Protein and Health

Sources of ProteinProtein serves a variety of important functions in the body. One function is the synthesis and repair of cells, tissues, and structures like collagen, elastin, and muscle. Our bodies require protein for the synthesis of hormones, enzymes, antibodies, and peptides.

Protein also serves to transport various compounds through the body, such as minerals (e.g. calcium) and fats. Furthermore, protein may be used for energy if there is an inadequate amount of carbohydrates or fats to be used. The body always uses carbohydrates (glucose) and fats (fatty acids) as its primary energy sources. In this article, I will talk about protein and health. I’ll share my knowledge on the recommended daily intake of protein, tell you some facts that are important to know before you decide on the source and amount of protein to consume in a day, explain how not all proteins are created equal and discuss how a low-calorie diet may require an increased amount of protein.

Building Blocks of ProteinAmino Acid

Protein is made up of amino acids in sequences, that are linked together by peptide bonds. Amino acids are required by the body to synthesize and repair proteins.

There are 20 amino acids. Of these, 9 are considered essential, meaning that they must be provided by the diet because the body doesn’t create or store them.

The other 11 amino acids are non-essential, which means that they are already present in the body.

Protein turnover is the process by which the body breaks down proteins and recycles the amino acids for incorporation into new proteins or other compounds.

Sources of ProteinAmino Acids

Dietary protein (protein obtained through food sources) is important because it contributes to the body’s amino acid pool, especially the 9 essential amino acids. There are complete and incomplete proteins. A complete protein is one that contains all the necessary amino acids. Incomplete proteins are proteins that are missing one or more of the 9 essential amino acids.

Complete proteins include;

  • Leucine
  • Isoleucine
  • Valine
  • Methionine
  • Phenylalanine
  • Threonine
  • Lysine
  • Histidine

Incomplete proteins include:

  • Alanine
  • Arginine
  • Aspartic acid
  • Asparagine
  • Cysteine
  • Glutamic acid
  • Glutamine
  • Glycine
  • Proline
  • Serine
  • Tyrosine

Protein can be found in most food, except fruits and oils. Some foods provide incomplete proteins and some provide complete protein. Protein from animal sources is generally considered to be a complete protein source. These include meat, poultry, fish, eggs, dairy, soy, hemp, quinoa, and buckwheat.

Incomplete protein sources include legumes (beans, nuts, peas, lentils, and seeds), grains (millet, amaranth, rice, cous cous, and oatmeal), and vegetables (spinach, bok choy, asparagus, broccoli, collard greens, brussel sprouts, and avacado.

Most people who eat both animal and plant foods will easily get all the essential amino acids in their diet. Vegan and vegetarians need to include a wide range of plant protein sources in order to get adequate amounts of the essential amino acids. Beans and rice, when combined, provide all 9 essentials.

A person doesn’t have to combine it all in one meal. They could eat rice for dinner and beans for lunch. Of course, that wouldn’t be all the protein they eat in a day. They’d need ample amounts of protein balanced throughout their meals.

Body of FoodWhat Protein Does in the Body

When a source of protein is consumed, it is denatured by hydrochloric acid in the gastrointestinal tract. Enzymes in the stomach begin to digest the proteins by breaking them up into smaller fragments and molecules.

It then moves into the small intestine where pancreatic and intestinal enzymes continue to break it down smaller, before being absorbed through the intestinal wall. Then, it enters the bloodstream and is directed to the liver. From there, amino acids may be directed to different tissues and used in a variety of ways (e.g. repair of muscles).

How Much Protein is Needed

Protein needs vary from person to person. Age, size, caloric needs, current body composition, physical activity, health status, and injury status all play a part in how much a person needs to consume a day. If an individual exercises regularly (especially resistance training), or is trying to build muscle, they will need enough protein to repair the muscles that they work.

The USDA says that the recommended daily allowance for protein is 0.8g/kg of body weight. But remember, protein needs increase under certain circumstances. Most often, the actual protein intake of the average person falls between 10% and 35% of total calories.

If you want to know how much protein you should be eating, you can calculate that easily at MyPlate. You can also speak with a Registered Dietician or another nutrition professional for specific protein needs based on your specific circumstances. They can help you determine your overall needs and optimal range of protein intake.

It is important to note that when a person is on a calorie-restricted diet to lose weight, their protein needs may increase. This is because the body won’t have enough carbohydrates or fats to properly fuel the body, so the body will start using protein. This will lead to loss of lean muscle mass along with fat. So, if you are restricting calories, talk to a Registered Dietician or another nutrition professional about the appropriate amount of protein you should consume in a day.

Some people think that they will not lose weight if they consume a moderate to high amount of protein. This simply is not true, and it may in fact help you to lose more fat than without the extra protein.

Optimal protein intake should support health and fitness goals, while not compromising the structure of an overall balanced diet that includes adequate nutrients.

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