Impact of high-fats food regimen on immune activity, tumor growth.

This article was exclusively written for The European Sting by Ms. Gaëlle Antoine SALIBA, a Biochemist and a Nutritionist at the Lebanese University, and practiced her internship in Lebanese hospital Maritime. She is affiliated with the International Federation of Medical Students Associations (IFMSA), cordial partner of The Sting. The opinions expressed in this piece belong strictly to the writer and do not necessarily reflect IFMSA’s view on the topic, nor The European Sting’s one.

The incidence of obese and overweight is growing worldwide, and the evidence base for a hyperlink among obesity and most cancers is growing. In the United States, about 85,000 new cancer cases per year are related to obesity. Recent studies has observed that as the body mass index increases by 5 kg/m2, cancer mortality increases by 10%. Additionally, research of sufferers who’ve had bariatric surgical treatment for weight loss report reductions in cancer incidence and mortality, particularly for women ⁽¹⁾ but a detailed understanding of the interplay between obesity and cancer has remained elusive.^(1-3) In a new study in mice, researchers at Harvard Medical School have exposed a new piece of this puzzle, with sudden implications for most cancers’ immunotherapy: Obesity allows cancer cells to out compete tumor-killing immune cells in a conflict for fuel. ⁽²⁾ 

The findings, posted in Harvard’s study, monitor that a high-fats weight loss plan reduces the numbers and antitumor interest of CD8+ T cells, a vital sort of immune cell, inner tumors. This takes place because tumor cells increase fat uptake with high-fats diet, whereas tumor-infiltrating CD8⁺ T cells do not. These differential adaptations lead to altered fatty acid partitioning in high-fats diet tumors, impairing CD8⁺ T cell infiltration and function. Further, blocking fat-related metabolic reprogramming significantly reduced tumor volume in mice on high-fat diets. ^(2-3)  

To a great extend CD8+ T cells are the primary weapon utilized by immunotherapies to activate the immune system against cancer. “We now understand there’s a metabolic tug-of-war between T cells and tumor cells that changes with obesity” ⁽⁴⁾ According to Marcia Haigis, professor of cell biology in the Blavatnik Institute at HMS and co-senior author of the study, “Putting the same tumor in obese and nonobese settings reveals that cancer cells rewire their metabolism in response to a high fat diet.” ⁽¹⁾

Despite the fact that in patients with cancer, a high-fat diet may support the maintenance of both body weight and body cell mass. However, monitoring the lymphocyte count is advisable ⁽⁸⁾ since several experimental data showed that the composition of dietary fat, induces changes in gut microbiota leading to activation of pro-inflammatory pathways, and obesity as a consequence of over nutrition. ^(5-6) Nevertheless When evaluating the effect of dietary fat, it is necessary to focus not only on major classes of fatty acids (saturated vs. unsaturated ) but also on different members of these classes, for example, the consumption of plant monounsaturated fatty acids (MUFAs), particularly from olive oil, has been associated with lower cancer risk. In contrast, the impact of polyunsaturated fatty acids (PUFAs) on cancer risk depends on the ratio between ω-6 and ω-3 PUFAs. In vivo data showed stimulatory effects of ω-6 PUFAs on tumor growth while ω-3 PUFAs were protective. ⁽⁷⁾

Figure 1: Interplay among disturbances induced by excess of nutrients. Abbreviations: LPS—lipopolysaccharides; ROS—reactive oxygen species; SFAs—saturated fatty acids; TLR-4—toll-like receptor 4.

As a concerned Lebanese citizen, I would like to point the finger at the Lebanese population’s cancer rates. Analysis of data provided by the Lebanese National Cancer Registry showed that the rate of obesity in Lebanon is increasing alarmingly. According to a study published in 2016, 53.5% of the Lebanese population is overweight and 18.16% is obese.⁽⁹⁾ In parallel with the increase in the rate of obesity, according to local news agency Al Markazia, the World Health Organization estimated over 17,000 new cancer cases in Lebanon in 2018, and 242 cancer patients for every 100,000 Lebanese. Based on these figures, Lebanon is rated as having the highest incidence of Lung Cancer in females and the second highest after Malta in males in the entire MENA region. ⁽¹⁰⁾  In addition over the past year, the living standards of Lebanese people have taken a huge hit due mostly to the deteriorating economic conditions and the massive devaluation of the Lebanese Lira from 1500LL/USD to over 12000LL/USD as of the time of writing. The quality of food was unsurprisingly affected as well. Lebanon lacks sufficient food production and has had to rely on imports to fulfill the demand for many basic ingredients including meat, poultry…etc. With the economy as is, such items have become prohibitively expensive for many and people have been increasingly relying on cheap fast food as a replacement. While the less fortunate have had to forgo certain ingredients entirely.

For all that has been said above and much more, it is crucial to inaugurate the important role of Nutritionists and healthcare professional in limiting the consumption of fatty foods and unhealthy foods to reduce risk of obesity as much as possible. Last but not least, everyone including nutritionists, should work toward eating fresh, natural foods, and offer accompanying education to further promote healthy eating in order to reach a better and sustainable future.

References:

1. Basen-Engquist, K., & Chang, M. (2010). Obesity and Cancer Risk: Recent Review and Evidence. Current Oncology Reports, 13(1), 71–76. https://doi.org/10.1007/s11912-010-0139-7 
2. Ringel AE;Drijvers JM;Baker GJ;Catozzi A;García-Cañaveras JC;Gassaway BM;Miller BC;Juneja VR;Nguyen TH;Joshi S;Yao CH;Yoon H;Sage PT;LaFleur MW;Trombley JD;Jacobson CA;Maliga Z;Gygi SP;Sorger PK;Rabinowitz JD;Sharpe AH;Haigis MC;, A. E. (2020, December 9). Obesity Shapes Metabolism in the Tumor Microenvironment to Suppress Anti-Tumor Immunity. Cell. https://pubmed.ncbi.nlm.nih.gov/33301708/
3. Ackerman, S. E., Blackburn, O. A., Marchildon, F., & Cohen, P. (2017). Insights into the Link Between Obesity and Cancer. Current Obesity Reports, 6(2), 195–203. https://doi.org/10.1007/s13679-017-0263-x
4. Duan Y;Zeng L;Zheng C;Song B;Li F;Kong X;Xu K;, Y. (2018, November 13). Inflammatory Links Between High Fat Diets and Diseases. Frontiers in immunology. https://pubmed.ncbi.nlm.nih.gov/30483273/
5. Font-Burgada, J., Sun, B., & Karin, M. (2016). Obesity and Cancer: The Oil that Feeds the Flame. Cell Metabolism, 23(1), 48–62. https://doi.org/10.1016/j.cmet.2015.12.015
6. Ringel AE;Drijvers JM;Baker GJ;Catozzi A;García-Cañaveras JC;Gassaway BM;Miller BC;Juneja VR;Nguyen TH;Joshi S;Yao CH;Yoon H;Sage PT;LaFleur MW;Trombley JD;Jacobson CA;Maliga Z;Gygi SP;Sorger PK;Rabinowitz JD;Sharpe AH;Haigis MC;, A. E. (2020, November 9). Obesity Shapes Metabolism in the Tumor Microenvironment to Suppress Anti-Tumor Immunity. Cell. https://pubmed.ncbi.nlm.nih.gov/33301708/.
7. Bojková, B., Winklewski, P. J., & Wszedybyl-Winklewska, M. (2020). Dietary Fat and Cancer—Which Is Good, Which Is Bad, and the Body of Evidence. International Journal of Molecular Sciences, 21(11), 4114. https://doi.org/10.3390/ijms21114114
8. Breitkreutz, R., Tesdal, K., Jentschura, D., Haas, O., Leweling, H., & Holm, E. (2005). Effects of a high-fat diet on body composition in cancer patients receiving chemotherapy: a randomized controlled study. Wiener Klinische Wochenschrift, 117(19-20), 685–692. https://doi.org/10.1007/s00508-005-0455-3
9. Mallat, S., Geagea, A. G., Jurjus, R. A., Rizkallah, A., Oueidat, D., Matar, M., Tawilah, J., Berbari, A., & Jurjus, A. R. (2016). Obesity in Lebanon: A National Problem. World Journal of Cardiovascular Diseases, 06(06), 166–174. https://doi.org/10.4236/wjcd.2016.66017
10. Salhab, H. A., Fares, M. Y., Khachfe, H. H., & Khachfe, H. M. (2019). Epidemiological Study of Lung Cancer Incidence in Lebanon. Medicina, 55(6), 217. https://doi.org/10.3390/medicina55060217

About the author

Gaëlle Antoine SALIBA, 24 years old woman. She is holder of a Master Degree in Nutrition and Dietetics and a Bachelor degree in biochemistry at the Lebanese University, and practiced her internship in Lebanese hospital Maritime. Activist in social work, certified for attending and organizing many healthcare and social workshops and current member of IFMSA. Since her third year at the university she became an active member of the Public Relations and Communication where she engages in writing scientific articles on the relevant health issues. But most importantly, Gaëlle tends to share her big interest in nutritional and medical research. She has always believed that our Nutrition is our remedy. Throughout nutrition, she wants to see what others could not see.