There's no amino acid provided by meats that you can't get from plants. Soy is a complete protein.

https://www.aafp.org/afp/2009/0101/p43.html

https://www.ncbi.nlm.nih.gov/pubmed/19145965

https://en.wikipedia.org/wiki/Complete_protein

Now, to be fair, soy _does_ have a low level of tryptophan. Leafy greens are the best way to boost that, if that's your concern.

Soy also needs to be avoided by people with thyroid problems.

Sure, there's also a fair number of people with allergies to soy. It's not the only complete protein from the plant world though. There's also:

  * Quinoa
  * Buckwheat
  * Hemp & Chia seed
  * Spirulina
  * Mycoprotein

Not to mention the estrogen effects on the male body caused by soy. (Yes, the studies say it doesn’t affect testosterone levels of men, but men also need a certain level of estrogen to be healthy and too much..not good)

The studies show it doesn't affect testosterone levels because the phytoestrogens in soy for the most part don't react with estrogen receptors to trigger a response from your body (at least not when going through normal digestive mechanisms). The amount of phytoestrogens you consume has no causal relation to the amount of estrogen in your hormone system.

Sure, do whatever is right for you. My research into the meat industry indicated that I was actually consuming a lot of stuff along with the meat that just isn't good for you. Sure you can go fully organic, free-range etc, but the meat we eat today is nothing like when we were hunter-gatherers. In those times we ate wild animals that lived free and healthy. As far as I can tell, it is impossible to get that level quality of meat at your local supermarket.

Elsewhere you said you occasionally eat fish for the omega fatty acids, what kind of fish?

There's been a number of reports describing farmed fish as some of the most toxic food sources on the planet. It's definitely changed my attitude towards defaulting to a fish option at restaurants where its provenance is unknown or at best ambiguous.

My goto has become canned wild sardines in water, consumed similarly for omegas in an otherwise mostly plant-based paleo-like diet.

My prio list is as follows:

Salmon > mackerel > sardines > herring > trout.

I love salmon, but any of the above will do. I also switch it up for variety.

Honourable mention is shrimp, which only has 1/4 the Omega of salmon, but is usually the easy option at BBQs (and avoids the annoying conversations about how not eating meat isn't manly).

I make sure I go for wild fish, and also buy it fresh (never in packaging unless I'm absolutely desperate).

Apart from the environmental impacts right?

Everything you do on Earth has an environmental impact. You think your veggies are collected and sorted and shipped to stores without impacting the Earth at all? Sometimes you gotta pick your battles and I think eating chicken is pretty low on the list of bad things we’re doing to the environment.

You mean growing soy in the area of the rain forest? (scnr)

And the chickens' perspective, which matters to many people.

And the workers' perspective depending on the source of the chickens.