Hidden Dangers of Cooked Food

How to Avoid the Worst Dangers of Cooked Food

There are nutritional benefits to eating most of your fruits and vegetables raw, mainly in what relates to nutrient and enzyme preservation. However, certain foods do benefit from cooking (e.g., mushrooms) as cooking may help kill potentially harmful bacteria, and some nutrients may become more bioavailable when foods are cooked. It all depends on the method.

At An Oasis of Healing we follow a raw vegan diet for the duration of our patients treatment, and when going back home our recommendation is trying to stay close to 80% raw, 20% cooked. So, the important question when talking about cooking food is which cooking methods are safer and which methods may have some “hidden dangers”.

Why “hidden dangers”?

Naturally, humans are regularly exposed to toxicants from food, and those compounds can be genotoxic. Genotoxic chemicals are agents that damage the genetic information within a cell causing mutations, which may lead to cancer. Genotoxic compounds are primarily found in processed and cooked foods, because their formation is related to the methods used or chemicals added. These gene-environment interactions, when considering genotoxic compounds, may cause different types of DNA damage, including nucleotide alterations and gross chromosomal aberrations. Most genotoxic compounds begin their action at the DNA level by forming carcinogen-DNA adducts, which result from the covalent binding of a carcinogen or part of a carcinogen to a nucleotide¹.

High Temperature Cooking

High temperature cooking has proven to have some dangers, especially associated with the cooking method and type of foods you are using. Some potentially mutagenic/carcinogenic compounds are formed during high temperature cooking, namely:

Heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs)

• Mostly with cooking methods such as pan frying or grilling directly over an open flame
• Formation of different varieties and content of HCAs and PAHs depends on cooking method, and “doneness” level.^2,3
• HCAs and PAHs have been found to be mutagenic in laboratory testing
• HCAs and PAHs become capable of damaging DNA only after they are metabolized by specific enzymes in the body, a process called “bioactivation.” Studies have found that the activity of these enzymes, which can differ among people, may be relevant to the cancer risks associated with exposure to these compounds⁴
• Mutagenesis causes DNA changes which increases the risk of cancer – carcinogenesis

How to avoid HCAs and PAHs

• Reduction of HCAs in food can be accomplished by avoiding high-temperature cooking⁶.
• Avoid prolonged cooking and broiling and direct exposure to flame¹³.
• Ways to prevent or reduce the production of HCAs in different cooking methods include low temperature pan frying (although this method always has some mutagenic activity associated), the use of a fan-heated ovens, and cover food in grease-proof paper.
• When grilling or barbecuing, place food away from the heat source to avoid contact with flame to try and minimize carcinogenic fumes (preventing PAHs too)¹⁴.

Acrylamide

• Acrylamide is not only a synthetic material used in industry, but also a carcinogenic, cyto- and genotoxic compound formed in foods during a heat-induced process¹⁶.
• The toxicity of acrylamide has been acknowledged since 2002. The identified toxicological effects on humans are neurotoxicity, genotoxicity, carcinogenicity, and reproductive toxicity¹⁷.
• Acrylamide is a by-product of the cooking process and is formed when reducing sugars (glucose or fructose) react with the amino acid asparagine during the Maillard reaction¹⁸.
• Maillard is a common reaction, responsible for the browning of food during baking, frying, and roasting.
• Mostly found in starchy foods, carbohydrate-rich ingredients, potatoes, other root vegetables and plant derivatives products, and in bakery products (bread, crispbread, cakes, batter, breakfast cereals, biscuits, pies, etc.) and coffee¹⁶.
• Created in food when it’s roasted, fried or grilled at very high temperatures for a long time.
• Reaction can be noticed when the starch within those foods starts to darken. Food starts to turn golden brown or to look burnt.
• Exposure to dietary acrylamide depends on the amount of acrylamide present in food, the portion size consumed, and the frequency of consumption, as well as cooking and storage methods¹⁸.
• Different factors determine the levels of acrylamide in cooked foods, including the cooking temperature, length of cooking time, moisture content, and the amount of reducing sugar and asparagine in raw foods¹⁸.
• Acrylamide can also be found in some industrial processed foods.
• After metabolization, acrylamide is distributed to all organs and tissues in the human Acrylamide was found to cause apoptosis by mitochondrial dysfunction.
• Based on the evidence of carcinogenicity proven in laboratory animal studies, the International Agency for Research on Cancer has classified acrylamide as a group 2A carcinogen, which means a probable carcinogenic agent in humans¹⁹.
• Two recent studies based on systematic review of literature and meta-analysis of epidemiological studies found no statistically significant association between dietary acrylamide intake and various cancers, and few studies reported increased risk for renal, endometrial, and ovarian cancers. However, the authors of one of the papers also indicated that exposure assessment in most cases was inadequate which may lead to potential misclassification or underestimation of exposure^18,20.
• Acrylamide is also classified as human neurotoxin (effect observed in humans occupationally exposed)¹⁶.

How to avoid acrylamide:

• Buy unprocessed or minimally processed foods and when buying processed, check the label to avoid buying foods with added acrylamide.
• Avoid overcooking: when cooking starchy foods aim for “golden yellow” and not “golden brown”.
• Avoid refrigerating starchy foods, such as potatoes, before cooking, since it frees up sugar molecules that will then combine with amino acids to form acrylamide.
• Most importantly, eat the majority of your foods raw

Stay tuned for next week were we cover the dangers of cooking smoke and oils

References

1. Jägerstad M, Skog K. Genotoxicity of heat-processed foods. Mutat Res. 2005 Jul 1;574(1-2):156-72. doi: 10.1016/j.mrfmmm.2005.01.030. Epub 2005 Apr 1. PMID: 15914214.
2. Abid Z, Cross AJ, Sinha R. Meat, dairy, and cancer. Am J Clin Nutr. 2014 Jul;100 Suppl 1(1):386S-93S. doi: 10.3945/ajcn.113.071597. Epub 2014 May 21. PMID: 24847855; PMCID: PMC4144110.
3. Cross AJ, Sinha R. Meat-related mutagens/carcinogens in the etiology of colorectal cancer. Environ Mol Mutagen. 2004;44(1):44-55. doi: 10.1002/em.20030. PMID: 15199546.
4. Chemicals in Meat Cooked at High Temperatures and Cancer Risk. Reviewed: July 11, 2017 https://www.cancer.gov/about-cancer/causes-prevention/risk/diet/cooked-meats-fact-sheet#r1, accessed May 19, 2021
5. Kravchenko JS. Diet and Cancer, Editor(s): Stella R. Quah, International Encyclopedia of Public Health (Second Edition), Academic Press, 2017, Pages 294-304, ISBN 9780128037089, https://doi.org/10.1016/B978-0-12-803678-5.00110-7.
6. Choi SW, Mason JB. COLON | Cancer of the Colon, Editor(s): Benjamin Caballero, Encyclopedia of Food Sciences and Nutrition (Second Edition), Academic Press, 2003, Pages 1543-1550, ISBN 9780122270550, https://doi.org/10.1016/B0-12-227055-X/00279-0.
7. Kohlmeier M. Heterocyclic amines, Editor(s): Martin Kohlmeier, In Food Science and Technology, Nutrient Metabolism, Academic Press, 2003, Pages 85-92, ISBN 9780124177628, https://doi.org/10.1016/B978-012417762-8.50006-5.
8. IARC Working Group on the Evaluation of Carcinogenic Risks to Humans. Red Meat and Processed Meat. Lyon (FR): International Agency for Research on Cancer; 2018. PMID: 29949327.
9. World Cancer Research Fund/American Institute for Cancer Research. Diet, Nutrition, Physical Activity and Cancer: A Global Perspective. Continuous Update Project Expert Report, 2018.
10. Zheng W, Lee SA. Well-done meat intake, heterocyclic amine exposure, and cancer risk. Nutr Cancer. 2009;61(4):437-46. doi: 10.1080/01635580802710741. PMID: 19838915; PMCID: PMC2769029.
11. Skog KI, Johansson MA, Jägerstad MI. Carcinogenic heterocyclic amines in model systems and cooked foods: a review on formation, occurrence and intake. Food Chem Toxicol. 1998 Sep-Oct;36(9-10):879-96. doi: 10.1016/s0278-6915(98)00061-1. PMID: 9737435.
12. Liao GZ, Wang GY, Zhang YJ, Xu XL, Zhou GH. Formation of heterocyclic amines during cooking of duck meat. Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2012;29(11):1668-78. doi: 10.1080/19440049.2012.702928. Epub 2012 Jul 30. PMID: 22838849.
13. Sugimura T, Wakabayashi K, Nakagama H, Nagao M. Heterocyclic amines: Mutagens/carcinogens produced during cooking of meat and fish. Cancer Sci. 2004 Apr;95(4):290-9. doi: 10.1111/j.1349-7006.2004.tb03205.x. PMID: 15072585.
14. Robbana-Barnat S, Rabache M, Rialland E, Fradin J. Heterocyclic amines: occurrence and prevention in cooked food. Environ Health Perspect. 1996 Mar;104(3):280-8. doi: 10.1289/ehp.96104280. PMID: 8919766; PMCID: PMC1469314.
15. Phillips DH. Polycyclic aromatic hydrocarbons in the diet. Mutat Res. 1999 Jul 15;443(1-2):139-47. doi: 10.1016/s1383-5742(99)00016-2. PMID: 10415437.
16. Koszucka A, Nowak A, Nowak I, Motyl I. Acrylamide in human diet, its metabolism, toxicity, inactivation and the associated European Union legal regulations in food industry. Crit Rev Food Sci Nutr. 2020;60(10):1677-1692. doi: 10.1080/10408398.2019.1588222. Epub 2019 Mar 25. PMID: 30907623.
17. Sarion C, Codină GG, Dabija A. Acrylamide in Bakery Products: A Review on Health Risks, Legal Regulations and Strategies to Reduce Its Formation. Int J Environ Res Public Health. 2021 Apr 19;18(8):4332. doi: 10.3390/ijerph18084332. PMID: 33921874; PMCID: PMC8073677.
18. Virk-Baker MK, Nagy TR, Barnes S, Groopman J. Dietary acrylamide and human cancer: a systematic review of literature. Nutr Cancer. 2014;66(5):774-90. doi: 10.1080/01635581.2014.916323. Epub 2014 May 29. PMID: 24875401; PMCID: PMC4164905.
19. IARC Working Group on the Evaluation of Carcinogenic Risks to Humans. Volume 60. Some Industrial Chemicals. Lyon (FR): International Agency for Research on Cancer; 1994.
20. Pelucchi C, Bosetti C, Galeone C, La Vecchia C. Dietary acrylamide and cancer risk: an updated meta-analysis. Int J Cancer. 2015 Jun 15;136(12):2912-22. doi: 10.1002/ijc.29339. Epub 2014 Nov 26. PMID: 25403648.
21. Ma Y, Deng L, Ma P, Wu Y, Yang X, Xiao F, Deng Q. In vivo respiratory toxicology of cooking oil fumes: Evidence, mechanisms and prevention. Journal of Hazardous Materials. Volume 402. 2021. 123455. ISSN 0304-3894. https://doi.org/10.1016/j.jhazmat.2020.123455.
22. Chen TY, Fang YH, Chen HL, Chang CH, Huang H, Chen YS, Liao KM, Wu HY, Chang GC, Tsai YH, Wang CL, Chen YM, Huang MS, Su WC, Yang PC, Chen CJ, Hsiao CF, Hsiung CA. Impact of cooking oil fume exposure and fume extractor use on lung cancer risk in non-smoking Han Chinese women. Sci Rep. 2020 Apr 21;10(1):6774. doi: 10.1038/s41598-020-63656-7. PMID: 32317677; PMCID: PMC7174336.
23. Wang G, Bai Y, Fu W, Feng Y, Chen W, Li G, Wu X, Meng H, Liu Y, Wei W, Wang S, Wei S, Zhang X, He M, Yang H, Guo H. Daily cooking duration and its joint effects with genetic polymorphisms on lung cancer incidence: Results from a Chinese prospective cohort study. Environ Res. 2019 Dec;179(Pt A):108747. doi: 10.1016/j.envres.2019.108747. Epub 2019 Sep 16. PMID: 31557604.
24. Jia, PL., Zhang, C., Yu, JJ. et al. The risk of lung cancer among cooking adults: a meta-analysis of 23 observational studies. J Cancer Res Clin Oncol 144, 229–240 (2018). https://doi.org/10.1007/s00432-017-2547-7
25. Peng CY, Lan CH, Lin PC, Kuo YC. Effects of cooking method, cooking oil, and food type on aldehyde emissions in cooking oil fumes. J Hazard Mater. 2017 Feb 15;324(Pt B):160-167. doi: 10.1016/j.jhazmat.2016.10.045. Epub 2016 Oct 20. PMID: 27780622.
26. de Alzaa F, Guillaume C, Ravetti L. Evaluation of Chemical and Physical Changes in Different Commercial Oils during Heating. Acta Scientific. 2018;2(6):2-11.
27. Allouche Y, Jiménez A, Gaforio JJ, Uceda M, Beltrán G. How heating affects extra virgin olive oil quality indexes and chemical composition. J Agric Food Chem. 2007 Nov 14;55(23):9646-54. doi: 10.1021/jf070628u. Epub 2007 Oct 13. PMID: 17935291.
28. Guillén MD, Uriarte PS. Study by 1H NMR spectroscopy of the evolution of extra virgin olive oil composition submitted to frying temperature in an industrial fryer for a prolonged period of time. Food Chemistry. Volume 134. Issue 1. 2012. Pages 162-172. ISSN 0308-8146. https://doi.org/10.1016/j.foodchem.2012.02.083.
29. Robles H. Nitrosamines, Editor(s): Philip Wexler, Encyclopedia of Toxicology (Third Edition), Academic Press, 2014, Pages 584-585, ISBN 9780123864550, https://doi.org/10.1016/B978-0-12-386454-3.00523-6.
30. Scanlan RA. NITROSAMINES, Editor(s): Benjamin Caballero, Encyclopedia of Food Sciences and Nutrition (Second Edition), Academic Press, 2003, Pages 4142-4147, ISBN 9780122270550, https://doi.org/10.1016/B0-12-227055-X/00831-2.
31. Scanlan RA. Formation and occurrence of nitrosamines in food. Cancer Res. 1983 May;43(5 Suppl):2435s-2440s. PMID: 6831466.