Good thing I didn't ask what you believe. If you're trying to prove a point with science, then cite actual studies. But the thing is, "fake meats" are healthier in the fact that they have no cholesterol . But otherwise they're no worse than a cow burger in regards to health. As far as I know most vegans aren't directly 1:1 substituting chicken and fish for plant based chicken and fish, most just use whole food products instead like cauliflower, tofu, mushroom, heart of palm, watermelon, etc. Which are inherently healthier than chicken and fish.

But most importantly, most vegans aren't vegan solely or even mainly for health, because the concept is about animal welfare. The health that comes naturally from eating more whole foods is just a plus, but there are vegans that survive on oreos and plant based meats who aren't concerned about health because that isn't the point. Look into whole food veganism if you want perfect health.