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Diet soda and colon cancer: What you need to know

Michael Joyce is a writer-producer with HealthNewsReview.org and tweets as @mlmjoyce

It doesn’t help matters when a news release opens with a quote like this from one of the study’s lead authors:

Artificially sweetened drinks have a checkered reputation in the public because of the purported health risks that have never really been documented. Our study clearly shows they help avoid cancer recurrence and death in patients who have been treated for advanced colon cancer, and that is an exciting finding.

Actually, it’s not that clear at all.

Mainly because this is an observational study suggesting that colon cancer patients who regularly drink diet soda have a lower risk of their tumors coming back, or of dying from their cancer. With this type of study it’s inaccurate and misleading to imply this is a cause-and-effect relationship.

Two other reasons make it not so clear:

First, the data on diet soda consumption are drawn from participants trying to accurately fill out food and drink questionnaires months after the fact. This sort of self-reporting has been shown to be highly unreliable.

Second, the study could not determine if other risk factors — such as diet, activity level, smoking, and other lifestyle choices — might contribute to lower cancer recurrence and mortality.

We were glad to see these limitations included in a HealthDay news story, but it’s not good journalistic practice to reprint quotes regarding the touted benefits directly from the Yale news release, which the story did.

It’s noteworthy that the quote featured above, from Charles Fuchs MD, MPH (Director, Yale Cancer Center) is at odds with more cautious language he used in the video embedded in the news release. He says:

Do I think that (artificial sweeteners like) Nutrasweet or Stevia actually have an anti-cancer effect? I do not.

As self-evident as that may seem to some, for the general public, that’s a very important point — if only to keep cancer patients from making a run to the soft drink section of their local grocery with the misguided notion that diet soda will stave off recurrence … or from focusing on Fuch’s ill-advised quote that this research “clearly shows (these sweeteners) help avoid cancer recurrence and death.”

Here’s what IS clear and it’s mentioned in the very last line of the published research:

Further studies are needed to confirm these findings.

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Comments (3)

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roxanne nelson

July 23, 2018 at 1:46 pm

I wrote up this story for Medscape, and I knew a lot of the media would go wild over it. Dr. Fuchs clearly said that his theory is the “substitution effect,” that substituting sugar laden sodas for the diet ones helped curb recurrence and death. Not the diet soda itself. He also emphasized that maintaining a healthy weight, exercise and eating a low glycemic diet were extremely important, and not just drinking diet soda. But for patients who do drink soda, he felt it was reasonable for doctors to suggest switching to low/no cal drinks, as it was a better option, as people find it hard to give up the craving for sugar. So it is a shame that most news outlets didn’t take the time to speak with the authors, or actually read the full study–as much of this information is in their paper. The Yale press release spun it to make it sound like soda was a new anti-cancer agent.

Emmanuel Hipolito

July 29, 2018 at 4:15 am

Very consistent with my own thoughts no real evidence based literature I take diet pop.

Matt Hudkins

July 30, 2018 at 3:05 pm

At the same time, I wouldn’t agree in wholly discounting the role sweeteners, such as monk fruit and stevia, play in decreasing cancer recurrence and metastasis.