I think much of it depends on how you feel about it, as spirituality is very subjective. People on all kinds of diets can have ''spiritual experiences''. You get your vegetarian Krishna priest and you get your meat-eating shaman. If you think you're doing the right thing on a vegan or vegetarian diet then this will reduce stress.
Your level of knowledge is key as well. He that increased knowledge increases sorrow. Every form of farming deliberately kills animals. Either the farm animals if you eat meat, or the insects are sprayed in a crop field. Then there's rodents, boar and geese shot or poisoned because they eat crops meant for us. There's always animals that are killed intentionally by the farmers. This could be limited in some places and with some farming practices but then you're not looking at a modern world any more.
If you're looking at this question from a spiritual practice point of view then it can be said that some foods and drinks could be disturbing if you're going to sit cross legged and seek to silence the mind. Eating a bowl of ice cream or potatoes or steak can all make you feel stuffed and some foods will make your skin itchy, just like sugar and drinks like coffee can overstimulate the mind if you're sensitive to them.
Experiment away and see what works for you. :-)