Cancer, Diary of a bodacious dietitian, Nutrition

Coffee and acrylamide: Should we really be worried coffee may cause cancer?

A judge in California ruled that Starbucks must now put a warning label on our cup of Joe. Why? To inform us that drinking their coffee may raise our risk of cancer.

Gasp. Shock. Pour cold water over my head. I had to investigate!


As obvious from my previous post about the benefits of java, I adore coffee. My whole family does. It makes us more interesting. For example, my mom is a famously odd house guest because of her coffee addiction.

Dr. P to my mom: Umm, what are you doing over there?

Mom to Dr. P as she plays around with the Nespresso machine at 11 o’clock at night: I need a shot of espresso to get the energy to get ready for bed.

Dr. P: You are insane.


She once went through 37 Nespresso capsules in a single 4-day visit. After that, Dr. P bought her a Nepresso machine of her own (son-in-law points abound), but I think it may have been a ploy to teach her how expensive the espresso capsules really were.

My sister is also an avid drinker. She loves coffee so much she married a Bean. Mr. Bean, that is. And no, he’s not British.

Dr. P is also not immune. He likes to make a “DrP-achhino”. Coffee with a shot of espresso in it.

Common colloquialisms in our family use coffee shops’ geographical locations as verbs. “Hey! Let’s bottom of the hill” or “I want to plaza“.

If coffee causes cancer, we are doooomed.espresso

So what is the problem?

News stories are spilling forth with one word: acrylamide.

It sounds like a sneeze to me. AAAAAcylllamiiiide.

Bless you.

According to the National Cancer Institute, it’s a light weight and water-soluble Group 2A carcinogen (probably carcinogenic to humans) that we’ve known about since the 1950s, but historically, it’s an environmental toxin and a carcinogenic component in tobacco smoke.

Acrylamide is metabolized to glycidamide which is genotoxic and causes DNA changes in our cells.

What we know about it is mostly from animal studies. In rodents, when acrylamide is introduced at levels >203 mg/kg (that is MILLIGRAM per kilogram) it causes developmental and reproductive abnormalities in rat neonates. Human studies, however, aren’t finding a consistent correlation.

Two large-scale prospective studies found no association between breast cancer and acrylamide intake, while another study found a weak association. Overall, there isn’t strong evidence in epidemiological studies, because it is difficult to study exact intake and exposure. Smoking is also a confounder, because smokers have 3 to 5 times the levels of acrylamide in their systems.

There is one concerning study I came across, though, that found an increased risk of endometrial and ovarian cancer with high acrylamide intake as compared to a group with low intake. This same study did not find an increased risk of breast cancer.

Even with this one concerning study, it wasn’t focused on coffee, per se, but intake overall. I needed more information.

latteSo how does acrylamide end up in our food?

Acrylamide forms in food through cooking. Here’s what happens:

  • A carbohydrate-rich food has the amino acid asparagine present (such as potato)
  • The amino acid then reacts with a reducing sugar such as sucrose and fructose
  • There is low moisture as in dry cooking, grilling, frying
  • High temperatures are present
  • Longer cooking time allows for greater acrylamide content

In 2002, the Swedish National Food Agency and the University of Stockholm put out a report on the content of acrylamide levels in foods. Potato crisps, French fries, breakfast cereals, coffee, biscuits, and even jarred baby food were on the list.

Another report listed the greatest food sources as French fries and potato chips; crackers, bread, and cookies; breakfast cereals; canned black olives; prune juice; and coffee.

Gingerbread also has surprisingly high levels. I was bummed about that.

In a 2008 study, mashed roasted potato was the worst offender with 8,974 μg/kg compared to 816 μg/kg in coffee and 282 μg/kg in roasted Turkish coffee (that is MICROGRAMS, not MILLIGRAMS- see above. They were using MILLIGRAMS in animal research exposure studies). In roasted almonds, the average acrylamide content is 582 μg/kg, with other nuts having levels between 196 and 357 μg/kg.

A recently study done in Turkey found potato crisps had 834 μg/kg as compared to a Chinese study where potato crisps had 3016 μg/kg. Huge difference, right?

It’s an imperfect measurement, because the levels vary based on amino acid and sugar content of that exact food being measured which is determined by level of ripeness, agricultural factors, additives and ingredients, and it is also affected by temperature and cooking method.

And these studies are looking at what is in the food- not the average intake. Here is the dietary intake in one study from each of the food groups (notice how it is a lot less):

acrylamide levels in foods

Chart from this study:

One thing that is obvious to me, however, is the levels in animal studies are far higher than what we are finding in our food.

drinking coffee

Other research: “Coffee is ok”

Coffee can cause apoptosis in human cancer cells.

Apoptosis, btw, is one of my fav science-y words- it means “cell death”.

Effectively, the cell recognizes something isn’t right and commits suicide for the greater good. Essentially, coffee causes cancer cells to die. The polyphenolic compounds in coffee seem to have a leg up on the acrylamide.

In 2016, 23 scientists around the world gathered for the International Agency for Research on Cancer. Their goal? Discuss whether coffee caused cancer. They decided that… no, no, it does not.

Five large-scale cohort studies and a meta-analysis looking at coffee and endometrial cancer showed an inverse relationship- the more you drank, the more protected you were.

There was also a 15% decreased risk of liver cancer for every cup of coffee. And for breast cancer? A slight protective effect.

There was not enough evidence for 20 other cancers to say there was any risk at all. And in recent well-designed randomized controlled trials (the “Gold Standard” in research), a strong antioxidant effect was found.

With all this evidence pointing towards a protective effect, despite the acrylamide level, the scientists deemed coffee “unclassifiable as to its carcinogenicity” or a Group 3- the same as tea.


So acrylamide, at high levels, is carcinogenic to animals and probably humans. It’s in some foods- coffee included- and more research is needed to determine the level at which it becomes carcinogenic to humans.

The average intake in humans is far less than the problematic level in animal studies.

And in the evidence we have pointing toward a link between dietary acrylamide intake and cancer, like the one concerning study I read about endometrial and ovarian cancer, the levels of acrylamide could be more likely due to commonly eaten, high-level foods like roasted potatoes or French fries.

Coffee-as a whole- contains compounds and polyphenols that are protective to humans, and it’s not carcinogenic, according to experts. For some people, coffee is the greatest source of antioxidants in their diet.

So why is a California Judge making us label our coffee with a warning?

Acrylamide isn’t good. But are we going to put warning labels on potatoes, too? And gingerbread cookies? Where does it end?

My concern is this premature labeling (we need more research!) only serves as a confusion-promoter.

I think this Judge made a mistake. And not just because, as we know, I love coffee. But because a hazard sticker may be more dangerous than the actual problem it is warning against.

xoxo Joanna


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