insights

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When it comes to food, much attention is paid to “what” we eat—whether it’s organic, gluten-free, whole, or processed—and rightfully so; the nutritional value of the foods we consume significantly influences our trajectory of health and disease. And yet, the effects of foods extend beyond their inherent nutritional value. The way food is prepared affects its healthfulness as well.

Cooking Methods: Meat, High Heat, & Health Concerns

The cooking method chosen in food preparation may affect the flavor, texture, presentation, and potentially the nutrient value of a meal. When preparing meat, certain cooking methods may even present health concerns. During high-heat exposures, such as frying, roasting, braising, and grilling meat, potential carcinogens are formed.^1–4 Specifically, heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs) are carcinogenic chemicals that have been found when meat is charred or cooked over high heat.^1,5 Temperature, duration, heat transfer, and added antioxidants are some factors that may affect the formation of these carcinogens,^1,2 with increased mutagenic activity noted with increased temperatures and time as well as with better heat transfer, as seen in cooking methods with direct contact, such as frying and grilling.¹

Small amounts of meat prepared with high heat are likely just fine to consume, but for people with a history of cancer and/or high consumption, these are red flags to consider. While human studies have not been definitive, a review of epidemiological studies suggested that high exposure to meat carcinogens, particularly HCAs, may increase the risk of cancer in humans.⁶ For inhibition, antioxidant-rich marinades that include herbs commonly used as meat flavoring (garlic, ginger, thyme, and rosemary) are just one method that may prevent the formation of potential carcinogenic compounds during frying or grilling.^7–9

Plastics and Cookware

In addition to how a meal is prepared, the container in which a food is cooked or stored may also hold potential for contamination, or toxic chemical release. A 2021 study into food safety and the migration of chemicals from plastic containers or food contact materials that are used for microwave and conventional oven heating found that 74 different chemical compounds had migrated into the tested food samples.¹⁰ These chemicals included both substances that were intentionally added in the production of the plastics and byproducts from the degradation of the materials and plastics. In addition, the levels of 20 chemicals were noted as statistically higher when microwaved.¹⁰ Another 2021 study specific to microwaveable plastic food containers used for storage, cooking, and take-out boxes also found migration of multiple chemical substances into food, including microplastics.¹¹

Manmade perfluorinated chemicals are ubiquitous in the environment and another source of potential toxicant exposure in the kitchen. Some types of these persistent chemicals are used in consumer products such as non-stick cookware and have been reported as potential endocrine and metabolic disruptors.^12,13 For example, a 2020 review reported that several epidemiologic studies on women’s health, mostly with cross-sectional designs, identified associations between higher exposure levels to perfluoroalkyl and polyfluoroalkyl substances (PFAS) and later menarche, irregular menstrual cycles, earlier age of menopause, and reduced levels of estrogens and androgens.¹⁴ One member of this PFAS chemical family, polytetrafluoroethylene (PTFE), more commonly known as Teflon, is used to coat a number of commercial products, from cookware to carpets. When heated, studies have shown this compound emits additional pollutants such as perfluoroalkyl carboxylic acids (PFCA).¹⁵

Conclusion

From the potential for increased toxic chemical exposure to the retention of nutrients, food preparation techniques are important tools in promoting health. In addition to occasional grilling with marinades and removing any charred portions of meat before eating, other tips to help avoid toxicants in the kitchen include heating and storing foods in glass containers, using stainless steel or cast-iron cookware, opting for gentle cooking methods such as roasting and steaming, and choosing the fat or oil best suited for cooking over low, medium, or higher heats.

IFM has a wealth of information for clinicians to use as a reference when talking to patients about chemicals and food preparation, including, for IFM members, the following materials, which are printable and can be distributed to patients in the office:

• A Guide to Grilling Food
• Non-Toxic Choices for Food Preparation, Cookware, and Dishes
• A Guide to Cooking with Fats and Oils
• Cooking to Preserve Nutrients

Related Articles

Detoxification: Supporting Liver Function With Nutrition

Talking to Patients About Toxins

References

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2. Janoszka B, Nowak A, Szumska M, Sniezek E, Tyrpien-Golder K. Human exposure to biologically active heterocyclic aromatic amines arising from thermal processing of protein rich food. Wiad Lek. 2019;72(8):1542-1550.
3. Cheng Y, Yu Y, Zhou X, et al. Heterocyclic amines in braised chicken may mainly infiltrate from reused marinade during braising, instead of thermic generation. J Sci Food Agric. 2020;100(5):1867-1874. doi:10.1002/jsfa.10176.
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9. Sepahpour S, Selamat J, Khatib A, Manap MYA, Abdull Razis AF, Hajeb P. Inhibitory effect of mixture herbs/spices on formation of heterocyclic amines and mutagenic activity of grilled beef. Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2018;35(10):1911-1927. doi:10.1080/19440049.2018.1488085.
10.  Sapozhnikova Y, Nuñez A, Johnston J. Screening of chemicals migrating from plastic food contact materials for oven and microwave applications by liquid and gas chromatography – Orbitrap mass spectrometry. J Chromatogr A. 2021;1651:462261. doi:10.1016/j.chroma.2021.462261.
11.  He YJ, Qin Y, Zhang TL, et al. Migration of (non-) intentionally added substances and microplastics from microwavable plastic food containers. J Hazard Mater. 2021;417:126074. doi:10.1016/j.jhazmat.2021.126074.
12.  Wan MLY, Co VA, El-Nezami H. Endocrine disrupting chemicals and breast cancer: a systematic review of epidemiological studies. Crit Rev Food Sci Nutr. Published online April 5, 2021. doi:10.1080/10408398.2021.1903382.
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14.  Ding N, Harlow SD, Randolph JF Jr, Loch-Caruso R, Park SK. Perfluoroalkyl and polyfluoroalkyl substances (PFAS) and their effects on the ovary. Hum Reprod Update. 2020;26(5):724-752. doi:10.1093/humupd/dmaa018.
15.  Schlummer M, Sölch C, Meisel T, Still M, Gruber L, Wolz G. Emission of perfluoroalkyl carboxylic acids (PFCA) from heated surfaces made of polytetrafluoroethylene (PTFE) applied in food contact materials and consumer products. Chemosphere. 2015;129:46-53. doi:10.1016/j.chemosphere.2014.11.036.