Food is any material consumed to provide nutrition to an organisms. In a human body, food is composed of carbohydrates, protein, fat, vitamins, or mineral contents. Food serves a number of functions in our daily lives and has different roles in human development, growth and metabolism. Some food is used to supply energy, others to enhance the growth and health of the body, while still others play a role in immunity or serve a variety of other functions.
The main constituents of food include carbohydrates, proteins and fat. Carbohydrate provides the bulk of the calories we consume. It can be derived from starch plants (e.g., glucose) or from simple sugars, which can also be derived from fruits and vegetables. The starch can be converted to glycogen, which can be stored in muscles and liver and utilized during exercise or storage during times when food does not readily enter the body (e.g., at night). Most protein comes from animal sources like milk, meat and poultry, whereas fat is generally derived from plant sources, including butter and some fats derived from nuts and seeds.
Some food types are complex carbohydrates, where one or more sugar molecules are bound together to form a bond. Examples of such carbohydrates include fruits, vegetables, whole grains, breads and cereals. Complex carbohydrates provide energy and are typically stored in the body as glycogen, which can be converted into glucose. While they provide energy, they are low in fat, therefore making them good dietary sources of macronutrients. Some examples of low glycemic index food are pasta and potatoes, which contain relatively low amounts of carbohydrates.
The glycemic index, which refers to the effect of increasing levels of blood sugar on blood insulin levels, can be a useful tool in determining what type of food is good for people with diabetes. A study session 2 study concluded that a food item that contained 30 g of carbohydrates/day and one gram of protein would increase blood sugar levels in people with diabetes. Foods that are considered to be a good source of carbohydrates are fruits, vegetables, whole grains, breads and cereals. These items were rated highly in the glycemic index category, making them a staple food for diabetics.
Oils are another important group of nutrients and should be included in a person’s diet. Examples of healthy oils are omega 3 fatty acids found in oily fish, nuts, soybeans, sesame seeds and sunflower oil. These fats are very nutritious, but some people with diabetes may have a problem absorbing these fats, which can result in hypoglycemia. Nuts, soybeans and sesame seeds are considered excellent sources of essential fats.
Vitamin A is also a fat-soluble vitamin, meaning it is not stored in the liver, as is vitamin E. However, some studies indicate that excessive intake of vitamin A may play a role in the development of cancer. Unbalanced levels of vitamin A and phosphorus can cause bone disorders and weakening of the bones, especially among women. Milk is a good source of vitamin A, but most individuals gain vitamin A through beta-carotene in orange and yellow vegetables. Some plants contain vitamin A naturally, while others must be consumed in specific proportions and amounts. These include liver, sweet potato, carrots, kiwi, spinach, apricots, watermelon, cantaloupe, kale, tomatoes and parsley.