The Inside Track | Fruits & Vegetables
Your five a day doesn't have to be raw – cooking your fruit and veg may help you to get your vitamins and nutrients
Everybody
knows that fruit and vegetables contain antioxidants, and are good for
you, although we still don't know exactly why. Current research no
longer supports the use of antioxidant supplements, but high antioxidant
levels in the blood do seem to be associated with a reduced risk of
heart disease and some cancers.
However,
we're often told that if you cook vegetables you "remove the goodness".
This was always code for removing the vitamin C, which does oxidise
quickly and is sensitive to heat. But vitamin C is not something we tend
to be short of these days, because of all the juice we drink, and how
much fruit and veg is available all year round. In fact, plenty of other
vitamins are not affected by heat at all, while some, such as
beta-carotene, are actually absorbed better because of it.
Beta-carotene
is a form of vitamin A, which is valuable for immune function, healthy
skin and healthy eyes. It is found in the cell wall of carrots, among
other things, which means that if you eat raw carrot you would only be
able to absorb a certain amount because your gut cannot break down all
the cells. The rest will simply pass right through your digestive tract.
When you cook carrots, however, you are weakening some of those cell
walls and making the beta-carotene more available, so a greater
percentage is absorbed. This is something we can measurably demonstrate
in blood levels.
There
are antioxidant compounds too, which are also absorbed better from
cooked foods. Lycopene, for instance, which is a pigment in tomatoes. Or
a group of chemicals called polyphenols. These are not classed as
nutrients, meaning that there isn't a deficiency state, but they are
associated with healthy effects, and all of them benefit from heat
treatment.
The
bottom line is: eat a lot of fruit and vegetables, but eat them however
you like. Salad, soup, casseroles, boiled, frozen, tinned, stir-fried,
whatever. And by all means add garlic, olive oil, cheese sauce or
anything else that will help you to eat more of them. Until you're
deep-frying peas in batter, I think the balance will always be in your
favour.
The writer Ursula Arens is a registered dietitian
The Guardian
