A diet is the combination of foods typically eaten by a specific group of people or other organisms. Human diets are determined by nutritional needs, the types of food available in a particular region, and cultural beliefs.

Nutritional Needs

A balanced diet is one that provides all of the nutrients needed for good health and proper growth.

No single food can provide all the nutrients people require. As a result, people combine many different kinds of foods in many ways to meet their nutritional needs.

The nutrients we need include carbohydrates, fats, proteins, minerals, and vitamins. Carbohydrates mostly come from plants, and include starches and sugars. Fats come from both plants and animals, and include vegetable oils such as corn oil and olive oil, and animal fats from meat, fish, dairy products, and eggs.

Proteins are found in nearly all foods in varying amounts. Animal products, legumes, whole grains, and nuts are particularly rich in proteins.

Vitamins and minerals are also found in most foods in varying amounts. Different foods are rich in different vitamins and minerals. Orange vegetables such as carrots, sweet potatoes, and pumpkins are all high in vitamin A. Citrus fruits contain lots of vitamin C. Meat, legumes, and spinach provide iron. Dairy products are high in calcium.

Most animals have the same dietary requirements as people: vitamins and minerals, proteins, carbohydrates, and fats.

Herbivores are organisms that consume only plants. They digest the tough fibers in plants and do not need meat for nutrition. Herbivores are often called primary consumers because they are the first (primary) eaters of autotrophs, or organisms that produce their own food.

Some herbivores, such as pandas and koalas, have such specialized diets that they need to eat all day. Pandas mostly eat bamboo, while koalas mostly eat leaves from eucalyptus trees. Both bamboo and eucalyptus have very low nutritional value. Pandas and koalas must eat tons of the plants to fulfill their dietary requirements for nutrition.

Animals that eat meat are secondary consumers. Carnivores, which mostly eat meat, and omnivores, which eat both plants and meats, are secondary consumers. The diets of secondary consumers are often more varied than primary consumers. Because meat usually has more energy and calories than plants, secondary consumers often eat less often than primary consumers. While koalas and pandas eat for hours every day, a lion may only eat once a week.

Regional Foods

Before the development of modern transportation and food storage, people’s diets depended on the plants and animals that thrived in the areas where they lived. Even today, people who live by the ocean tend to eat a lot of seafood. People in tropical climates have access to a variety of tropical fruits such as coconuts, bananas, or breadfruit. People in temperate lands can grow wheat easily, and people in warm, wet climates often grow rice in waterlogged soils.

Most traditional diets rely on a food staple—usually a grain or tuber (potato or root vegetable)—and a variety of other foods that are eaten in lesser amounts. For example, rice is prominent in Japanese cuisine, along with fish, noodles, soy products such as miso and tofu, vegetables, and tea.

In Mexico, corn is a staple food, often in the form of corn tortillas. The traditional Mexican diet also includes tomatoes, squash, sweet potatoes, and chocolate. Mexican foods are often flavored with chili peppers such as jalapenos, poblanos, and serranos.

Diet and Culture

Culture plays a major role in dietary choices. Our social values influence what we eat, how we prepare food, and when we consume it.

For example, culture dictates which edible plants and animals are considered food. In the United States, most people consider dogs and horses to be pets, not food. However, horsemeat is a common dish in Central Asian countries like Kazakhstan, and dog meat can sometimes be found in restaurants in some Southeast Asian countries, including Vietnam. Most westerners also object to the thought of eating insects, but they are considered delicacies in other parts of the world. People native to Australia and the island of New Guinea enjoy grubs. In Bali, Indonesia, dragonflies boiled in coconut milk are considered a delicacy. People in Ghana enjoy fried or roasted termites.

Religion often plays a role in diet. For example, Hindus will not eat beef because cattle are considered sacred. Jewish and Muslim beliefs forbid eating pork. Many Hindus, Jains, and Buddhists avoid eating animals altogether.

A diet that does not include meat, fish, or poultry is called a vegetarian diet. Religion is just one reason people choose to become vegetarians. Other reasons include personal health, concern for animal welfare, or concern about the environment.

Vegans are vegetarians who avoid all animal products, including eggs, milk, cheese, and honey.

In addition to affecting what people eat, culture also shapes how foods are prepared and served. For instance, people in India typically use a complex combination of spices to season their dishes. Japanese cuisine, on the other hand, embraces simplicity to showcase the freshness of the ingredients.

Traditional diets developed around the foods that were available in a particular location and the traditions of each particular cultural group. Today, however, we have the ability to import foods from all over the world, and modern communications make it easy for us to learn about and try many different cuisines. No one is surprised today to find Greek food in Cincinnati, Ohio; fast-food burgers in Tokyo, Japan; or a Pakistani restaurant in London, England.

In developed countries, many people have abandoned traditional diets in favor of highly processed foods. The high levels of sugar, salt, and refined grains in these foods, however, have led to increased levels of diabetes and heart disease. Obesity is a common problem in countries with an abundance of these inexpensive, high-calorie foods.

As a result, many people in developed countries are adopting new, healthier diets. For example, some people are choosing to buy only seasonal, locally grown foods. Others are seeking out organically grown foods. Many people seek out more humanely produced animal products such as free-range chicken or grass-fed beef. A lot of foods today also contain additives that increase their nutritional value, such as orange juice containing calcium or eggs fortified with omega-3 fatty acids.

Many people are also rediscovering healthier, traditional diets. For example, Native American communities have a high risk of diabetes. Recently, some Native American communities in California, such as the Pomo, have encouraged the use of acorns and acorn flour. Acorns were a staple food in the Pomo diet for centuries. A diet with acorns, squash, and other traditional ingredients is full of nutrients and does not contribute to a risk of heart disease or diabetes.