[guygurari]

I fail to see how sprint speed, or indeed any other sports-based metric, is related to health. A strictly vegetarian diet is more healthy in the sense that it dramatically reduces the chances of getting various diseases. These include some of the top killers in developed countries, like heart disease and stroke. Vegans are also far less likely to be obese, and obesity is an important risk factor of many diseases.

The three main factors that influence health (in the sense above) are smoking habits, diet, and exercise. The factors you mention are secondary. I refer you to the sources I cited above for more details and evidence.

> Basically there is no such one-fits-all scenario for a diet.

That's a bit like saying that not everyone should avoid arsenic... There are of course personal variations, but the fact that meat, dairy and eggs are bad for you is not one of them. The basic mechanisms that cause animal-based food to be harmful, like the fact that saturated fats increase bad cholesterol, are well-studied and do not vary greatly from person to person.

On the other hand, a vegan diet is not one-size; it's not like we just eat lettuce all day. In fact, when you go vegan you discover that you do not lose any diversity, because there are many plant foods that non-vegans usully don't consider eating (for no good reason).