How can cooking reduce the vitamin content of food?

Cooking processes can reduce the vitamin content of food primarily through exposure to heat and chemical reactions.

The most significant factor is the use of severe heat treatment during methods like canning. High temperatures can lead to a decrease in the nutritive value of vegetables, with vitamin C being the nutrient most susceptible to destruction during these processes.1

Additionally, vitamins can be degraded through oxidation. For instance, the oxidation of vitamin C and carotenoid pigments can occur during food processing and storage, a process known as photosensitized oxidation. While techniques such as high-temperature–short-time (HTST) processing are used to minimize these losses by reducing the duration of heat exposure, traditional heating methods generally result in a lower nutrient profile compared to fresh or frozen alternatives.21