In a story for the The Atlantic (The protein madness has started- it has come to protein iced tea), the author, Lila Schroff, relates her experiences with the proliferation of protein supplemented foods and health claims made about them.
Concerns
Fad recommendations are going way beyond standard dietary recommendations, and this is a real worry. In general, intake of either too little or too much of a nutrient causes problems for metabolic regulation. What are the potential problems with very high protein intake?
I researched this for a bit when writing my book, because the levels of certain amino acids called branched chain amino acids (BCAA)s in the blood may be a biomarker for insulin resistance, and may link insulin resistance to inflammation. Ultimately, I decided to omit it from the book because it really seemed relevant only when someone is consuming a very high protein diet. And who does that?
Well, lots of people are at risk now, it seems.
What are the BCAAs?
The three BCAAs are leucine, valine, and isoleucine and are three of the nine essential amino acids. They are considered essential because our bodies cannot make them so we need to get them from our food. Normally, we get them in protein-rich foods such meats, poultry, fish, eggs, and dairy.
Findings from animal and in vitro studies indicate that higher levels of BCAAs are associated with accelerated aging, insulin resistance, and mTor activation. What is mTOR? mTOR is an enzyme contributes to the regulation of insulin sensitivity, and may link BCAAs to diabetes (Bloomgarden 2018, Liang 2024).
Elevated levels of branched chain amino acids may drive inflammation, especially associated with aging. A caveat is that most of the studies done in dishes/in vitro, or in flies, and may not reflect reality. However, human genes associated with BCAA transport and metabolism are associated with aging-related inflammation (Liang 2024). Further, epidemiological studies link type 2 and gestational diabetes to elevated BCAA levels (Tanase 2023). A study with 19,000+ women who were not diabetic and did not have cardiometabolic disease, higher levels of circulating BCAAs were associated with higher levels of inflammatory mediators and dyslipidemia (Hamaya 2021). Together with findings from studies addressing molecular effects of BCAAs in cells (Liang 2024), research indicates that too many BCAAs in blood dysregulates metabolic pathways, including the insulin signaling pathways, and may contribute significantly to disease. Still, this is a fairly new focus of research and we need more studies with human participants. Unfortunately, with the latest high protein fads, we may be inadvertently generating more data on the link between high protein, especially BCAA, intake and disease.
The bottom line
We need protein and BCAAs in our diet, but too much can disrupt the metabolic pathways in cells of our bodies (Yadao 2018), potentially leading to inflammation, accelerated aging, insulin resistance and type 2 diabetes, and atherosclerosis. It seems like a good idea to steer clear of protein supplemented foods, as well as BCAA supplements.