What does proteins mean

Proteins are fundamental components of all living cells and include many substances, such as enzymes, hormones, and antibodies, that are necessary to the functioning of an organism. They are essential in the diet of animals for the growth and repair of tissue and can be obtained from foods such as meat, fish, eggs, milk, and legumes. Published by Houghton Mifflin Company. Any of a large class of complex organic chemical compounds that are essential for life.

Proteins play a central role in biological processes and form the basis of living tissues. They consist of long chains of amino acids connected by peptide bonds and have distinct and varied three-dimensional structures, usually containing alpha helices and beta sheets as well as looping and folded chains. Enzymes, antibodies, and hemoglobin are examples of proteins.

A Closer Look Proteins are the true workhorses of the body, carrying out most of the chemical processes and making up the majority of cellular structures. Proteins are made up of long chains of amino acids, but they don't resemble linear pieces of spaghetti.

Any of a large class of complex organic chemical compounds that are essential for life. Proteins play a central role in biological processes and form the basis of living tissues. They consist of long chains of amino acids connected by peptide bonds and have distinct and varied three-dimensional structures, usually containing alpha helices and beta sheets as well as looping and folded chains.

Enzymes, antibodies, and hemoglobin are examples of proteins. Any of a large class of complex polymers consisting of long chains of polypeptides often bonded with nucleic acids, lipids, etc. Origin of protein. The nine amino acids that humans cannot produce on our own are called essential amino acids , according to the NIH.

Essential amino acids are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. Protein foods that contain all essential amino acids are called complete proteins, according to Crandall. They are also sometimes called ideal proteins or high-quality proteins. Complete proteins include meat and dairy products, quinoa, hemp seeds, chia seeds and soy. Many plant-based proteins are not complete proteins.

These include beans, grains and legumes as well as vegetables, which contain small amounts of protein. According to the University of Massachusetts at Amherst , incomplete proteins can be combined to create complete proteins. Beans and rice, peanut butter and whole grain bread, and macaroni and cheese are examples of combinations that create complete proteins. For a long time, nutritionists thought that complementary proteins had to be eaten together to make a complete protein.

Most Americans do not get close to the 35 percent mark; they eat about 12 to 18 percent of their calories as protein , according to the NIH. Therefore, most commercial high-protein diet plans suggest intakes in the upper levels of the recommended spectrum. For example, the Atkins diet allows for up to 29 percent of calories to come from protein, and the South Beach Diet suggests protein levels at about 30 percent.

Some high-protein diets, however, come in at higher than 35 percent. The efficacy and safety of high-protein diets is still being studied. Often, they lead to a quick drop in weight-loss but their overall sustainability is unclear.

Futhermore, high-protein diets can carry some health risks. They usually advocate cutting carbohydrates, which can lead to nutritional deficiencies, fiber deficiencies, headache, constipation, increased risk of heart disease and worse kidney function in those suffering from kidney disease, according to the Mayo Clinic.

What are the health benefits of protein? Protein and Weight Control Eating protein-rich foods has been shown to increase our feeling of fullness also known as satiety more than foods high in fat or carbohydrate. Protein and athletic performance Protein has long been associated with athletic performance. What happens if you eat too much protein? Red and Processed Meat and Cancer Risk Protein is essential for good health, but some high protein foods may be better for our health than others.

References EFSA Consultation, F. Dietary protein quality evaluation in human nutrition. FAO Food Nutr. Pap, 92, pp. Phillips, S. Current concepts and unresolved questions in dietary protein requirements and supplements in adults.

Frontiers in nutrition, 4, p. Leidy, H. The role of protein in weight loss and maintenance. The American journal of clinical nutrition, 6 , pp. The Lancet. International society of sports nutrition position stand: protein and exercise. Continuous Update Project Expert Report Meat, fish and dairy products and the risk of cancer. Poore J, Nemecek T.

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