[Sam Brown (OP)]

Julie has asked:

"Is it true that vitamins are lost if you wash your vegetables after you cut them?"

What do you think?

[evan_au]

Why do you wash your vegetables?
- Take off mud?
- Wash off any loose bacteria that may be present from irrigation or handling in packaging/shop?
- In the above cases, it sounds like you should wash the vegetables before you cut them?
- Washing out seeds or other inedible bits sounds like something you might do after you cut open the vegetables or fruit

Dirt, bacteria, seeds and other inedible bits all will have some nutritional value, no matter how slight. But it is generally expected that you would not eat such things unless you were starving.

If you (say) cut a potato into 4 parts, you will burst open many cells.
- If you now wash the pieces under running water, you will lose the contents of these cells
- If you threw the unwashed pieces into a stew, you would keep the contents of these cells
- In either case, it is a negligible fraction of the cells in a potato

If, however, you put a vegetable into a blender, you would break open a large fraction of the cells
- If you now washed what came out of the blender, you would be left with some good roughage (rather tasteless), but little in the way of cell contents
- If you drank everything that came out of the blender, you would be able to absorb a lot of the nutrition in the vegetable (in fact, probably more than if you ate the vegetable whole)

So, please clarify: why do you wash it, and why do you cut it? And in what sequence?

[Bored chemist]

There's a lot of vitamin B12 in sewage sludge...