and contribute to the obesity epidemic in the US," said Clive Svendsen, director of the institute.

The findings are published in a study in the journal Nature Communications.

Breakfast cereal
Some cereals add BHT to preserve fats, but this additive has been linked to damage to gut tissues that could boost appetite. Soozie Bea