Cooking is one of the fundamental methods of processing food by application of heat or pressure to make it safer, convenient, and enjoyable for consumption. Over time, the process of cooking has undergone various innovations to make food more appealing and pleasurable to consume. We not only consume food for the sake of energy and nutrition but also to relish, as it is deeply connected to our emotions and has the capability to elevate our mood. However, it is important to know which cooking methods to use, and which to avoid, for enhanced health and nutrition.
One of the primary reasons we cook our food is that it plays a very important role in making the food safe and palatable. Cooking by means of applying heat or using non-thermal methods such as high-pressure processing protects the food from microorganisms that can spoil it and make it unsafe for consumption1. Cooking also enhances the digestibility of foods like cereal and vegetables, etc., by breaking them down into smaller components, which enables the body to assimilate them quickly2. Apart from safety and digestibility, cooking initiates a series of chemical and physical changes in food, like the development of flavor, changes in texture, and the formation of color — all of which makes it appealing and enjoyable to consume3.
We utilize many different ways of cooking like frying, grilling, baking, smoking, boiling, steaming, and so forth4. Cooking methods like frying, grilling, baking, smoking, and roasting use a combination of dry heat, fats, and high temperature ranges greater than 110⁰C (230⁰F). They are usually appealing to consumers due to the wide variety of flavors that they develop due to the process of caramelization and the Maillard reaction, which gives browned food its distinctive flavor. Other cooking methods like steaming, poaching, microwaving, simmering, and boiling use moist heat and apply lower temperatures in the range of 80 to 100⁰C (176 to 212⁰F).
Though the process of cooking food has positive effects, it also has its disadvantages. The nutrient content in food is greatly affected, depending upon the type of cooking that we adopt. Certain cooking methods like boiling, baking, and grilling can result in loss of vitamins and other essential nutrients. Exposure of vegetables to air and heat may cause degradation of vitamin C and color5. Extended cooking time at high temperatures results in the loss of as much as 40% of vitamin B6. Although desirable flavor, texture, and color compounds can be created while cooking, several undesirable and potentially toxic compounds can also be created, which may have detrimental effects on our health.
Usage of high temperature and dry heat, as in the case of grilling, barbequing, smoking, frying, baking, and roasting, can lead to the formation of toxic compounds. Deep fat frying and cooking or grilling meat at higher temperatures result in the formation of heterocyclic amines (HCA), which have been linked to causing cancer. Addition of nitrites to meat combined with these high-temperature cooking methods results in the formation of nitrosamines, which are also said to be carcinogenic in nature. Baking, grilling, and barbequing of meat and fish results in the formation of polycyclic aromatic hydrocarbons (PAH), which are also believed to be cancerous 7. In the US, consumption of grilled/barbecued meat constitutes a major proportion of the consumption of PAHs, which raises grave concerns that need to be addressed8. Applying high temperature to foods rich in carbohydrates results in the formation of acrylamides, which are found in potato chips, coffee, biscuits, rolls, and toasts9. There are no established threshold limits on acrylamides, and even consuming the smallest quantities may have health risks.
Additionally, cooking meat, meat products, and foods rich in protein and fat at high temperatures along with sugar results in the formation of advanced glycation end products (AGE) which can cause mutations to the genes in our DNA and can be harmful to our health10. Grilled, pan-fried, and broiled beef hot dogs are said to contain toxic levels of AGEs. AGEs affect proteins in the body by causing them to lose functionality, which may result in premature aging11. AGEs have also been found to cause inflammation in the body, which unchecked can cause cancer and other deadly conditions like diabetes and obesity12. A study found that when men consumed one or more servings of well-done red meat and processed meat weekly, their risk of prostate cancer jumped by 50%13. Cooking foods in dry heat and at high temperatures results in the formation of methylglyoxal — a form of AGE which, when exposed to mice, caused weight gain, insulin resistance, inflammation, and type 2 diabetes14. People with diabetes are more prone to the formation of AGEs due to the high level of sugar in their blood, which may lead to further complications.
While all this sounds alarming, there are methods to prepare food that can avoid these toxic compounds and thereby lead to a healthier life. Cooking foods at low temperatures and with moisture can prevent the formation of these detrimental compounds. As mentioned previously, cooking methods like steaming, poaching, simmering, microwaving, and boiling are water-based cooking methods and can prevent the formation of AGEs12. Although in boiling there is a loss of nutrients, as major vitamins and minerals are retained in the water used for boiling, boiled fish has been found to retain most of its omega-3 fatty acid15. A study found that foods cooked at low temperatures reduced the glycated LDL by 33%16. Cooking meat, eggs, fish, and vegetables using steam was found to preserve most of the nutrients, including the water-soluble vitamins that are sensitive to heat and water. Though steaming may render the food to be bland, its taste can be improved by using seasonings such as herbs and spices. Also, the use of acidic marinades like vinegar and lemon juice before cooking can limit the formation of AGEs in food such as meats12.
By knowing the detrimental effects and the benefits that can be achieved using different cooking methods, we can make the right choices in selecting the appropriate cooking methods for leading a healthy and happy life.