There’s a few few particular myths on protein that just won’t go away, no matter how much research comes out to disprove them. How much can you absorb in one sitting? Does too much damage your kidneys? Do older people need more or less? Does more protein lead to more muscle growth? Read on to find out.
Myth 1- You can only absorb 30 grams of protein at once
Consider that a 12-ounce porterhouse steak has 80 grams of protein. So if you only absorb 30 of those grams, where do the other 50 grams go? Do you see a gigantic steak like turd in the toilet the next day? So what happens to the other 50 grams if we are supposedly not absorbing it?
The confusion may be because 20-30 grams of protein delivers the maximum stimulus for MPS (muscle protein synthesis). In other words, eating more than 20 grams of protein at once does not lead to extra muscle growth. But that doesn’t mean the protein is simply excreted, amino acids are precious and the body will put them to good use.
Myth 2- The brain doesn’t need protein (and protein is only for athletes)
Protein is for everyone, and is known to have far greater satiating effects in the brain compared to fats and carbohydrates. After consumption, peptide hormones released from the GI like CCK (cholecystokinin), GLP-1 (glucagon-like peptide-1), and NPY (neuropeptide Y) communicate with the brain. These signals promote satiety by acting on brain regions involved in energy homestasis (including POMC neurons) in the brainstem and hypothalamus. There is also limited hedonic responses to protein, meaning it is not addicting like carb because of neuronal responses in the limbic regions. It also provides essential amino acids required for production of certain neurotransmitters and DNA in the brain. These are just a few of the examples, so you could say that it is important for the brain.
Myth 3- Too much protein is bad for your kidneys
Your kidneys will work harder to break it down yes, but that does mean damage. Just like in the gym, if you work harder your muscle will adapt and ultimately become stronger. Well, it’s the same with the kidneys. A 2011 study by Lowrey et al. followed bodybuilders eating high amounts of protein (1.67-3.33 g of protein/kg) and found that markers of kidney work were elevated, but markers of kidney damage (like microalbuminuria) were not.
Myth 4- As you age you need less protein
I’m not sure if people believe this one, but it’s actually the opposite. It becomes harder to retain LBM (lean body mass) as we age. Sarcopenia is a major risk of aging, which is the progressive wasting of muscle tissue, you want to hang onto that precious lean muscle as long as possible. Once it’s gone in your 60s, 70s, and 80s, it’s going to be extremely hard to regain because elderly just don’t build muscle like younger individuals. Not only is the LBM crucial for obvious reasons, like maintaining everyday physical capabilities, but it also serves as an energy depot – burning energy consumed (and diverting it away from fat stores), and improving insulin sensitivity which is crucial for staving off dementia and Alzheimer’s.
One study showed that older individuals (average age 70) required twice as much protein as the younger bucks in the study to stimulate the same amount of MPS (40 grams vs. 20 grams). So, they actually need more.
Myth 5- Athletes don’t need more protein than average individuals
The RDA recommends 60 grams of protein per day. Okay, that’s enough if you are a professional chess player, otherwise, you are looking at anywhere from 1.4 – 2.0 grams per kilogram of body weight. Athletes need more protein because amino acid oxidation increases during exercise.
Many vegetable sources of protein are incomplete because they do not contain all EAAs, but here are some exceptions:
Quinoa, hemp seeds, chia seeds, soybeans, and buckwheat.
Areta, J. L., Burke, L. M., Ross, M. L., Camera, D. M., West, D. W. D., Broad, E. M., … Coffey, V. G. (2013). Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis. The Journal of Physiology, 591(Pt 9), 2319–2331. http://doi.org/10.1113/jphysiol.2012.244897
Nowson, C., & O’Connell, S. (2015). Protein Requirements and Recommendations for Older People: A Review. Nutrients, 7(8), 6874–6899. http://doi.org/10.3390/nu7085311