A patient recently brought this study to my attention: as reported in the journal Nature Metabolism, high protein diets apparently lead to heart disease. Or, as the New York Post put it in their headline:
At the risk of sounding like a broken record, this is another example of the “Academic-Media Complex” that I often warn about, in which a terribly designed study that tells us nothing about human health is reported on in sensational terms by our “if it bleeds, it leads” media.
Let’s break this study down a bit:
They took 23 people and separated them into two groups (of 11 and 12 respectively)
They fed both groups a “Boost” brand shake, which is a mix of sugar and a whole slew of processed ingredients, artificial additives, etc. One group got a higher dose of protein in their Boost shake than the other.
Then they took blood samples one and three hours after drinking the shake, and found that the higher protein group had increased levels of a signaling molecule in their blood that has been linked in some studies to a higher risk of heart disease in mice.
See the problems with this study? There are many, but here are a few of the most important ones:
The sample size was very small, so even if anything else about the study were helpful, there weren’t enough people in the study to confidently draw conclusions.
The experiment could be confounded by the fact that Boost has sugar and a lot of artificial ingredients in it. Any effect could be due to this, rather than just the protein. In other words, the effect we are seeing might be due to the mixture of sugar/artificial ingredients plus protein, rather than just protein. Perhaps the consumption of lentils, a hamburger, or a chicken breast – in other words, actual foods that real humans eat on a regular basis – would have yielded very different results.
The only finding of note was a temporary elevation in a blood protein that has been linked to heart disease in MICE. The study didn’t at all look at the actual development of heart disease in humans, nor even at a signaling molecule that has clearly been demonstrated to be harmful in humans.
The follow up was only for a few hours after the shake was consumed. Even if the signaling molecule in question can lead to heart disease in humans, it wouldn’t prove that the increase observed in the study causes heart damage. An analogy might make this clearer. If you ate an apple right now, you would almost certainly have a brief rise in your blood sugar as your body metabolized the natural sugars in the apple. Does this mean that eating apples leads to diabetes or can cause you to suffer diabetic complications such as going blind? Of course not. Diabetes is a problem because it leads to extremely high blood sugars that persist for months and years. The mild, transient elevation in blood sugar that occurs after eating a piece of fruit is a totally separate issue, and in fact science suggests that modest fruit consumption is a healthy habit. Why then would we assume that a small rise in a particular signaling molecule after consuming a protein rich meal would lead to heart disease, even IF that signaling molecule played a role in creating heart disease in humans?
A better headline for this study would have been: “Study shows that drinking an artificial concoction of protein, sugar, and a bunch of chemicals leads to a brief rise in a signaling molecule that might contribute to heart disease in mice.”
