Meat eater for 31 years. Been a vegan for the past 1 year. Of course, just my one example is not statistically strong enough to make a case for veganism, however, I welcome anyone to post their questions on veganism here. There are 2 undisputable aspects to veganism, environmental and health.
Environmental:
Like it or not, it is a lifestyle that directly contributes to reducing the carbon emissions. Animal farming contributes about 25% of overall greenhouse gas emissions. That is almost on par with emissions due to fossil fuels. The EU has a made a decision to reduce the carbon emissions by 55% by 2030. Unfortunately they will not address the factory farming situation. They will only target the fossil fuels when they should be targeting both. So, if you are a person who respects science and cares for the environment, if you believe that man made global warming is a real thing, there is a certain hypocrisy in turning a blind eye to the obvious fact that meat and dairy industries are destroying the environment.
Health:
I have been a meat eater for 31 years. I have been mostly plant-based for the past 3 years and strictly a vegan for the past year. I grew up in a family that loves their meat, dairy and fish. In fact, for most of my life, I could not eat a meal without meat or fish in it. I despised vegetarian foods. After doing my research in various diets for about 2 years, I decided to go plant-based. I was sick of the chronic asthma and being over-weight. I have never felt better. I am a scientist by profession and I could not ignore both my health and the environmental impact of the meat and dairy industry, not to mention the deeply immoral practice of factory farming.
But I get the skepticism and indifference. I hated on vegans as well for the longest time because I feared what I did not know. I could not fathom living without meat or dairy. As far as the discussion in this thread is concerned, there is a lot of BS flying around. You eliminate all risk of a heart attack on a whole food plant-based diet. It is nothing but a paper tiger. The only thing that can cause it is blockage in arteries. Saturated fats cause that and they are primarily present in meat (mostly red meat), dairy and processed foods (vegetarian and otherwise). The research showing the reduced risk of cancer on a plant-based diet is immense.
I can go on and on, but I encourage a constructive dialogue. If you have specific questions, I can quote sources with proper research not funded by vested interests. Vegan athletes are outperforming non-vegan athletes as far as leveraging every last bit of potential is concerned. In every sport. We can debate on that as well.
Lastly, you will need supplements for B12 on a vegan diet. Nothing else. You get every other vitamin and mineral you need on a plant-based diet. However, these days, the super market aisles are full of plant-based milks fortified with B12 and other vitamins. Nutritional yeast comes loaded with B12 and it is delicious. My most recent bloodwork had a higher than normal levels of B12 and every other vitamin despite eating no meat for 12 months. Please do not fall for the stereotyped BS. Do your research and when you look at research papers, always see who funded the research.