人体需要多少水果和蔬菜？

Experts say eating a range of fruit and veg is best, as part of a balanced diet, to protect against illness

Research suggests eating at least seven portions of fruit and vegetables a day is more effective at preventing disease than the government's current five-a-day recommendation.

Is five a day enough?

Yes - but people should eat at least five portions of fruit and vegetables a day, the government says. The advice is based on World Health Organization guidelines, which are 25 years old.

Dieticians say eating five a day is enough to get the protective benefits of fruit and veg - although eating more may be additionally beneficial.

What counts as a portion?

Fruit juice counts towards one portion of the recommended five portions per day

For an adult, a minimum of 400g of fruit and vegshould be eaten every day, or five portions of 80g.

The amount varies for children, based on activity levels and age, but a rough guide is that one portion should fit in the palm of their hand.

Fruit and vegetables do not have to be eaten on their own and can be cooked in dishes such as soups, stews or pasta meals.

Do tinned fruit and fruit juice count?

Yes. But juice should be unsweetened, and only counts as one portion a day, as it contains less fibre than whole fruits and vegetables.

Fruit must be tinned in natural juice, or water, with no added sugar or salt, and not in syrup, which lots of fruit is.

Beans and pulses also count, but again only as one portion as they contain fewer nutrients than other fruits and vegetables.

Smoothies may count towards more than one portion if they contain all the edible pulped fruit or veg, and depending on their ingredients.

Recommendations include frozen fruit and vegetables, and dried fruit, such as currants, dates, sultanas and figs.

Those in ready-meals and shop-bought pasta sauces, soups and puddings are also included, but advice urges "only to have them occasionally" or in small amounts as they are often high in salt, sugar and fat.

What about potatoes?

Potatoes do not count towards one of the five-a-day, but sweet potatoes do.

Potatoes are not one of the five-a-day items. This is because they mainly contribute starch to a healthy diet, which is a good source of energy and helps digestion.

They are classified in the same group as bread or pasta by the government.

Skins should be left on when cooking as they are a good source of fibre.

But sweet potatoes, parsnips, swedes and turnips do count as five-a-day foods, as they are usually eaten as well as the starchy bit of the meal.