Is Too Much Protein Bad For You?

Is Too Much Protein Bad For You?

Proteins are the building blocks of life and every living cell uses them for both structural and functional purposes. They’re made up of long chains of amino acids linked together like beads on a string.

There are 9 essential amino acids we must get from food, and 12 non-essential that the body can produce itself. The amino-acid profile of a food determines its quality as a source of protein. The best sources of protein in the diet contain all the essential amino acids in ratios that are appropriate for humans.

Now per gram meat is the top source of high quality protein for humans. There are many plant-based foods with a strong amino acid profile too, but there are also many without.

There’s a theory that a high protein intake increases the acid load of your body, which then causes the body to take calcium out of the bones to neutralize the acid.

But longer term studies do not support this idea at all.

A review published in 2011 concluded that there is no evidence that increased protein harms the bones. If anything, the evidence points to a higher protein intake improving bone health, NOT the other way around.

The same was found in a more recent review, with higher protein intake linked to better bone health. Although the authors note that increased protein may only be beneficial alongside an adequate calcium intake.

So you can see the argument that protein causes bone health problems is not evidence-based. A large component of this theory overlaps with the acid-alkaline diet theory, which we’ve already debunked.

The kidneys are a remarkable organ that filters unneeded substances out of the bloodstream, producing urine.

Some say the kidneys need to work hard to clear the metabolites of protein from the body, leading to increased strain. But kidneys are always under loads of stress, that’s what they’re designed for.

In fact about 20% of the blood pumped by the heart goes to the kidneys. They filter a total of 180 liters (48 gallons) of blood, every single day. Additional dietary protein increases a healthy kidney’s workload by insignificant amounts.

Looking through the literature, there are no studies showing harmful effects of protein in the average person with healthy kidneys.

In this thorough review the authors concluded there is no significant evidence for a detrimental effect of high protein intakes on kidney function in healthy persons after centuries of a high protein Western diet.

Even bodybuilders who tend to eat very large amounts of protein, both from food and supplements, have healthy kidneys.

Additionally, the two main risk factors for kidney failure are high blood pressure (hypertension) and diabetes. A higher protein intake does not contribute to either of those conditions, and some studies suggest it may actually improve them.

Now in saying that, if you already have existing kidney damage, then an increased protein intake can be harmful and is NOT recommended. Kidneys working at sub-optimal levels should not be worked anymore than is necessary, even if it’s just a tiny bit.

Just like you wouldn’t walk or run on a broken ankle.

Lastly let’s look at how much you should eat per day, assuming your kidneys are healthy.

If you are sedentary [and not looking to change body composition much], a daily target of at least 0.8 g/kg body weight (0.36 g/lb) is a good target. This should prevent protein deficiency.

If you are an active person or attempting to lose body fat while preserving muscle, then a daily intake of 1.0-1.5 g/kg body weight (0.45-0.68 g/lb) is a good target. For athletes, aim for 1.5-2.2 g/kg body weight (0.68-1 g/lb) per day.

I tend to eat around 1.5 grams per kg, and typically recommend the 1.0-1.5 g/kg body weight range, just because of all the health benefits a high protein intake has.

Studies mentioned:

STUDY 1: https://www.ncbi.nlm.nih.gov/pubmed/21102327
STUDY 2: https://www.ncbi.nlm.nih.gov/pubmed/24316688
STUDY 3: https://www.ncbi.nlm.nih.gov/pubmed/16174292