Coffee causes cancer. Coffee prevents cancer. Who to believe?

California might soon start requiring Starbucks to warn its customers that coffee causes cancer. Has  California gone nuts, or is there something to this?

A lawsuit filed in 2010 by a group called the Council for Education and Research on Toxics is in its final stages, and the judge might rule soon unless the plaintiffs settle the case. Several of the plaintiffs, including 7-Eleven, have already settled and agreed to post warnings in their stores.

The basis for the lawsuit is that brewing hot coffee produces acrylamide, which is on a list of substances that California claims cause cancer or reproductive toxicity. (It's a very long list.) Even though acrylamide has been on the list since 1990, it wasn't until 2002 that Swedish scientists discovered that acrylamide is present in many foods.

As the American Cancer Society explains,

"Acrylamide is found mainly in plant foods, such as potato products, grain products, or coffee. Foods such as French fries and potato chips seem to have the highest levels of acrylamide."

Uh oh. Coffee, french fries, and potato chips. Where's the joy in life without these?

But wait a second: how come people aren't keeling over with cancer left and right, especially in our coffee-loving, french-fry-loving society? (And what about the French?)

It turns out the evidence against acrylamide is pretty sketchy. If you give it to mice in the lab, at doses 1000 times greater than the amounts found in food, it does seem to increase their risk of cancer. But mice are not people, and 1000 times is a whole lot of acrylamide. The ACS concludes that

"it’s not yet clear if acrylamide affects cancer risk in people."

It's just as easy to find claims that coffee prevents cancer. A 2017 review found that one cup of coffee a day is associated with a slight reduction in the risk of liver cancer and endometrial cancer. A 2010 review of over 500 studies found the same reductions, but a slight increase in the risk of bladder cancer among heavy coffee drinkers. Another large review in 2017, by Robin Poole and colleagues in the UK, found not only a reduced risk of cancer, but a reduction in heart disease and overall mortality.

The Poole study concluded:

"Coffee consumption seems generally safe within usual levels of intake, with [the] largest risk reduction for various health outcomes at three to four cups a day, and more likely to benefit health than harm."

Coffee lovers, rejoice! But let's not kid ourselves: no one is drinking coffee for its health benefits, are they? The stuff just tastes good.

Finally, in answer to my own question at the top of this article: yes, California has gone a bit nuts. Or, as the nonprofit American Council on Science and Health put it:

"If coffee is deemed carcinogenic, then the State of California will be required to give up all pretense at common sense and sanity."

An afterthought: the lawsuit may be just about money. As Bloomberg News explained last October, in a story about the California coffee case: "Unfortunately, it is very easy for ‘bounty hunters’ to file Prop. 65 lawsuits against even small businesses and the cost of settlement and defense often exceeds other types of abusive litigation." The American Council on Science and Health was even more blunt, calling it an attempt to grab "a giant bag of money."

Let's hope the judge in the California case pays attention to the science. Meanwhile, the rest of us can focus on more important questions, such as: dark roast or light? French press or drip?

The federal government is wasting over half a billion dollars a year on chiropractic and osteopathic manipulation

A book on the abuses of chiropractic,
written by a former chiropractor

Here's a quick way for the U.S. government to save over half a billion dollars. Stop paying for coverage of medical procedures that have little or no evidence to support them.

The Centers for Medicare and Medicaid Services (CMS) now releases annual reports of how much it spends, broken down according to the procedures. Their latest data, for the year 2015, reveals that Medicare spent $564,165,721 on pseudoscientific medical practices.

I'm talking about chiropractic and osteopathic manipulation. These are similar but distinct belief systems, both involving bones, and both with little high-quality evidence to back them up. Most people think that chiropractors' spinal "adjustments" can relieve pain from injured or aching backs. It turns out that it's just an elaborate placebo: a back rub at home is likely to work just as well. And that home treatment is probably safer–I'll get to that below.

Osteopathic manipulative therapy (OMT) was invented out of whole cloth in the mid-19th century by Andrew Still. Still believed that every part of the body was linked by a mysterious "myofascial continuity" and that manipulating it could treat a vast range of aches, pains, and other ailments. Most of this is not true. (There is some evidence that OMT can be beneficial in carefully selected cases of lower back pain, but the evidence is quite thin (see this review), and the CMS codes don't distinguish different uses of OMT.)

Osteopathic manipulation is what Larry Nassar, the now-convicted sexual predator, claimed he was doing to the hundreds of young girls whom he molested over the years when he was a sports doctor at Michigan State University and a doctor for the U.S. Olympic gymnastics team. (Osteopathic physicians, which is what Nassar was, generally practice real medicine, and I don't mean to suggest that any of them endorse Nassar's awful abuses. However, OMT is a relic of their pseudoscientific past, and Medicare should not be covering it.)

Chiropractic is no better than OMT. It was invented by D.D. Palmer in the 1890s, around the same time that Andrew Still was concocting OMT.  Palmer mistakenly believed that misalignments of the spine, which he called subluxations, caused a vast range of health problems, even infectious diseases. As retired chiropractor Samuel Homola has written,

there is "no evidence at all to support chiropractic subluxation theory," 

but thanks to clever marketing, chiropractors have convinced millions of people to see them on a regular basis. (See chirobase.org for much, much more.)

Even more alarming is that chiropractic adjustments carry a small but frightening risk of causing a stroke, as a result of tearing the vertebral artery, as I've written about before. In fact, the American Heart Association issued a warning in 2014 that "neck manipulation may be associated with stroke". Not surprisingly, the chiropractors association strenuously denied this, but the evidence speaks otherwise. Indeed, a 2015 study that I described when it appeared showed that Medicare patients–the same cohort whom we are paying half a billion dollars a year to provide chiropractic treatments–suffered a significantly higher risk of stroke after seeing a chiropractor than those who instead saw a real doctor.

And a 2003 study in the journal Neurology show an equally alarming increased risk of stroke due to tears in the vertebral artery after chiropractic in younger patients. The lead author of that study, Dr. Wade Smith, warned that

"physicians and patients should be aware of spinal manipulation therapy as a rare but potentially causal factor in stroke."

[Update: note that a 2016 study, in the journal Cureus, found that the link between chiropractic neck manipulation and arterial dissection was not causal; i.e., that chiropractic did not appear to cause arterial tears. However, concerns remain, as demonstrated in this 2017 case report of cerebral hemorrhage following chiropractic activator treatment.]

The 2015 numbers from the Centers for Medicare and Medicaid Services show that the vast majority of the wasted funds, $545 million, went to chiropractic treatments, with another $19 million going to osteopathic manipulation. Neither amount is justified by scientific evidence.

Let's stop wasting our money on procedures that don't help, and may harm, Medicare patients. If we want to help patients, let's insist that Medicare spend our money on real medicine.