Beef, lamb and seafood are fine. Pork and poultry are not necessary but many of us like them for variety. You don't have to do 100% pastured if you decide you want pork or chicken once in a while.
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No pork or chicken for me! They're generally fed corn or soy = not good.
"I think the basic anti-aging diet is also the best diet for prevention and treatment of diabetes, scleroderma, and the various "connective tissue diseases." This would emphasize high protein, low unsaturated fats, low iron, and high antioxidant consumption, with a moderate or low starch consumption.
In practice, this means that a major part of the diet should be milk, cheese, eggs, shellfish, fruits and coconut oil, with vitamin E and salt as the safest supplements."
- Ray Peat
Pork tends to be slightly higher in overall micronutrient quantity for a lot of vitamins and minerals as opposed to beef and lamb (but not fish). The difference is not really that much of one however. Also less risk of getting too much iron since it has quite a BIT less than red meat and you CAN get too much iron.
But these are not really huge concerns.
I eat chicken when others make it or I'm going out for wings but I NEVER make it for myself. So mostly I avoid it. Pork is mostly the occasional packet of the ground stuff because I have an AMAZING source of pastured pork and it tastes GREAT in my "combo" meatloaf (ground beef, lamb, and pork). But that's about it.
I don't notice I feel any worse for it.
Here in the UK it is easy to get hold of free range (which I think you call pastured) pork and outdoor chickens which eat grubs, slugs etc etc. The eggs are just great and I eat pork and chicken at least once a week. But also lamb, beef, fish etc - as long as it is naturally (or as naturally as possible given that it isn'e actually wild) reared. I don't worry about the O6 / O3 ratio as I feel that the free range aspect helps even that out, as does lots of fish... It's the flavour - good pork is in a class of its own, and a well roast free range chicken is sublime!
My last blood check showed high iron, i felt pretty crap, definitley overdoing the red meat and to top it off eating offal and whatnot. Primal diet will easily lead to building up of iron stores, which has been linked to cancers, inflammation etc, particularly because the primal minimizes foods which prevent nutrient absorption and probably 8 out of 10 times your eating some vitamin c with that red meat.
I buy most of my meats and poultry from a farm run by Mennonites. They have free range chicken, pork, beef and turkey. They occasionally have rabbit. Their pork tastes so much better than grocery store. I also buy eggs from them. The only thing I don't buy from them is their ground beef it just tastes too gamely for me, so I either buy ground bison or regular ground beef at the supermarket.
Paul Jaminet of the "Perfect Health Diet" fame refuses to eat pork or ANY poultry for just this reason, as do several other paleo/ancestral health gurus. Matt Lalonde, a noted biochemist has also come straight out and said that grass-fed red meats are a far better choice for overall health and avoiding inflammation and long term issues than pork or poultry and he's studied the chemistry behind this stuff.
I'm not saying they're trying to scare us off of pork or chicken forever but they make a good point. Nobody is saying that to have a piece of chicken, or that pork chop is going to kill you, but the suggestion here is merely to make red meats the main focus of the diet with fish a couple of times a week to ensure you're getting the o3 you need. The inflammation issues are worth considering when you realize that inflammation just might be the greatest indicator of future heart disease risk.
Grassfed beef, pastured eggs, and seafood (not farmed) make up the bulk of my animal protein. I do like pork and chicken though so I have either for a meal or two a week. Bacon is usually reserved for a few weekend breakfasts/brunches a month. I try to use up any of the saved bacon fat before I make more bacon. Doesn't always work out but I try. Pastured bacon is too expensive to waste the fat, lol.