Strawberries are good for you but having them in a cocktail may make them even healthier, a study suggests.

The fruit contains compounds that can protect against cancer, heart disease and arthritis.

But having them with alcohol, such as in a daiquiri, boosts these antioxidant properties, the Journal of the Science of Food and Agriculture says.

Nutritionists said the "detrimental effects" of such drinks could cancel out such benefits.

The most common cocktail to include strawberries is the daiquiri - which also includes lime or lemon juice, strawberry liqueur, sugar - and rum.

The researchers, from the Kasetsart University in Thailand and the US Department of Agriculture Research Service, were actually looking for more effective ways of keeping fruit fresh during storage.

'Detrimental effects'

They found that treating strawberries with alcohol enhanced the antioxidant capacity within the fruit - which boosts the fruit's power to neutralise destructive molecules called free radicals - by a third.

Free radicals are highly reactive oxygen molecules which damage DNA and cell membranes.

They are linked to a wide range of diseases and are thought to be one of the chief causes of ageing.

Treating blackberries in the same ways also had beneficial effects.

But Dr Frankie Phillips of the British Dietetic Association said: "It's well known that some preparation of fruit and veg can enhance the availability of nutrients and other plant chemicals including antioxidants.

"For example, cooking tomatoes or stir frying pepper facilitates availability of the lycopene and beta-carotene they contain.

"That's why the five-a-day message states to include a variety of fruit and veg as fresh, frozen, juice, dried and canned, and encourages different preparations."

She added: "Whilst this study suggests that consuming strawberries with alcohol increases the antioxidant capacity, there are clearly detrimental effects of consuming alcohol in terms of cell damage.

"So any potential antioxidant benefits may be cancelled out by the potential liver damage caused by too much alcohol.

"Our advice is to enjoy summer berries but don't expect a panacea in the form of a strawberry daiquiri."