This tweet came through my feed last week: “Whole grains are approximately 10-12% protein. The exact percentage we should be eating. Nature knows best!” I started to respond via twitter but I couldn’t keep it down to 140 characters. Lucky you, you get to read my rant in response.
I’m not sure where the notion that 10-12% of calories from protein is optimal came from. Acceptable Macronutrient Data Ranges put protein needs at anywhere from 10-35% of total calories. The 10-12% is within this range, but it’s at the low-end. Also, I’m sure you’ve heard the saying that “man cannot live on bread alone”. Even if this is the amount of protein that you’re obtaining from whole grains, they’re not going to be the only food that you’re consuming so you’ll need to eat other protein-containing foods to ensure that you’re getting enough protein.
I looked at the protein content of a few whole grains. 3/4 cup of cooked rolled oats contains 2.85 grams of protein. That means that of total calories in a serving, about 8% come from protein. About 9% of calories in long-grain brown rice come from protein. Quinoa fares better, coming in with 14.6% of calories from protein. Multi-grain whole-grain bread actually has about 20% of calories coming from protein (although this amount is likely to vary considerably depending on the recipe). My point here is that not all whole grains consist of 10-12% protein.
The last point that I want to make is that not all proteins are created equal. Proteins are made up of amino acids of which there’s a recommended pattern of consumption (we need more of some than of others). Grains do not generally contain the pattern of amino acids that we need, making it necessary for us to consume other sources of protein to ensure that we get all of the amino acids we need.
Sure, nature knows best. Nature also knows that grains are not our best or only source of protein.