One of the most meaningless stats bantered about by sophists is “grams of protein”. Why? Because proteins from different sources of food have different amino acid compositions and different bio-availability. So arguing that 100 grams of kidney beans has the same amount of protein as 100 grams of beef is not only not true, but is also quite asinine. Though, no matter how many times you point this out whenever you see popular memes littered around the internet, food religious zealots seem to even more fervently stick to their cultist beliefs.
Regardless, for shits and giggles, let’s deconstruct the frequently posted 100 grams of beef versus 100 grams of kidney bean meme.
To begin with, per nutritondata.self.com,
100 grams of cooked kidney beans has only 8.6 grams of protein. Whereas 100 grams of a beef, rib, eye has 26.2 grams of protein
So you need to eat 300 grams of beans to get a similar weight in grams of protein. But again, “grams of protein” is a meaningless stat. To have something more meaningful and relevant, you have to look at the amino acid compositions of the proteins. Thus in this side by side comparison of the amino acid compositions of beef versus beans, one can see for example, that in order to get the same amount of lysine, one would have to eat approximately 370 grams of beans.
Worth also noting is the importance of high quality protein including adequate levels of leucine (high in meat proteins & low in plant proteins) for muscle synthesis as noted in this following clip:
Another issue with protein is the bio-availability of these amino acids. So again, not all “grams of protein” are equal. Some grams can be better absorbed and utilized by your body than other grams from other sources. The Digestible Indispensable Amino Acid Score [DIAAS] is a way to measure protein availability from different sources of food. The DIAAS measures the amount of amino acids digested at the end of the small intestine. The higher the score the better absorption and utilization of amino acids. The no-nonsense guide to absorbing protein gives a more detailed explanation. As this source notes, many plant sources of protein contain phytic acid, trypsin inhibitors and other compounds that limit protein absorption and availability. Kidney beans have a much lower DIAAS score than beef as shown in the table below. Therefore, protein from kidney beans is a lot less bioavailable than protein from beef.
Yes, kidney beans contain fiber and beef doesn’t. That’s why beans make you bloat….and fart. (I’m also not sure I want to be around someone who eats 300+ grams of beans to get all their protein requirements). Now many think that fiber is absolutely essential to feed microbes in your gut microbiome to support the gut lining through the production of short chained fatty acids. Well, as explained in the below video clip, fiber isn’t the only pathway. The gut lining can also be supported by ketones in the blood on the other side of the of this barrier as well as by fermented proteins. So the belief that dietary fiber is the only way to support the gut lining is a myth.
Minerals are equally problematic and misrepresented by this meme. Though here, the numbers are at least a bit closer to being correct (from nutrition self data, 100 grams of kidney beans have 3.9 mg of iron, 74.3 mg of magnesium and 62 mg of calcium or about 1/2 of what this meme claims). Beef is also a much better source of zinc and selenium.
However, these numbers once again don’t tell the entire story. Why? The anti-nutrients- phytates, oxalates and lectins– that beans contain also block mineral absorption. So what’s consumed isn’t what’s necessarily utilized. In general, minerals from animal sources are much more bio-available than those from plants, especially iron, zinc and calcium. Why? Animal sources of these minerals don’t contain these anti-nutrients.
Plus for calcium to be metabolized properly, a person also needs vitamins A1, K2 and D3. Plants don’t have A1 or D3. Plants contain A2 not A1. The conversion of A2 to A1 varies in different people based on an array of different factors including SNP mutations, and other mineral availability. This conversion issue might be worthy of its own post, so I won’t go into any more detail here.
Regardless, soaking beans to remove lectins and phytates helps reduce these anti-nutrients. But soaking also leaches some of those minerals (and phytonutrients) in the plants. So does cooking.
Unless you’re a hyper responder, the cholesterol you consume has little impact upon your serum level of cholesterol. So that’s really not an issue for the majority of people. Moreover, LDL cholesterol by itself, as noted in the below video, is a very poor marker for cardiovascular disease [CVD] or coronary heart disease [CHD]. So the benefit of lowering cholesterol (and by proxy lowering saturated fat) is more myth based on outdated science than anything most people have to be concerned about.
Costs vary, so using the numbers provided in the meme, to get the same “grams of protein” in the meme, a person needs to eat at least 300 grams of beans to get the same amount of grams. So the more accurate cost is $3.00 for the beef and $1.50 for the beans. When you factor in quality, absorption and availability using the DIAAS figures, the costs numbers are even more similar since the kidney beans DIAAS is closer to 55% that of beef’s.
The water numbers, based on water footprints, are also deceptive. With beef, most (98%) of the water footprint number is the number required to grow the feed or forage fed to a head of cattle over its entire life time. Most of that number is “green” water. Green water is rainfall that falls regardless of the land use. With grass finished beef, 97% of the total water used is green water. With feedlot finished beef , around 93% of the total water used is green water. Blue water (ground water) is what’s critical…not green water.
Well managed grazing in grasslands also improves soil health and restores native perennial plant species. Unlike bean crops, those perennial plants have deep root systems. So the grasses and forbs beef cattle graze actually require less water than what’s required to grow beans. Moreover, improved soil health- with increased soil organic matter- greatly increases the amount of water that infiltrates and is retained by soil. One of the many short comings of the water balance equations used for water footprints is that these equations do not account for a lot of parameters including and especially soil health and the amount of soil organic matter in range or crop land. Thus they’re not very good indicators of environmental impacts of different land uses. A lot of land that can be used for grazing cannot be used for growing beans crops due to the lack of water availability or because the land is too steep or susceptible to wind. On such range land cattle are upcycling inedible to human grasses into nutrient dense high quality proteins. Cattle are doing the same with a lot of inedible to human crop residues and by-products as explained in this below video clip by Dr. Don Layman, a protein specialist and professor emeritus at the University of Illinois. So, as Dr. Layman, states, ruminants are a very important part of the food chain because the bacteria in their rumen convert low quality amino acids into high quality amino acids. Beans, obviously, don’t do this.
One thought on “Grams of protein in context”
I stumbled across your site via a random Twitter post (and I rarely go on Twitter). It’s articles like this that make me wonder how I’ve never found your site before. Wonderfully written, informative and scientifically based facts. Just what I needed ❤️