Association of ultra-processed food consumption with colorectal cancer risk among men and women: results from three prospective US cohort studies

Dear Editor:
I read with great interest the article by Wang L and colleagues, 1 who contributed to investigate the association between ultra-processed food (UPF) consumption with risk of colorectal cancer (CRC), by using three prospective cohort of 206,248 participants in the USA. The results indicated that high consumption of UPF increased the risk of CRC, especially for distal color cancer. The findings provide public health implications for limiting certain types of UPF for the prevention of CRC. I consider there are still several questions that could entail challenges and opportunities in this new frontier.
The global food system plays a vital role in driving growth in UPF production and consumption. It is reported that UPF already contributes more than 50% of total energy intake in western countries such as the USA, the UK, and Canada, and food sales data indicates that these products are the most rapidly growing dietary component globally.2 However, research exploring associations between the consumption of UPF and cancer risk is still very scarce. In the study by Wang L and colleagues, the study participants are US health professionals and predominantly non-Hispanic white. The generalizability of the findings may be limited. The effects of UPF exposure are complex, due to the diverse types of UPF, and global food system varies in countries or ethnicities. Thus, associations between UPF consumption with risk of CRC must be assessed in terms of a range of comprehensive factors.
Moreover, I argued that the authors might have overlooked a major confounder in this study: the geographical variations within the sample. Since the Nurses’ Health Study and the Health Professionals Follow-up Study covered various areas in the USA, the geographic disparities within the sample may be a potential factor affecting the CRC risk. Such a claim can be justified by the fact that the incidence and mortality of CRC in the USA are lowest in the West and highest in Appalachia and parts of the South and Midwest during 2012-2017, due to different availability of health care and screening. 3 Moreover, a multi-center cohort study in the USA showed that the spatial variations of the ambient air pollution such as PM2.5 level might influence the CRC risk. 4 In this way, the geographical area should be controlled in the analyses.
To strengthen the findings, it would be instructive for authors to exclude deaths occurring within the first five years of follow-up to alleviate the potential influence of reverse causation. In addition, it is noted that UPF belongs to a very broadly defined food category, which includes various types such as processed meat, artificially or sugar-sweetened beverages, savoury snacks, and etc. However, to our knowledge, the studies on specific UPF subgroups on cancer risk are mainly conducted in Europe 5 and America, 1 other research performed in the East Asia and the Middle East or other areas are still lacking. Moreover, UPF conceptualized based on different food-processing systems has been suggested to demonstrate inconsistency in their health impacts.
Future research priorities are to investigate the relationships between UPF consumption with CRC risk in different populations worldwide, prospective trials or Mendelian randomization studies of these foods to examine causality, and further experimental studies to help explore the biological mechanisms. Public health policies could be facilitated by promoting the availability, affordability, and accessibility of unprocessed or minimally processed foods.

References
1.Wang L, Du M, Wang K, et al. Association of ultra-processed food consumption with colorectal cancer risk among men and women: results from three prospective US cohort studies. BMJ 2022:e068921.doi: 10.1136/bmj-2021-068921
2.Popkin BM, Barquera S, Corvalan C, et al. Towards unified and impactful policies to reduce ultra-processed food consumption and promote healthier eating. Lancet Diabetes Endocrinol 2021;9(7):462-470.doi: 10.1016/S2213-8587(21)00078-4.
3.Siegel RL, Miller KD, Goding Sauer A, et al. Colorectal cancer statistics, 2020. CA: a cancer journal for clinicians 2020;70(3):145-164.doi: 10.3322/caac.21601
4.Chu H, Xin J, Yuan Q, et al. A prospective study of the associations among fine particulate matter, genetic variants, and the risk of colorectal cancer. Environ Int 2021;147:106309.doi: 10.1016/j.envint.2020.106309.
5.Fiolet T, Srour B, Sellem L, et al. Consumption of ultra-processed foods and cancer risk: results from NutriNet-Sante prospective cohort. BMJ 2018;360:k322.doi: 10.1136/bmj.k322.

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Dear Editor,

Beyond the anti-cancer benefit of coffee consumption, it is difficult to identify the factors that defend us or expose us to Colorectal Cancer (CRC): is there a possible relationship between Asbestos in drinking water and CRC?

I sincerely thank Prof. Song for this important answer in Rapid Responses to the question I had asked.

I hope that the new research of Prof. Song will lead to good results for those who drink coffee.

It is very difficult to identify what are all the components determining the result, whether a food or a drink, are protective against a certain disease.

In the case of coffee and protection against CRC, I reflect on how important it can be in real life:

• the quality of the raw material that may be contaminated with ochratoxin [1], pesticides, or other roasting-related substances [2], etc.
• the method of intake: it is different if in a cup or glass glass, or in a plastic container drunk hot at high temperature, perhaps dissolving harmful chemical factors right from the container.
• if the coffee is drunk very hot, could it have an aggressive interaction on the surfaces of the materials of fillings or dental prostheses? If poured into a pan dirty with grease, you can clean it better.
• keep in mind the containers in which it is prepared, often consisting of plastic components or toxic metals

I also add the water quality among the components of the preparation: in some areas there are toxic elements such as arsenic, and various contaminants, in the drinking water (even naturally).

Precisely by linking to drinking water, I would like to express my doubt about asbestos pipes carrying drinking water. In some areas of Italy, unfortunately there are still old water systems built with asbestos and some authors suspect that drinking water, containing fibers of this material, if ingested and used in food preparation, can cause tumors in the digestive tract, including CRC [3,4].

References:
[1] Pakshir K, Dehghani A, Nouraei H, Zareshahrabadi Z, Zomorodian K. Evaluation of fungal contamination and ochratoxin A detection in different types of coffee by HPLC-based method. J Clin Lab Anal. 2021 Nov;35(11):e24001. doi: 10.1002/jcla.24001. Epub 2021 Sep 15. PMID: 34528313; PMCID: PMC8605134.
[2] Mojska H, Gielecińska I. Studies of acrylamide level in coffee and coffee substitutes: influence of raw material and manufacturing conditions. Rocz Panstw Zakl Hig. 2013;64(3):173-81. PMID: 24325083.
[3] Totaro M, Giorgi S, Filippetti E, Gallo A, Frendo L, Privitera G, Baggiani A. Asbestos in drinking water and hazards to human health: a narrative synthesis. Ig Sanita Pubbl. 2019 Jul-Aug;75(4):303-312. Italian. PMID: 31887736.
[4] Di Ciaula A, Gennaro V. Clinical risk from ingestion of asbestos fibers in drinking water [Possible health risks from asbestos in drinking water]. Epidemiol Prev. 2016 Nov-Dec;40(6):472-475. Italian. doi: 10.19191/EP16.6.P472.129. PMID: 27919155.

Dear Editor,

What important epidemiological differences regarding colorectal cancer (CRC) protection could affect the results of this study considering the regular intake of coffee, distinguishing whether decaffeinated or with caffeine and the various methods of coffee preparation: boiled black coffee, black coffee (espresso), instant coffee, and filter coffee?

Some studies report, like this one cited, that coffee consumption may be inversely associated with risk of CRC in a dose-response manner [1].

References:
[1] Schmit SL, Rennert HS, Rennert G, Gruber SB. Coffee Consumption and the Risk of Colorectal Cancer. Cancer Epidemiol Biomarkers Prev. 2016 Apr;25(4):634-9. doi: 10.1158/1055-9965.EPI-15-0924. PMID: 27196095; PMCID: PMC4874555.