It’s the one thing I can always count on. It’s the building block of life, the fuel for my muscles, and the key to recovery. Protein is the MVP of my diet.
However, I recently came across a study that challenged the validity of this hypothesis. This study, published in the Journal of the American Medical Association (JAMA), found that the hypothesis was not supported by the evidence. This study, along with other research, has led me to reconsider my understanding of the role of dietary protein in kidney health.
Urea is a toxic substance that needs to be filtered out of the body. The kidneys are responsible for filtering urea from the blood and excreting it in urine. The process of protein breakdown and energy production from protein is called catabolism. This process is essential for maintaining energy balance and overall health. Catabolism is a complex process that involves multiple steps and enzymes.
What some nephrologists fear is that, even in people with healthy kidneys, this increased blood flow and pressure will eventually damage the delicate filtering structures in the kidney—which in turn will force the remaining kidney structures to work even harder, triggering a kidney death spiral. The evidence for this sequence of events is clear for people (and animals) who already have kidney problems. But it’s basically non-existent for people with normal kidney function. That means it becomes a question of weighing different kinds of indirect evidence. Why Sports Nutritionists Don’t Worry About Protein The International Society of Sports Nutrition, in its official position stand on protein and exercise, is unequivocal: “no controlled scientific evidence exists indicating that increased intakes of protein pose any health risks in healthy, exercising individuals.” Moreover, the position stand cites a series of studies led by Jose Antonio, the cofounder of the ISSN, in which athletes consumed as much as 4.4 grams of protein per kilogram of body mass each day, more than five times the recommended daily allowance of 0.8 g/kg/day, without any ill effects.
They argue that the benefits of creatine supplementation are not as significant as often claimed. They point out that the benefits are often exaggerated in the strength and power sports, where athletes are already highly trained and have a high baseline level of performance. De Lorenzo and his colleagues argue that the benefits of creatine supplementation are not as significant as often claimed.
This is a crucial point. The summary states that the strength of the evidence is weak. This means that the arguments presented are not well-supported, and there is a lack of concrete data or reliable sources to back them up.
8 grams per kilogram of body weight. This is a relatively low number, and it’s been criticized for being too low. The protein RDA is based on the average person’s needs, and it doesn’t account for individual differences in protein requirements. For example, athletes, pregnant women, and people with certain medical conditions may need more protein than the RDA suggests.
The average daily protein intake among Americans, as of 2015-2016, was 97 grams for men and 69 grams for women. Depending on weight, that’s in the range of 1.0 to 1.5 g/kg/day. In broad strokes, then, I suspect that the average person could probably still benefit from upping their protein intake. In particular, focusing on getting more protein throughout the day rather than cramming in a huge load at dinner might (though not necessarily) help build more muscle. But I’d pause before pushing too far into the extremes, like 3 or 4 g/kg/day—not because there’s strong evidence that it’s dangerous, but because it’s conceivable that there might be downsides and not clear that there are significant upsides.
As it happens, that balancing act is evident in another new study that was published last month looking at protein intake and mortality in older adults who already have chronic kidney disease—in other words, the group that we know will be hurt by too much protein. The results were the opposite of what you’d expect: the more protein subjects ate, the less likely they were to die during the study. Higher protein intake is associated with all sorts of interconnected benefits in older people: more muscle, stronger bones, less frailty, lower rates of heart disease, and so on. In this cohort, these benefits outweighed whatever theoretical harm protein might inflict on the kidneys. For muscle-challenged endurance athletes like me, that’s a message to keep in mind.
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