In my area (Romania) vegetarianism is something rather new and has a small number of proponents. While being a vegetarian I heard from time to time some persons (including medical doctors) that one should necessarily eat meat because it has "higher quality proteins".

However, no one really managed to explained what does this means.

I have searched a little bit and found this article which makes me feel that protein quality assessment is far from being trivial:

Protein quality describes characteristics of a protein in relation to its ability to achieve defined metabolic actions. Traditionally, this has been discussed solely in the context of a protein's ability to provide specific patterns of amino acids to satisfy the demands for synthesis of protein as measured by animal growth or, in humans, nitrogen balance. As understanding of protein's actions expands beyond its role in maintaining body protein mass, the concept of protein quality must expand to incorporate these newly emerging actions of protein into the protein quality concept. New research reveals increasingly complex roles for protein and amino acids in regulation of body composition and bone health, gastrointestinal function and bacterial flora, glucose homeostasis, cell signaling, and satiety. The evidence available to date suggests that quality is important not only at the minimum Recommended Dietary Allowance level but also at higher intakes.

Question: is it true that the proteins one gets from meat are superior from those coming from vegetarian sources?

In my area (Romania) vegetarianism is rather new and has a small number of proponents. While being a vegetarian, from time to time, I hear from some persons (including medical doctors) that one should necessarily eat meat because it has "higher quality proteins".

However, no one has really managed to explain me what that means.

I have searched a little bit and found this article which makes me feel that protein quality assessment is far from being trivial:

Protein quality describes characteristics of a protein in relation to its ability to achieve defined metabolic actions. Traditionally, this has been discussed solely in the context of a protein's ability to provide specific patterns of amino acids to satisfy the demands for synthesis of protein as measured by animal growth or, in humans, nitrogen balance. As understanding of protein's actions expands beyond its role in maintaining body protein mass, the concept of protein quality must expand to incorporate these newly emerging actions of protein into the protein quality concept. New research reveals increasingly complex roles for protein and amino acids in regulation of body composition and bone health, gastrointestinal function and bacterial flora, glucose homeostasis, cell signaling, and satiety. The evidence available to date suggests that quality is important not only at the minimum Recommended Dietary Allowance level but also at higher intakes.

Question:

Is it true that the proteins one gets from meat are superior to those coming from vegetarian sources?