I was talking with a colleague during lunch yesterday. We were discussing the nutritional value of certain vegetables and how they are prepared. We reached an agreement that while some vegetables taste better when they are cooked, it is best to consume all vegetables raw. I realized that this would be a great topic to discuss on the blog. After some research, I even learned a thing or two myself.
I want to begin by stating that there is no perfect way to prepare all vegetables. Each time you heat food, you run the risk of losing vitamins (as this process breaks down some of the chemical bonds). On the flip side, food preparation can also release vitamins that would otherwise be difficult to absorb or simply remain in the skin (for similar reasons).
A basic understanding of vitamins is necessary to realize what, if any, method of preparation should be enacted. Water soluble vitamins (B and C) are absorbed in water. For this reason, vegetables high in these vitamins, like green lettuce and arugula, are best eaten raw. If you boil these vegetables, the vitamins will be extracted and remain in the water. Fat soluble vitamins (A, D, E, and K) are absorbed best in the presence of lipids. For this reason, it is a good idea to eat peppers and onions with some olive oil as part of a salad or when sautéing vegetables to promote vitamin absorption.
There wouldn’t be such a big commotion about vegetables if they didn’t offer so many benefits. Aside from the primary vitamins listed above, vegetables may help to prevent cancer, heart disease and general inflammation. As I mentioned above some are best consumed raw, while others taste better and are more effective when prepared. Two primary examples are kale and spinach. Research has shown that slightly cooking kale promotes the absorption of carotenoids (a primary antioxidant) and cooked spinach releases stores of iron, calcium, and magnesium. Tomatoes contain very high amounts of the antioxidant lycopene. This powerful force against cancer becomes active when heated.
On the contrary, broccoli is more nutritious when eaten raw. This vegetable is often cooked in order to ease mastication and digestion; however, that is might not be the best decision. The liver cleansing enzyme myrosinase, which is potent in broccoli, is destroyed by heat. Another vegetable best consumed raw is garlic. Allicin, the primary compound which provides garlic with its antibiotic, antiviral, and anti-inflammatory effects is also heat sensitive. Be sure to add some raw garlic to your diet.
At the end of the day, life is about balance. As a general recommendation, it is always good to eat a variety of fruits and vegetables of different colors, shapes, and sizes. Just remember that the vitamins and minerals you get from the foods you consume are better than those you would not consume. So even if you lose out on a percentage of the Vitamin B when cooking mushrooms, you retain their minerals and dietary fiber. Be sure to make a note to eat raw mushrooms next time around.
Now that you understand that potential benefits and drawbacks of cooking foods, be sure to employ them in your diet. As a helpful tool, here is a brief list to provide cooking instructions for most common vegetables:
Best consumed Raw: Green Lettuce, Arugula, Garlic, Broccoli, Cucumber
Best steamed: Kale, Green Beans, Brussel Sprouts, Onions
Best baked: Squash, Sweet Potatoes, Beets
Best cooked: Spinach, Tomatoes, Carrots, Asparagus, Cabbage, Peppers