London: It`s now official: Walnuts are the healthiest nuts to eat.
Scientists have discovered that walnuts are loaded with antioxidants and snacking on as few as seven a day could help ward off disease and lower cholesterol.
They found that walnuts contain very high levels of polyphenol, an anti-oxidant which can protect the body from molecules which damage tissue.
Tests carried out on nine commonly eaten types of nuts showed that walnuts contained the most polyphenol than others.
Brazil nuts and pistachios were close behind, and cashews and hazelnuts had slightly lower levels of antioxidants, said the researchers from the University of Scranton, Pennsylvania.
"Walnuts rank above Brazil nuts, pistachios, pecans, peanuts, almonds, macadamias, cashews and hazelnuts," Prof Joe Vinson, who led the study, was quoted as saying by Daily Mail.
"Walnuts had the highest free and total polyphenols in both the combined and roasted samples," he added.
Despite the "superfood" potential of walnuts, peanuts are the favourite with consumers and account for 45 percent of the nuts bought in Europe.
According to the researchers, the antioxidants found in raw walnuts were 15 times as powerful as Vitamin E, which can protect the body against damaging natural chemicals.
Roasted cashew nuts contained just double the level found in Vitamin E, while the antioxidants in peanut butter were considerably lower than in roasted peanuts, the study found.
According to the researchers, pecans contain around asixth of the recommended daily allowance for zinc, which is vital for the functioning of white blood cells that fight bacteria and viruses, including colds and flu.
A couple of handfuls of shelled pistachios have more potassium than a banana. This can help control blood pressure, as part of a healthy diet, because potassium blunts the effects of salt. And the brazil nut is the richest source of selenium, a nutrient that helps protect cells, they said.
Higher selenium levels have been linked with a reduced risk of certain cancers such as bladder and prostate, they added.