Red Meat vs Plants: The Science Behind the Headlines

Bret: 
Welcome to the Metabolic Mind Podcast. I’m your host, Dr. Bret Scher. Metabolic Mind is a non-profit initiative of Baszucki Group where we’re providing information about the intersection of metabolic health and mental health and metabolic therapies, such as nutritional ketosis as therapies for mental illness.

Thank you for joining us. Although our podcast is for informational purposes only and we aren’t giving medical advice, we hope you will learn from our content and it will help facilitate discussions with your healthcare providers to see if you could benefit from exploring the connection between metabolic and mental health.

It looks like it’s a good week for plants, and a bad one for red meat. Eat plants and lower your risk for cancer. Eat red meat, increase your risk for diabetes. Clean and simple, right? That is, if you believe the headlines and don’t actually look at the papers on which they’re based. And unfortunately, that’s probably what most people do.

Most people would like to believe they’re being told the truth or as close to the truth as we can get. And let’s be honest, who has the time and the energy to research every headline? I don’t blame anybody for that. My job is to do that. But yours likely isn’t, right? You’ve got so many other things to worry about.

But the problem comes when we aren’t just talking about everyday people. Instead, we’re talking about doctors, health advocacy groups, dietitians, and other health professionals, and they’re doing the same. They’re the ones simply believing the headlines and not reading the studies. That’s a problem. And in some cases, they’re even the ones creating the headlines.

But when you better understand these studies, you realize the headlines of red meat causing diabetes or eating vegan automatically lowering your risk for cancer, it’s simply too superficial and likely doesn’t apply to you as an individual because of that superficial, low-quality research. So, let’s take a look at these papers.

So, one published in the British Journal of Nutrition concluded that red meat intake was associated with a 49% increased risk of diabetes. Forty-nine percent. That sounds pretty alarming. And it fits this familiar narrative that meat is bad for health, whether it’s cancer or heart disease, or in this case, diabetes.

But once again, we need to realize how these data are low-quality evidence and not really clinically reliable. So, this entire data set is based on two 24-hour dietary recalls. The study duration is 13 years, but they only assessed what these individuals ate twice in that 13 years. And remember, there was no intervention.

They simply observed their life, and there were crucial differences between the groups that ate the most and least amount of red meat. They weren’t randomized, right? They weren’t controlled. They were completely different. The one that jumps out the most to me is that the meat eaters ate 2,500 calories per day, and the ones that ate the least amount of meat ate 1,700 calories per day.

That’s 800 calories per day more. Almost a 50% increase. And of those calories, the meat eaters also consumed 75% more calories from sugar-sweetened beverages. Take a guess, take a guess where those other calories are coming from. Are they mostly like whole foods or veggies and nuts and seeds, or were they processed refined carbs, refined grains, sugars?

The study doesn’t tell us, but we can pretty much guess, right? And especially since they drank more alcohol and smoked more, and they were overall less healthy. But the problem is that we believe that they can control for all these factors. They can certainly try, but there’s no way to control for this complete healthy or unhealthy user bias.

And given that the ultimate resulting effect size is so small, the results end up being essentially meaningless, and that’s unfortunate. But it also says nothing about how they even defined red meat or processed meat, which is also rarely very poorly done in these studies. So, let’s rewind for a second.

What do I mean by small effect size? So, remember, observational studies on smoking and cancer demonstrate a hazard ratio or odds ratio of between 15 and 20. And that’s a 1,500 to 2,000% increased risk. So, compare that to the 49% increased risk or the 1.49 hazard ratio. It sounds like a lot, but in the scheme of observational data, it’s essentially meaningless for how it applies to you as an individual.

But that doesn’t stop the headlines or the vegan advocacy groups, like PCRM, from denouncing red meat yet again. And this is where doctors and dieticians, we need to do a better job. We’re supposed to be trained to understand levels of evidence and the quality of research. So, we should be the ones saying, “Hold on.

Don’t believe everything you read. Since the level of evidence doesn’t support strong, if any, conclusions.” Whether we agree with those conclusions or not, that shouldn’t factor in to how we relate the impact of this evidence. Okay, now what about the second paper? So, this one was published in the British Journal of Cancer, and it reports that a vegetarian diet reduces the risk of five different cancers compared to people who ate meat.

This paper combined multiple different studies. It wasn’t one study. It combined multiple different studies to reach 1.8 million subjects, which is obviously very impressive in terms of that number. But the problem is that the individual studies all have the same problems mentioned in that red meat study and diabetes paper that I just talked about.

It’s all low-quality nutrition observational studies. For instance, if we look at one, the EPIC-Oxford study. Once again, the meat eaters ate more total calories. And by the way, they still ate 50% of the calories from carbohydrates. So, it wasn’t low carb by any means. They drank more alcohol, they were heavier, and overall less healthy.

So again, take a guess as the quality of the food they ate, and especially the quality of the carbohydrates, right? These factors aren’t even really measured. So, they’re hard to fully account for, even with the statistical adjustments that they try. But here’s what really gets me. That same study about vegan, vegetarian diets and cancer showed that vegan and vegetarians had higher risks of some cancers. Yet, the headlines didn’t emphasize that at all.

So, as you can see in this graph, anything to the right is a higher risk, and to the left is a lower risk. And it is significant if the entire line is to one side of the center line. So, the vast majority were not statistically significant and were merely trends, which really don’t tell you much. But not only did the increased cancer associations not make the headlines, but many articles tried to explain that as not being reliable. Yet, they didn’t do the same for the cancers that decreased in vegetarians.

Why not? So, here’s just one excerpt. “While being vegetarian appeared to be protective overall, the scientists also found that those who follow a vegetarian diet had nearly double the risk of the most common type of cancer of the esophagus, known as squamous cell carcinoma, compared with meat eaters.

This may be due to vegetarians being deficient in key nutrients, such as B vitamins, the team suggested. Vegans had a 40% higher risk of bowel cancer when compared with meat eaters. This may be due to the low average intake of calcium, 590 milligrams a day compared with the UK recommendation of 700 milligrams a day, and lower intakes of other nutrients.

So, interesting that we didn’t see that same efforts to explain away the increased association with eating meat. So, clearly a very biased report here, which is really troubling. And again, from a media standpoint, they rely on the experts they interview. So, that’s a problem. Maybe they just need to pick a broader range or different experts.

But where I think we really need to focus our attention is calling out the health institutions, the medical societies, and the individual health experts who speak on the results as being individually meaningful, and they fail to consider the low-quality of the evidence. So, if we look past the misleading headlines, what’s a more accurate conclusion from these two studies?

I would say that it’s higher overall calorie intake, poor dietary quality, and other unhealthy lifestyle factors are likely contributing to diabetes and cancer risk, but not necessarily the meat itself. But the headlines don’t focus on that nuance. They jump straight to red meat causes diabetes and cancer, and that jump oversimplifies the evidence in a way that reinforces pre-existing biases.

‘Meat is bad, plant-based is good,’ which in truth is a false dichotomy. And for people trying to make decisions about their health, this really matters. What are you supposed to do if you’re trying to find the right eating pattern for you when you can enjoy and maintain that helps you improve your metabolic health, improve your energy level, and is still logistically doable and affordable?

‘Meat is bad, plants are good’ doesn’t help with that. It presents this impression that a healthy diet cannot contain meat, and a diet with mostly plants is by default healthy. And that is very far from the truth. A high meat diet can absolutely be healthy if it focuses on nutrient dense, high-quality whole foods.

Likewise, a low meat or plant-based diet can be very unhealthy if it’s high in refined carbohydrates and sugars. And a diet high in meat and plants combined can be healthy as well. They’re not mutually exclusive. So, it’s time to expect more from our doctors, from our dieticians, and our health societies.

It’s time to stop relying on low-quality evidence and time to realize we don’t have strong enough data to know what is the best diet for everyone. That simply doesn’t exist. There’s far too much individuality. We need to recognize that we are all individuals and the best diet for us and our metabolic health may vary from person to person, and that’s okay.

We don’t need to have the one answer for everyone. That’s the false dichotomy. So, let’s focus on improving health, improving metabolic health, and worry less about the dogma that we think will achieve that

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