Raw vs. Cooked: How to Get the Most Out of Your Vegetables
Heat, oil, and cook time can all impact a vegetable's nutritional value. Here, a registered dietician shares how to maximize the amount of vitamins and minerals you get out from your veggies.
For many Canadians, making sure to get enough vitamins is part of a regular routine. More than half of us take supplements on a weekly basis, some of us partake in non-beneficial juice cleanses, and a few of us even get unnecessary vitamin injections. But it turns out, the key to maximizing our nutrition may not be in a bottle (or needle) but in the kitchen.
Vegetables are packed with vitamins, minerals, antioxidants and fibre and the amount of nutrition we retain from our veggies is influenced by the way the food is prepared. “We tend to absorb some nutrients better from raw vegetables, and some we get more through cooked vegetables,” says Lyndsay Hall, registered dietitian at JM Nutrition in Toronto. “We get more soluble vitamins, minerals and antioxidants in vegetables cooked certain ways because their fibre or cell walls get broken down, so their nutrients become more accessible.”
We asked Hall for her tips on what vegetables to eat raw vs. cooked in order to get the most nutritious bang for our veggie buck.
Raw vs. cooked vegetables offer different health benefits
While cooked vegetables can grant us access to more nutrients, raw vegetables offer more fibre, which Hall explains helps maintain healthy digestion, lower cholesterol and control blood sugar levels. What’s more, some vegetables offer different vitamins depending on if they’re raw or cooked. Hall uses spinach as an example: In its raw form, this leafy green offers vitamin C, and in its cooked form, it offers more vitamin A. “So be mindful of including a combination of vegetables in their cooked and raw form in your diet,” says Hall.
The benefits of steaming vegetables
Some studies show that cooking methods impact a vegetable’s nutritional value. For example, Zhejiang University researchers compared five home-cooking methods for broccoli. They found that stir-frying, microwaving, and boiling broccoli all deplete levels of chlorophyll, soluble protein, sugars and vitamin C. Steaming broccoli did not have that same effect. Hall says this is because certain cooking methods cause water-soluble nutrients (like vitamin C, B, and D) to seep out, meaning their nutrient levels decrease. “Steaming has been shown to be a really good cooking method overall,” says Hall. “Roasting and grilling are also suitable ways of cooking vegetables and retaining a decent amount of nutrients.”
Try to cook fast
Researchers suggest that the reason stir-frying vegetables deplete their nutrients could be due to the length of cook time. Hall says the key to cooking vegetables is to do so quickly so the nutrients and vitamins have less time to escape. She recommends roasting, barbecuing, or grilling vegetables, as these methods allow for the fastest cook time. Steaming and pan-frying can be healthy options too. “In those cases, you’re covering the vegetables with a lid, which helps to retain nutrients and vitamins,” she says. Keep in mind that you should avoid cooking veggies at a high temperature as well, as high heat can “affect the nutrient composition of vegetables,” says Hall.
Raw vegetables aren’t for everybody
Hall warns some raw vegetables may be hard for some people to tolerate, particularly those with gastrointestinal issues. “Cruciferous vegetables, like cabbage, broccoli, cauliflower, and Brussel sprouts, are very nutritious raw and cooked. They are full of antioxidants and they’re a good source of vitamin C. But these vegetables are more likely to cause gas or bloating,” she says. Hall suggests eating cruciferous vegetables in soft, cooked form to eliminate the risk of stomach issues.
Pair vegetables with a healthy fat
Healthy fats can actually boost a vegetable’s nutritional value. “Olive oil and avocado have phenols in them, which is an antioxidant, so when you pair them with some vegetables [like leafy greens], they absorb those antioxidants, which increases the diversity of nutrients,” says Hall. It’s also important to be mindful of the amount of healthy fats used and consider the oil’s smoke point. When cooking with olive oil, for instance, Hall suggests warming about a tablespoon on medium heat, then adding the veggies and placing a lid on top of the pan to cook them quickly.
What about air frying vegetables?
Air-fried foods are perceived as a better, lower-fat alternative to deep-fried foods because less oil is used, but Hall says in terms of nutrition, the two methods are actually not that different. “Like deep-dried foods, air-fried ones can potentially increase the risk of certain cancers,” says Hall. “Air fryers work by using a pressurized type of heat, and the temperature diminishes nutrients.” That doesn’t mean you need to avoid an air fryer altogether, instead treat it as an occasional cooking method.
Don’t rely on veggie juice
Juicing vegetables causes the loss of nutrients and vitamins, so Hall encourages eating whole fruits and vegetables. “With juicing, we lose a lot of the fibre and nutrients that are present in the skins of these foods,” she says. A healthier option would be a smoothie made with whole vegetables. “Add some greens (i.e. spinach or kale) to smoothies or shakes, which can be a great way to provide some extra micronutrients and fibre,” says Hall.
Make healthy vegetable soups—and drink the broth, too
Since soups are typically made by slowly cooking vegetables in broth on the stove, it’s right to assume the vitamins and nutrients will seep out. But Hall says that’s not a concern: “We’ll end up consuming the liquids the foods are in, so we’ll get them back!”
Buy frozen vegetables
Freezing vegetables at home will result in the loss of vitamins and nutrients, particularly because the process takes a long time, says Hall. “Commercially frozen products, on the other hand, are flash-frozen, which means they end up retaining a lot of their nutrients,” she says. “For that reason, I encourage people using frozen vegetables as their staple.”
Cook vegetables in the tastiest way
Some vegetables, particularly root vegetables like carrots and potatoes, taste better when they’re roasted—and we’re more likely to eat them when they’ve gotten a bit caramelized, says Hall. For that reason, Hall says the best way to cook vegetables is the way that entices you to eat them, so you can ensure you get the recommended servings of fruits and vegetables every day.