Vitamins in Soup

My HS science teacher claimed that when you cook fruits and vegetables, all the vitamins go out of them and into the liquid. Which would mean that if you were eating soup and concerned about vitamins, there is no reason to specifically eat the vegetables in the soup, as long as you’re eating the soup itself.

OTOH, most of what my HS science teacher said (which was not in the textbooks) was completely bogus. So what’s the story here?

I doubt that all leech into the water. Otherwise, wouldn’t we suffer from nutritional deficiency if all we ate were *cooked *vegetables?

What other claims did your HS science teacher make?

Some water soluble vitamins will be dissolved in the water, but not all and none of vitamins A and D (the fat soluble). Microwaving preserves more vitamins, as does steaming. So you do lose some of the vitamins by cooking in water, but not all.

also E and K are fat soluble

It’s not only a question of water vs. fat solubility. Heat destroys a certain percentage of both water- and fat-soluble vitamins. Boiling vegetables, as in a soup, lowers the vitamin C content of the food about 50 %, but about 10 % of vitamin A, as well. Folic acid is another water-soluble vitamin that is massively destroyed by boiling. Other vitamin Bs are also affected, although not as much as folic acid.

OTOH, cooking food makes it a lot easier to digest, and it’s possible this helps more nutrients get absorbed.