MONDAY, Oct. 13, 2014 (HealthDay News) -- A compound extracted from broccoli sprouts may improve some social and behavioral problems that affect people with autism, a new study suggests.

The study was short-term and small, including just over 40 teenage boys and young men with autism. And experts stressed that no one is saying broccoli -- or its extracts -- is a magic bullet.

"This is just one study, and it's a preliminary study," said lead researcher Dr. Kanwaljit Singh, of Massachusetts General Hospital for Children.

It's also important to note that not everyone responded to the treatment. About one-third of those treated with the compound didn't have a positive response, according to the study.

Still, the findings are "promising" and should be followed up by larger studies that also include women and young children, Singh said.

The compound in question is called sulforaphane, and it's naturally found in broccoli and other cruciferous vegetables. The chemical has been widely studied for its potential benefits against cancer, according to Singh.

But in the new study, reported on Oct. 13 in the Proceedings of the National Academy of Sciences online, researchers chose to test sulforaphane as an autism therapy.

Why study a broccoli sprout extract? According to Singh, one reason is related to a phenomenon known as the "fever effect," seen in some children with autism -- where problems such as repetitive behavior temporarily fade when the child has a fever.

The researchers theorize that the improvement stems from the fact that fevers trigger a heat-shock response -- a cascade of events designed to shield body cells from stress. In lab research, sulforaphane has been found to spark such a heat-shock response, according to the researchers.

To test the compound, Singh's team recruited 44 boys and young men, aged 13 to 27, with moderate to severe autism. They were randomly assigned to take either sulforaphane capsules or identical-looking placebo capsules every day for 18 weeks.

Based on parents' reports, many of the boys taking the extract started showing improvements in irritability, repetitive behaviors, hyperactivity and communication by the fourth week, according to the study.