Do you remember school dinners – the smell of the cabbage, stewed for hours and soggy carrots boiled to death? We didn’t know it then – but there was precious little goodness left in them, the vitamins had fled in terror, leached out into the cooking water.

These days we all know vegetables should be cooked for the shortest time possible. When immersed to boiling water their nutrients disappear at an alarming rate – 45% of Vitamin C is lost, 40% of vitamin B6 and folic acid, and 35% of vitamin B1.

But new tests show that vegetables boiled in filtered water retain more vitamins than those cooked in plain tap water. Filtering water prevents impurities ‘attacking’ vegetables during cooking, preserving more of the vitamins.(insert image carrots)

Filtered water is known to reduce scum and produce better tasting drinks, especially tea. Now research by German scientists, backed up by tests at the Good Housekeeping Institute, has proved that filtered water in cooking can improve taste, texture, colour and – most importantly – vitamin content in foods.

In tests conducted by the Good Housekeeping Institute, carrots cooked in filtered water retained 25% more vitamin C and 36% more beta carotene than carrots cooked in unfiltered tap water. Spinach retained 28% more vitamin C and 50% more vitamin B2 (riboflavin) when cooked in filtered water.

Too good to be true?

About 50% of all our cooking depends either directly or indirectly on water. So impurities in our water are bound to have an effect on the food we cook in it. But is the news that we can do something as simple as filtering our water to prevent nutrient loss just too good to be true?

Research conducted in Germany showed that foods cooked in filtered water retained more flavour and colour than those cooked in unfiltered tap water. And less salt was needed for cooking pasta, potatoes and vegetables when cooked in filtered water too.

A variety of foods was cooked in identical conditions in samples of unfiltered tap water and the same tap water, filtered. The food cooked in the filtered water cooked more evenly, with less destruction to outer cells, and had a better texture.