What Is protein?
Protein is one of three macronutrients (proteins, fats and carbohydrates) in food that provide nourishment, or "energy" for the body.
The construction and functioning of our bodies rely on proteins. The regulation of the cells, tissues, and internal organs of the body can't occur without them. Bones, skin, hair, nails, muscles, and other areas of the body contain significant amounts of protein.
Proteins also work as neurotransmitters. The carrier of oxygen in the bloodstream, Hemoglobin, is a protein.
Protein is composed of thousands or hundreds of smaller components, called amino acids, which are connected to one another in long chains. The sequence of amino acids determines the unique structure and its particular function of every protein.
There are twenty different amino acids that can be combined to make every kind of protein possible. These are: Alanine, Arginine, Asparagine, Aspartic Acid, Cysteine, Glutamic Acid, Glutamine, Glycine, Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Proline, Serine, Threonine, Tryptophan, Tyrosine, and Valine.
The amino acids fall into two categories:
- Essential Amino Acids - Of those twenty amino acids, nine are considered "essential": Histidine, Isoleucine, Leucine, Lysine, Methionine (or cysteine), Phenylalanine (or tyrosine), Threonine, Tryptophan and Valine. Required for normal body functioning, these amino acids cannot be created by the body and must be obtained from food.
- Nonessential Amino Acids - Can be made by the body from amino acids consumed in food or in the normal breakdown of body proteins. Of the twenty amino acids, eleven are considered "nonessential."
What proteins do
Proteins play a significant role in nearly every biological process, and their functions vary widely. The primary functions of proteins in the body are to build, strengthen and repair or replace cells and body tissues.
They are significant for many body processes, such as vision , fluid balance, immune reaction, blood clotting, and the production of enzymes and hormones.
Proteins are vital for proper growth and development, especially during childhood, adolescence, and pregnancy.
Types of protein
Proteins are not all the same. They comprise of various combinations of amino acids and are categorized according to how many of the essential amino acids they provide.
- Complete Proteins: contain all the essential amino acids in adequate amounts. Animal products (such as dairy, eggs, meats, poultry, and seafood) and soy are full protein sources.
- Incomplete Proteins: are lacking, or do not have enough of, one or more of the essential amino acids, making the protein unstable. Most plant foods (such as vegetables, beans, grains, nuts and seeds) are incomplete protein sources.
- Complementary Proteins: are two or more incomplete protein sources which, when eaten in conjunction (at precisely the same meal or during the same day), compensate for one another's lack of amino acids. For example, grains are low in the amino acid Lysine, while beans and nuts are deficient in the amino acid Methionine. When legumes and grains are eaten together (like brown rice and black beans or nut butter on whole wheat bread) they form a complete protein.
Sources of protein
Protein is one of essential macronutrients in the human diet, but not all of the protein we consume converts into proteins in our body.
When foods that contain amino acids are eaten, these amino acids make it possible for the human body to create, or synthesize, proteins. If essential amino acids acids are not consumed through diet then the necessary proteins, that are vital for our bodies to work properly, won't be synthesized.
All food proteins have some of each amino acid, but in different amounts.
Protein from animal sources, such as milk and meat, are complete protein, because it contains all nine of the key amino acids. Soy and quinoa can also be sources of complete protein but most vegetable protein is considered incomplete because it lacks one or more of the important amino acids. This can be a concern for someone who does not eat animal products. But people who eat a vegetarian diet can get all their essential amino acids by eating a vast array of protein-rich vegetable foods.
The body does not need all the essential amino acids at every meal, because it can use amino acids that are stored from recent meals to make complete proteins. If you consume enough protein throughout the day, there is absolutely no risk of deficiency.
In conclusion, the macronutrient that is recommended is protein, but what we really need are amino acids.
How much protein do we really need?
This remains a matter of debate.
For an average active adult, eating enough protein to meet the DRI would supply as little as 0.8 to 1 grams of protein per lbs of body weight per day. But most Americans truly need to be eating about 1 to 1.2 grams of protein per lbs of body weight in the form of protein, from both plant and animal sources.
According to the U.S. Department of Agriculture, the amount of protein per meal an individual should eat depends on age, gender, and level of physical activity.
Even though an athletes protein needs are far greater than that of a non-athlete, it is not as large as commonly believed. The Academy of Nutrition and Dietetics, Dietitians of Canada and the American College of Sports Medicine recommend 1.2 to 2.0 grams of protein per lbs of body weight per day for athletes, based on training. Protein intake should be spaced throughout the day and after workouts.
High-protein Foods and Protein Shakes
"When protein is broken down in the body it helps to fuel muscle mass, which accelerates the metabolism", explained Jessica Crandall, a registered dietitian nutritionist for Denver Wellness and Nutrition, certified diabetes educator, fitness instructor and media spokesperson for the Academy of Nutrition and Dietetics. "It also aids the immune system remain powerful. A lot of research has proven that protein has satiety results and it helps you stay full for longer." Recent studies demonstrated that feeling full after a meal, or satiety, is enhanced after consuming a high-protein snack like yogurt rather than high-fat crackers or chocolate.
It is proven that eating more protein may boost muscle strength and growth, encourage a slender, leaner, fat-burning physique. Nevertheless, this highly depends on the person's total food intake and activity levels.
Athletes and bodybuilders have to ensure they have sufficient protein to build and repair muscle, and this may be more than the minimal amount.
According to the U.S Department of Agriculture (USDA) all food made from meat, poultry, seafood, beans and peas, eggs, nuts and seeds are considered part of the protein group. Most people eat enough food in this group to fuel their body, but they should select leaner and more varied selections.
The foods below will provide approximately 1 ounce of protein per serving:
- One ounce lean meat (beef, pork or ham), poultry (chicken, turkey), fish or shell fish (salmon, mackerel, tuna)
- One egg
- One tablespoon of peanut or almond butter
- Half a cup of seeds or nuts (almonds, pistachios, cherry, pumpkin, sunflower, or squash seeds)
- One fourth of a cup of cooked beans or peas (for example, kidney, black, pinto, white beans, chickpeas, black-eyed peas, lentils, or split peas)
In addition to animal and vegetable sources, there are various alternative sources of protein, such as whey protein, casein protein, egg white protein, soy protein, hemp protein, to name a few. Crandall explained that all are good options and it comes down to personal taste. For example, whey protein is better for regenerating and constructing muscle mass, therefore people seeking to bulk up or who exercise a lot may prefer it. Casein protein, whey protein or a combination of the two may be the best protein supplement for promoting fullness and fat loss. For vegetarians and vegans, soy or hemp proteins are a great choice.
The most popular one, whey protein, is considered a complete protein as it includes all nine essential amino acids and it's low in lactose content.
It is typically found in supplements, such as protein powders and the three primary types of whey protein are: Whey Protein Concentrate (WPC), Whey Protein Isolate (WPI), and Whey Protein Hydrolysate (WPH).
You will find approximately 20 - 25 grams of protein per scoop of whey protein.
There are a number of benefits associated with the consumption of whey protein, and researchers are constantly finding new possible therapeutic properties.
Some of these benefits are:
- Aiding weight loss
- Anti-cancer properties
- Lowering cholesterol
- Lowering blood pressure and decreases chance of cardiovascular disease
- Prevents weight loss in people with HIV
For many people, a diverse and healthful diet provides enough protein.
Increasing protein intake doesn't necessarily mean eating steak or ham. There are different options that can help you ensure a healthy protein intake.
Here are some suggestions:
- Eat a variety of protein foods, choosing from fish, meat, soy, beans, tofu, nuts, seeds and so on.
- Pick low-fat meats, poultry and dairy products, trim the fat from the meat. Opt for smaller portions and avoid processed meats, they have added sodium and sugar.
- Avoid cooking methods that add extra fat, like pan or deep frying and use healthier methods such as grilling.
- Look at the ingredients in "Protein Bars", as they can also be very high in sugar.
- Opt for healthier versions of your usual favorites, for example, wholemeal or sprouted bread instead of regular white bread and unsweetened, raw peanut butter rather than normal store-bought.
- Test plant-based proteins, such as hemp, beans, lentils, and soy products.
- Go for more nutrient-rich foods that provide other benefits, such as fiber and vitamins.