Weekly Blog

Dec 19

I can already imagine the social media clickbait. A title like "everything you've ever been told about diet is wrong," which overlays an image of a person with a perfect physique or a distinguished-looking professional in a lab coat. Then, for those who decide to expand beyond the headline, a short summary of one or both of the two studies out this week, quite possibly burying or leaving out critical details, depending on the source. Maybe it's a sign of the times, or maybe it's just what commandeers our attention. Either way, since I prefer to pick them apart for my own understanding, I figured, why not share? So, for others who might be curious, here's my summary of the deeper dive. 

Study 1 - from the Annals of Internal Medicine (a publication of the American College of Physicians), dated 12/16/25. The big finding on this one is that after a review of randomized controlled trials, researchers found little to no benefit in measures of heart health by reducing saturated fat in certain groups. At face value, this is a potentially big finding with implications for everything from public policy to health advice. The risk, however, is in missing the details, which make this a far more narrow finding, limited to a far more narrow group of people in a relatively short time frame. 

What the research team really found was that in at-risk groups, lowering saturated fat produced a significant benefit, while in low-risk groups (i.e., healthy people), there was little to no additional benefit in a 5 year period. There is nuance here, and it's important. First, it's entirely possible that a risk "floor" exists - healthy people (those at low risk) didn't get even healthier. However, if current projections are correct, this is, sadly, a very small number of people. The most recent statistics show that 2 out of 10 US adults transition from high risk to diagnosable heart disease in their 20's and 30's, with more and more each year. By the time we are in our retirement years, more than 7 out of every 10 have been diagnosed. This means not only are there very, very few who are in the applicable low-risk category, but in a disease that takes decades to develop, a 5-year window is probably not long enough to set a lifetime plan to. 

In addition to a risk-floor, it is also possible that the strategies that lower risk (in those who have it) are not the same as the things that prevent risk (in those who don't). There might definitely be more important levers for these few, but to me, it seems shortsighted to ignore the up to 25% risk lowering effect seen when the at-risk group changed from saturated fats to polyunsaturated fats. There's almost definitely more to come on this one, but one thing feels certain: the headline doesn't quite capture the story.

Study 2 - this one from The Lancet as part of their December 2025 Europe Regional Health journal. The sexy headline finding on this massive data review (63,000 participants over 9 years on average) was that certain plant-based diets were associated with an increase in cardiovascular disease risk. Unfortunately, anyone who stops there will likely be misled. What the study really found was that when they compared the effect of dietary choices across 3 different known risks including: dietary makeup which ranged from mostly plant-based, such as the often heralded Mediterranean diet to minimally plant-based which might be something closer to a standard American diet as well as quality (high nutrient to low nutrient) and level of processing (low process to ultra-processed), all 3 groupings mattered. 

While a mostly plant-based diet is widely regarded as a powerful preventative choice (which might be scary in some professions), it probably shouldn't surprise anyone that more data now supports what seems obvious - when we eat highly nutritious foods that are close to their natural state (fruits, veggies, nuts, seeds, legumes, etc) we do significantly better than when we try to use only the parts that are easy, convenient or taste good. In much the same way that fruit and fruit juice may come from the same source but can yield very different effects, something that is minimally changed from how it started is wildly different than something that has been significantly altered to look, smell, or taste different and sit on a shelf longer before it spoils. Junk food is junk food, even if it started as a plant.

At the end of the day, these two big studies, which are sure to make waves in some areas and might even sell some news, don't change things all that much for me. Author Michael Pollan may still be able to lay claim to the most accurate and simplest take on how to eat for health - "Eat Food, Not Too Much, Mostly Plants.

Have a great weekend,
Mike E.