When cooking, the method that we use can enhance or leach the nutrients in foods. For the cooking of vegetables, light steaming is advised, as this helps make some nutrients more available to the body and the food easier to digest. For example, carrots are easier to digest cooked and their beta carotene easier to absorb.
Steaming helps retain the nutrients in the foods with less leaching into the water than when they are boiled. One solution if you prefer to boil is to either use the cooking water for making sauces, or drink it alongside your meal. Your choice of cookware can make a difference too - copper and iron pots can add much needed additional minerals to a meal. But with long term and frequent use, these metal pots could potentially lead to excess consumption of the minerals and cause an imbalance in the ratio of nutrients in the body. For long term use, stainless steel pots are the metal of choice.