The refrain seems as old as motherhood itself: Eat your vegetables. Now, high school students have some advice for the cook: Vegetables are better with seasoning.

Vegetables with a dash of herbs and spices are preferable to plain ones — and that may lead to students liking and eating them more often, new research shows. The type of seasonings didn’t seem to matter much to students, who were part of a study by researchers at Pennsylvania State University. What did matter was that the vegetables were anything but plain.

Some students were given vegetables dressed with a small amount of oil and salt. Other students got a seasoning blend specifically developed for each vegetable. In one case, corn and peas were coated with a nacho-flavored seasoning.

Overall, eight varieties of frozen and canned vegetables were tested, with about 100 students participating in each test. They preferred the seasoned versions of cauliflower, broccoli, green beans, carrots — as well as a blend of corn and peas and a mix of black beans and corn — to their plain counterparts.

Researchers say the findings have important implications for school cafeterias: Federal rules require a variety of vegetables to be served throughout the week, but that doesn’t mean kids will eat them.

Vegetables are essential for good health. The current Dietary Guidelines for Americans calls for two-and-a-half to four cups of vegetables a day for those between 14 and 18 years old. Only about 2 percent of teenagers actually eat that amount, the researchers noted.

So, if you want your teenager to eat their vegetables, a little dash of flavor can do a lot.