The importance of vegetables in daily meals is not a new discovery. Primitive doctors advised patients that vegetables would help keeping a balance between the fluids of the body: blood, phlegm, choler, yellow bile, and melancholy (black bile). In Greek "melan" means "black" and "holi" means "bile", hence, "melancholy" = "black bile". Mothers encouraged children to eat up their vegetables long before anyone had heard of food science.
Leave your drugs in the chemist's pot
if you can heal the patient with food.
(Hippocrates, Greek Philosopher)
Modern biochemists have found that vegetables provide almost all of the specialized vitamins and minerals needed to keep human beings in good health, in addition to their energy-giving carbohydrates.
Mix protein foods with vegetables
But nutrition and food science only confirmed what good cooks have always known instinctively, even when it comes to skilful combinations of ingredients.
Indeed, to get the best from your vegetables, you don't need to turn your kitchen into a laboratory, nor to become an expert in plant nutrients. Just know that variety and combinations of vegetables with even small quantities of meat, eggs, milk or cheese is the best way of giving your body the full range of amino acids, protein, carbohydrates, vitamins and minerals it needs.
A mixture of different proteins is more effective than any of them separately and no single vegetable contains all amino acids you need, but most vegetable proteins do include at least some of the essential acids, and if you eat several different vegetables together, certain combinations - green beans and sweet corn for example, - can give your body the complete proteins it needs.