Not at the rate that we consume it. But having beef, chicken and pork once per week? Definitely something that is healthier for our bodies, the planet and the livelihoods of these animals.
> All plant foods contain all 20 essential amino acids including the 9 essential amino acids in varying amounts.
> Though historically, protein combining was promoted as a method of compensating for supposed deficiencies in vegetables as foods, studies on essential amino acid contents in plant proteins have shown that vegetarians and vegans typically do not need to complement plant proteins in each meal to reach the desired level of essential amino acids as long as their diets are varied and caloric requirements are met. The position of the Academy of Nutrition and Dietetics is that protein from a variety of plant foods eaten during the course of a day supplies enough of all essential amino acids when caloric requirements are met.
Definitely? The reality is that there is no high-quality research which establishes the healthiest weekly frequency of meat consumption. We can't say whether it's 0, 1, or some higher number. The studies so far have generally been too short, relied on subject reported data (i.e. junk), used proxy metrics only loosely correlated with overall health, had small effect sizes, and failed to control for confounding variables (i.e. healthy subject effect).
Let's have some humility in this area. There is very little in human nutrition that we know for sure.