The nutritional advice given to the public is that we should eat a minimum of five portions of fruit and vegetables every day. But little clarification is given about the best food choices to make to get the maximum health benefit. Some people like to count chips/French fries and crisps towards their "five a day"! While healthily cooked (without fat) potatoes do qualify, those cooked in fat certainly do not.

Some fruit and veg like apples and cucumber are undoubtedly good for you, but there are other choices you can make that will give substantially greater benefit. All fruit and veg at least provide fiber, which is essential for a functional digestive system.

The most popular choices are not the best. These are: corn, potatoes, apples, bananas, and iceberg lettuce. Iceberg lettuce is pretty much just an expensive way to buy water. Always choose the dark green lettuces instead - or other green salad leafs.

You should be looking for the so-called "power house" fruit and vegetables, which have a lot of vitamins A and C, as well as beta carotene. Get a variety of different colored produce: dark green, yellow, orange and red. They each have their own important qualities.

Green: leafy vegetables such as romaine lettuce, Brussels sprouts, brocolli or spinach.

Yellow/orange: carrots, winter quash, oranges, peppers in various colors (including red and green).

Red: tomatoes, berries, peppers.

Raw food retains the most nutrients. Vitamins are lost, to varying extents, through canning, drying, freezing and pickling. For example, canned apricots have half the vitamin A/beta carotene of fresh. But carrots are odd in that they actually are more beneficial if cooked - but not overdone. This unleashes more beta carotene. This is also better absorbed by the body if eaten with a little oil such as olive oil, or even a few nuts or seeds.

Here's a basic recipe for Roasted Root Vegetables, that you can improvise on by adding other vegetables such as sliced peppers (seeds removed).

Serves 6 as an accompaniment to a meal - perhaps 3 as a main meal.

Ingredients

2 medium red onions, each cut into 8 wedges
1 3/4 cups coarsely chopped peeled turnips (about 1/2 pound)
3 1/2 cups coarsely chopped carrot (about 1 1/2 pounds)
3 cups coarsely chopped parsnip (about 1 pound)
2 tablespoons olive oil
1 teaspoon brown sugar
1/2 teaspoon sea salt
2 tablespoons chopped fresh parsley
1 tablespoon balsamic vinegar
1/4 teaspoon freshly ground black pepper

Method

Preheat oven to 230 Celcius/Centigrade (Gas mark 8).

Combine first 7 ingredients in a shallow roasting pan; toss well. Bake for 1 hour, stirring after 30 minutes. When removed from the oven, toss the parsley, vinegar, and pepper to coat the vegetables.