Red Meat, Dementia, Sympathy

You've probably guessed the topic. I'll be discussing a study published last week showing that eating processed red meat increases the risk of dementia.

The majority of Americans eat red meat, at least on occasion, and 42% of us who reach age 55 are now expected to develop dementia later in life. It seems important to know whether we can trust the new study and, if so, how much some of us should change our diets.

But what about that reference to sympathy?

I feel sorry of course for people who experience dementia, not to mention the farm animals who, through no fault of their own, turn out to be delicious.

I also sympathize with people who know less than others about how to stay healthy. It's not their fault either that the information they need is distorted – or never shared with them in the first place.

The new study is creating some buzz, but most of the news reports miss or misrepresent key details. There are also hints of siloing, in that liberal sources have been far more likely than conservative ones to cover the study.

I'm getting ahead of myself. Let's start with a quick definition.

Dementia

Dementia refers to a decline in cognitive functioning, over and above what happens during normal aging.

Just as "fever" is not a disease but rather a symptom that can arise from many causes, so "dementia" consists of symptoms (impairments in memory, reasoning, verbal skills, etc.) that can stem from many underlying conditions, the most common being Alzheimer's disease.

Rates of dementia are higher in more affluent countries. There's debate about why, but experts agree at least that contributors include longer lives and unhealthy lifestyles.

As for red meat consumption, links to dementia have not been consistently shown. The new study is larger, longer in duration, and in some ways more thorough than earlier ones. In theory, the findings should be more trustworthy.

The new study

This study, led by Yuhan Li and colleagues in the Harvard School of Public Health and Medical School, appears in the February 11 2025 issue of Neurology and was posted online January 15.

Li and colleagues looked at 133,771 individuals (average age 48.9 years) who were dementia-free when they joined the study in 1980 or at some later point. By 2023, 11,173 of these people had been diagnosed with dementia. The researchers tried to figure out whether red meat intake increased the chances of that diagnosis.

The sample consisted of nurses and other health care professionals. In theory this limits the generalizability of the data, but in practice it's a plus, because you'd expect these folks to be more accurate than most in describing their diets and other health-related behaviors.

Another strength of the study arises from the kinds of variables that Li and colleagues controlled for. Here's the simplest way to put it: The researchers asked whether red meat consumption increases the risk of dementia, independently of any risks introduced by smoking and drinking, activity levels, BMI, family history of dementia, and so on.

Separate analyses were run for processed and unprocessed red meats. Processed red meats include products like bacon, sausage, salami, bologna, and hot dogs, while the unprocessed variety includes burgers, cutlets, steaks, ribs, and chops. (Feeling hungry?) Based on survey responses, each participant was classified as low, medium, or high in consumption of each type.

Key findings

The main finding – the one most commonly highlighted in news reports – is that people who ate the most processed red meat had a 13% higher risk of developing dementia than those who ate the least.

High-consumption individuals also did more poorly on a simple, over-the-phone cognitive test administered roughly two decades after the study had gotten underway, and on a subjective measure in which they were simply asked whether or not they'd been experiencing problems with attention, memory, and other cognitive processes.

As for unprocessed red meat, no group differences were found for dementia or for the cognitive test, although people in the high-consumption group were more likely to report problems with cognitive functioning.

What do the findings tell us?

The most common mistake when interpreting a study is to ignore how variables were measured.

I'm as impatient as the next person. I want to know what a study found. I want to talk about the findings and, if possible, put them into practice. But data can't be trusted unless the approach to measurement is sound. You can't spin gold out of straw.

In this study, each person's red meat consumption was measured once every 2 to 4 years. Participants viewed a list of foods and rated how often they ate each one on a 9-point scale ranging from "never or less than once per month" to "6+ per day."

For processed red meats, here are the researchers' three groups:

• Low: < 0.1 servings per day.

• Medium: Between 0.1 and 0.24 servings per day.

• High: > 0.25 servings per day.

That's it.

This approach suffers from two honkingly obvious sources of imprecision.

First, a measurement issue. Very few of us can remember exactly how much red meat (or anything else) we've eaten over the past 2 to 4 years. The amount probably varies from week to week or month to month. Importantly, serving size is not a very informative number, given how much individual eaters can differ in size.

Another source of imprecision comes from the groupings. The high-consumption group has no upper limit. Folks who are eating excessive amounts of processed red meat most days are lumped in with people who average just a quarter-serving per day.

(The researchers don't define serving size. News releases from their affiliate organizations suggest that a quarter serving per day would equate to just under two hot dogs per week, or four slices of bacon, or three slices of bologna. Clearly there would be huge variability within the high-consumption group, as it would lump together someone who merely eats two hot dogs per week with someone who has bacon every morning, hot dogs for lunch several times a week, BBQ sausages on Sundays, etc. For all we know, only the latter person would have a greater risk of dementia.)

What the researchers should done instead (or in addition) was to explore dose-response relationships between how much processed red meat people ate and signs of decline, such as whether or not they developed dementia. I was surprised not to see this.

I'm not questioning the general credibility of the findings. I am persuaded that red meat consumption is associated with cognitive decline later in life, because the data consistently points to this, and because there are compelling reasons to expect a link (e.g., high levels of sodium, saturated fats, and chemicals like nitrites found in processed red meats have all been implicated as contributors to cardiovascular disease and dementia).

What I am questioning is that eating a lot of red meat increases the risk of dementia by exactly 13%, and that we can define how much "a lot" would be. I don't trust any numerical takeaways from this study.

I realize you may not find this conclusion very satisfying. Certainly I don't. What I want most are concrete details. I want to know more or less exactly how much red meat people can safely eat. The study just can't tell us anything specific.

Should you change your diet?

If you eat processed red meat, you might consider eating less of it, for your own sake (excessive consumption of both processed meats and red meat have been linked to cancer, for instance) and for the health of the planet (check out, for instance, The Omnivore's Dilemma). Li and colleagues also found that replacing one serving per day of nuts and legumes for processed red meat significantly reduces the risk of dementia, although this finding suffers from the same measurement issues described above. In any case, if you're concerned about dementia later in life, you should also be focusing on maintaining or improving your cardiovascular health.

For instance, high blood pressure and cholesterol increase the risk of dementia (and many other problems). If your cardiovascular health is less than ideal, you might consider lifestyle changes such as increasing your activity levels and eating a healthier diet, rather than simply capping the number of hot dogs you eat per week.

Media coverage

Most national news organizations have covered the new study. Sadly, even the best of these reports are misleading, owing to lack of attention to the measurement issues I've described. Processed red meat is unhealthy, but it's unclear how much consumption increases the risk of dementia.

Informational siloing also seems to be occurring.

Among national news organizations with the highest online/print circulation and/or online visitors, most liberal or liberal-leaning outlets covered the new study (e.g., New York Times, Washington Post, CNN, Time, etc.).

In contrast, the New York Post is the only major conservative or conservative-leaning organization to cover the study. The Wall Street Journal and Fox News didn't mention it anywhere.

This may reflect a coincidence rather than political bias, but it reinforces an informational silo concerning the health risks of red meat. Beef in particular is viewed among conservatives as both quintessentially American and baselessly impugned by climate change activists and other liberals. In May 2021, Marjorie Taylor Greene and others spread a fake news report that President Biden planned to ration red meat. No surprise that an Ipsos poll conducted the same month found that 44% of Republicans but only 13% of Democrats agreed there's a movement underfoot in the U.S. to ban red meat altogether, and that three years later, Donald Trump and J.D. Vance each falsely claimed that Kamala Harris supported such a ban.

I feel sympathetic toward the misled (if not toward those who mislead them). The health consequences of informational siloing can be severe.

One of the most dramatic examples is that during the early months of the pandemic, conservative sources such as Fox News downplayed the seriousness of the threat and the need for precautions. Sure enough, exposure to conservative media during this time predicted less social distancing and masking, as well as higher infection rates.

The story gets worse though. You may have heard that among registered voters, Republicans had higher COVID-19 mortality rates than Democrats did. Here's a sad twist: The difference didn't emerge until after vaccines were rolled out. Pre-vaccine mortality rates were the same. But, with Fox News and other conservative sources questioning vaccine safety and effectiveness, especially early on, Republicans who stuck to conservative media were hearing a different – and more dangerous – message than their Democratic counterparts were, and a partisan difference in mortality rates soon emerged.

Reluctance to acknowledge the health risks of red meat consumption will probably never undermine public health to the extent that misinformation around COVID-19 has done. Even Fox News regularly warns against overconsumption of red meat and processed foods. But we should still be concerned about what their audience does and doesn't hear.

The problem doesn't boil down to partisan politics. Organizations that concentrate on science journalism and seem politically neutral sometimes mislead their audiences too. I nominate the often reliable StudyFinds as the worst offender of the week, because what they say about this study (one slice of bacon "is all it takes to raise your risk of dementia") is most definitely not what the study finds.

Final thoughts

Alzheimers.gov provides a thoughtful list of recommendations for how to reduce your risk of dementia. As you might expect, this list draws upon a familiar triad: Good physical, mental, and social health all help keep us clear-minded as we age.

I read the list, because I want to be writing this newsletter when I'm 90. I hope you're still with me.

Thanks for reading!