One of the six essential nutrients, protein is perhaps best known as a bodybuilders best friend. While necessary for growth and maintenance of muscle, protein has many other attributes. These include functioning as enzymes, providing functional support to cells and tissues, and helping to maintain the acid-base balance in our bodies. This post will cover the basics of protein along with current dietary recommendations.
What is Protein?
Protein is an organic (carbon containing) nutrient composed of the elements carbon, hydrogen, oxygen, and nitrogen. These elements make up different amino acids, which are the building blocks necessary for protein synthesis.
Depending on who you talk to, the number of amino acids required by the body is anywhere from 20-22. Regardless, 9 amino acids cannot be made by the body and thus must be consumed within our diet. These "essential" amino acids include: Histidine, Lysine, Methionine, Tryptophan, Threonine, Phenylalanine, Leucine, Iso-leucine, and Valine. The last three are of special consideration due to their roles as branched chain amino acids (BCAAs).
Protein has a physiological fuel value of 4. This means that each gram of protein provides around 4 kcal (calories) of energy. The Acceptable Macronutrient Distribution Range for protein is set at 10-35% of ones total energy needs.
Ex: Using a standard 2000 kcal reference point, we get a range of 200-700 calories (2000 x 0.10 = 200 calories, 2000 x 0.35 = 700 calories).
Furthermore, we can calculate the amount of protein in grams as followed:
--- 200/4 = 50g
---700/4 = 175g
So, if you consume 2000 calories a day then you should be getting 200-700 of your energy needs from protein which translates to 50-175 grams of protein respectively.
Depending on who you talk to, the number of amino acids required by the body is anywhere from 20-22. Regardless, 9 amino acids cannot be made by the body and thus must be consumed within our diet. These "essential" amino acids include: Histidine, Lysine, Methionine, Tryptophan, Threonine, Phenylalanine, Leucine, Iso-leucine, and Valine. The last three are of special consideration due to their roles as branched chain amino acids (BCAAs).
Protein has a physiological fuel value of 4. This means that each gram of protein provides around 4 kcal (calories) of energy. The Acceptable Macronutrient Distribution Range for protein is set at 10-35% of ones total energy needs.
Ex: Using a standard 2000 kcal reference point, we get a range of 200-700 calories (2000 x 0.10 = 200 calories, 2000 x 0.35 = 700 calories).
Furthermore, we can calculate the amount of protein in grams as followed:
--- 200/4 = 50g
---700/4 = 175g
So, if you consume 2000 calories a day then you should be getting 200-700 of your energy needs from protein which translates to 50-175 grams of protein respectively.
Protein is Protein:
It is a good idea to consume protein from both plant and animal sources as both offer unique benefits:
Animal Protein
- Only source of complete protein (containing all 9 essential amino acids)
- Better overall quality:
*Currently, the Protein Digestibility Corrected Amino Acid Score (PDCAAS) is the most recognized measure of protein quality. The highest PDCAAS score is a 1.0, in which whey, casein, and most animal proteins are equal to. According to Wardlaws "Perspectives in Nutrition", animal protein has a total digestibility around 90-100% while plant protein is only 70%.
Plant Protein
- One of the main advantages of plant protein is no cholesterol and minimal saturated fat! Diets high in saturated fats have been linked to numerous health risks including: weight gain, diabetes, and heart disease.
- Produces significantly lower levels of greenhouse emissions compared to animal sources
- Plants have the added benefit of providing fiber along with vitamins, minerals, and phyto-chemicals (biologically active compounds in plants boasting various beneficial properties)
- Check out what the FDA has to say about Soy protein and cardiovascular disease!
How Much Do I really Need?
There is a ton of misinformation concerning the amount of protein needed by the body. Consuming excess protein can in fact be harmful and here's why:
- Nitrogen (one of the elements found in protein) is excreted by our kidneys in the form of urea. Consuming protein in excess of what our bodies need can tax the kidneys and lead to long term damage.
- By choosing a high protein diet (specifically animal protein) you risk limiting the amount of fiber, vitamins, and minerals that you obtain from fruits and vegetables.
- Athletes (and those looking to gain muscle) risk amino acid toxicity if they supplement with protein powder or BCAA supplements.
The current Recommended Dietary Allowance (RDA) for protein is 0.8 g/kg body weight. This means that a 150 pound man requires 54.5 grams of protein a day. (Keep in mind, to calculate kg you must first divide the weight in pounds by 2.2)--------- (150lb / 2.2 = 68.18----- 68.18 x 0.8 g = 54.5)
Athletes and Bodybuilders:
According to the "Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine", the breakdown of protein needs is as followed:
| Group | g/kg |
| Muscle Mass Maintenance Phase | 1.0-1.2 |
| Muscle Mass Gain Phase | 1.5-1.7 |
| Moderate Intensity Endurance Athletes | 1.2-1.4 |
| High Intensity Endurance Athletes | 1.7 |
Infants:
Calorie needs for infants are 2-4 times what is needed for most adults and protein needs are similar. Infants should strive to get around 1.5 g/kg of body weight, due to their quick rate of tissue synthesis.
Did you Know:
- The most abundant protein in our bodies is collagen which provides structure and strengthens bones.
- Egg whites have a biological value of 100 which is the highest value of any single food protein
- Protein comes from the Greek word "protos" (to come first) Examples of proteins in the body include: hemoglobin, hormones, antibodies, and DNA.
References:
Enzyme. Genome.gov. https://www.genome.gov/genetics-glossary/Enzyme. Accessed May 24, 2020.
Branched-chain amino acid. Wikipedia. https://en.wikipedia.org/wiki/Branched-chain_amino_acid. Published April 13, 2020. Accessed May 24, 2020.
Wolfe RR, Cifelli AM, Kostas G, Kim I-Y. Optimizing Protein Intake in Adults: Interpretation and Application of the Recommended Dietary Allowance Compared with the Acceptable Macronutrient Distribution Range. Advances in nutrition (Bethesda, Md.). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5347101/. Published March 15, 2017. Accessed May 25, 2020.
Clausen T. PDCAAS to DIAAS: A new way to look at protein quality. Agropur Ingredients. https://www.agropuringredients.com/pdcaas-to-diaas-a-new-way-to-look-at-protein-quality/. Published February 12, 2020. Accessed May 24, 2020.
Facts about saturated fats: MedlinePlus Medical Encyclopedia. https://medlineplus.gov/ency/patientinstructions/000838.htm. Accessed May 24, 2020.
Protein Scorecard. World Resources Institute. https://www.wri.org/resources/data-visualizations/protein-scorecard. Published May 31, 2018. Accessed May 24, 2020.
CFR - Code of Federal Regulations Title 21. accessdata.fda.gov. https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=101.82. Accessed May 25, 2020.
urea. The Free Dictionary. https://medical-dictionary.thefreedictionary.com/urea. Accessed May 25, 2020.
Nutrient Recommendations: Dietary Reference Intakes (DRI). NIH Office of Dietary Supplements. https://ods.od.nih.gov/Health_Information/Dietary_Reference_Intakes.aspx. Accessed May 25, 2020.
Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine. Journal of the American Dietetic Association. 2000;100(12):1543-1556. doi:10.1016/s0002-8223(00)00428-4
Hoffman JR, Falvo MJ. Protein - Which is Best? Journal of sports science & medicine. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3905294/. Published September 1, 2004. Accessed May 24, 2020.
Byrd-Bredbenner C, Moe G, Berning J, Kelly D. Wardlaw's Perspectives in Nutrition. Place of publication not identified: Mcgraw-Hill Education; 2015.
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