Are you someone who just can’t get started in the mornings without coffee? If so, you might be wondering whether it’s associated with a higher risk of cancer or whether it’s safe to drink during and after treatment. There have been conflicting stories in the media for years over whether it’s a safe drink or not, so let’s take a look at what the evidence says.

Understand the Research on Coffee and Cancer Risk

Most of the research done is epidemiological. These studies take a large population and ask the participants to record what they ate and drank over a specified period, and also record data about their age, weight, diet and lifestyle.

A couple of recent reviews concluded that coffee had a protective effect against most cancers, with the exception of cancer of the oesophagus (1), (2). It was suggested that the oesophagus might have been damaged by drinking hot coffee and that the subsequent chronic inflammation could have resulted in cancer cells forming. Alternatively, they suggested that coffee could have caused reflux, as it is a common trigger, and that this might have irritated the lining of the oesophagus and also resulted in carcinogenesis.

The problem with epidemiological studies is that they don’t always take into account other factors that could contribute to disease, particularly diet. Someone who eats meat, for example, might either eat organic meat that’s cooked in a healthy way or live on hamburgers cooked in vegetable oils that are unhealthy.

An alternative method was used by a study in 2022 (3). They looked at the genetics of the people involved and whether they had a genetic tendency to drinking coffee and for the likelihood of certain cancers. They were then adjusted for genetic differences affecting Body Mass Index (BMI), likelihood of smoking and also alcohol consumption, which are all factors that can increase the risk of cancer.

The results of this study again showed that there was an association between a genetic likelihood of drinking coffee and the risk of developing oesophageal cancer. This time, they found a link between a higher risk of developing pancreatic cancer and multiple myeloma, and the likelihood of drinking coffee. But they also found that there was a protective effect on ovarian cancer.

Another interesting piece of epidemiological research looked at the effect of coffee drinking on women who had been diagnosed with Stage I to III breast cancer (4). This was a very large study involving 8,900 women over a period of 30 years. They found that drinking more than 3 cups of coffee a day after diagnosis was associated with a significantly higher survival rate both from breast cancer and all other causes. They also discovered that decaffeinated coffee had similar effects but slightly less so.

Why does coffee have any effect on cancer?

Coffee is very high in various chemicals which could have an effect on cancer outcomes. These include caffeine and polyphenols, a kind of antioxidant. In 2005, a report showed that coffee was the main source of antioxidants in the American diet, providing the average American with nearly 1,300 mg daily from polyphenols, with black tea and bananas in 2nd and 3rd place providing about 25% and 6% of that amount respectively (5).

Both caffeinated and decaffeinated coffee also lower blood levels of C-peptide, a chemical that is a marker for inflammation and insulin resistance, which can both contribute to cancer growth (4).

What to consider before drinking coffee for cancer prevention

There are some things to consider if you’re planning to drink coffee, some of which I cover in my book.

Firstly, use non-dairy milk if you prefer white coffee. Cow’s milk has been shown to increase cancer risk (6).

Consider using a lighter roast to reduce acrylamides, which also has been found in some studies to increase the risk of cancer, particularly breast, endometrial and ovarian cancers (7). The evidence on this is very mixed, though, and the International Agency for Research on Cancer (IARC) has recently announced that they are planning to re-evaluate the link between acrylamides and cancer (7). It remains to be seen whether they reclassify it from their original assessment in 1994 that acrylamides were a probable human carcinogen. If you want to reduce the amount of acrylamides you consume from coffee, one study suggested that instant coffee has about twice as much acrylamide as natural roasted coffee (8). Coffee substitutes, like roasted chicory, were even higher than instant coffee (8).

Don’t add sugar to your coffee. If you must sweeten it, use monk fruit or stevia in preference to other sweeteners. I discuss why these are best in this article and in my book. Sugar provides a good source of energy for cancers.

Are there any drawbacks to drinking coffee?

If your sleep is affected by coffee drinking, avoid drinking it after lunch. That way, your body will probably have broken it down by the time you go to bed. If that doesn’t help, then you might want to consider drinking decaffeinated instead. Sleep is really important to all of us, but to cancer patients it’s crucial.

Coffee can cause significant problems for people who suffer from anxiety, as it can cause the jitters, heart palpitations and even panic attacks. If you fall into this category, you may even find that decaffeinated coffee is problematic. If that’s the case, try drinking tea, particularly green tea, which also contains antioxidants but significantly less caffeine.

Coffee is a diuretic and so it can raise blood pressure (9). Generally speaking, it eventually stabilises but you might end up with a rise of 1-2 mmHg, which could be a problem if you have high blood pressure that isn’t well controlled.

If you suffer from gastro-oesophageal reflux disorder (GORD), you are probably aware that it can make the problem worse. Decaffeinated coffee significantly reduces the problem (10).

Pregnant women should cut down on coffee consumption or drop it completely.

You can find much more advice like this on diet and lifestyle in my book. If you’d like to buy the book, click on the button below.

References

1.      Gapstur SM, Anderson RL, Campbell PT, et al. Associations of coffee drinking and cancer mortality in the cancer prevention study-II. Cancer Epidemiology, Biomarkers & Prevention. 2017;26(10):1477-1486. doi:10.1158/1055-9965.epi-17-0353

2.      Ismail T, Donati-Zeppa S, Akhtar S, et al. Coffee in cancer chemoprevention: An updated review. Expert Opinion on Drug Metabolism & Toxicology. 2020;17(1):69-85. doi:10.1080/17425255.2021.1839412

3.      Carter P, Yuan S, Kar S, et al. Coffee consumption and cancer risk: A mendelian randomisation study. Clinical Nutrition. 2022;41(10):2113-2123. doi:10.1016/j.clnu.2022.08.019

4.      Farvid MS, Spence ND, Rosner BA, Willett WC, Eliassen AH, Holmes MD. Post-diagnostic coffee and tea consumption and breast cancer survival. British Journal of Cancer. 2021;124(11):1873-1881. doi:10.1038/s41416-021-01277-1

5.      Schor J. Coffee lowers risk of breast cancer recurrence. Natural Medicine Journal. https://www.naturalmedicinejournal.com/journal/coffee-lowers-risk-breast-cancer-recurrence. Published August 4, 2021. Accessed January 6, 2023.

6.      Fraser GE, Jaceldo-Siegl K, Orlich M, Mashchak A, Sirirat R, Knutsen S. Dairy, soy, and risk of breast cancer: Those confounded milks. International Journal of Epidemiology. 2020;49(5):1526-1537. doi:10.1093/ije/dyaa007

7.      Hogervorst JG, Schouten LJ. Dietary acrylamide and human cancer; even after 20 years of research an open question. The American Journal of Clinical Nutrition. 2022;116(4):846-847. doi:10.1093/ajcn/nqac192

8.      Mojska H, Gielecinska I. Studies of acrylamide level in coffee and coffee substitutes: influence of raw material and manufacturing conditions. Rocz Panstw Zakl Hig. 2013;64(3):173-181. doi:PMID: 24325083

9.      Noordzij M, Uiterwaal CSPM, Arends LR, Kok FJ, Grobbee DE, Geleijnse JM. Blood pressure response to chronic intake of coffee and caffeine: A meta-analysis of randomized controlled trials. Journal of Hypertension. 2005;23(5):921-928. doi:10.1097/01.hjh.0000166828.94699.1d

10.    Wendl B, Pfeiffer A, Pehl C, Schmidt T, Kaess H. Effect of decaffeination of coffee or tea on gastro-oesophageal reflux. Alimentary Pharmacology & Therapeutics. 1994;8(3):283-287. doi:10.1111/j.1365-2036.1994.tb00289.x