Bioavailability refers to the proportion of a nutrient that is absorbed and utilized by the body. In the context of protein, the bioavailability also implies how efficiently the body can use the protein once it’s absorbed. The bioavailability of protein can be measured using the Protein Digestibility Corrected Amino Acid Score (PDCAAS) and the Digestible Indispensable Amino Acid Score (DIAAS), among other metrics.

Given that, here’s a general ranking of protein bioavailability from various sources:

1. Whey Protein: Often touted as the most bioavailable protein, widely used in protein supplements due to its rapid absorption and rich amino acid profile.
2. Eggs: Particularly egg whites, have a high bioavailability and provide a complete protein source.
3. Milk: Rich in casein and whey protein, it provides a good balance of quick and slow-releasing proteins.
4. Soy: Among the plant-based proteins, soy protein isolates have comparatively high bioavailability and also provide all essential amino acids.
5. Beef: Animal proteins like beef are usually high in bioavailability and contain a complete amino acid profile.
6. Chicken: Much like beef, chicken is also a highly bioavailable source of protein and it’s leaner than beef.
7. Fish: High-quality protein that is typically lean and readily utilized by the body.
8. Quinoa: A complete protein that is relatively rare among plant sources due to its amino acid profile.
9. Lentils and Legumes: Although lower in methionine, they are still a good protein source, especially for plant-based diets.
10. Nuts and Seeds: Not as bioavailable as other protein sources and also come with higher fat content, but they are a valuable protein source, especially for vegan diets.

It’s important to note that utilizing a variety of protein sources in your diet is key to ensuring you get a comprehensive array of amino acids and other nutrients. This is particularly vital for those on plant-based diets, where combining different protein sources (like beans and rice) can provide a complete amino acid profile. Remember that personal digestive health, food sensitivities, and dietary choices will also influence the best protein sources for each individual. Always consult a healthcare professional or a registered dietitian when making significant changes to your diet.