From the outside, medical progress looks a lot easier than it really is. Well, I realize that’s true of a lot of things, but it’s especially true in progress against disease, and that’s especially especially true (as I’ve said here before) when you’re talking about dietary influences and what can be learned from them. Butter, whole milk, and other dairy products – bad for your cardiovascular health, right? Not according to this new observational study of 136,000 people across 21 countries. In fact, they found the opposite: higher dairy consumption was associated with a cardiovascular benefit. OK, salt consumption, at most any level, is associated with high blood pressure, right? Not according to this new study on 97,000 patients: the only correlation was seen with people who consumed over 5 grams per day of sodium (current guidelines sound the alarm at 2g and lower). Probiotics help to restore your gut flora after taking antibiotics, right? Not according to this new study on both mice and humans: treatment with a standard probiotic mix actually slowed down the reconstitution of the previous microbiome.
OK, dietary science is a mess – at least we can all agree on that. How about we shift over to a population of patients with a clearly defined disease? Omega-3 fatty acids are supposed to be good for cardiovascular health, right? And diabetic patients most definitely have a higher cardiovascular risk, so how about supplementing them? This new study looked at 15,480 diabetic patients without pre-existing cardiovascular trouble who got either omega-3 fatty acids or were given olive oil capsules as control. Over 7 years of observations – no significant difference between the two cohorts.
All right, enough dietary stuff in general. Let’s talk about giving specific compounds to patients and get some clarity, OK? Diclofenac is the most widely prescribed NSAID in the world, so it should be safe, right? Not according to this new study observing the entire population of Denmark over a twenty-year period. Unfortunately, the adverse event rate among those starting diclofenac went up by 50%, after controlling for everything else the authors could reasonably control for (take ibuprofen instead!) All right then, giving low-dose aspirin to older patients at risk for cardiovascular events is beneficial, right? Not according to this new study on 6200 moderate-risk patients (with 6200 in the control group), which found no meaningful differences in adverse events. And definitely not according to this new study with 9500 patients in each group – they also saw no benefit, but also report slightly higher mortality in the aspirin treatment group, apparently due to cancer.
Well now. I’m not sure if I’ve ever seen consensus medical advice take such a beating in such a short time (thanks to Eric Topol on Twitter for mentioning the whole range of these). I have no reason to celebrate any of these results, other than celebrating new and powerful data, which should always be welcome. But what all this does is illustrate just how tricky this whole business is. Aspirin! How long have we been recommending low-dose aspirin? And apparently not only recommending it to no avail, but quite possibly causing actual harm besides. Now, it may well be that in patients who have already experienced a cardiovascular event that low-dose aspirin may be worthwhile. But in the general population? Apparently not.
But I’m not just going to moan about how complicated everything is and how hard it is to get good answers. Both of those are true, big-time, but there’s actually something to celebrate here, odd as that may sound. What we’re seeing here is actual progress in human scientific knowledge, in all its messy infuriating glory. We know more than we did before. We’ve learned something. Even if you’re not sure about the situation in all of the cases mentioned above, what we’ve found is that you can (at the very least) run large well-executed trials and not get the results you’d expect, which is certainly something to think about. Science really does march on, and sometimes it steps on things along the way.