Which method of cooking vegetables preserves the most antioxidants?
The Best Way to Cook Vegetables
5/5 - (3 votes)
Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
You may remember when I compared the effects of different cooking methods on certain phytonutrients in bell peppers, mushrooms, and a few other veggies. Well, food scientists have outdone themselves in this study. They looked at six different cooking methods on 20 different vegetables, comparing three distinct measures of antioxidant activity. That’s more than 300 separate experiments to figure out the best way to cook our vegetables.
First, though, let’s figure out the worst in terms of loss of antioxidant content. Consider boiling, microwaving, pressure-cooking in water, griddling, like cooking in a frying pan without oil, frying in a frying pan, and baking at about 400 degrees Fahrenheit (200°C). What’s your guess for the worst? The worst is boiling when it comes to losing antioxidants. The second worst? Boiling under pressure. When we use wet cooking methods, some of the nutrition is lost into the cooking water; when it comes to preparing vegetables with their antioxidants in mind, water is not a cook’s best friend.
But how bad is bad? It may be less than you think. Averaging over those 20 vegetables, boiling only removes about 14 percent of the antioxidants. So, if you really like boiled broccoli, fine—just eat one more floret. Seven florets of boiled broccoli have all the antioxidant power of six florets of raw broccoli. So, the best way to eat your veggies is really whichever way will get you to eat the most of them—with the exception of frying, which not only adds empty calories but also toxic byproducts that are produced when oils are heated to frying temperatures.
What’s the gentlest cooking method? The one that preserves the most antioxidants? Microwaving, which preserves more than 97 percent of the antioxidants.
One vegetable has antioxidants that can really get clobbered, no matter how you cook it, losing up to 75 percent of its antioxidant capacity. What’s the one vegetable that’s really best eaten raw? Was it artichoke hearts, asparagus, beets, broad beans (also known as fava beans), broccoli, I hope we don’t have to eat raw Brussels sprouts, cauliflower, carrots, celery, eggplant, garlic, green beans, leeks, corn on the cob, onions, peas, bell peppers, spinach, Swiss chard, or zucchini? The most vulnerable vegetable is the bell pepper. So, I try to eat those raw or add them right at the end to whatever I’m cooking, like pasta sauce, so they just kind of get warmed up without really getting cooked.
On the other hand, three vegetables are hardly affected by cooking at all. You could even boil them and still retain nearly all their antioxidants. Can you guess at least one of the three? They’re artichokes, beets, and onions. Boil away. Asparagus gets an honorable mention here. It’s pretty much unaffected by any cooking method except for frying, so you can boil asparagus, too.
Final question, and perhaps it’s the most interesting. There are two vegetables that, no matter what you do to them, tend to increase in antioxidant value. They may become even healthier upon cooking. Which two are they? First, the runner-up: green beans. With the exception of boiling and pressure cooking, they actually increase in antioxidant power when cooked, so microwaved green beans have more antioxidants than raw.
And, tied for first? Which two vegetables nearly always increase in value, no matter how you cook them? Carrots and celery. So, when we make a nice vegetable soup, we can actually boost their nutrition.
One vegetable that wasn’t covered was one of my favorites—kale. As I discuss in my video How to Cook Greens, kale can be cooked by blanching or steaming to boost antioxidants. It can even be boiled and not lose antioxidant nutrition.
Please consider volunteering to help out on the site.
- Jiménez-Monreal AM, García-Diz L, Martínez-Tomé M, Mariscal M, Murcia MA. Influence of cooking methods on antioxidant activity of vegetables. J Food Sci. 2009;74(3):H97-H103.
- Grootveld M, Percival BC, Leenders J, Wilson PB. Potential adverse public health effects afforded by the ingestion of dietary lipid oxidation product toxins: significance of fried food sources. Nutrients. 2020;12(4):974.
- Armesto J, Gómez-Limia L, Carballo J, Martínez S. Effects of different cooking methods on the antioxidant capacity and flavonoid, organic acid and mineral contents of Galega Kale (Brassica oleracea var. acephala cv. Galega). Int J Food Sci Nutr. 2019;70(2):136-149.
Motion graphics by Avo Media
Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
You may remember when I compared the effects of different cooking methods on certain phytonutrients in bell peppers, mushrooms, and a few other veggies. Well, food scientists have outdone themselves in this study. They looked at six different cooking methods on 20 different vegetables, comparing three distinct measures of antioxidant activity. That’s more than 300 separate experiments to figure out the best way to cook our vegetables.
First, though, let’s figure out the worst in terms of loss of antioxidant content. Consider boiling, microwaving, pressure-cooking in water, griddling, like cooking in a frying pan without oil, frying in a frying pan, and baking at about 400 degrees Fahrenheit (200°C). What’s your guess for the worst? The worst is boiling when it comes to losing antioxidants. The second worst? Boiling under pressure. When we use wet cooking methods, some of the nutrition is lost into the cooking water; when it comes to preparing vegetables with their antioxidants in mind, water is not a cook’s best friend.
But how bad is bad? It may be less than you think. Averaging over those 20 vegetables, boiling only removes about 14 percent of the antioxidants. So, if you really like boiled broccoli, fine—just eat one more floret. Seven florets of boiled broccoli have all the antioxidant power of six florets of raw broccoli. So, the best way to eat your veggies is really whichever way will get you to eat the most of them—with the exception of frying, which not only adds empty calories but also toxic byproducts that are produced when oils are heated to frying temperatures.
What’s the gentlest cooking method? The one that preserves the most antioxidants? Microwaving, which preserves more than 97 percent of the antioxidants.
One vegetable has antioxidants that can really get clobbered, no matter how you cook it, losing up to 75 percent of its antioxidant capacity. What’s the one vegetable that’s really best eaten raw? Was it artichoke hearts, asparagus, beets, broad beans (also known as fava beans), broccoli, I hope we don’t have to eat raw Brussels sprouts, cauliflower, carrots, celery, eggplant, garlic, green beans, leeks, corn on the cob, onions, peas, bell peppers, spinach, Swiss chard, or zucchini? The most vulnerable vegetable is the bell pepper. So, I try to eat those raw or add them right at the end to whatever I’m cooking, like pasta sauce, so they just kind of get warmed up without really getting cooked.
On the other hand, three vegetables are hardly affected by cooking at all. You could even boil them and still retain nearly all their antioxidants. Can you guess at least one of the three? They’re artichokes, beets, and onions. Boil away. Asparagus gets an honorable mention here. It’s pretty much unaffected by any cooking method except for frying, so you can boil asparagus, too.
Final question, and perhaps it’s the most interesting. There are two vegetables that, no matter what you do to them, tend to increase in antioxidant value. They may become even healthier upon cooking. Which two are they? First, the runner-up: green beans. With the exception of boiling and pressure cooking, they actually increase in antioxidant power when cooked, so microwaved green beans have more antioxidants than raw.
And, tied for first? Which two vegetables nearly always increase in value, no matter how you cook them? Carrots and celery. So, when we make a nice vegetable soup, we can actually boost their nutrition.
One vegetable that wasn’t covered was one of my favorites—kale. As I discuss in my video How to Cook Greens, kale can be cooked by blanching or steaming to boost antioxidants. It can even be boiled and not lose antioxidant nutrition.
Please consider volunteering to help out on the site.
- Jiménez-Monreal AM, García-Diz L, Martínez-Tomé M, Mariscal M, Murcia MA. Influence of cooking methods on antioxidant activity of vegetables. J Food Sci. 2009;74(3):H97-H103.
- Grootveld M, Percival BC, Leenders J, Wilson PB. Potential adverse public health effects afforded by the ingestion of dietary lipid oxidation product toxins: significance of fried food sources. Nutrients. 2020;12(4):974.
- Armesto J, Gómez-Limia L, Carballo J, Martínez S. Effects of different cooking methods on the antioxidant capacity and flavonoid, organic acid and mineral contents of Galega Kale (Brassica oleracea var. acephala cv. Galega). Int J Food Sci Nutr. 2019;70(2):136-149.
Motion graphics by Avo Media
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The Best Way to Cook Vegetables
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