Research from the Grand Forks Human Nutrition Research Center, a U.S. Department of Agriculture facility in North Dakota, has determined that test subjects who ate vegetables were happier than people who didn’t. The conclusion is based on a questionnaire called the Subjective Happiness Scale, which scientists use to evaluate a person’s mood and hopefulness.

“We observed an increased in SHS scores in participants from the group that followed the… recommendations for vegetable intake, whereas SHS scores stayed the same for the control group, who didn’t change their diet,” said USDA research biologist Shanon Casperson in a release from mid-July. “Results suggest that increasing the amount of vegetables you eat every day may benefit your mental health.”

For the experiment, one group of adults, aged 18 to 65, received daily servings of cucumbers, peppers and other veggies. The other group ate their usual diet, without adding more vegetables.

After eight weeks, the group that consumed veggies had higher SHS scores than they did when they started the study. There was no change in perceived happiness from the control group.