Eating a wide variety of colorful veggies is key to supporting your health goals. Not only does the high fiber content keep you full longer, but veggies also provide important vitamins, minerals and antioxidants. However, you may not be reaping as many of their nutrients as you thought. Depending on the vegetable and its preparation, various nutrients may be lost or enhanced through the cooking process.
There are three different categories of micronutrients affected differently by cooking:
- Water-soluble vitamins,
- Fat-soluble vitamins and
The water-soluble vitamins most affected by cooking are B vitamins and vitamin C. Thus, if you’re looking to obtain 100% of the water-soluble vitamins in red peppers, winter squash and leafy greens, your best bet is to eat them raw.
However, water-soluble vitamins can be preserved, depending on how the food is prepared. Microwaving and roasting generally retain more nutrients due to short cooking times and minimal water use. On the other hand, boiling vegetables results in the greatest nutrient loss, due to a large amount of water used and an extended cook time.
Fat-soluble vitamins, like vitamins A, D, E and K, have a different chemical composition that help these vitamins stay intact when cooked, even when using rigorous methods like boiling. Cooking these vegetables (i.e. cauliflower, cabbage and Brussels sprouts) in small amounts of oil or other healthy fats increases the absorption of fat-soluble vitamins by breaking down the cell wall of the vegetable and adding lipids for the vitamins to be metabolized with.
Lastly, the mineral content of a food can be decreased through cooking. Potassium is the most vulnerable mineral, but magnesium, sodium and calcium content may decrease through cooking as well.
Broccoli is an excellent source of vitamin C and folate, which are both water-soluble vitamins. Studies have shown microwaving broccoli retains 70–80% of its vitamin C, and steaming preserves 85–91% of vitamin C. Though the research did not give specific data regarding broccoli’s other water-soluble vitamins and minerals, like folate and potassium, similar effects can be assumed.
Additionally, broccoli is high in vitamin K, a fat-soluble vitamin enhanced by cooking with fat. However, because of the other micronutrients present, your best bet to maximize broccoli’s nutrient content is still to eat it raw, microwaved or steamed. To add flavor, try adding olive oil and seasoning after the broccoli is cooked.
Carrots are uniquely rich in fat-soluble vitamins A and K. Vitamin A promotes healthy vision, immune function and growth; vitamin K helps with blood clotting and healthy bone development.
Eating carrots raw won’t necessarily decrease the nutrient content, but since they contain fat-soluble nutrients, sauteing or stir-frying them can increase the absorption of vitamins A and K by 6.5 times compared to raw.
Take advantage of this by adding sauteed carrots to your favorite stir-fry or pasta recipe.
Spinach, a common superfood, is packed with water-soluble B-vitamins, vitamin C and fat-soluble carotenoids, which are converted to vitamins A and K. Due to the mix of water- and fat-soluble vitamins, all cooking methods compromise some nutrients. For example, microwaving results in the greatest loss of vitamin K.
That said, spinach’s diverse nutrient composition means several nutrients are still present, regardless of how you cook it. Or, if you enjoy raw spinach, that is an excellent option, too.
Like many other vegetables mentioned, tomatoes are also rich in vitamins C and K, potassium and B vitamins, but tomatoes have a distinctive nutrient called lycopene. Lycopene is a fat-soluble antioxidant that improves heart health and can defend against sun damage and certain types of cancer.
Lycopene is metabolized significantly better when cooked with oil than when consumed raw or without oil. In fact, blood lycopene increased 80% when eaten alongside olive oil compared to without.
So whether you eat your tomatoes raw or cooked, don’t shy away from your favorite oil-based dressing.
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