[Updated May 10, 2018]
Q: Does roasting vegetables at high temperatures, such as 425 degrees Fahrenheit, destroy nutrients in the vegetables?
Katelyn Castro, a dietetic intern at Tufts’ Frances Stern Nutrition Center, responds:
A:“The caramelization that occurs during the roasting process can enhance the flavor of vegetables and increase your enjoyment of them. However, roasting vegetables has some nutritional trade-offs. Cooking vegetables increases the availability of some nutrients, such as beta-carotene and lycopene, by breaking down plant foods’ cell walls. At the same time, roasting vegetables can reduce levels of heat-sensitive nutrients, such as vitamin C and folate.”
Nutrient loss with heat is not unique to roasting. Other forms of cooking can also reduce heat-sensitive nutrients, and cooking methods that use water, such as boiling, result in nutrient losses from water-soluble nutrients leaching into the water. “So, consider varying your preparation methods, such as by eating raw vegetables and salads as well as roasted, steamed or sauted vegetables.”
It’d be helpful to know whether roasting vegetables at a lower temperature (such as 350) for a longer time period would result in less nutrient loss than roasting at 425.