Cooked vegetables, including asparagus, mushrooms and spinach, often provide more nutrients than when raw, as cooking releases essential vitamins and antioxidants for enhanced health benefits.
Raw food diets are a relatively new trend, including raw food. The belief is that the less processed the food, the better. However, not every food is more nutritious when eaten raw. Indeed, some vegetables are actually more nutritious when cooked. Here are nine of them.
All living things are made of cells, and in vegetables, important nutrients are sometimes trapped in these cell walls. When vegetables are cooked, the walls break down, releasing the nutrients, which can then be more easily absorbed by the body. Cooking asparagus breaks down its cell walls, making vitamins A, B9, C and E more available for absorption.
Mushrooms contain large amounts of the antioxidant ergothioneine, which is released when cooked. Antioxidants help break down “free radicals,” chemicals that can damage our cells, causing disease and aging.
Spinach is rich in nutrients including iron, magnesium, calcium and zinc. However, these nutrients are more easily absorbed when spinach is cooked. This is because spinach is full of oxalic acid
Cooking, using either method, greatly increases the antioxidant lycopene in tomatoes. Lycopene is associated with a lower risk of a number of chronic diseases, including heart disease and cancer. This increased amount of lycopene comes from the heat, which helps break down the thick cell walls that contain several important nutrients.
Although cooking tomatoes reduced their vitamin C content by 29%, their lycopene content increased by more than 50% within 30 minutes of cooking.
Cooked carrots contain more beta-carotene than raw carrots, which is a substance called a carotenoid that the body converts to vitamin A. This fat-soluble vitamin supports bone growth, vision and the immune system.
Cooking carrots with their peels doubles their antioxidant power. You should boil carrots whole before slicing them, as this prevents these nutrients from leaching into the cooking water. Avoid frying carrots as this has been found to reduce the amount of carotenoid.
Peppers are a great source of immune-boosting antioxidants, especially the carotenoids beta-carotene, beta-cryptoxanthin, and lutein. The heat breaks down the cell walls, making the carotenoids easier for your body to absorb. As with tomatoes, vitamin C is lost when peppers are boiled or steamed, as the vitamin can leach into the water. Try baking them instead.
Brassicas, which include broccoli, cauliflower and Brussels sprouts, are high in glucosinolates (sulphur-containing phytochemicals), which the body can convert into a number of cancer-fighting compounds. In order for these glucosinolates to be converted into cancer-fighting compounds, an enzyme in these vegetables called myrosinase must be active.
Research has found that steaming these vegetables preserves both vitamin C and myrosinase, and therefore the cancer-fighting compounds you can get from them. Cutting broccoli and letting it sit for a minimum of 40 minutes before cooking also allows this myrosinase to activate.
Likewise, sprouts, when cooked, produce indole, a compound that may reduce the risk of cancer. Cooking sprouts also causes glucosinolates to break down into compounds known to have anti-cancer properties.
8. Green beans
Green beans have higher levels of antioxidants when baked, microwaved, grilled, or even fried, as opposed to boiled or pressure-cooked.
Kale is healthiest when lightly steamed, as it deactivates enzymes that prevent the body from using the iodine it needs for the thyroid gland, which helps regulate your metabolism.
For all vegetables, higher temperatures, longer cooking times, and larger amounts of water result in more nutrient loss. Water-soluble vitamins (C and many of the B vitamins) are the most unstable nutrients when it comes to cooking because they are leached from the vegetables into the cooking water. So avoid soaking them in water, use minimal amount of water when cooking and use other cooking methods like steaming or baking. Also, if you have leftover cooking water, use it in soups or sauces as it contains all the leached nutrients.
Written by Laura Brown, Senior Lecturer in Nutrition, Food and Health Sciences, Teesside University.
Adapted from an article originally published on The Conversation.