Kidney beans are interesting. On the one hand they’re very common, appearing in dishes like chili, and on the other hand they’re clearly being overlooked as a fantastic source of protein. (There is more protein per calorie in a kidney bean than a black bean.
Couple this with the fact that the protein is very nearly/virtually complete and you should begin to see the strategic value of kidney beans as a protein source.
Is Kidney Bean Protein Complete?
Close but not quite complete. The issue is with the methionine+cysteine content. You’ll notice immediately in the chart below that it really only slightly under.
Protein Density of Kidney Beans
The density of protein relative to Calories is actually quite good. You’ll notice that it’s denser than black beans which is interesting given the popularity of black beans in the slow carb community.
In the table below we express protein density relative to Calories as the equivalent Calories per gram of protein.
Source Density (Calories per g of protein)
Pure Protein 4.00
Pacific Cod 4.54
Egg Whites 4.77
Turkey Breast 4.88
Alaskan Halibut 5.11
Chicken Breast 5.32
Whey 4.40
Tofu, Soft 8.51
Lentils 12.86
Kidney Beans 14.65
Black Beans 14.90
Pinto Beans 15.87
Quinoa 27.27
Oatmeal 27.95
Brown Rice 48.28
Other Nutrients and Minerals in Kidney Beans
The values below are for 100g of boiled kidney beans. Nothing added.
Notice that, like virtually all beans, kidney beans are a great source of minerals and B vitamins.
%DV
Manganese 24%
Iron 16%
Phosphorus 14%
Potassium 12%
Copper 12%
Magnesium 11%
Vitamin B1/Thiamin 11%
Vitamin K 10%
Comparison with Lentil and Soy Protein
If you look at the chart below you’ll see that kidney beans really give soy a run for it’s money in terms of the branch chain amino acids. Maybe they should make kidney bean curd (kidney bean tofu)? In any event, the leucine content is high relative to lentils and soy. We’ll see just how high when we look at whey next.
Comparison with Whey Protein
Our next benchmark is whey. We’re specifically looking at leucine for this one as whey is one of the highest sources of leucine.
Conclusion
Break out the chili powder and start cooking because kidney beans are back on the menu. If you hate soaking beans remember that kidney beans are available in canned form. Just remember to rinse them well.
