 In 2015, a Harris Poll National Survey of 2,017 adults aged 18 and over found that eight million Americans, or 3.4%, ate a solely vegetarian diet, and that one million, or 0.4%, ate a strictly vegan diet.Many American children whose parents follow vegetarian diets follow them because of religious, environmental or other reasons.In the government's first estimate of how many children avoid meat, the number is about 1 in 200.