Steamers are used to cook foods with moist heat. Steamers can range from electrical models with a single basket to those with multiple tiers, to combination rice-cooker/steamers, to traditional Asian-style wicker basket steamers that can be used on a conventional gas or electric stove. By experimenting and learning how to use a steamer you may find that the health benefits override and cancel out the cons.
Pro: Nutrient Retention
Steamers rely on a small amount of water to cook foods. This allows foods cooked in a steamer to retain more of their vitamins and other nutrients. Steamers seal in the nutrients instead of allowing them to escape into a pot of boiling water or get stripped away by frying or grilling.
Con: Longer Rice-Cooking Time
Steamers can take longer to cook rice in comparison to conventional methods such as boiling rice to cook it. For example, while cooking brown rice in a steamer maintains the Vitamin B-1 content, it can take an hour or more to cook. The downside in rice cooking time (whether it is brown or white) is why many Asian cooks use a combination rice-cooker/steamer in a fashion similar to the way cooks in the United States use a slow cooker. If you have an electric steamer with a programmable timer you can put your rice on before you go to work, follow the settings specific to your model, and return home from work with a steamer full of rice that's cooked to perfection.
Pro: Vegetables Maintain Natural Flavor and Color
Steamed vegetables maintain more of their natural colour and flavour. Steaming is as close as you can get to a raw vegetable taste and flavour with cooking. By learning to appreciate the pure, unadulterated taste of steamed vegetables, diners may build a preference. The newfound love of a pure flavour may even motivate them to reduce their use and intake of salts, oils and other additives.
Con: Can't Use for Certain Meats and Vegetables
One "con" to steam cooking is that it is does not work for meats such as beef, pork and lamb as it does for fish and poultry. This is because the heat level of a steamer is not adequate to thoroughly cook beef, pork and lamb. Porous vegetables like mushrooms, eggplant and squash can also be a problem if you overcook them, because they contain lots of water and can become somewhat soggy in texture.
Pro: Multi-Tier "One Pot" Cooking
There are many steamer models for cooking an entire meal. They have one to three tiers of baskets or containers that stack on top of each other, so you can put your fish or poultry in one tier, broccoli in a second tier and pasta in a third tier. Then all you have to do is time and stage the food types appropriately so they don't overcook or undercook. This efficiency "pro" eliminates the need for multiple pots and pans, reduces your use of energy and shortens your cleanup and dishwashing time after meals.