Does Cooking Vegetables Increase Their Nutrient Value?

How Heat Releases Trapped Nutrients

Eating vegetables is an important part of a healthy diet. Athletes and fitness enthusiasts understand them as a valuable source of phytochemicals. These chemical compounds provide antioxidant properties, according to chronic research. Antioxidants are powerful substances stabilizing free radicals (cell-destroying atoms) in our body and helpful in disease prevention. Because of this benefit, consuming vegetables is linked to decreased incidence of cancer, heart disease, and degenerative illness.

Cooking Can Enhance Nutrient Value

High Angle View Of Roasted Asparagus By Cup On Table
Adam Sargent / EyeEm / Getty Images

It has been said eating raw vegetables provides the best nutrients. While this may be the case for most veggies, cooking actually increases nutrient value in some vegetables. There appears to be positive and negative feedback in current research with how veggies are prepared. According to an article published in The Journal of Agricultural and Food Chemistry, antioxidants are enhanced when some vegetables are cooked. 

Several vegetables are actually shown to have improved nutrient value when cooked. It appears beneficial phytochemicals are trapped in the cell wall without applying a heating method. So while eating vegetables is good and recommended for improved health, cooking appears to make some even more nutritious. Below are just a few vegetables that benefit from being cooked:  

  • Tomatoes
  • Broccoli
  • Carrots
  • Pumpkin (includes other winter squash)
  • Asparagus
  • Mushrooms

Tomatoes

High Angle View Of Cherry Tomatoes In Plate On Table
Yin Jiang / EyeEm / Getty Images

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

The Journal of Agricultural and Food Chemistry published a study on the nutritional benefits of cooking tomatoes. Several cooking trials were conducted heating raw tomatoes to 88 degrees Celsius for two, 15, and 30 minutes. Vitamin C and lycopene values were measured at each interval. Research results indicated a significant drop in vitamin C but in contrast, a substantial increase in lycopene.

Steaming or boiling tomatoes is the preferred method of cooking to bring out more lycopene for optimal nutrition. Research indicates lycopene reduces the risk of cancer, improves heart health, and enhances neurological response. 

Broccoli

Close-Up Of Broccoli In Bowl on wooden table
Edelweiss Spykerman / EyeEm / Getty Images

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 are shown to decrease cancer by reducing inflammation in our blood vessels. Broccoli is well-known as a detox vegetable and superfood.

The International Journal of Food Sciences and Nutrition published an article on how cooking broccoli affects nutrient value. It was determined 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 cooking broccoli. In fact, longer heating time extracted even more.

According to research published in The Journal of Agricultural and Food Chemistry, cooking broccoli promotes the release of carotenoids. Carotenoids are bioactive compounds shown to have numerous health benefits when consumed. Cooking was shown to increase these levels enhancing the nutrient value in broccoli even more. Broccoli is said to supply the largest amount of carotenoids in the American diet than any other similar vegetable.   

Steaming and boiling broccoli are the preferred methods of cooking to enhance carotenoids like lutein and phytoene. Studies show phytoene reduces the risk of prostate cancer, improves heart health, and reduces inflammation in our blood vessels.

   

Carrots

High Angle View Of Carrots On Table
Alexandra Ribeiro / EyeEm / Getty Images

Carrots are a popular root vegetable. They are a rich source of beta-carotene, fiber, and numerous vitamins and minerals. 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 percent. 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. It’s suggested to use the best cooking method for carrots and all vegetables to preserve or improve nutritional and antioxidant qualities.

 

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 lack sweetness and more savory, pumpkins have been labeled vegetables for culinary purposes. Pumpkins are also related to winter squash, cucumbers, and cantaloupes.

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

The health benefits of consuming cooked pumpkin 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 wrapped in twine, on wooden boards.
Paul Strowger / Getty Images

Asparagus is considered one of the most nutritionally balanced vegetables. It contains numerous vitamins, minerals, and powerful antioxidants. It does contain 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 being high in folate. Folate also helps maintain our blood cells, especially bone marrow, and promotes healthy growth and development. It’s also a rich source of vitamin A, vitamin E, vitamin K, magnesium, niacin, and other important nutrients. 

The strong antioxidant properties found in cooked asparagus are shown to protect our cells, tissue, and organs by reducing oxidative damage. Asparagus is also high in fiber recommended for weight loss and a healthy diet. 

 

Mushrooms

overhead shot of mushrooms in a basket on a wooden table
Westend61 / Getty Images

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, increasing your fiber intake. Proper fiber intake is shown to help with 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 are suggested to help with reducing 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 eating them raw or cooked, the health benefits of eating a wide variety of vegetables are shown to significantly improve your health.

Sources:

Dewanto V et al. Thermal Processing Enhances the Nutritional Value of Tomatoes by Increasing Total Antioxidant ActivityJournal of Agriculture and Food Chemistry. 2002.

Hwang ES et al. Effects of various heating methods on glucosinolate, carotenoid and tocopherol concentrations in broccoliInternational Journal of Food Sciences and Nutrition. 2013. 

Joanne L. Slavin et al. Health Benefits of Fruits and Vegetables. Journal of Advances in Nutrition. 2012.

Miglio C et al. Effects of Different Cooking Methods on Nutritional and Physicochemical Characteristics of Selected Vegetables.  Journal of Agriculture and Food Chemistry. 2008.

Continue Reading