A simple rule for cooking to preserve nutrients and avoid unhealthy fats: “Steam, don’t boil. Bake, don’t fry.”
Even though it is convenient, using a microwave oven for cooking or heating food on a regular basis is generally not a good idea. Two health concerns to be aware of are (1) non-uniform heating of foods that may contain harmful bacteria (e.g., raw meats) and (2) the leaching of chemicals from plastic containers into the food while heating. The potential contamination of food from plasticizing chemicals is widely recognized and the subject of ongoing research.
However, the risks are easily avoided by using non-leaching, microwave-safe containers, such as glass, Pyrex, CorningWare or lead-free ceramic. A plastic container labeled “microwave-safe” only means it will not melt or crack when heated. It’s almost as fast to put leftovers or a frozen meal in a pan, add a few tablespoons of water, cover and warm for a few minutes over low heat.
Good choices for cookware and bakeware are stainless steel, cast iron, enamel-over-cast iron and glass. The coating on most brands of non-stick cookware contains a chemical called PFOA that can emit toxic fumes when heated to high temperatures. Scratched non-stick cookware may also contaminate food with loosened particles.
When certain carbohydrate-rich, starchy foods are prepared using long cooking times or high-temperature cooking methods, such as frying, broiling, baking or roasting, a chemical reaction between sugars and an amino acid can create acrylamide. Acrylamide, widely recognized as a potentially harmful substance, is found in especially high levels in potato chips and French fries. You might also want to discard burned or over-browned toast and baked goods as these are also likely to contain unhealthy levels of this chemical.
A few words of caution are also needed when it comes to the all-American backyard barbeque where hot dogs and hamburgers are usually on the menu for kids. The concern is that these meat products are highly processed, and may contain harmful preservatives as well as trace amounts of antibiotics and hormones. Meat from large commercial processors also brings more risk of contamination with E.coli and salmonella, both of which are imperative to avoid for children with compromised immune systems. If this is not enough to give you pause, the high heat, dripping fat and smoke also expose cooking meats to several toxic chemicals and chemical compounds. These chemicals are produced when meat, poultry or fish (muscle proteins) are cooked at high temperatures (above 350 degrees), such as when grilling, broiling and frying.
But don’t put away your grill! All kinds of vegetables, tortillas, quesadillas, veggie-burgers and veggie-dogs are safe to grill, and may even become new family favorites. Just be careful not to char or blacken.
Non-Stick Cookware (PFAS)
The EPA weighs in on PFAS - chemicals used in non-stick cookware.
Green Science Policy Institute provides answers to FAQ on per- and polyfluoroalkyl substances (PFAS).
HealthyChildren.org is a parenting website from the American Academy of Pediatrics. Here is a link to their page on how to limit children's exposure on PFAS.
The American Cancer Society weighs in on acrylamide.
Q&A about acrylamide from the U.S. Food and Drug Administration (FDA) .
Health Canada's Q&A on acrylamide.
Health Canada is the Canadian equivalent of the U.S. Health and Human Services Department
The National Cancer Institute's fact sheet on Acrylamide in Food and Cancer Risk.
Duke University oncology dietician Denise Snyder on avoiding the harmful substances created by grilling – The Greenstreet Radio interview.
The National Cancer Institute provides a fact sheet on Chemicals in Meat Cooked at High Temperatures and Cancer Risk.
Special care should be taken when microwaving food that may harbor harmful bacteria. Research into the molecular changes in food when heated in a microwave oven – and the debate about whether it poses a potential risk – is ongoing. Until scientists agree that there is no risk associated with microwaving food, you may want to limit its use.
Beth Israel Lahey Health/Winchester Hospital has an excellent document on safe microwave cooking and additional resources.