For years, experts have been telling us to cut back on red meat. Now, a new analysis says there's no reason to. Everyone claims to have science on their side. What's a health-conscious consumer to do?
For the last two weeks, the nutrition world has been consumed by a rancorous debate, triggered by the publication of a highly controversial and hotly contested paper in the Annals of Internal Medicine.
An international team of researchers undertook what they've pitched as the largest and most rigorous analysis to date of the effects of red meat consumption on human health. According to their analysis, the evidence that current consumption is causing harm, or that reducing consumption would lower risks. is too weak and uncertain to justify the recommendation that people should eat less red meat.
This, as you might imagine, provoked a massive counterprotest from the experts and institutions that have been counseling us to eat less red meat. As they have been telling any media outlet that will listen, the evidence linking red meat consumption to harm is overwhelming and unambiguous. To suggest otherwise is not just an attack on public health, but also on the public’s trust in nutrition science and research.
At its heart, this argument is really about methodology—how we gather data, how we analyze it, and how that gets translated into recommendations.
Nutrition research is messy
Nutrition research is notoriously challenging to conduct and interpret. It can take a really long time—often decades—for our food choices to translate into health outcomes. The amount of calcium you get in your teens, for example, directly affects your risk of osteoporosis ... but not for another 70 years. A change in diet may raise or lower your risk of colon cancer, but it might take 15 years for that to be revealed. And then there’s the fact that we don’t all respond the same way to the same diets due to genetic and epigenetic factors.
In order to detect any signal in all that noise, you have to study lots of people over a long period of time. As a result, most human dietary studies involve free-living subjects and rely on people’s ability to recall (and their willingness to report) precisely what and how much they ate over the last 24 hours or 30 days or 12 months. It’s not a perfect way to collect data.
In order to detect any signal in all that noise, you have to study lots of people over a long period of time. There are also a ridiculous number of variables.
There are also a ridiculous number of variables. We eat 3 or 4 times a day. We may eat dozens of different foods over the course of a typical week and hundreds of different foods over the course of a typical year. We eat those foods prepared in dozens of different ways and in thousands of different combinations. Other variables include sleep, stress, activity levels, exposure to environmental pathogens—all of which generally change over time. How do we capture or control for all of that?
And then, when it comes time to map all of that information onto our health outcomes, which of the thousands of different markers, measures, signs, symptoms, and states of health are we monitoring? And how do we compare the results of one study with another that chose a slightly different set of things to measure?
We are all biased
Suffice it to say that human nutrition research does not lend itself to tidy datasets and airtight conclusions. There’s a lot of interpretation required. In fact, it’s possible to make the data say pretty much anything you want them to. And the fact is, researchers have biases that influence how they interpret the data. All of us, including researchers, tend to look for evidence to confirm what we already believe is true as well as reasons to discount evidence that undermines our beliefs.
Human nutrition research does not lend itself to tidy datasets and airtight conclusions.
If your family has been raising beef cattle for generations, or you’ve made your career advocating for a high protein diet, or you just love steak, you’re probably going to be predisposed to believe evidence showing that red meat is healthful. If you grew up believing that eating animals is morally wrong, you’ve staked your career or reputation on the superiority of plant-based diets, or you sell lentils for a living, you’re more likely to see the flaws in that same evidence.
More heat than light
Like so many of the debates taking place right now in our civic life, this latest argument over whether red meat is killing us or making us stronger is unlikely to change any minds. Those who, for whatever reason, want to believe that red meat is harmless or beneficial will line up behind one set of experts and data. And those who are committed to the position that reducing or eliminating red meat will improve our health will line up behind the other. And everyone will claim that science is on their side.
I understand why people get so frustrated when the experts can’t seem to get their story straight.
Caught in the crossfire are hapless consumers who just want to do the right thing. They look to scientists, experts, and institutions for guidance. And I understand why people get so frustrated when the experts can’t seem to get their story straight.
Should you eat less meat? Should you eat more?
I’m not going to take sides in this debate. I’m not going to argue over which data should be included, how they should be analyzed, and which criteria should be applied to determine whether or not the outcome of this analysis is valid. These methodological discussions won’t really help you decide what to have for dinner tonight.
Here’s what I think we need to keep in mind:
No food is good or bad in a vacuum. It's always going to depend on how much you eat, how you prepare it, what you eat it with, and what you might be eating if you weren’t eating that instead. Context is everything.
Compared with other sources of protein, red meat has both nutritional advantages and disadvantages. It’s high in B12 but contains no fiber. It’s a great source of iron but provides very little omega-3. When you get your protein form a variety of sources, including plants, you’ll get a broader array of benefits and reduce your exposure to any potential concerns.
Our health is not the only factor to consider here. And I mean that statement in two ways. First, our health is not the only factor. Our dietary choices also have environmental impacts and animal welfare implications. And secondly, our health isn’t the only factor. Preference, culture, convenience, cost, and enjoyment also play a role in our dietary decisions.
Interestingly, the authors of the new analysis exhonerating red meat note that they did not consider environmental impact in their analysis but did consider consumer preferences. How you balance these factors against one another is going to be a highly individual decision.
From a purely nutritional perspective, I wouldn’t have any concerns about eating 3-4 servings of red meat per week in the context of a healthy diet. In other words, lots of vegetables, not too much sugar or fried food, and taking steps to minimize the formation of harmful compounds that are created when animal protein is charred over flames or hot coals.
But I’m also concerned about the environmental impacts of raising animals for meat. Because I also really enjoy and benefit from other sources of protein like fish, eggs, and legumes, I choose to limit my red meat consumption to once a week or less.
JOIN THE NUTRITION CONVERSATION
How have you balanced these conflicting concerns and narratives in your own dietary choices? Do these sorts of arguments among researchers make you feel less confident in your own conclusions, or do you just tune it out? Come join the conversation on the Nutrition Diva Facebook page or find me on Twitter. I’d be interested to hear your thoughts.
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