We all know that we need to eat protein, but what is it? How does protein help someone gain weight or build muscle? How much protein should you eat? And most importantly, what are the sources of Protein for maximum results? I am writing a two-part article with the first part aiming to simplify what protein is and how the body uses it (without getting too nerdy) and the second part enumerating the different protein sources for the body.
What is Protein?
Protein is one of the six essential nutrients that the body needs for daily functioning. The essential nutrients are those that the body needs to take in from outside sources, that is the food that we eat. Non-essential nutrients are those that the body can produce by itself. Proteins are made up of amino acids, a term that you may have heard of before that is usually associated with Protein. Simply put, amino acids are the building blocks, that is, the smaller chemicals that composes the structure of Protein. Smaller chemicals are called Peptides, but as promised, this article won’t be nerdy.
Proteins can be found in every cell of the body and is used for a myriad of very important purposes.
What are the uses of Protein?
Proteins are found in every cell of the body and serve various important purposes:
- Proteins are needed for the growth and repair of our body’s tissues and cells.
- Proteins are involved in a variety of metabolic and hormonal activities. For example, Enzymatic proteins in the digestive system helps break down food. Hormonal proteins help control your blood sugar concentration.
- Other proteins are used for nerve cell signaling processes.
- The antibodies of our immune system which help fight infections and foreign substances are also made up of proteins.
- Proteins move important molecules in our body such as the protein hemoglobin which transports oxygen through the blood.
- Proteins compose the actin and myosin filaments, the cells in our muscles which are responsible for muscular contraction.
- And lastly, proteins are needed by our cardiac muscle — the muscles in our heart.
One more notable use of protein is that during fasting, the body uses the protein from our muscles to produce energy. This means that if your diet has insufficient carbohydrate and fat for energy, or if you refuse to eat 2 to 3 days to lose weight, your body will resort to the best way to produce its needed energy to survive carbohydrate and fat deprivation, which is to break down protein.
What makes up the proteins in our body?
As I have said earlier, amino acids are the building blocks of Protein. There are twenty-two different kinds of amino acids that the body uses to make proteins which includes eight essential amino acids; and again ‘essential‘ means that the body cannot produce it on its own and should get it from outside sources. These are the eight essential amino acids:
Don’t be too blown away by the names of these amino acids. Being familiar with them may be helpful especially when you want to know which sources of protein is better, or which supplement would work best for you. Apart from the eight essential amino acids, there are seven conditionally essential amino acids. These are amino acids that the body has difficulty in processing (nerdy term: synthesizing) so they usually are needed to be obtained from your diet as well to make sure that you’re getting enough. The seven conditionally essential amino acids are:
- Cysteine (cystine)
What are the kinds of protein that we can eat?
Protein sources from our diet are also classified into two. Dietary protein can be a complete source of protein or an incomplete source of protein. A complete source of protein means that it contains adequate amounts of the essential amino acids. Animal sources such as meat, fish, and poultry contain all essential amino acids and are thus considered complete sources of protein. Incomplete sources of protein are food sources that lack some of the essential amino acids, such as vegetables, red beans, and nuts.
Also, these protein sources vary with the quality of protein it contains depending on its amino acid profile and how the protein is easily digested. This helps determine which kind of protein source or supplement produce good quality proteins.
How does our body digest and absorb protein?
Protein digestion (the breakdown of food into smaller components) and absorption (the process of absorbing the nutrients into the body) is also valuable to note. The body digests carbohydrates and fats as soon as you put the food into your mouth and the enzymes in your saliva breaks them down. However for proteins, digestion does not begin until the food reaches your stomach and the acids in your stomach breaks them down. Then the amino acids are absorbed through the wall of the small intestine. After being absorbed by the small intestine, they are transported through the blood to the liver to be utilized by the body. This means that dietary protein sources travel a long way first and takes several hours for the body to be able to use it.
In application, after a long or intense bout of physical activity, your body would need sufficient protein supply to replace the broken down protein from your exercise or sports training. If you fail to replenish your amino acids, or if you fail to eat sufficiently after your workout, you are already depriving your body of its protein needs. The body digests protein for several hours, but once these amino acids are available, they can freely enter the blood and are cleared within 5 to 10 minutes. This gives you reason to drink that chocolate milk soon after your workout or take in an extra amino acid supplement.
How much Protein does our body need?
Can we eat too much Protein? The answer is yes. We can actually ingest too much protein and it may be detrimental for our body. Note that the cells of our body only uses the amount of amino acids that they need for a certain time. The unused amino acids are processed again (called deamination) which eventually leads to that processed amino acid being required to be excreted by the body. This all happens in the liver where the deaminated amino acid is converted into ammonia. Ammonia then is converted into urea which travels through the blood and is finally removed from the body by the kidneys in the urine.
The easiest way to know how much you need is to calculate your body weight with the recommended dietary allowance. As a standard, children ages 11 to 14 years need 1.0 g/kg of body weight per day; adolescents 15 to 18 years of age needs 0.8 to 0.9 g/kg of body weight per day; and adults need 0.8 g/kg of body weight per day. This means that if you are a 75 kg adult male, you need (0.8 g x 75 kg) 60 grams of protein per day. If you are a 50 kg adult female, you need 40 grams of protein per day. Here are some references for better understanding of how much these values are in food (source: www.cdc.gov):
- 1 cup of milk has 8 grams of protein.
- A 3 ounce piece of meat has around 20 grams of protein. Four ounces of meat is like a deck of cards, so 3 ounces would be 3/4 of that deck of cards.
- 1 cup of dry beans has about 16 grams of protein.
- An 8-ounce container of yogurt has about 11 grams of protein.
Other factors such as pregnancy, obesity, and exercise affects the protein requirements of the body. It is proven that intense exercise increases the body’s protein needs. Athletes are recommended to consume 1.5 to even up to 2.0 g/kg of body weight of protein per day to make sure that the body receives enough protein supply. Generally, the more intense the physical activity, the higher the amount of protein is needed by the body. Moderate intensity exercises would require a lower amount of protein from this range. Aerobic activities also require sufficient protein replenishment that is higher than the average recommendations. Ingesting amino acids after an intense workout, then can help the body replenish its protein requirements quickly as amino acids can be readily absorbed and used by the body.
- Protein is one of the six essential nutrients that the body needs for daily functioning. This means that protein can only be obtained by the body through ingesting food sources.
- Protein is used by the body for different important purposes.
- Some food sources are complete sources of protein and some are incomplete. It is best therefore to have a balanced diet that provides all the essential amino acids and other nutrients that are needed by the body.
- Proteins are composed of amino acids which takes a long time to be processed by the body. Our food sources for protein then should have good quality so that the body can replenish its protein supply effectively.
- Check the Recommended Daily Allowances for Protein to know how much protein you will need on average.
- Intense physical activities require athletes to consume more protein than the recommended average.
My next post will be about the sources of protein and how they rate as your option.
Also check out my post about the effects of Branched Chain Amino Acid (BCAA) Supplements for performance.
Visit my Articles page for more nerdy posts. 🙂
Reference: NSCA’s Guide to Sport and Exercise Nutrition. National Strength and Conditioning Association. Campbell and Spano. 2011.