Evidence Based Nutrition

This blog is meant to go through the link between cancer and nutrition, and what the science says about this topic. This does not mean cancer should be only treated with nutritional strategies always consult professionals.

Cancer is reported as the second most global cause of death with first being cardiovascular disease (CVD) (13). The types of cancer vary from region to region for example lower-income countries have greater cases of infection-related cancers such as cervix, liver and stomach whereas as higher income countries cancers such as breast cancer and prostate cancer are more common with lung cancer is common worldwide (13, 6). A cancerous cell is a cell that has lost the ability to control their own growth, and this continues to morph if the immune system is unable to maintain surveillance of the organism and destroy it as soon as it appears, which the immune system should be able to do, then this can cause further mutations and potentially tumour growth in a tissue (11). 

Dietary factors have been thought to account for about 30% of cancers in western countries making it second to tobacco, the American Institute for Cancer Research and the World Cancer Research Fund estimated that 30-40% of all cancers can be prevented by appropriate diets, physical activity and maintenance of a healthy body weight (7,4). Diets rich in fruit and vegetable intake have been associated with a reduced cancer risk as it has been found that vegetarians and vegans in general enjoy a lower risk of some cancers as well as CVD, obesity and type 2 diabetes (3). Whereas diets high in refined carbohydrates have been associated with cancer, more specifically prostate cancer and diets high in animal products and fat has an association with the high rates of colorectum and breast cancer in western diets (1, 7). An analysis of a prospective study from 10 European countries found a lower risk of cancer in a population that has higher intake of fruits and vegetables but more notably vegetables however, this was also associated in this population with lower intake of alcohol, short duration of tobacco smoking and higher levels of physical activity which all may contribute to lowering cancer risk, therefore it cannot be said that intake of fruit and vegetables alone was the reason for the results (2). There are many protective substances in fruits and vegetables such as carotenoids, flavonoids, fibre, antioxidants and more which could all work together in their protective effects so is unlikely to be down to just one single nutrient, similar to how just a diet high in fruit and vegetables may not be the only reason for reduced cancer risk (4). 

Those with higher BMI either obese or overweight have been found to have higher death rates for a lot of adult cancers, in fact BMI has been positively associated with incidence and mortality (9). A study in patients with colon cancer found those with healthy body weights ate a diet rich in fruits, vegetables and whole grains had a 42% lower risk of death than those who did not (12). Weight loss can be one strategy to apply in cancer patients as weight management is encouraged at all phases of cancer although, those diagnosed with breast cancer weight gain often occurs this is more prevalent in premenopausal women and those who are receiving chemotherapy as part of their treatment (8). Therefore, more care is needed when applying a weight management strategy in these cases. Men with prostate cancer who lose weight may also reduce their risk of a more aggressive cancer however, findings in weight loss and cancer mortality are not conclusive (9). Numerous studies say healthier diets can possibly modulate cancer risk although those with healthier diets are associated with healthier lifestyle choices (6). However, life-threatening events such as being diagnosed with cancer has been found to be a powerful agent for a lifestyle change, studies on women with breast cancer have found the majority to be interested in making healthful changes in their diet (8). It should be noted that different cancers require different nutritional approaches for example those with lymphoma may benefit differently with various supplements than patients with sarcoma (1). An example of this is Lycopene which is a carotenoid with no provitamin A activity however has been found to be very protective against prostate cancer, Lycopene can be found mostly in tomatoes as associations of high Lycopene intake have been found with reduced risk of prostate cancer (4). Whereas diets high in fibre have been associated with low rates of colorectal cancer (8). 

Cancers in children can be more complicated as it would take years for cancers to develop usually which Is why adults mostly develop cancer later on in life but being genetically predisposed to cancer can develop at the earlier ages (13). It is unknown what environmental factors interact with the genetic factors for this to develop however, depending on the cancer nutritional strategies may also be a useful tool for children. Children who are malnourished at diagnosis with solid tumours and lymphomas have poorer survival rates compared to those that are well-nourished, a good nutritional status also improved survival in children with localised disease or lymphomas but not those with advanced disease (10). Little is known about the impact of nutrition on the health of the child later on in life and the effects nutrition can have on cancer survival in children with more research required to provide conclusive evidence (13). 

There are a lot of studies saying the same that diets high in fruit and vegetables have lower risks of developing most cancers and can possibly prevent common cancers such as colon, breast, lung and prostate from being fatal. Although the evidence is not conclusive a good take away message from this blog can certainly be that a diet rich in fruits, vegetables and whole grains along with physical activity and a healthy maintenance of body weight can protect against almost all diseases including cancer. 

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• The Mediterranean Diet
• Everything You Need To Know About Vitamin E

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References

1. Bazzan, A., Newberg, A., Cho, W. and Monti, D. (2013) ‘Diet and Nutrition in Cancer Survivorship and Palliative Care’. Evidence-Based Complementary and Alternative Medicine, 2013 pp.1-12.
2. Boffetta, P., Couto, E., Wichmann, J., Ferrari, P., Trichopoulos, D., Bueno-de-Mesquita, H., van Duijnhoven, F., Büchner, F., Key, T., Boeing, H., Nöthlings, U., Linseisen, J., Gonzalez, C., Overvad, K., Nielsen, M., Tjønneland, A., Olsen, A., Clavel-Chapelon, F., Boutron-Ruault, M., Morois, S., Lagiou, P., Naska, A., Benetou, V., Kaaks, R., Rohrmann, S., Panico, S., Sieri, S., Vineis, P., Palli, D., van Gils, C., Peeters, P., Lund, E., Brustad, M., Engeset, D., Huerta, J., Rodríguez, L., Sánchez, M., Dorronsoro, M., Barricarte, A., Hallmans, G., Johansson, I., Manjer, J., Sonestedt, E., Allen, N., Bingham, S., Khaw, K., Slimani, N., Jenab, M., Mouw, T., Norat, T., Riboli, E. and Trichopoulou, A. (2010) ‘Fruit and Vegetable Intake and Overall Cancer Risk in the European Prospective Investigation Into Cancer and Nutrition (EPIC)’. JNCI: Journal of the National Cancer Institute, 102(8) pp.529-537.
3. Craig, W. (2009) ‘Health effects of vegan diets’. The American Journal of Clinical Nutrition, 89(5) pp.1627S-1633S.
4. Donaldson, M. (2004) ‘Nutrition and cancer: A review of the evidence for an anti-cancer diet’. Nutrition Journal, 3(19).
5. Forman D & Bray F (2014) ‘The burden of cancer. In The Cancer Atlas, 2nd ed.,’ [A Jemal, P Vineis, F Bray, L Torre and D Forman, editors]. Atlanta, GA: American Cancer Society. pp. 36–37
6. Grosso, G., Bella, F., Godos, J., Sciacca, S., Del Rio, D., Ray, S., Galvano, F. and Giovannucci, E. (2017) ‘Possible role of diet in cancer: systematic review and multiple meta-analyses of dietary patterns, lifestyle factors, and cancer risk’. Nutrition Reviews, 75(6) pp.405-419.
7. Key, T., Schatzkin, A., Willett, W., Allen, N., Spencer, E. and Travis, R. (2004) ‘Diet, nutrition and the prevention of cancer’. Public Health Nutrition, 7(1a) pp.187-200.
8. Rock, C. and Demark-Wahnefried, W. (2002) ‘Nutrition and Survival After the Diagnosis of Breast Cancer: A Review of the Evidence’. Journal of Clinical Oncology, 20(15) pp.3302-3316.
9. Rodriguez, C., Freedland, S., Deka, A., Jacobs, E., McCullough, M., Patel, A., Thun, M. and Calle, E. (2006) ‘Body Mass Index, Weight Change, and Risk of Prostate Cancer in the Cancer Prevention Study II Nutrition Cohort’. Cancer Epidemiology Biomarkers & Prevention, 16(1) pp.63-69.
10. Sala, A., Pencharz, P. and Barr, R. (2004) ‘Children, cancer, and nutrition – A dynamic triangle in review’. Cancer, 100(4) pp.677-687.
11. Valdés-Ramos, R. and Benítez-Arciniega, A. (2007) ‘Nutrition and Immunity in Cancer’. British Journal of Nutrition, 98(S1) pp.S127-S132.
12. Van Blarigan, E., Fuchs, C., Niedzwiecki, D., Zhang, S., Saltz, L., Mayer, R., Mowat, R., Whittom, R., Hantel, A., Benson, A., Atienza, D., Messino, M., Kindler, H., Venook, A., Ogino, S., Giovannucci, E., Ng, K. and Meyerhardt, J. (2018) ‘Association of Survival With Adherence to the American Cancer Society Nutrition and Physical Activity Guidelines for Cancer Survivors After Colon Cancer Diagnosis’. JAMA Oncology, 4(6) pp.783-790.
13. Wiseman, M. (2019) ‘Nutrition and cancer: prevention and survival’. British Journal of Nutrition, 122(5) pp.481-487.