Hinduism is one of the largest religions in the world, encompassing almost one billion adherents who believe a variety of things. Depending on the sect that someone follows and the region that he or she is from, a Hindu may have an assortment of dietary restrictions that should be considered when cooking a meal. Because of the wide variance in beliefs, you should ask your guest, if possible, about forbidden or unsafe foods. If you cannot do this, you may want to consider serving a strict vegan meal, which will exclude most foods forbidden to most Hindus.
Many Hindus believe that the foods they eat contribute to their personal and spiritual purity. Because most sects of Hinduism involve a belief in a cycle of life which is impacted by individual actions, they place restrictions on harmful foods, meaning foods which are harvested in a way that might negatively impact the karma of the consumer. On certain occasions, a Hindu may observe a more strict diet, or choose to fast as part of a cleansing process. Because of the wide variance of traditions, most adherents welcome questions from people who are curious about their religion, especially when the questions are intended to make a guest more comfortable.
It's quite common for Hindus to be vegetarians, meaning that they not eat the flesh of animals, in accordance with ahimsa, the idea that a Hindu should avoid harm, violence, and suffering. Dairy products and eggs are usually permitted, except in some regions and on certain festival days. Certain food products can be deceptive; some cheeses, for example, are made with rennet, an animal product, and you should take care to purchase vegetarian cheese. Certain sects, such as the Jains, eat a strict vegan diet which contains no animal products. In addition, a Jainist refrains from eating certain fruits and vegetables at certain times of the year, out of concern that animals may be living on them.
If a Hindu guest informs you that he or she eats meat, you should most certainly avoid serving beef of any form. The cow is a holy and sacred animal, and should not be slaughtered, although drinking milk is acceptable. Some Hindus also avoid pork, and in some areas, animals like ducks and crabs are considered unclean, and should not be eaten. Do not be afraid to ask a guest to elaborate on which meats he or she can eat.
Many Hindus have specific beliefs about individual fruits and vegetables. Garlic, onions, and tomatoes, for example, are considered to be foods which excite the body, and some choose to avoid them. In many cases, red foods are also avoided, because the color is reminiscent of blood.