Watercress is the most nutrient dense vegetable on earth, according to a new US study.

The study names the top 41 “powerhouse fruit and vegetables”, ranking them in order of the amount of critical nutrients they contain.

• Click the advisor owl for the top 41 fruit and vegetables  

‘Superfoods’ have become household staples in recent years, with things like kale and quinoa in high demand across the country.

The study, conducted by researchers at William Paterson University in New Jersey, tested fruit and vegetables for nutrients that are protective against chronic diseases like cancer.

Watercress received a nutrient density score of 100, followed by Chinese cabbage at 91. Fad superfood kale was ranked 15th with a score of 49.

Spinach was scored higher than kale with a score of 86.

Fruit appearing on the powerhouse list were mostly citrus, but berries like strawberries and blackberries also made the cut.

Speaking to the Washington Post, lead researcher Jennifer Di Noia said that this was the first classification which ranked powerhouse vegetables and fruit.

Dr Noia said the consumption of all of the 41 powerhouse vegetables should be considered.