There are about a dozen common ones that limit bioavailability of things like vitamin A or iron from plant sources. I don't keep the list in my pocket, and the enshittification of search has risen to the point where trying to find it again just gets me lectured by an AI about how I should go vegan.

Also:

some people believe the "you can't get nutritionally complete diet from veganism" thing, which isn't true. All vitamins, proteins, and nutrients we need are available while vegan.

While that's technically true, it's not actually easy to get things like Omega-3 from plant sources, and most of the nuts and seeds that have it are expensive and/or difficult to source.

You also have to basically spend a lot more of your free time figuring out a meal plan that will allow you to actually get all the vitamins, minerals, and nutrients you need on a plant based diet, and you'll still likely wind up eating the same meals every week bcs there's only so many vegan sources of things your body really needs.

At the end of the day, veganism is a consumerist solution to structural problems. Much like snake oil to "reduce your carbon footprint", it pushes responsibility for a societal problem back on the individual.

Is eating less meat, and having that meat be mostly fish and poultry a good thing for both your health and the environment? Absolutely. Is it nearly as impactful on either as getting rid of your car? I'd say probably not.

It IS true.

There are not many nutrients only available on meat, but they do exist nevertheless, just as there are some nutrients on vegetables not present at all in meat, and the same for mushroom with these two.

But even if we don't count that, the amounts and forms matter. For example, both have iron, yeah, but almost only animals have hemo iron, while there's barely vegetables with hemo iron, although in mushrooms is more common, but even then in those two hemo iron is found in really low concentrations, and the non-hemo iron is barely metabolized by human body because it needs structures that we humans lost. Like, cows have a crazy big stomach with four compartments to be able to process non-hemo iron. And even if so, they still have to be most of their day eating to be able to survive, because vegetal nutrients are simply not as dense as their counterparts in meat.

That's only one example.

Copy-paste from another comment I made:

The problem is that's an elitist and exclusionary take.

Vegan and vegetarian replacements are way too expensive for almost the 99% of the population, and while you can theoretically replace some of these with medication and supplementation, it will never be the same as the synthetic replacements will never have the exact nutritional matrix that the natural animal source has, and as such it will not interact the same with our metabolism and our organs, thus causing a higher probability on related diseases and health issues.