There’s a lot of confusion surrounding protein intake. We hear it’s important, but we’re also told getting too much can be a bad thing. So is too much protein bad for you? And how much protein is, in fact, too much? And what stance does the science actually support?
Myth vs. Research
MYTH: A high-protein diet makes you “overly acidic,” damages your kidneys and compromises calcium levels, like many health gurus say it does.
RESEARCH REVEALS: A high-protein diet does none of these things.
Protein, Acidity and Your Kidneys
In order to function properly and keep disease in check, the human body needs to exist in a balance between acidity and alkalinity. If you’re a healthy human being, this pH generally falls around 7.4 on the pH scale (7.41 for arterial blood, 7.36 for venous blood), while your urine pH ranges from 4.6-8.0, depending on foods you consume.
It is widely believed in this day and age that eating too much protein increases the body’s acidity and damages the kidneys. This simply isn’t the case.
The only people who need to watch out for higher protein are people whose kidneys are already damaged, or if you have a genetic condition known as cystinuria.
The truth of the matter is if you’re healthy and you consume more protein than you need for the day, your body responds by inducing hyperfiltration of the kidneys (meaning your kidneys work more to filter waste). Studies have shown hyperfiltration does not damage the kidneys in healthy people—in fact it is an adaptive mechanism that is part of a healthy response.1, 2, 3
What Happened When Two Guys Ate Only Meat for An Entire Year
There is an incredible study published in The Journal of Biological Chemistry from 1930 that observed two men who ate only meat for an entire year. The meat included muscle, liver, kidney, brain, bone marrow, bacon and fat from beef, lamb, veal, pork and chicken, with a bit of butter and a few eggs on rare occasions when meat was not available during travel. (Keep in mind, back in 1930 meat was not riddled with chemicals and toxins.)
The two men were allowed to eat any amount of meat as suited their appetites (usually consisting of around 100-140g protein, 200-300g fat, and 7-12g carbs—all from the meat).
These men lost weight during the first week then enjoyed stable weight, and remained active and mentally alert.
One man’s blood pressure remained the same, the other’s systolic pressure decreased while his diastolic pressure stayed the same.
Their bowel health remained healthy (yep, they were able to “go,” even without fiber).
They didn’t have any vitamin deficiencies.
Their urine was more acidic, but tests showed their kidneys remained healthy and free of damage, just like all their other organ systems.4
Kind of amazing, isn’t it?
Granted, health hackers eat veggies and other foods, but seriously, if you’re a healthy person, don’t fear higher protein, including protein from animal sources.
Also, I should point out that higher protein might not cause kidney damage, but being overweight certainly can. Good thing eating protein helps you lose weight and keep it off.
How Protein Affects pH: The Reality
This also goes to show that if you’re eating a real food diet, without processed foods or much sugar (yes, even natural sugar), the foods you eat–benignly–affect your urinary and salivary pH.
It takes an awful lot to push the body into metabolic acidosis (where your blood pH is imbalanced); doing so generally requires copious amounts of processed foods, sugar, as well as environmental culprits beyond food.
Lower-pH (meaning higher-acid) urine or saliva does not mean you have metabolic acidosis. More myths. [Eyeroll.]
(If you ever work with a practitioner who comes at you with a urinary or salivary test-strip, know that you now know more about what s/he he doesn’t know s/he doesn’t know–knowwhatImean?)
A Meta-analysis of 61 Studies Demonstrates Higher Protein Doesn’t Harm Calcium Levels in Bones, Increase Calcium Excretion in Urine, Or Make You Overly Acidic
It’s also important to note a meta-analysis of sixty-one studies demonstrates higher protein intake doesn’t lower bone mineral density (BMD), nor does it increase calcium excretion in the urine, nor make your body overly acidic. In fact, eating higher protein foods actually helps your body excrete acid more efficiently. This goes for protein from both plant and animal sources.5
Why You Need to Care About Getting Quality Protein
Here are some risks and symptoms of protein deficiency:
- Muscle wasting
- Lowered immunity
- Increased risk of heart disease
- Lower energy levels, fatigue
- Weak and brittle hair and nails
- Thinning hair, or hair loss
- Slow wound-healing
- Fluid retention (edema)
- Diarrhea, constipation. 6,7
So how much protein is too much? For most people, there is no such thing as “too much” protein. So don’t make the mistake of obsessing about or fearing protein.
Learn which food sources provide you with the best quality protein in my article Plant Protein vs. Animal Protein: The Myths and Facts
Protein Intake and Bio-individuality
Ultimately, the question “how much protein is too much” should be reframed, becoming “how much protein is right for you?”
The answer will vary from person to person, and for each person can vary from day to day week to week, and month to month, based on your own unique requirements for satiety, for energy, and can vary depending on various influences (levels of stress, hormones, amount of sleep, etc.).
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1. Friedman, A. et al. “Comparative Effects of Low-Carbohydrate High-Protein Versus Low-Fat Diets on the Kidney.” Clinical Journal of the American Society of Nephrology 7(7), July 2012: pp. 1103-11. https://pubmed.ncbi.nlm.nih.gov/22653255/
2. Martin, WF et al. “Dietary protein intake and renal function.” Nutrition and Metabolism 2:25, 20 September 2005. https://nutritionandmetabolism.biomedcentral.com/articles/10.1186/1743-7075-2-25
3. McClellan, Walter S. and Eugene F. Du Bois. “Prolonged Meat Diets with a Study of Kidney Function and Ketosis.” Journal of Biological Chemistry. 13 February 1930. http://www.jbc.org/content/87/3/651.full.pdf
5. Kerstetter, Jane E. “Dietary protein and bone: a new approach to an old question.” American Society for Nutrition 90(6): 28 October 2009. https://academic.oup.com/ajcn/article/90/6/1451/4598058
6. “Protein-Energy Undernutrition.” The Merck Manual for Health Care Professionals Online. Updated November 2012. http://www.merckmanuals.com/ professional/nutritional_disorders/undernutrition/protein-energy_undernutrition. html?qt=&sc=&alt=
7. “Overview of Undernutrition.” The Merck Manual for Health Care Professionals Online. Updated November 2012. http://www.merckmanuals.com/professional/ nutritional_disorders/undernutrition/overview_of_undernutrition.html?qt=diet%20 protein%20deficiency&alt=sh
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Feature image copyright Erika Herman. “Meat Icon” illustration copyright vectortradition.