Dietary vegans (or strict vegetarians) refrain from consuming animal products, not only meat but also eggs, dairy products and other animal-derived substances. The term ethical vegan is often applied to those who not only follow a vegan diet, but extend the vegan philosophy into other areas of their lives, and oppose the use of animals or animal products for any purpose. Another term used is environmental veganism, which refers to the rejection of animal products on the premise that the harvesting or industrial farming of animals is environmentally damaging and unsustainable. The key to a nutritionally sound vegan diet is variety. A healthy and varied vegan diet includes fruits, vegetables, plenty of leafy greens, whole grain products, nuts, seeds, and legumes. .