A new study declares that drinking coffee may decrease a person’s risk of developing and dying of liver diseases including cancer, but it is not quite cause to drop everything and dash down to Dunkin.
This latest attempt to present coffee as a cure-all appeared in BMC Public Health, a peer-reviewed journal that is published in Great Britain. The authors tracked 494,585 participants between the ages of 40 and 69 over the course of 11 years. Of that group, 384,818 were coffee drinkers and 109,767 were non-coffee drinkers.Read More
“During a median follow-up of 10.7 years, there were 3,600 cases of incident Chronic Liver Disease (CLD), 5,439 cases of incident CLD or steatosis, 184 cases of incident hepatocellular carcinoma (HCC) and 301 deaths from CLD. Compared to non-coffee drinkers, coffee drinkers (all types and amounts combined) had 21, 20 and 49% reduced risks of incident CLD, incident CLD or steatosis and death from CLD, respectively,” reads the study.
“The maximal protective effect was seen at around 3–4 cups each day.”
One issue with the study is that the participants were pulled from the UK Biobank, a biomedical database whose membership is disproportionately white. A 2019 study published by Teri A. Manolio, M.D., Ph.D, director of the Division of Genomic Medicine at the National Human Genome Research Institute said that studies pulling from these databases only served a small and specific group of people.
“Euro-centricity of genomic research has serious implications for the health and medical care of non-(european ancestry) populations, as it increases the likelihood non-EA individuals will receive inconclusive results of genetic testing or, worse, erroneous interpretations of genomic variants,” wrote Manolio.
That study, which was published in Science Direct, also revealed the ethnic breakdown of Biobank participants. Manolio pointed out that this was a group with 500,000 members, “88% of whom self-identified as being of white British ethnic background and another 6% as other white background.” Of the remaining six percent, “9400 were self-reported “Asian or Asian British ethnic background (mostly from the Indian subcontinent)” and more than 7,600 were “Black or Black British.”
This means there was virtually no Latinx representation, a group that makes up close to 20 percent of the US population. The study notes that the group was largely middle to upper-middle class.
Finally, the study also assumes that participants’ coffee habits did not change over the 11 years of the study, basing coffee consumption on how registrants answer that question at the time they joined the UK Biobank.
What Is The Link Between Coffee And Cancer?
The heated debate began in 2010, when a California-based group called the Council for Education and Research on Toxins sued the coffee industry in the state of California for not including warning labels to alert consumers about the presence of a chemical called acrylamide, which has been linked to cancer in animals in high doses.
Because acrylamide is one of many chemical compounds generated in coffee’s brewing process, the Council for Education and Research on Toxins said in their lawsuit, California’s Office of Environmental Health Hazard Assessment should include coffee in their Proposition 65 law, requiring sellers to list the cancer warning on their products, and for the state to include coffee on a list of potentially toxic chemicals.
The lawsuit stirred up years of debate while the Los Angeles Supreme Court weighed the evidence. Then in March of last year, the Los Angeles judge finally sided with the pro-warning group, deciding that coffee should indeed carry the ominous label.
But then came the backlash from legitimate health agencies and groups such as the U.S. Food and Drug Administration (FDA) and the World Health Organization (WHO), along with doctors and scientists across the country that decried the unnecessary warning, arguing that the presence of acrylamide is not likely to cause cancer. Some pointed out that doctors and researchers should be the ones deciding this lawsuit, not the L.A. judge.
Shortly after the judge issued the ruling, then-FDA Commissioner Dr. Scott Gottlieb issued a statement saying that adding the Proposition 65 warning to coffee would mislead consumers more than it would benefit them. He explained his argument in a science-backed statement:
“Acrylamide can form in many foods during high-temperature cooking, such as frying, roasting and baking. Acrylamide in food forms from sugars and an amino acid that are naturally present in food. It doesn’t come from food packaging or the environment. In coffee, acrylamide forms during the roasting of coffee beans. Although acrylamide at high doses has been linked to cancer in animals, and coffee contains acrylamide, current science indicates that consuming coffee poses no significant risk of cancer.”
The current science Dr. Gottlieb referenced wasn’t one study alone, but more than 1,000 studies, which were included in a comprehensive report by the WHO’s International Agency for Research on Cancer (IARC).
The overall consensus was that coffee does not cause cancer.
Not only is the acrylamide in coffee not scientifically known to be a carcinogen (the agency calls it a “probable” carcinogen, but has never proven it), but the cancer-preventing elements of coffee may actually outweigh any trace amounts of risk at all.
Following the WHO report and the FDA’s involvement, California exempted coffee from the warning label law.
“Coffee is a complex mixture of hundreds of chemicals that includes both carcinogens and anti-carcinogens,” Sam Delson, a spokesman for California’s Office of Environmental Health Hazard Assessment told the Associated Press, further confirming the consensus. “The overall effect of coffee consumption is not associated with any significant cancer risk.”
Wait… Does This Mean All These Studies Are Misleading?
Not necessarily. Our SurvivorNet team of experts has taken a close look at these studies in the past, and what we found was while many of these studies were coming out of legitimate institutions with legitimate researchers, they were observational in nature, meaning they could only observe people’s coffee-drinking habits and cancer incidence side-by-side, but could not prove any sort of causality between the two.
For example, in 2019 we looked at a study by researchers at Vanderbilt University that highlighted a link between coffee and lung cancer. Though the study found that people (non-smoking people, that is) who drank two or more cups of coffee per day had a higher risk of developing lung cancer than those who didn’t, we noticed that the researchers could not say that this higher risk was because of the coffee. And they didn’t take note of other known cancer-causing variables, either, like exposure to second-hand smoke.
Long story short, if you’re one of the 64 percent of U.S. adults that drinks at least one cup of coffee per day, you can go back to enjoying your beverage.
Contributing: Caroline Hopkins