How Cooking Affects Nutrients

Don’t pour all the vitamins down the drain. Find out how to keep more nutrients in your food.

Monica Reinagel, M.S.,L.D./N
3-minute read
Episode #22

"Hi Monica! I’m a nutrition student at Montana State University and I was wondering if you could tell me about how cooking affects the nutritional value of foods. I love cooking and I also want to get the most out of my foods."

Thanks for your question! Cooking or reheating foods can diminish their nutritional value because some vitamins are degraded by heat. One quick and dirty tip for retaining maximum nutrition in your food is to minimize cooking time.

Heat isn’t the only problem, though. When you cook foods in water or other fluids, some of the nutrients end up leaching out of the food and into the cooking liquid. So, another quick and dirty tip is to incorporate cooking liquids into the finished dish whenever possible.

A Few Details

Now, some nutrients are more affected by cooking than others. Calcium is pretty sturdy, for example, while vitamin C, folate, and potassium are quite fragile. Different cooking methods also affect various nutrients differently.

As a general rule, minerals can take the heat. In fact, dry heat, such as baking or roasting hardly affects mineral content at all. Vitamins, on the other hand, seem to do slightly better with moist cooking methods, such as boiling—mostly because the cooking times are shorter.

A large raw potato, for example, contains a decent amount of both calcium and vitamin C. If you bake the potato, the calcium content remains the same but you lose about 60% of the vitamin C. If you boil the potato instead of baking it, you’ll lose about half the vitamin C but, in addition, you’ll also lose about three-quarters of the calcium.

When you cook foods in water or other liquids, both vitamins and minerals leach out into the cooking liquid and end up going down the drain. If you can figure out a way to include the cooking liquid in the meal, you’ll salvage a lot of that nutrition. For example, when you make vegetable soup, a lot of the nutrients from your vegetables may up in the broth. But that’s okay, because you’re going to eat the broth too.

You can also use vitamin-rich cooking liquids to make rice or couscous, thereby recapturing a lot of those vitamins. Another good option is to steam vegetables in a rack placed above boiling water. That way, the vegetables don’t actually come into contact with the water so more of the vitamins stay in the veggies. Some still end up in the water, however, so you can use that water to cook with as well.

Guidelines for Preserving Nutrient Content

So, if you’re trying to get the most nutrition out of your foods, how you prepare them can make a big difference. Here, in order from worst to best, are your options: