Vegetables are healthy, period. However, there are several factors that decide whether or not the health benefits reach our body. A crucial factor involved is the way in which we cook the vegetables. For instance, boiling vegetables is one thing that you should avoid doing.
When vegetables are boiled, the nutrients that are present in are wasted along with the water. This is due to the presence of water-soluble vitamins in most of the vegetables. An alternative approach you can do is steaming. Steaming vegetables give you a similar taste and at the same time, keeps the essential nutrients intact.