Does Cooking Vegetables Increase Their Nutrient Value?

How Heat Releases Trapped Nutrients

Eating vegetables is an important part of a healthy diet. Health professionals know that veggies are a valuable source of phytochemicals. These chemical compounds provide antioxidant properties. Antioxidants are powerful substances that stabilize free radicals (cell-destroying atoms) in the body and help in disease prevention. So consuming vegetables is linked to decreased incidence of cancer, heart disease, and degenerative illness.

Cooking Can Enhance Nutrient Value

Roasted asparagus
Paperclip Images/Stocksy United

For most veggies, consuming them raw offers the most nutrients. But cooking actually increases nutrient value in some vegetables. According to a study published in the Journal of Agricultural and Food Chemistry, antioxidants are enhanced when some vegetables are cooked. Heating releases beneficial phytochemicals that are otherwise trapped in cell walls.

Tomatoes

Tomatoes

Verywell / Alexandra Shytsman

Tomatoes are scientifically labeled a fruit, but for cooking purposes, they are considered a vegetable. They’re nutrient-dense and a rich source of vitamin C and lycopene. Lycopene is the phytochemical that gives the tomato its red hue, along with significant antioxidant properties.

One study on the nutritional benefits of cooking tomatoes involved several cooking trials. Researchers heated raw tomatoes to 88 degrees Celsius for two, 15, and 30 minutes. Vitamin C and lycopene values were measured at each interval. Results indicated a significant drop in vitamin C but in contrast, a substantial increase in lycopene.

Steaming or boiling tomatoes brings out the most lycopene; canned tomatoes and jarred marinara sauces are very accessible sources of lycopene. Research indicates lycopene may reduce the risk of cancer, improve heart health, and enhance neurological response.

Broccoli

Broccoli

Verywell / Alexandra Shytsman 

Broccoli is a cruciferous vegetable with superior antioxidant properties. Research has indicated broccoli contains phytochemicals, carotenoids, polyphenols, and glucosinolates. It’s also a rich source of lutein and tocopherol. These chemical compounds may decrease the risk of cancer by reducing inflammation in the body.

Research on how cooking broccoli affects nutrient value determined that various heating methods reduced the nutrient levels of five glucosinolate antioxidant compounds. At the same time, significant increases in lutein, carotene, and tocopherols were reported. In fact, longer heating time extracted even more of these beneficial compounds.

Other research shows that cooking broccoli promotes the release of carotenoids. Carotenoids are bioactive compounds shown to have numerous health benefits when consumed. Cooking increase these levels, enhancing the nutrient value in broccoli.

Steaming and boiling broccoli enhances carotenoids like lutein and phytoene. Studies show phytoene may reduce the risk of prostate cancer, improve heart health, and reduce inflammation.

Carrots

Carrots

Verywell / Alexandra Shytsman

Carrots are a popular root vegetable. They are a rich source of beta-carotene and numerous vitamins and minerals, and they also contain fiber. Carrots provide antioxidant health benefits attributed mostly to high concentrations of vitamin A and beta-carotene.

Research published in the Journal of Agricultural and Food Chemistry examined different cooking methods on the nutrient value of carrots. Antioxidant samples were measured after boiling, steaming, and frying. Carotenoids, polyphenols, glucosinolates, and ascorbic acid (vitamin C) were analyzed after cooking the carrots.

Research results indicated boiling carrots increased all carotenoids (antioxidants) by 14%. The other cooking methods caused a decrease in antioxidant value with frying reflecting the worst decline. Total antioxidant capacities (TAC) were compared during the cooking trial. Results were similar to prior research showing a significant increase of carrot TAC when heated to 130 degrees Celsius for 20 minutes.

Boiling carrots retained the most vitamin C and carotenoids.

Pumpkin

overhead shot of pumpkins in a box
Kristin Lee / Getty Images

Pumpkins belong to the Cucurbita family and you may be surprised to discover they’re a fruit. Because they are more savory than sweet, pumpkins are labeled vegetables for culinary purposes. Pumpkins are also related to winter squash, cucumbers, and cantaloupes.

Pumpkins are an excellent source of antioxidants and fiber. Cooking releases compounds like lycopene and carotenoids, making them easier to absorb. Pumpkins also contain numerous vitamins and minerals and are considered a heart-healthy food.

The health benefits of consuming cooked pumpkin may include reducing the risk of certain cancers, managing diabetes, reducing hypertension, and improved eye health. Cooked pumpkin seeds are also a healthy snack alternative and a rich source of nutrients.

Asparagus

Asparagus

Verywell / Alexandra Shytsman

Asparagus contains numerous vitamins, minerals, and powerful antioxidants. It does have a tough outer lining. Cooking helps break down the thick cell walls for better absorption of essential nutrients. 

Asparagus is considered a heart-healthy food, because it is high in folate. Folate also helps maintain our blood cells, especially bone marrow, and promotes healthy growth and development. Asparagus is also a rich source of vitamin A, vitamin E, vitamin K, magnesium, niacin, and other important nutrients. 

The antioxidants in cooked asparagus may protect cells, tissue, and organs by reducing oxidative damage. Asparagus is also high in fiber, which can help with digestion and weight management.

Mushrooms

Shiitake Mushrooms

Verywell / Alexandra Shytsman

Mushrooms are classified as vegetables but they’re actually fungi. Fungi are a large class of organisms including yeasts, molds, and mushrooms. That may not sound very appetizing or even nutritious, but there are edible classes of mushrooms. The most common edible mushrooms include the white button, crimini, and portabella varieties. 

Research indicates nutrients are comparable between cooked and raw mushrooms, but fiber is increased when they’re cooked. The cooking process shrinks down the mushrooms, allowing for consumption of more per serving, which increases fiber intake. Proper fiber intake may help weight loss and weight management.

Mushrooms are a rich source of quality plant protein, vitamins, minerals, and antioxidants. According to research published in the Journal of Nutrition, mushrooms may help reduce the risk of chronic diseases, including cancer.  

A Word From Verywell

Vegetables are an essential part of our daily nutrition. Cooking may enhance the nutrient value of some veggies allowing for better absorption of nutrients and antioxidants. Regardless of whether you eat them raw or cooked, the health benefits of eating a wide variety of vegetables are shown to significantly improve your health.

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  1. Slavin JL, Lloyd B. Health benefits of fruits and vegetables. Adv Nutr. 2012;3(4):506-516. doi:10.3945/an.112.002154

  2. Dewanto V, Wu X, Adom KK, Liu RH. Thermal processing enhances the nutritional value of tomatoes by increasing total antioxidant activity. J Agric Food Chem. 2002;50(10):3010-3014. doi:10.1021/jf0115589

  3. Story EN, Kopec RE, Schwartz SJ, Harris GK. An update on the health effects of tomato lycopene. Annu Rev Food Sci Technol. 2010;1(1):189-210. doi:10.1146/annurev.food.102308.124120

  4. Fuentes F, Paredes-Gonzalez X, Kong A-NT. Dietary glucosinolates sulforaphane, phenethyl isothiocyanate, indole-3-carbinol/3,3′-diindolylmethane: antioxidative stress/inflammation, nrf2, epigenetics/epigenomics and in vivo cancer chemopreventive efficacy. Curr Pharmacol Rep. 2015;1(3):179-196. doi:10.1007/s40495-015-0017-y

  5. Hwang E-S, Kim G-H. Effects of various heating methods on glucosinolate, carotenoid and tocopherol concentrations in broccoli. Int J Food Sci Nutr. 2013;64(1):103-111. doi:10.3109/09637486.2012.704904

  6. Miglio C, Chiavaro E, Visconti A, Fogliano V, Pellegrini N. Effects of different cooking methods on nutritional and physicochemical characteristics of selected vegetables. J Agric Food Chem. 2008;56(1):139-147.

  7. Meléndez-Martínez AJ, Mapelli-Brahm P, Benítez-González A, Stinco CM. A comprehensive review on the colorless carotenoids phytoene and phytofluene. Arch Biochem Biophys. 2015;572:188-200. doi:10.1016/j.abb.2015.01.003

  8. Grube BJ, Eng ET, Kao Y-C, Kwon A, Chen S. White button mushroom phytochemicals inhibit aromatase activity and breast cancer cell proliferationJ Nutr. 2001;131(12):3288-3293. doi:10.1093/jn/131.12.3288