Do sugary fruit juices cause cancer?

Bottling plant

Does fruit juice cause cancer?

Probably not. Despite what the recent headlines say.

CNN: A small glass of juice or soda a day is linked to increased risk of cancer, study finds

Don’t get me wrong. I am a vigorous opponent of consuming fruit juice, even so-called “natural” fruit juice.

If you want some sugar and carbs, eat an apple or an orange. Don’t sit down and drink 10 of them. That essentially is what natural fruit juice is. It is the concentrated sugar from fruit without the fiber to slow it down or make us feel the least bit full. The end result is that juice sends our blood glucose and insulin levels on a wild rollercoaster ride. We don’t need any more reason to avoid them than that! But the claims that they cause cancer are outlandish based on the cited study.

You know how in the movies there is a car wreck on the side of the road and the police officer is there, waving people past saying, “Move along, there is nothing to see here”? That’s my response to the most recent study published in the journal BMJ. Move along. There is nothing to see here.

The new study is observational. The authors observed over 100,000 French subjects using food frequency questionnaires (a notoriously inaccurate way of recoding food intake) to assess their diets. Subjects were followed for 5 years. By crunching the data, the authors concluded that for those drinking fruit juice, there was a 18% increased risk for any cancer and 22% for breast cancer.

As we have mentioned many times before, this is the weakest quality of evidence that does not come anywhere near showing cause and effect. With such low hazard ratios and weak study design, the chances are higher that the result is more likely due to confounding variables — meaning other activities juice drinkers do to increase their risk of cancer — and not due to the juice itself. It amounts to little more than statistical noise.

That doesn’t mean you should go running to your grocery store for “healthy” fruit juice. We still have plenty of reason to avoid it. If you need proof, just check your blood glucose before and after drinking it and watch the rollercoaster go. That is reason enough to stick to water!

Thanks for reading,
Bret Scher MD FACC

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