We all know we should try to get our five a day (or seven if we're being really sensible), but which fruits and vegetables are the best to eat?
Researchers at William Paterson University of New Jersey aimed to find out by defining "powerhouse fruit and vegetables" which could help to tackle chronic disease.
They tested 47 different types of fruit and vegetables for their levels of 17 nutrients - the foods were scored by their content of potassium, fibre, protein, calcium, iron, thiamin, riboflavin, niacin, folate, zinc, and vitamins A, B6, B12, C, D, E, and K.
The study leaders defined foods as 'powerhouse' if they provided, on average, 10% or more daily value per 100 kcal of 17 qualifying nutrients. Of the 47 foods studied, 41 satisfied the powerhouse criterion.
The nutrient density score was based on the percentage of a person’s daily needs for each nutrient the food provides.
Watercress achieved the top score of 100 thanks to its particularly high levels of vitamin K- important for bone health - and vitamin A which help eye health.
The six fruits and vegetables that didn't make the powerhouse list were raspberries, tangerines, cranberries, garlic, onions and blueberries.
The paper was published in the CDC journal Preventing Chronic Disease.
Here's the list of the full results:
Chinese cabbage 91.99
Beet green 87.08
Leaf lettuce 70.73
Romaine lettuce 63.48
Collard green 62.49
Turnip green 62.12
Mustard green 61.39
Dandelion green 46.34
Red pepper 41.26
Brussels sprout 32.23
Iceberg lettuce 18.28
Winter squash 13.89
Sweet potato 10.51
Grapefruit (white) 10.47