News flash: There are plenty of ways to cook up juicy and flavorful food without adding tons of unnecessary extras. While most people know to ditch the fryer when cooking up healthy meals, many don’t think about how their cooking method affects the nutritional makeup of their entrée.
Heat can break down and destroy 15 to 20 percent of some vitamins in vegetables—especially vitamin C, folate, and potassium. And as you'll see below, some methods are more detrimental than others. This is why raw foodists cut out cooking altogether, claiming that uncooked food maintains all of its nutritional value and supports optimal health.
But other studies suggest certain foods actually benefit from cooking. When cooking carrots, spinach, and tomatoes, for example, heat facilitates the release of antioxidants by breaking down cell walls, providing an easier passage of the good guys from food to body. Let's dive into the details.
Some research suggests that nuking may be the healthiest way to cook because of its short cooking times, which results in minimal nutrient destruction. Microwaves cook food by heating it from the inside out. They emit radio waves that “excite” the molecules in food (read: make them move all round), which generates heat, cooking the food.
While microwave cooking can sometimes cause food to dry out, keep things moist by splashing the item with a bit of water before heating, or by placing a wet paper towel over the top of your dish. Regardless, the way that microwaves cook food nixes the need to add extra oils (bonus points). The best part? You can microwave just about anything, from veggies and rice to meat and eggs (and studies suggest it may just be one of the best ways to preserve nutrients in veggies). Just make sure to use a microwave-safe container.
Boiling is quick, easy, and requires nothing but water and a touch of salt. (Oh, and whatever food you’re cooking.) But in addition to the high temperatures, the large volume of water dissolves and washes away water-soluble vitamins and 60 to 70 percent of foods' minerals.
While this method can dissolve vitamins and minerals in some foods (especially vegetables), it's not the worst way to cook food. “Some antioxidants are more available when cooked. Lycopene in tomatoes, for example, is more readily available when cooked,” says Abbie Gellman, MS, RD, CDN. Carrots also fall into this category, and one study concluded that the level of beta-carotene increases after carrots are cooked.
Steaming anything from fresh veggies to fish fillets allows them to cook in their own juices and retain all that natural goodness. (Again, no need for fat-laden additions to up the moisture.) It’s always good to add a little seasoning first, whether that’s a sprinkle of salt or a squeeze of lemon juice. If the carcinogen-fighting glucosinolates in broccoli are important to you, some research suggests steaming could be the best way to cook the little green trees. In the body, glucosinolates become compounds called isothiocyanates, which some studies suggest inhibit the growth of cancer cells.
The only downside? Steaming doesn't always taste so great. “So many people get steaming wrong, leading them to dislike veggies even more, so I don’t typically recommend it,” says Sara Haas RDN, LDN. She admits that you don’t get a ton of flavor from steaming and that can lead to reaching for excess butter or salt.
The same goes for boiling’s cousin, poaching—no additions required. Basically, poaching means cooking the given food in a small amount of hot water just below boiling point. It takes slightly longer (which some experts believe can decrease nutrient retention), but is a great way to gently cook delicate foods like fish, eggs, or fruit. Plus, it’s just about the most delicious way to cook an egg in our book.
Broiling entails cooking food under high, direct heat for a short period of time. Broiling is a great way to cook tender cuts of meat, but may not be ideal for cooking veggies, as they can dry out easily. The hotter temperature also tends to degrade the enzymes in the produce, causing more nutrient losses.
In terms of getting maximum nutrition without sacrificing flavor, grilling is a great cooking method. It requires minimal added fats and imparts a smoky flavor while keeping meats and veggies juicy and tender. While these are definitely healthy benefits, not everything about grilling is so peachy. Some research suggests that regularly consuming charred, well-done meat may increase the risk of pancreatic cancer and breast cancer.
Cooking at high heat can also produce a chemical reaction between the fat and protein in meat, creating toxins that are linked to the imbalance of antioxidants in the body and inflammation, which can lead to an increased risk of diabetes and cardiovascular disease. This doesn’t mean BBQs are forbidden—just stick with lean cuts of meat that require less cooking time and keep dark meats on the rarer side.
While this method does require some oil in the pan, it should only be a moderate amount—just enough to get a nice sear on your meat and veggies. It’s effective for bite-size pieces of meat, grains like rice and quinoa, and thin-cut veggies like bell peppers, julienned carrots, and snow peas.
Some studies actually found that cooking veggies in a little bit of olive oil may increase the antioxidant capacity of the food. This may come as no surprise, as olive oil is a large part of the heart-healthy Mediterranean diet.
No Cooking (Raw)
Raw food diets have gained tons of attention, and for good reason. Many studies suggest there are benefits to incorporating more raw foods into the diet: Eating the rainbow consistently reduces the risk of cancer, but the jury’s out on whether raw or cooked is really best overall.
Plus, since the diet is mostly plant-based, more vitamins, minerals, and fiber are consumed with no added sugars or fats from cooking. And while some raw items might be super healthy, studies have found that cooking can actually amplify some nutrients, like lycopene in tomatoes and antioxidants in carotenoids such as carrots, spinach, sweet potatoes, and peppers.
We say: Do your best to eat your fruits, veggies, and lean proteins, but don't always cook them the same way (besides, then your taste buds will get bored and nobody wants that).