I'll start: some years ago, a medical professional recommended I take a daily omega-3 supplement. What I got naturally was fish oil capsules, and these of course had the nutrients I needed. So problem solved. But not only did these make me queasy, they also (I'm so sorry for this imagery for those who've never had these) gave "fish burps". Basically, after ingesting them, they can (and for me consistently did) give you these nasty, tic-like burps that taste like you let a fish decay in a bucket for three days and drank that water.
This goes on for a while until the I realize that they sell "burpless" fish oil. The day was saved, and I went home with a new lease on life. Well, until I tried it and I realized that it's not so much "burp-less" as it is "burp-lite". It just reduced the severity of the symptoms but meant I still felt slightly sick and could still have those nauseating burps. I eventually gave up on it because even just one stray burp felt that gross.
Later on, I went vegetarian (I'm now vegan), and although at that point I had plenty of ALA in my diet, I decided to look back into an omega-3 supplement as a precaution since my diet had shifted so dramatically. Of course fish was out of the question, so I looked into alternatives and landed on flaxseed oil capsules. These were more expensive per capsule, but I felt that they made up for it by having 1.6x the omega-3 per capsule. Taking one for the first time, I felt 100% normal. No upset stomach, no burps, no weird fish taste (in fact, if you crack open the capsule, the oil is quite bland). It worked flawlessly. At that time I didn't avoid the gelatin in the capsule as I would now, but you can find flaxseed oil in plant-based capsules for a slightly higher price from suppliers like Deva.
TL;DR: flaxseed oil supplements omega-3 without nasty side effects like fish oil capsules. It just works, and I wish I'd known about it so much sooner.
That's a good question but hard to nail down. In terms of nutrition, I was in decent shape as an omnivore in my late teens, early twenties, but nutrition was miles away from any thoughts I had on my diet. And even then, back in the late 90s/turn of the millinea, most substitutes and otherwise interesting plant-based foods didn't exist, had limited availability or were pretty rough (cheeses, burgers etc...). Best we had was Morningstar corn dogs, boca and tofutti slices.
I think Soy Curls were hitting the market up in Portland around that time (2k-ish), and that would have been mega when I was younger. But I was in Sac/San Diego at that time and distribution wasnt as widespread, or at least I hadn't seen them. Though, now that I think of it, you could get big tvp chunks in 16oz bags at Trader Joe's in that timeframe, so I guess that's my primary answer.
That said, I suppose I would have loved to discover Sunflower Cafe in Fair Oaks (Sacramento CA area) earlier on before going vegan. The super nut-burgers are amazing and that might have driven me to joining the dark side a lot sooner.
Do you remember Veat? It was a fake chicken breast molded into a little chicken shaped tray, and it was incredible. I don't think I saw it after 2003, but it was one of the first truly delicious meat substitutes. Besides riblets and corndogs.
I had totally forgotten about Veat. But you also reminded me about the Morningstar riblets. If those were around in the late eighties, early ninties, that would be my answer. It would have made me rethink the whole meat industry.
Of course the barbarisim and inefficiencies of meat/dairy production as a whole should be enough, but I wasn't exactly the deepest thinker when I was younger.