Beer and Wine Isinglass, a gelatin-based substance derived from fish, is used as a clarifying agent in some beer and wine. Other non-vegan ingredients sometimes used are casein (from milk) and egg whites.

Taking stock. The account presented above shows that vegan diets can fulfil all the nutritional requirements that are needed to support good health. Nutrients that present particular concerns are vitamin B12 and omega-3 fatty acids as few vegan foods that are currently used for human consumption contain these.

At a minimum, people who call themselves vegans avoid products including meat, fish, dairy, honey, gelatin, leather, wool, suede, fur, feathers, and silk—but being vegan means more than simply changing one's dietary habits. It's also a lifestyle.

One of the earliest followers of what we now consider a vegan diet was Arab philosopher and poet Al-Maʿarri who abstained from animal products for his health and beliefs on the transmigration of souls and animal welfare.