Bicyclist traffic fatalities

As Americans have spent more on probiotic supplements, more cyclists have been killed on US roads, a correlation that connects gut health to road safety with the surreal confidence of a chart that does not know the difference between a microbiome and a bike lane. The coefficient is 0.858 across eighteen years, during which Americans invested in their intestinal flora and died on their way to the health food store with almost equal consistency. The probiotics colonize. The roads devastate.

Probiotic supplement sales grew from a niche market to over 3.2 billion dollars between 2005 and 2022, driven by the microbiome wellness trend and the cultural conviction that gut bacteria are the key to everything from digestion to mental health. Cycling fatalities grew from about 780 to over 1,000 during the same period. Both trends serve the same health-conscious, urban demographic: the people buying probiotics at Whole Foods and the people cycling to Whole Foods are substantially the same population. The shared variable is the wellness lifestyle—a set of choices that the supplement industry serves profitably and the transportation department serves inadequately.

Eighteen years of probiotics and cycling deaths growing together is a story about a demographic that takes excellent care of its gut and terrible care of its commute. The microbiome thrives, the cyclist is at risk, and the correlation between them is the biography of a health-conscious consumer living in an infrastructure-deficient city. The bacteria are balanced. The road budget is not.