Dec. 23, 2024

Drinking Coffee and Tea and the Prevention of Cancer

Coffee and tea are widely consumed around the world and for decades researchers have attempted to investigate and analyze the protective health benefits of them. Although the association between health and coffee and tea consumption is not new, there are still no conclusive answers. [1]

What is clear is that numerous studies have shown that coffee drinking is associated with an overall lower risk of dying from all causes of death. Systematic reviews and meta-analysis found a trend towards a protective effect of coffee, linking it to a lower risk of Alzheimer's disease [2], dementia [3] Parkinson's disease, [4][5], and T2DM.[6]

However, the association with specific types of cancer remains unclear and, according to the American Cancer Society (ACS), the potential ways in which coffee may lower the risk of cancer are not completely understood.[1]

Unclassifiable

According to the International Agency for Research on Cancer (IARC)*, the link between coffee consumption and cancer risk, and "coffee as a carcinogenic" is still unclassifiable.[1]

Based on their analysis published in 2016, the IARC concluded that coffee consumption is not associated with the development of (female) breast cancer, pancreatic cancer, or prostate cancer, but may reduce the overall risk for uterine, endometrium, and liver cancers. [1]

They also found that coffee drinking is not a cause of female breast, pancreas, and prostate cancers, but may reduce the risk of uterine endometrium and liver cancers. The evidence was judged to be not convincing and inadequate for many other types of cancer types.

Coffee and Cigarette Smoking

In other cases, the link between coffee consumption and cancer is difficult to ascertain. One reason is that people who drink coffee may also smoke cigarettes, linking traditionally tobacco-related cancers to the consumption of coffee.

For example, researchers found that coffee may be linked to an increased risk of bladder cancer. However, their results were inconsistent and with a possible association depending on a residual confounding effect of smoking, rather than the consumption of coffee. [7]

An epigenome-wide association study on coffee and tea consumption in 15,789 people of European and African American ancestry by scientists at the IARC, published in May 2021, revealed 11 specific epigenetic (DNA methylation) changes that are significantly associated with coffee consumption and 2 changes that are associated with tea consumption.[8]

The scientists found that among the genomic regions that are significantly associated with coffee consumption, identify genes associated with hepatic lipid metabolism, suggesting that coffee-associated epigenetic variations may explain the mechanism of action of coffee consumption in modulating disease risk.[8]

However, the scientists also found that one of the methylation markers associated with coffee consumption overlapped with smoking-specific markers. These markers may be related to chemicals formed during coffee-roasting processes, including acrylamide (also known as acrylic amide)**. [8][15] In their analysis, the investigators accounted for smoking status, given that cigarette smoking is often associated with drinking coffee and that smoking has a notable effect on DNA methylation.[8]

Tea and health

Next to water, tea is the most widely consumed beverage around the globe. Epidemiological, in vitro, and in vivo animal studies have shown that the consumption of tea,*** including black tea (fermented,) green tea (unfermented), or oolong tea (semi-fermented), inhibits tumorigenesis. [9][10][11][12]

The main active components in tea are a type of polyphenols known as flavonoids, including catechins and theaflavins. Numerous animal studies as well as epidemiological studies investigating the link between drinking tea and the development of cancer in humans, suggest that through several mechanisms, tea polyphenols present antioxidant and anticarcinogenic activities and may inhibit the development of prostate cancer and breast cancer. [13]

Other studies have demonstrated that green tea polyphenol epigallocatechin-3-gallate (EGCG) causes a G0/G1-phase cell cycle arrest and apoptosis in human epidermoid carcinomas (also called squamous cell carcinoma).[10]

While many different mechanisms have been considered, including the modulation of signal transduction pathways (i.e. growth factor-mediated, mitogen-activated protein kinase (MAPK)-dependent, and ubiquitin/proteasome degradation pathways) that lead to the inhibition of cell proliferation and transformation, induction of apoptosis of preneoplastic and neoplastic cells, and inhibition of tumor invasion as well as angiogenesis, have been proposed explaining the inhibition of carcinogenesis by tea, most studies have not resulted in definitive conclusions about the protective effects of tea consumption against cancer in humans. Most studies confirm that the preventive potential of naturally occurring tea polyphenols against cancer has still to be evaluated in clinical intervention in human trials. [12]

Head & Neck Cancer

A recent pooled analysis of data from more than a dozen studies suggests that coffee and tea consumption may have a potentially protective effect, linking it with lower risks of developing head and neck cancer, including cancers of the mouth and throat.

These findings were published by Wiley online in CANCER, a peer-reviewed journal of the American Cancer Society (ACS).[15]

Head and neck cancer is the seventh most common cancer worldwide, and rates are rising in low- and middle-income countries. Many studies have assessed whether drinking coffee or tea is associated with head and neck cancer, with inconsistent results. To provide additional insight, investigators examined data from 14 studies by different scientists associated with the International Head and Neck Cancer Epidemiology Consortium, a collaboration of research groups around the globe.[15]

Study participants completed questionnaires about their prior consumption of caffeinated coffee, decaffeinated coffee, and tea in cups per day/week/month/year.

When investigators pooled information on 9,548 patients with head and neck cancer and 15,783 controls without cancer, they found that compared with non-coffee-drinkers, individuals who drank more than 4 cups of caffeinated coffee daily had 17% lower odds of having head and neck cancer overall, 30% lower odds of having cancer of the oral cavity, and 22% lower odds of having throat cancer.

Drinking 3–4 cups of caffeinated coffee was linked with a 41% lower risk of having hypopharyngeal cancer (a type of cancer at the bottom of the throat).

Decaffeinated drinks

Drinking decaffeinated coffee was associated with 25% lower odds of oral cavity cancer. Drinking tea was linked with 29% lower odds of hypopharyngeal cancer. Also, drinking 1 cup or less of tea daily was linked with a 9% lower risk of head and neck cancer overall and a 27% lower risk of hypopharyngeal cancer, but drinking more than 1 cup was associated with 38% higher odds of laryngeal cancer.

“While there has been prior research on coffee and tea consumption and reduced risk of cancer, this study highlighted their varying effects with different sub-sites of head and neck cancer, including the observation that even decaffeinated coffee had some positive impact,” said senior author Yuan-Chin Amy Lee, PhD, of Huntsman Cancer Institute and the University of Utah School of Medicine.

“Coffee and tea habits are fairly complex, and these findings support the need for more data and further studies around the impact that coffee and tea can have on reducing cancer risk,” Lee concluded.

Note:* The International Agency for Research on Cancer (IARC) is a part of the World Health Organization (WHO) that coordinates and conducts research on the causes of human cancers, including the mechanisms of carcinogenesis

** Acrylamide or acrylic amide (C₃H₅NO) is a white, odorless, crystal compound.[3] It is known to be a neurotoxin in humans and the IARC classifies it as a “probable human carcinogen," however, based on epidemiologic studies, the American Cancer Society (ACS) believes that dietary acrylamide isn’t likely to be related to risk for most common types of cancer.[12][16]

*** In this article we refer to tea from Camellia sinensis, which belongs to the family Theaceae.

Reference

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[7] Alicandro G, Tavani A, La Vecchia C. Coffee and cancer risk: a summary overview. Eur J Cancer Prev. 2017 Sep;26(5):424-432. doi: 10.1097/CEJ.0000000000000341. PMID: 28288025.

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[12] Khan N, Mukhtar H. Tea polyphenols for health promotion. Life Sci. 2007 Jul 26;81(7):519-33. doi: 10.1016/j.lfs.2007.06.011. Epub 2007 Jun 28. PMID: 17655876; PMCID: PMC3220617.

[13] Tareke E, Rydberg P, Karlsson P, Eriksson S, Törnqvist M. Analysis of acrylamide, a carcinogen formed in heated foodstuffs. J Agric Food Chem. 2002 Aug 14;50(17):4998-5006. doi: 10.1021/jf020302f. PMID: 12166997.

[14] Nguyen T, Koric A, Chang CE, Barul C, Radoi L, Serraino D, Purdue MP, Kelsey KT, McClean MD, Negri E, Edefonti V, Moysich K, Zhang ZF, Morgenstern H, Levi F, Vaughan TL, La Vecchia C, Garavello W, Hayes RB, Benhamou S, Schantz SP, Yu GP, Brenner H, Chuang SC, Boffetta P, Hashibe M, Lee YA. Coffee and tea consumption and the risk of head and neck cancer: An updated pooled analysis in the International Head and Neck Cancer Epidemiology Consortium. Cancer. 2024 Dec 23. doi: 10.1002/cncr.35620. Epub ahead of print. PMID: 39711146.

[15] González de Mejía E. El efecto quimioprotector del té y sus compuestos [The chemo-protector effects of tea and its components]. Arch Latinoam Nutr. 2003 Jun;53(2):111-8. Spanish. PMID: 14528600.

[16] Acrylamide and Cancer Risk. American Cancer Society (ACS). Online. Last accessed on December 23, 2024.

This article was first published in Onco'Zine on December 23, 2024

DOI 10.14229/onco.2024.12.23.001