Raw vegetables not always healthier than cooked
Which is better for you: raw or cooked vegetables? The answer, according to Tammy Roberts, a nutrition and health education specialist with University of Missouri Extension, may surprise some people.
"We've always heard that raw vegetables are healthier than cooked because cooking destroys nutrients. In many cases that is true, but in some cases it is not," said Roberts.
For example, lycopene content in tomatoes is actually increased when tomatoes are cooked. Lycopene is a phytochemical that is responsible for the red color of the tomato. Studies have linked high lycopene (an antioxidant) intake with lower risk of cancer and heart attacks.
"Antioxidants help to prevent or repair damage to body cells which is important for decreasing risk of cancer. They are also thought to improve immune function," said Roberts.
Cooking carrots actually increases the beta carotene content. Beta carotene is an antioxidant that the body converts to vitamin A (also an antioxidant) and helps to promote normal vision, protect from infection and helps regulate the immune system.
There may also be additional antioxidant activity in cooked spinach, mushrooms, asparagus, cabbage and peppers.
"The cooking method found to be the best for preserving antioxidants was boiling or steaming. Frying is not recommended because the antioxidants get used up in the frying process," said Roberts.
In other instances raw vegetables are better. For example, polyphenols (which are also antioxidants) are lost when carrots are cooked. In broccoli, heat damages the enzyme myrosinase which breaks down compounds in the broccoli to form sulforaphane which is thought to kill precancerous cells.
Vitamin C, also a powerful antioxidant, is found in many of the vegetables mentioned and it can be destroyed by heat.
So should we be eating our vegetables raw or cooked?
"Most likely you already have been eating your vegetables sometimes raw and sometimes cooked, which is what is recommended," said Roberts. "This way you get the best of both worlds. When they are cooked you are getting higher levels of some nutrients and when they are raw you get higher levels of other nutrients."