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A new study has found that when added into the profile of healthy eating, red meat improved adequacy of nutrients related to mental health and was associated with favorable shifts in gut microbial diversity.
The research had notable strongpoints, including data collected by the American Gut Project, known to be of high quality, and sought to control for the “healthy user bias,” a phenomenon in nutrition science that many studies fail to account for.
A glaring drawback in the study’s value was that it was funded by the National Cattlemen’s Beef Association, and so should be taken with a grain of salt.
That being said, anyone can go on Google Scholar or Pub Med and find studies funded by soybean interests that find soybean oil is better for you than butter and studies funded by sugary food and drinks manufacturers that find ultra-processed foods can be part of a nutrient-adequate diet. WaL has reported on these instances before.
Nutrition science is in general hard, so how the authors organize their study matters as to whether it’s of any value.
In this study from the University of South Dakota, authors Samitinjaya Dhakal, Mosharraf Hossain, and Sanam Parajuli gathered data from almost 5,000 people from the American Gut Project, an organization that keeps a data bank of fecal samples from tens of thousands of Americans for the purpose of providing scientists with information about gut microbiota and other biomarkers.
The authors targeted three end points: nutritional adequacy, mental health scores, and microbiome diversity. They then analyzed the data on the 5,000 people and divided them into four groups using the US Dept. of Agriculture’s Healthy Eating Index (HEI) as a reference score: high score and low score, with and without red meat.
Meat improved all markers
Regardless of whether or not the diet included red meat, if the HEI score was high (80 out of 100 or greater), the individuals maintained healthy BMI values, demonstrated lower odds of depression, PTSD, and bipolar disorder, and stayed within recommended limits of total fat and cholesterol levels.
However, the high-HEI group that also consumed red meat showed higher selenium, vitamin B12, zinc, calcium, vitamin D3, and choline levels, and increased gut microbiota richness and diversity, than the high-HEI group that avoided red meat.
In other words, when other dietary factors were equally laudable, removing red meat conferred no measurable benefit, but rather missed out on tangible benefits for micronutrient abundancy and gut health.
“What was really compelling was the significant nutritional benefit we saw in healthy eaters who consumed red meat,” Dhakal said. “This suggests the public health message shouldn’t be about complete elimination, but rather about building a high-quality diet into which lean red meat can fit”.
“What we saw is that people following a high-quality diet maintained a healthy weight, regardless of whether they ate red meat or not. But within that healthy context, the red meat consumers showed a benefit not just in protein intake, but importantly, in meeting their needs for brain health-critical nutrients like zinc, selenium, vitamin B12, and choline”.
So what is an American supposed to do with this information? The National Cattlemen’s Beef Association funded a study that found red meat to be advantageous in all measured categories, and that alone is enough to make certainly some people ignore it completely. Context is key.
The healthy user bias was not controlled for, to use an example, in a much criticized 2024 study that discovered a relative risk of type-2 diabetes for 100 grams of unprocessed red meat to be 1.10, or 10%. At the time, Zoe Harcombe, Ph.D. explained the healthy user bias by writing “the burger/hot dog consumer is less healthy than the quinoa/kumquat consumer in many ways”.
In other words, high red meat consumption in America tends to be linked with smoking, drinking, less exercise, and other unhealthy lifestyle habits, while those who make a choice to stop eating red meat by definition are focusing more on their diet, and will likely make other good choices that influence data on their health.
In the case of this beef-funded study, the healthy user bias was controlled for by ranking diets according to the USDA’s HEI, which meant it measured how many vegetables, fruits, whole grains, fish, and legumes were consumed in addition to red meat. For that reason alone, it stands out among much of the nutrition literature as valuable. Additionally, it’s well known that meat is virtually the only good source of vitamin B12 and choline, so the reports finding these micronutrients enhanced in the high-HEI + red meat group makes sense, but the funding source is a black mark that will be hard for some to ignore. WaL
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