Some cultures and religions have restrictions concerning what foods are acceptable in their diet. For example, only Kosher foods are permitted by Judaism, and Halal foods by Islam. Although Buddhists are generally vegetarians, the practice varies and meat-eating may be permitted depending on the sects. In Hinduism, vegetarianism is the ideal. Jains are strictly vegetarian and consumption of roots is not permitted.
A negative-calorie food is food that supposedly requires more food energy to be digested than the food provides. Its thermic effect or specific dynamic action – the caloric "cost" of digesting the food – would be greater than its food energy content. Despite its recurring popularity in dieting guides, there is no scientific evidence supporting the idea that any food is calorically negative. While some chilled beverages are calorically negative, the effect is minimal and drinking large amounts of water can be dangerous.
Health food is food marketed to provide human health effects beyond a normal healthy diet required for human nutrition. Foods marketed as health foods may be part of one or more categories, such as natural foods, organic foods, whole foods, vegetarian foods or dietary supplements. These products may be sold in health food stores or in the health food or organic sections of grocery stores.
Rising food prices in those years have been linked with social unrest around the world, including rioting in Bangladesh and Mexico, and the Arab Spring. Food prices worldwide increased in 2008. One cause of rising food prices is wealthier Asian consumers are westernizing their diets, and farmers and nations of the third world are struggling to keep up the pace. The past five years have seen rapid growth in the contribution of Asian nations to the global fluid and powdered milk manufacturing industry, which in 2008 accounted for more than 30% of production, while China alone accounts for more than 10% of both production and consumption in the global fruit and vegetable processing and preserving industry.
"Seasonal" here refers to the times of year when the harvest or the flavour of a given type food is at its peak. This is usually the time when the item is harvested, with some exceptions; an example being sweet potatoes which are best eaten quite a while after harvest. It also appeals to people who prefer a low carbon diet that reduces the greenhouse gas emissions resulting from food consumption (Food miles).
Many cultures have a recognizable cuisine, a specific set of cooking traditions using various spices or a combination of flavors unique to that culture, which evolves over time. Other differences include preferences (hot or cold, spicy, etc.) and practices, the study of which is known as gastronomy. Many cultures have diversified their foods by means of preparation, cooking methods, and manufacturing. This also includes a complex food trade which helps the cultures to economically survive by way of food, not just by consumption.