Is Coffee One Of The Causes Of Cancer? An Outline Of A Few Basic Facts

by | Oct 21, 2019

We all know how much Americans, in particular, love a good cup of joe. The USA is in the top 25 countries for coffee consumption in the world and coffee is the second most popular drink in America. So, in 2018, when a California judge ruled that purveyors of coffee had to issue a cancer warning along with the drinks they served, there was consternation and dismay.

Coffee And Cancer Risk

In 1991, the International Agency for Research on Cancer (IARC) reported possible links between bladder cancer and coffee consumption. The IARC admitted that the evidence used at the time, however, was very limited. More recent studies have suggested that even for bladder cancer, the best available evidence does not imply that coffee is a cause.

Since 1991 there have been many more studies investigating whether there is a risk of cancer associated with drinking coffee. As more people have participated in the research, later studies show that coffee is unlikely to cause breast cancer, pancreatic cancer or prostate cancer.

In some cases, notably liver and uterine endometrial cancer, coffee has been shown to reduce the likelihood of disease. Even in the 1991 study, for 20 other cancers, the IARC concluded that there was not enough evidence to draw any conclusions one way or the other.


What Does The Research Show?

So does coffee cause cancer? In many of the clinical studies, the participants smoked as well as being heavy coffee drinkers. There is ample evidence to show that smoking is linked to cancer. When it comes to the links between coffee and cancer, however, the picture is less clear.

Once smoking is taken out of the equation, the response to the question, can coffee cause cancer, is a little more complex, although current evidence does point towards a firm “no”. When the IARC last updated their research analysis, they concentrated on other aspects of several hot beverages, not just coffee.

One concern was the temperature at which coffee, mate and other drinks are generally served.  The optimum brewing temperature for coffee is thought to be between 195 to 205 degrees Fahrenheit, or around 90.5 to 96.1 degrees Celsius. No one would suggest drinking it at this temperature, however, and in any case, personal preferences vary dramatically.

Some recent research suggests that drinking beverages at temperatures of above 149 degrees Fahrenheit or 65 degrees Celsius, can increase the risk of esophageal cancer in particular. Believe it or not, it is possible to calculate the optimum temperature at which to serve your drink to minimize the risk of scalds and maximize your enjoyment.

The temperature at which many coffee drinkers seem to enjoy the beverage best is around 140 degrees Fahrenheit, or 60 degrees Celsius. We personally like to drink our coffee on the cool side, but that’s our choice.


Can Coffee Increase The Risk of Cancer?

We’re always being told that diet is, at least in part, responsible for the increase in cancer. Cancer is the second leading cause of death worldwide. In 2018 alone, it was responsible for 9.6 million deaths. Tobacco remains the major risk factor, with lung cancer accounting for over 1.75 million of those deaths, followed by colorectal, stomach, liver and breast cancer. Other common cancers include prostate and skin cancer.

So can coffee increase the risk of any of these cancers? Let’s take a look at lung cancer as an example to investigate to what extent coffee is a carcinogen.

In an umbrella review published in 2017, initial findings suggest that high levels of coffee consumption might have links with the incidence of lung cancer. Once the figures were adjusted to exclude those who smoked, however, the findings were rather different. And for those who had never smoked, the risk of lung cancer actually diminished if they drank coffee.


Coffee Cancer Risk – The Good News

For some types of cancer, drinking coffee has actually been shown to be beneficial, reducing the risk rather than increasing it. It’s been shown that coffee drinkers are, in effect, less likely to contract colon, liver and prostate cancers, for instance.

The bigger picture is, however, a little hazy. Many of those who showed the greatest reduction in risks for particular types of cancer drank around 5 or 6 cups of coffee a day. This is rather more than is generally thought to be within the typical “safe zone”. As with so many investigations of this type, the conclusion seems to be, essentially, “we need more original research”.


Why Do People Think Coffee Might Cause Cancer?

The substance in coffee that can cause the problem is acrylamide, a chemical produced as a by-product of the roasting process. This chemical is also used in the manufacture of many items including dyes, paper, and plastic, and some studies show that it can be harmful to mice and rats.

Acrylamide is a by-product of roasting, toasting, grilling, frying, and baking. Acrylamide forms when starchy foods are cooked at temperatures in excess of 120 degrees Celsius.  It’s commonly found in French fries, toast, chips (or crisps in some parts of the world), cereals, cookies, cake, and coffee.

Coffee contains acrylamide, however, if it’s been roasted. At present, no coffee is free of the substance, although some companies are working on reducing the amount. Laboratory tests have shown that acrylamide can cause cancer in animals, which suggests to scientists that it may have the same effect in humans.

If you are concerned, you can minimize your acrylamide intake from coffee by choosing your bean carefully – Arabica beans contain less than Robusta. Filtering coffee also seems to result in lower levels of the substance than using the espresso method to brew that cup of joe, and darker roasts have lower levels of the chemical than lighter ones.


Are There Health Benefits To Drinking Coffee?

Contrary to what you might think if you only read some of the sensationalist headlines, coffee may not be one of the “baddies” in our diets. Doctors, scientists, and nutritionists are always updating their knowledge, and more recent  research and analysis have shown that drinking coffee can be beneficial for a range of conditions.

These include chronic liver disease and Parkinson’s Disease. In some situations, however, individuals are cautioned against drinking coffee: pregnant women, for instance, and those with pre-existing heart conditions.

For most of us, however, enjoying a few cups of coffee a day is not only pleasurable but can be beneficial to our health. While we tend to think of coffee in terms of caffeine, the world’s favorite caffeinated beverage is also packed with antioxidants (the “good guys” in our diets). And if you’re trying to keep your weight under control, coffee can be a godsend.

That’s before we even start on the beneficial effects of waking us up, keeping us awake, and making sure we’re at our most alert. Earlier studies didn’t always take into account the fact that many of those who drink copious amounts of coffee were also likely to be smokers, eat little fresh produce, or have a sedentary lifestyle.


Can You Keep Enjoying Your Morning Cup Of Joe?

So, after all that, what does it mean for those of us who just like a “fine cup of coffee”, first thing in the morning or at any other time of day? Can we continue to enjoy that morning cup of joe? Well, as with so many things that taste so good we worry that they might be bad for us, the answer is, yes, of course we can – ideally, in moderation.

In case you’re wondering, moderation, for a healthy adult, means around 2-3 cups of coffee a day, maybe 4 at the most. That’s 400 milligrams of caffeine at the outside. And, just to put your mind at rest a little more, the FDA has also issued guidance that we don’t need to worry too much about the levels of acrylamide in coffee.

And if you’re wondering what the state of play is on that California decision? Well, you’ll be glad to learn that, from October 2019, health warnings alongside your cup of coffee are no longer deemed necessary in the Sunshine State.


Does Coffee Cause Cancer? Our Conclusion

The jury’s still out, overall, on whether coffee causes cancer beyond all reasonable doubt, but other substances, notably tobacco, are far more carcinogenic. When many studies from the last three decades are compared, coffee does not affect your risk of many types of cancer. It may, in fact, even lower your risk for some types of the disease.

So we don’t know about you, but we’re going to continue enjoying our daily rations of coffee. Caffeinated, decaffeinated, with or without cream or sugar; and all, of course, in moderation.

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