Coffee & Potential in Health
Coffee and its possible health related potential: molecular mechanisms
It has been estimated that about 8 million people die each year to cancer related illness, of which 57% male 43% female (Siegel, R., Ma, J., Zou, Z., & Jemal, A. 2014). Nearly half of all cancer related deaths worldwide are caused by lung, stomach, liver and bowel cancers (Ferlay, J., Soerjomataram, I., Dikshit, R., Eser, S., Mathers, C., Rebelo, M., & Bray, F. 2015). Cancer is certainly global but emerging patterns show higher incidence in low-middle income developing countries. In a study published in The Lancet by Vineis, P., & Wild, C. P. (2014) have found that the risk factors that cause a third of all cancers are largely preventable. Primary prevention in terms of health, diet and lifestyle related topics could be most effective and easily relayed through media and educational campaigns to the target specific groups. The World Cancer Research Fund/American Institute for Cancer Research groups report on food-nutrition and its role in prevention have unequivocal evidence linking diet and nutrition to cancer prevention (Mayne, S.T.2015). The three key phases of how cancer affects the host are Initiation; Mutation in particular cellular genes which have direct control of the key regulatory pathways specific to function of the cell. Promotion; selective growth is initiated within the cell and continual growth due to chronic exposure to the promoting agent. Progression; is the term where the chromosomes evolve and further mutate due to the instability and spread as detailed in fig (1.1) (Benigni, R., & Bossa, C.2011).
Fig 1.1. Mechanisms of chemical carcinogenicity and mutagenicity (Benigni, R., & Bossa, C.2011).
With new technological advances especially in biological and genomics the understanding of cancer growth mechanisms and also potential functional food compounds as anti-carcinogenic agents are now being realised. One such functional food is the humble coffee bean. Coffee is one of the world’s key commodities and second most popular drink globally (Food and Agricultural Organization. 2015). Coffees relationship with several chronic diseases and the risk of mortality has been well examined with potential in numerous health related outcomes (Ding, M., Satija, A., Bhupathiraju, S. N., Hu, Y., Sun, Q., Han, J., & Hu, F. B. (2015). Coffee and its relationship with cancers have been extensively researched over the past decades with various results from low to moderate risk to inverse associations and beneficial (Tavani, A., & La Vecchia, C. 2000). This relationship between coffee and cancer has grown in interest as coffee may hold potential due to its abundance of bioactive compounds such as polyphenols and other possible compounds yet to be discovered. In this review I will examine coffees composition in relation to its chemo-protective effects and biological mechanisms of action. I will review the relevant evidence in relation to coffee and its beneficial effects on colorectal cancer.
Coffee composition and Biological effects:
The roasting of the coffee bean releases thousands of bioactive chemicals many of which may have a direct biological action on cancer sites and some showing evidence on suppression of cancerous tumours developing further (Waladkhani, A. R., & Clemens, M. R. 1998). These compounds have been identified and are present to varying degrees depending on processing, roasting and brewing techniques. As this roasting process results in chemical change within the bean so too does the ant oxidative potential rate. In a study by Del Pino-García, R., González-SanJosé, M. L., Rivero-Pérez, M. D., & Muñiz, P. (2012) three roasting variants (light, medium, dark) were analysed in instant coffee and the polyphenols biological presence of these melanoidins shown to have effects on gastrointestinal digestion. This effect was largely due to their total antioxidant capacity, protection against lipid peroxidation, DNA oxidative damage, hydroxyl scavenger ability, all of which have genoprotective effects to some degree depending on type, roasting time and temperature as shown in Fig (1.2).
Fig 1.2 Influence of the Degree of Roasting on the Antioxidant Capacity and Genoprotective Effect of Instant Coffee (Del Pino-García, R., González-SanJosé, M. L., Rivero-Pérez, M. D., & Muñiz, P. 2012).
These specific active compounds of interest are the alkaloids in caffeic acid and trigonelline, chlorogenic acids, meloanoidins; cafestol and kahweol (Ludwig, I. A., Clifford, M. N., Lean, M. E., Ashihara, H., & Crozier, A.2014; Lee, J. H., Khor, T. O., Shu, L., Su, Z. Y., Fuentes, F., & Kong, A. N. T. 2013). Caffeic acid is directly associated with inhibiting pathways in cancer development via stress and inflammatory reduction, cell cycle regulation by inhibiting DNA methylation (Fang, M., Chen, D., & Yang, C. S. 2007). The chlorogenic acid also contributes to overall anti-oxidative action of coffee but also has been shown to increase insulin sensitivity and reduce resistance directly linked to reduced risk of cancer site development (Trevisan, M., Liu, J., Muti, P., Misciagna, G., Menotti, A., & Fucci, F. 2001). The two other major components found to have anti-carcinogenic properties are cafestol and kahweal (Cavin, C., Holzhaeuser, D., Scharf, G., Constable, A., Huber, W. W., & Schilter, B. 2002). Their ability to induce enzymatic action at phase II which directly stimulates intracellular anti oxidative defence mechanisms found to inhibit carcinogenic activity (Liang, N., & Kitts, D. D. (2014). These phytochemicals together have been found to inhibit oxidative damage, increase cellular defence by signalling pathways which protect against ROS and reactive carcinogens, induce DNA repair, remove damaged cells and inhibit certain proteins involved in angiogenesis and adhesion see fig 1.3 (Bøhn, S. K., Blomhoff, R., & Paur, I. 2014; Lee, J. H., Khor, T. O., Shu, L., Su, Z. Y., Fuentes, F., & Kong, A. N. T. 2013; Ramos, S. 2008).
Fig 1.3. Coffee and cancer development epidemiological evidence, and molecular mechanisms (Bøhn, S. K., Blomhoff, R., & Paur, I. (2014).
Evidence and Colorectal cancer:
In the Fukuoka colorectal cancer study a community based case-control study in Japan a cohort of over 800 subject cases with colorectal cancers and same amount subjects in control group were assessed on consumption of 148 food items (Wang, Z. J., Ohnaka, K., Morita, M., Toyomura, K., Kono, S., Ueki, T., & Terasaka, R. 2013). Over ninety of the foods were specifically analysed in a database for polyphenol content and the dietary intake of polyphenols in coffee and tea was estimated and Odds ratio (OR) risk associated with colorectal cancer in each case analysed. Adjustments were made for age, sex, residence, parental history, diet and physical activity levels. The result for colorectal cancers (463) and 340 rectal cancer found an inverse relationship between coffee polyphenols all cause colorectal cancer depending on quintile of polyphenol intake. This study of a large cohort suggests an overall decreased risk of colorectal cancer which was found to be associated with higher coffee consumption. Similarly in a large Diet and health study in United States the NIH-AARP administered via questionnaire to over 480,000 men and women over a ten year follow up on Colorectal cancers (Sinha, R., Cross, A. J., Daniel, C. R., Graubard, B. I., Wu, J. W., Hollenbeck, A. R., & Freedman, N. D. 2012). The results also found that coffee intake especially >3 cups but <6 cups were also inversely associated with colorectal cancer tumours.
The overall epidemiological evidence between polyphenol intake from coffees and colorectal cancer is inconsistent largely due to prior study findings and also advances in research technology and experimental studies of more recent years finding new evidence to support the hypothesis of coffee being protective against certain cancers. However the European prospective investigation into cancer (EPIC) cohort study again with over 477,000men and woman over ten European countries also aimed to explore the association between polyphenol intake and cancer risk (Zamora-Ros, R., Romieu, I., Scalbert, A., & EPIC Study group. 2015). Complex analysis of polyphenol intake was conducted and associated risk factors to colorectal cancer were generated. Inherently coffee and tea were identified as important food sources of polyphenols in the research results. The findings also have found that increased coffee intakes were consistently associated with lowered risk of colorectal cancer and results were substantial and statistically significant.
In early research findings regarding coffee consumption an increased risk of various cancers was generally accepted (Arab, L. 2010). However now more comprehensive data from both case controls, perspective, experimental studies and epidemiological evidence show a shift in direction to more positive and beneficial aspectsof coffee on some cancers relative risk (Nkondjock, A. 2009). In large cohort groups the protective nature of coffee as an agent which can reduce overall risk with colorectal cancer has been outlined. This review also outlined mechanisms which coffee inhibits and reduces key aspects of cancer formation and progression. It is also clear that new and emerging experimental evidence will be required to further outline key and fundamental aspects to how coffee and its components can have beneficial effects on health and diseases such as cancers and in particular dose responses relative to this fascinating topic.
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