A group of US scientists hail plain popcorn as a great diet food for its low calorie content and claim it may even top fruits and vegetables in antioxidant levels.

Antioxidants – known as polyphenols – have huge health benefits as they help fight harmful molecules that damage cells.

Popcorn was found to have a high level of concentrated antioxidants because it is made up of just 4% water while they are more diluted in fruits and vegetables because they are made up of up to 90% water.

Researchers discovered one serving of popcorn has up to 300 mg of antioxidants – nearly double the 160 mg for all fruits per serving.

They also found that the crunchy hulls of the popcorn have the highest concentration of antioxidants and fiber.

The scientists from the University of Scranton in Pennsylvania unveiled their discovery at a meeting of the American Chemical Society in San Diego.

Popcorn was found to have a high level of concentrated antioxidants because it is made up of just 4 per cent water while they are more diluted in fruits and vegetables which are made up of up to 90 per cent water

Researcher Joe Vinson said: “Those hulls deserve more respect. They are nutritional gold nuggets.”

But Joe Vinson warned that people can’t forgo their five-a-day in favor of popcorn – as it doesn’t contain vital vitamins and nutrients found in fruit and vegetables.

Although he added that popcorn has many other health benefits, stating: “Popcorn may be the perfect snack food.

“It’s the only snack that is 100% unprocessed whole grain.

“All other grains are processed and diluted with other ingredients, and although cereals are called <<whole grain>>, this simply means that over 51% of the weight of the product is whole grain.

“One serving of popcorn will provide more than 70% of the daily intake of whole grain.

“The average person only gets about half a serving of whole grains a day, and popcorn could fill that gap in a very pleasant way.”

The scientists warned that preparation is key to culling popcorn’s health benefits.

Joe Vinson added: “Air-popped popcorn has the lowest number of calories while microwave popcorn has twice as many calories as air-popped.”