Vitamin kitchen.

Vitamins are not synthesizing in organism, we are getting theirs with meal, but in cooking we are losing theirs, how they are keeping right?
As a first of all to keep theirs right, and cook a meal with vitamins, as for vitamin c keeping,a cooking meal on steam, as in boiling they are loosing till 50 per.  of vitamin c, add theirs in boiling salting slight water, cook in enamel dish,closing, does not meal cook for a future, as in repeating warming she loosing an own effecting.