Does Cooking Change the Nutrition in Our Food?
Written by Dietetic Student Maryam
Understanding How Cooking Affects Nutrients
Did you know cooking a tomato can actually help your body access more of its beneficial compounds?
It might sound surprising if you’ve ever heard that raw fruits and vegetables are always healthier because cooking “destroys nutrients”. The answer is more complicated, and that’s the good news for busy families.
Cooking can change the nutrients in food, but not always in a negative way. Some nutrients may be reduced by water or heat, while cooking can make other nutrients easier for our bodies to access. What happens depends on the food, the nutrient, and how it's prepared. (Coe & Spiro, 2022).
What happens to nutrients when we cook? (1-2)
Think about a vegetable being boiled in a pot of water. Some vitamins, particularly vitamin C and certain B vitamins, dissolve in water. When vegetables are boiled, some of these vitamins can move from the vegetable into the cooking water. Longer cooking times can also lead to greater losses.
This doesn’t mean you need to avoid boiling vegetables. If you’re making a soup or stew, the cooking liquids become part of the meal, so those nutrients don’t simply disappear down the drain.
Other vitamins respond differently. Fat-soluble vitamins include vitamins A, D, E, and K. Because they dissolve in fat rather than in water, eating foods that contain certain fat-soluble vitamins or compounds alongside a source of fat can help our bodies absorb them (Lee et al., 2018).
For example, carrots contain beta-carotene, which is a vitamin A carotenoid, meaning our bodies can convert it into vitamin A. Beta-carotene is fat soluble, the way we prepare carrots can influence how much our bodies access.
The takeaway is that different cooking methods can have different effects.
Cooking can help your body access certain nutrients (3,4,7)
Let’s go back to the tomato.
Tomatoes contain lycopene, a natural compound that gives tomatoes their red colour. Lycopene is a fat-soluble carotenoid and functions as an antioxidant. When tomatoes are eaten with a source of fat such as olive oil, the fat can also help with the absorption of this fat-soluble compound. Research has found that consuming cooked tomatoes with olive oil can increase the amount of lycopene that becomes available in the body compared with cooked tomatoes without olive oil.
Carrots provide another example. Their beta-carotene is also fat-soluble, and cooking can help break down the plant’s structure, making the carotenoid easier for the body to access. Research comparing raw and stir-fried carrots found substantially greater availability of carrot-derived beta-carotene from the stir fried preparation.
Together, these examples show how both cooking and presence of fat can influence the availability of fat-soluble compounds.
But what about nutrients that dissolve in water?
Water soluble vitamins, such as vitamin C and some B vitamins, can be more vulnerable to losses during cooking, particularly when food is boiled for a long time. At the same time, cooking can have other benefits. Heating vegetables softens their structure and breaks down some of the plant’s tough components which make them softer and easier to chew and digest. Research on cruciferous vegetables such as broccoli, brussel sprouts, and cauliflower show that cooking changes their fibre structure and can shift some insoluble fibre, which adds bulk to stool, into soluble fibre, which helps support digestion.
So, cooking isn’t simply about “saving” or “losing” nutrients. It can change food in several ways at once.
The cooking method matters, but you don’t need to overthink it (1-2)
Imagine you have a bag of broccoli sitting in your fridge. You could steam it, cook it into a soup, or add it to a stir-fry. Each approach changes the broccoli in a slightly different way.
If you boil it, some water-soluble vitamins can move into the cooking water. But if the broccoli ends up in a soup, the cooking liquid stays in the meal.
If you steam it, the broccoli has much less direct contact with water. This can help retain some water-soluble nutrients while softening the vegetable.
If you roast it, you’re using dry heat. The broccoli develops a different colour, texture, and flavour, with crispy edges and a soft centre. Some heat-sensitive nutrients may decrease, but you also may end up with a preparation your family enjoys more.
If you stir-fry it, you are combining short cooking time with a small amount of oil. For vegetables containing fat-soluble carotenoids, that combination can help make some of these compounds more available to the body.
Even microwaving can be a useful option. It is quick and usually requires little water, which can help limit the amount of water-soluble nutrients that move out of the food. Research shows that nutrient retention varies depending on the food, cooking method, and nutrient, rather than one method consistently coming out on top.
Therefore, there is no single cooking method that preserves every nutrient best. It’s knowing that you have options when cooking and those options can help make nutritious foods more enjoyable for your family.
When your child won’t eat it: try changing how you cook it (5)
“I bought vegetables, prepared them, and my child still won't eat them.”
For parents, moments like this can make mealtimes feel frustrating and exhausting.
But before deciding that your child simply doesn’t like a particular food, consider whether they might respond differently to another version of it.
Cooking can change a food’s texture, smell, appearance, flavour, and crispness or softness. Texture, in particular, can influence children’s acceptance and rejection of foods (Chow et al., 2022).
If steamed broccoli is a no-go, try roasting it so the edges become crisp. If raw carrots are ignored, try roasting or steaming them. Chickpeas can be mashed into a spread, roasted until crunchy, or blended into a dip. Fish can be pan-cooked, baked, or incorporated into a familiar meal.
The goal is not to find the “correct” way to prepare a food. There are many ways to prepare the same ingredient.
A child rejecting one version of a food does not necessarily mean that the food has to disappear from the menu. Trying a different texture, preparation method, or flavour can provide another opportunity to experience it.
Remember there is no need to pressure a child to eat something simply because it’s nutritious. The goal is to make mealtimes more manageable while continuing to offer a variety of foods.
A few things to try at home (1,6)
Instead of worrying about finding the perfect cooking method:
Try different ways of preparing the same food.
Consider using cooking liquid in soups, sauces, or stews.
Include both raw and cooked foods.
Experiment with different flavours, shapes, and textures
Focus on overall dietary variety rather than maximizing one nutrient at every meal.
Canada’s Food Guide encourages eating a variety of fruits and vegetables and exploring different textures, shapes, and colours.
The bottom line
Cooking does change the nutrition in our food, but not in a bad way. Some nutrients may be lost during cooking, while others may become easier for our bodies to access. The effect depends on the food, nutrients, and how it is prepared.
Perhaps the most important thing for families is that you don’t need to cook perfectly to eat well. Sometimes, changing how you prepare a food can open the door to enjoying it in a whole new way.
Nutrition doesn’t have to be about getting every meal exactly right. It’s about flexibility, variety, and finding enjoyable ways to bring nutritious foods to the table.
References
Coe, S., & Spiro, A. (2022). Cooking at home to retain nutritional quality and minimise nutrient losses: A focus on vegetables, potatoes and pulses. Nutrition bulletin, 47(4), 538–562. https://doi.org/10.1111/nbu.12584
Lee, S., Choi, Y., Jeong, H. S., Lee, J., & Sung, J. (2017). Effect of different cooking methods on the content of vitamins and true retention in selected vegetables. Food science and biotechnology, 27(2), 333–342. https://doi.org/10.1007/s10068-017-0281-1
Fielding, J. M., Rowley, K. G., Cooper, P., & O' Dea, K. (2005). Increases in plasma lycopene concentration after consumption of tomatoes cooked with olive oil. Asia Pacific journal of clinical nutrition, 14(2), 131–136.
Ghavami, A., Coward, W. A., & Bluck, L. J. (2012). The effect of food preparation on the bioavailability of carotenoids from carrots using intrinsic labelling. The British journal of nutrition, 107(9), 1350–1366. https://doi.org/10.1017/S000711451100451X
Chow, C. Y., Skouw, S., Bech, A. C., Olsen, A., & Bredie, W. L. P. (2024). A review on children's oral texture perception and preferences in foods. Critical reviews in food science and nutrition, 64(12), 3861–3879. https://doi.org/10.1080/10408398.2022.2136619
Health Canada. Canada's Food Guide: Eat vegetables and fruits. Government of Canada. 2026
Nowak, K., Rohn, S., & Halagarda, M. (2025). Impact of Cooking Techniques on the Dietary Fiber Profile in Selected Cruciferous Vegetables. Molecules (Basel, Switzerland), 30(3), 590. https://doi.org/10.3390/molecules30030590