Does opting a vegan diet actually reduce any animal suffering?

Does opting a vegan diet actually reduce any animal suffering?

This thing is in fashion today. Celebrities like natalie portman, james cameroon and scores of others have adopted vegan/vegetarian diets citing reasons like 1) reducing animal suffering 2) reducing environmental damage. My question is whether such a choice actually reduces animal suffering and environmental damage or its a myth spread by vegans. Because many serious food production professionals in this section who have worked in production of food say that removing meat from your diet has absolutely no positive impact. Some of them even claim that vegan food is more environmentally damaging than non vegan food. What is the ACTUAL REALITY AND HOW