Correlation is not causation, or: the story of vitamin D

📖 73 years ago today, J.D. Salinger published the 10th bestselling book of all time (~65 million copies sold): The Catcher in the Rye. Some attribute its popularity to the fact that, unlike most books at the time, its narrator is highly unreliable yet oddly relatable.
Issue #120: kindness v. niceness + thinking like a 60-year-old
By Harris Sockel

One of the first things I learned in high-school science lab is that correlation does not prove causation. Classic example: Red wine and heart disease. In the ’90s, everyone was jubilantly clinking glasses of merlot after a single paper claimed people who drink wine at dinner have healthier hearts. Now we know those studies were flawed. Sure, you’ve got a perfect heart and you drink a glass of pinot every night… but that doesn’t prove much besides the fact that you’re probably generally pretty healthy (and maybe wealthy, too).

F. Perry Wilson, MD MSCE, a Professor of Medicine and Public Health at Yale, thinks there’s something similar going on with vitamin D — one of the most popular vitamin supplements (and which, confession, I take). D is special in the pantheon of vitamins; you can only get it via sunlight or from eating things that’ve spent lots of time soaking up sun (mushrooms, weirdly; and some oily fish). It strengthens your bones and your immune system. It was discovered in 1920 after an epic 20-year search for the reason why some kids had soft bones (AKA rickets).

Wilson zeroes in on one persistent finding from several studies: Taking vitamin D doesn’t have any statistically significant effects on your mortality. It might reduce cancer, but it might also increase heart disease. Most of the research around D’s benefits are vague. Around 50% of us are low in it (mostly because we spend too much time inside), but most benefits of supplements rely on correlation, not causation.

Denny Pencheva, MD, backs him up: “We have a supplement with dubious evidence behind it.” 81 randomized trials on over 50,000 people are pretty hard to doubt. This year, instead of taking a pill, she’s just going to try to get outside more and eat more of the foods that contain D.

🫶 From the archive: Be kind

Star Trek star Wil Wheaton revisits the time he shared his guiding principles with a class of 11th graders, including the importance of being kind (which is different from being nice). A room of rapt high-schoolers watched him demonstrate the difference between niceness (point to his head) and kindness (put a hand over his heart). “I saw a few kids look at each other like a trick had just been explained to them,” he remembers. “They heard me. They really, really heard me. And it was amazing.”

🎂 Your daily dose of practical wisdom: pretend you’re 60

Starting around age 60, something special happens: We stop caring about petty nonsense and start living more for the present than the future. We invest more in sure things instead of fleeting ones. And we deepen our relationships instead of chasing down people we think are cooler than us.

Health writer Markham Heid analyzes all the research on aging and happiness, and writes: “As far as mantras go, adopt a sixty-year-old’s mindset doesn’t have much curb appeal. It’s still good advice.”

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Edited and produced by Scott Lamb & Carly Rose Gillis

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