There are literally thousands of different types of food, each having specific roles in our bodies. The three main food groups are carbohydrates, protein and fat. Each group is made up of many different food types, some of which are found in more abundance in certain parts of the world, while others can be found in nearly all parts of the world. One of the major functions of the human body is the function of digestion, which involves the breaking down of food into simple compounds that can be absorbed into the blood stream. Digestive enzymes and bacteria are the main ways food is broken down, but there are other important functions that all food have to perform in the body.
Food is any material taken in to supply nutrition to an organism through digestion. Food is generally of animal, plant or fungi origin, and often contains various nutrients, including vitamins, carbohydrates, proteins, fats, or minerals. However, because of the way food is digested and broken down in the intestines, each food type can have a slightly different calorie level, depending on the process used to break it down.
A good example of a food that provides multiple nutrients is carbohydrates. Carbohydrates such as rice and pasta are easily digested and can provide a number of calories, depending on their individual characteristics. For instance, carbohydrates from vegetables are quickly broken down to form glucose, the main source of energy for the human body. Brown rice is a good source of carbohydrates that can be eaten daily, as it is low in fat, but contains higher levels of carbohydrates than does white rice.
Many carbohydrates don’t provide calories, but rather provide energy. These include sugar, which can be converted to energy by the body or stored in the blood as glycogen, as mentioned above. Another kind of sugar is referred to as “sugars,” and is generally produced by the liver. However, these kinds of sugars are digested slowly and absorbed through the intestines, allowing them to provide small amounts of energy over time. Some foods that are high in both carbohydrates and sugary fibers are fruits such as bananas, grapefruits, oranges, apples, and pears. These foods are typically consumed in large amounts on a daily basis, so consuming them in small amounts only infrequently may be beneficial.
Some foods that are high in both foods that provide energy (starchy foods) as well as other nutrients (milk and dairy) are considered healthy. A good example of a food group that is high in both nutrients and calories is the Inuit ( Eskimo) food group, which consist mostly of meat and seafood. Milk and yogurt are major sources of calcium, as well as iron, zinc, magnesium, and other important nutrients. Lean meats, especially grass-fed beef, provide many essential fatty acids and B vitamins. Dairy products, such as cheese and yogurt, are important sources of protein, as well as calcium, iron, magnesium, and other nutrients.
The quality of a food is determined by the percentage of vitamins and other nutrients it provides in comparison to the calories it contains. Low-fat or fat-free foods tend to have lower calorie values but no nutrients. Whole foods that have been cooked are easier to digest, increasing the percentage of nutrients in the food that remains unabsorbed. Foods that are categorized as whole can include vegetables, fruits, whole grains, legumes, nuts, seeds, and fruits. Some examples of low or no-nutrient food groups are ice cream, cottage cheese, low-fat ice cream, sherbet, and sherbet ester.