Recently a California judge ruled that coffee increases the
risk of cancer and must carry a warning label. The decision
came as a result of a lawsuit filed against companies like Starbucks
claiming they violated the state’s Safe Drinking Water
and Toxic Enforcement Act (popularly known as Prop 65) that
requires warning labels for any food that contains a chemical
that may cause cancer.
The
main argument in the lawsuit is that coffee contains acrylamide,
which is on the list of chemicals that the state of California
says are carcinogenic. While acrylamide is used in a number
of industrial processes, it also occurs naturally in our food.
When starchy foods are heated to a high temperature, the sugar
and amino acids combine to form acrylamide. Baked, roasted or
fried food is more likely to create acrylamide than food that
is boiled, steamed or microwaved.
The
discovery in 2002 that acrylamide is present in certain foods
was concerning. It can be found in french fries and potato chips,
although no one thought these foods were all that healthy in
the first place. But acrylamide can also be found in bread,
grain products and, of course, coffee, which is why the lawsuit
was filed.
In
high doses, acrylamide can be toxic. But this toxicity is based
on studies where the acrylamide fed to lab rats and mice is
roughly 1,000-10,000 times what people would be exposed to in
food. Data linking acrylamide in food to cancer is lacking.
Nevertheless,
the plaintiffs won their case. The judge’s ruling said
that the defendants had not met the burden of proof required
to prove that coffee was safe or beneficial.
I am
baffled, truly and utterly baffled.
There
is actually a wealth of human data suggesting coffee is either
neutral or possibly beneficial in terms of cancer risk. A 2017
meta-analysis in the BMJ found the evidence suggested coffee
either had no effect or was mildly protective for many forms
of cancer.
Claiming
that coffee protects you against cancer may be overstating the
case. These studies are observational, and not randomized trials,
however it seems very clear that there is no signal for harm.
There are two exceptions that deserve attention, however. There
have been studies suggesting that coffee consumption is linked
to an increase risk of lung and bladder cancer.
The
explanation probably has to do with smoking and the concept
of confounding. Smoking increases the metabolism and clearance
of caffeine from the body, which may explain why smokers tend
to drink more coffee than non-smokers. Smoking also increases
the risk of cancer, particularly lung and bladder cancer. Therefore,
smoking serves as confounder, a variable tied to both coffee
drinking and cancer risk, and it makes it seem as if coffee
is carcinogenic. Adjusting for smoking mitigates that risk.
The
wealth of scientific data argues against coffee as a risk factor
for cancer. To label it as such is, in my mind, ridiculous.
Coffee has always contained (very low doses) of acrylamide as
a consequence of the roasting process. Acrylamide in high doses
is toxic; the drinking of coffee is not.
The
consequence of repetitive health scares like “cell phones
cause cancer” and “smoked meat is as dangerous as
smoking” have unfortunately left the public numb to health
news. People now cynically say that everything causes cancer.
The problem with putting warning labels on everything is that
eventually people just ignore the labels.
I am
also worried that questions of science are being decided in
courtrooms rather than research labs. By the same token, doctors
and scientists should not start practising law. Too many innocent
people would end up in jail, and too many harmless things would
become labeled as dangerous.
