Ask the Expert: Cooking Foods

The Physicians Committee

Ask the Expert: Cooking Foods

Q: Does cooking vegetables generally destroy cancer-fighting compounds?

A: In a 2004 medical research review evaluating the effectiveness of raw and cooked vegetables on cancer risk, both raw and cooked vegetables were inversely related to cancer risk. Authors found more studies showing an inverse relationship between raw vegetable consumption verses cooked and total vegetable consumption, however the study designs were variable and evidence is still considered inconclusive.

When evaluating the benefits of raw verses cooked vegetables, it is important to note that water-soluble nutrients such as vitamin C and the B vitamins do seep out of foods during boiling or steaming. However, if you reuse the cooking liquid in soups or to cook grains, you will get all the nutrients that have seeped out of the vegetables. On the contrary, some antioxidants are actually released or activated by cooking, including the lycopene in tomatoes and the beta-carotene in carrots and sweet potatoes. Researchers have found that you can multiply the antioxidant power of your carrots three times by cooking and puréeing them before eating. It turns out that cooking and puréeing releases cancer-fighting compounds from the carrot cells. To reap the full cancer-fighting benefits from the carrot you prepare, wash them thoroughly, but avoid peeling them as the skins are rich with cancer-fighting compounds.

LB, Potter JD. Raw verses Cooked Vegetables and Cancer Risk. Cancer Epidemiol Biomarkers Prev. 2004;13(9):1422-1435.

Q: What is the safest cookware?

A: Every type of cookware seems to have its pros and cons. It is important that all cookware gets regularly replaced when dented or worn. If you see any chipping, this is a red flag to throw it out.

Teflon: It is important to not leave Teflon cookware on a burner or in an oven without liquid; this will release a group of chemical toxins called PFOA (perfluoroctanoic acid). Heating Teflon to extremely high temperatures releases these toxins. Studies show that these chemicals can be released when heated to as little as 464 degrees Fahrenheit.
The Environmental Working Group

Stainless Steel: Stainless steel is probably the safest choice of cookware if you take care of your pots and pans. This material is a highly engineered alloy composition of many metals—including nickel, chromium, and molybdenum—which provides high resistance to chemical reaction with the acids and enzymes in food, so these elements will rarely, if ever, leach into foods.  Steel alloyed with titanium tends to be the most resistant to corrosion and oxidation. Multi-ply construction conducts heat well and allows for low-heat cooking which protects the quality, purity, nutrients, and the flavor of food. Cookware with temperature indicators to assist in maintaining low temperature settings can be helpful.

Cast Iron: Cast Iron can help ensure that you are getting enough iron—as it seeps off the cookware into food in small amounts. Iron in large quantities becomes a pro-oxidant, causing stress and oxidation in the body that can lead to disease. Most cast iron pans need to be seasoned with oil after use. This is type of cookware is considered safe.

Aluminum: Aluminum contact should be limited or avoided as much as possible, because of its link with Alzheimer’s disease and its potential of having estrogen-like effects in the body. Anodized aluminum cookware is considered a safer alternative.

Washburn ST, Bingman TS, Braithwaite SK, Buck RC, Buxton LW, Clewell HJ, Haroun LA, Kester JE, Rickard RW, Shipp AM.  Exposure assessment and risk characterization for perfluorooctanoate in selected consumer articles. Environ Sci Technol. 2005;39(11):3904-3910.

Begley TH, White K, Honigfort P, Twaroski ML, Neches R, Walker RA. Perfluorochemicals: potential sources of and migration from food packaging. Food Addit Contam. 2005;22(10):1023-1031.

Darbre PD. Aluminium, antiperspirants and breast cancer. J Inorg Biochem. 2005;99(9):1912-1919.

Bosun Supplies Inc. Stainless Steel Info: What you need to know. Available at: Accessed Feb. 12, 2009.