All organisms contain proteins. The cells require protein to carry out all its functions. Proteins are organic compounds. They are formed by amino acids through the process of digestion of food in the stomach. Proteins are decisive for metabolism. Proteins, carbohydrates and fat are the main source of energy. Energy is expressed as calories that are contained in food items. The main source of protein that we take as food includes meats, nuts, eggs, legumes, grains, and dairy products like cheese and milk. The body breaks down the food particles continuously from which protein is derived. The enzymes in the stomach then break down protein through digestion. Men are estimated to need 56 grams of protein every day. Women need lesser protein per day estimated to be 46 grams. Consumption of protein below this level leads to protein deficiency.

Protein deficiency causes a number of health problems and may prove to be fatal. Kwashiorkor is a protein deficiency disease. It expresses itself with symptoms as diarrhea, apathy, fatty liver, failure to grow, edema of the legs and belly, flaky skin, and inactivity. Mental retardation is also known to be caused by protein deficiency. Poor people who face chronic hunger and nutritional deficiency are known to be the most susceptible. Those who are dieting and are on crash diet for weight loss also may face protein deficiency at times. Older people could develop protein deficiency when they do not have a balanced diet. A similar situation might also occur in people who are recovering from surgery, trauma or illness. The deficiency can be offset by the intake of protein rich food or special diet.

Dietary supplements containing proteins, fat, carbohydrates, minerals and vitamins are available in plenty in the market. Whey, soy and casein are the main source of protein in such dietary supplements. Flavors to make them tasty are added. These come in various forms as energy bars or energy drinks. There are energy bars that offer primarily protein. Worldwide Pure Protein Bar is one such. These also come in a variety of flavors.

Besides protein, they are also rich in calories. Proteins enter into the body system along with other nutrients.