Raw vs. Cooked
You may have heard that cooking destroys nutrients and raw foods are best. That is not exactly true. Cooking does destroy some nutrients, but it allows others to be absorbed more easily. In other words, depending on the vegetable, some cooking methods decrease the antioxidant levels while others increase them. During any cooking method, fat-soluble vitamins (A, D, E, and K) tend to hold up better than water-soluble vitamins (C and some B vitamins), whereas minerals are virtually unaffected.
It is worth noting that cooking also reduces the water content of a food, decreasing its overall volume. So, while cooked vegetables might contain slightly less nutrients per gram of food, the number of total grams in your meal will probably be higher because you will consume more of the cooked vegetables.
Finally, cooking destroys some anti-nutrients in foods that might prevent the absorption of vitamins and minerals and it also makes fiber rich foods easier to digest.
You can see that there is value to both cooked and raw vegetables. And it is best to include bother in your diet every day.
Below your will find the pros and cons of cooking using various methods.
In general, boiling results in the greatest loss of nutrients, but it is also the most destructive for anti-nutrients. In addition, boiling reduces the mineral content because they are lost to the water. It is best to save this method for soups and stews, or other recipes where the water used to boil the vegetables can also be used.
Stir-Frying or Sautéing
Because stir-frying or sautéing takes the shortest amount of time, it is one of the better methods for retaining nutrients. Frying also provides an excellent opportunity to get some healthy fat in with your vegetables, making the fat-soluble vitamins more absorbable. The key here is to use healthy oil such as sunflower or olive oil to fry your vegetables.
This method appears to be gentle on the nutrient content of vegetables, but some vitamins will be destroyed due to the high temperatures and extended cooking periods.
Due to the low cooking temperatures, slow-cooking is quite gentle on the nutrient level of the vegetables, but again, most recipes require water and nutrients and minerals are lost if you don’t also consume the water the foods are cooked in. On the other hand, the long cooking period draws more nutrients out of the food, so it is best to add vegetables toward the end of the cooking period and allowing them just enough time to cook rather than adding them in with the other ingredients such as a roast or chicken.
Steaming is a very gentle cooking method, and because there is virtually no water loss, this method maximizes nutrient content. It is important to note that because steaming doesn’t use any fat, the fat-soluble vitamins won’t be as easily absorbed, so sure and toss your steamed vegetables with olive or coconut oil.
With shorter cooking times and less water than many other methods, microwaving maximizes nutrient content. In fact, studies show that microwaving was one of the best methods for consistently preserving antioxidant levels across all the vegetables tested.