Why Do We Need Protein?
Do you catch yourself thinking “is protein really that important?” or “it’s only for people that go to the gym a lot”? Well, think again. If you are human, you need protein. We are here to explain why protein is important for everyone, not just exercise fanatics.
Why do we need protein in our body?
Proteins are large molecules that are made up of numerous amino acids (AAs), known as the building blocks of proteins.
Protein is essential for the structural and functional elements of all cells and tissues throughout the body, such as skin, hair, bone, muscle and even blood. Protein also plays a key role in the many biological processes that occur in the body and function as enzymes, hormones and antibodies to help fight infection.
In fact, protein is the second most abundant compound in the body after water[2].
In terms of diet, protein is one of the essential macronutrients, meaning that we need to eat relatively large amounts of it per day.
10 reasons why we need protein
1. Energy
First and foremost, protein is one of the three major macronutrients (discounting fibre) that provides dietary energy. That being said, the body typically favours using carbohydrates and fats as energy sources, but if someone’s stores are low the body will take AAs from the blood and body tissues (e.g. muscles) and oxidise them to provide energy.
It’s important to note that the body can’t store excess protein, so once the body has used what it can of the ingested protein, the surplus AAs are either used for energy, excreted or converted and stored as fat.
2. Protein helps to fill you up
Higher-protein meals have been shown to increase sensations of fullness more than those of a lower protein content[3]. Although the rationale for why protein foods help fill us up is somewhat convoluted, one of the key chemicals involved is the hormone Peptide-YY (PYY). This hormone lets our hypothalamus, a part of the brain that plays a vital role in many bodily functions, know when we’ve eaten enough from a meal. This process can explain why we begin to lose the desire to continue eating after a meal[4,5].
Interestingly, the sensation of feeling full is enhanced when there’s a greater amount of protein sensed in the intestine[6].
Find out more about this topic in our article here.
3. Enzyme function
Some proteins function as enzymes, which help to facilitate and accelerate chemical reactions. As an average, more than 100 chemical reactions occur every second, most of which require enzymes[7].
For example, when a protein source reaches the stomach there are enzymes called proteases which break down the peptide bonds of protein chains resulting in shorter chains or individual AAs.
4. Hormones
Proteins are responsible for some hormone synthesis.
Hormones are chemical messengers produced by the endocrine system that travel via the blood, relaying messages from one part of the body to another to help coordinate bodily functions. Hormonal shifts occur constantly throughout the whole body during the course of the day and are involved in things like regulating body temperature, helping us use food as energy and even to turn enzymes on or off, so some proteins are influencing the action of other proteins[8].
5. Transport & storage
Protein also plays an important role in the transportation of nutrients and molecules around the body.
In order to move nutrients and molecules from the blood into and out of cells as and where they are required, they first must travel through cell membrane channels. Think of these channels like gates, allowing movement from one place to another. These channels, as well as the taxi-like cells that transport molecules through these gates are types of proteins. A great example of a transport protein is haemoglobin, responsible for moving oxygen around the body in the blood.
Protein is also required to store certain nutrients.
For example, cholesterol and triglycerides (a type of fat) are insoluble in water, so they require lipoproteins to not only assist with their transportation around the body but also with their storage[9].
6. Immune function
When the body is exposed to foreign substances such as pathogenic viruses or bacteria, the immune system will deploy proteins called antibodies to attack and destroy these potentially harmful substances. Antibodies, or immunoglobulins as they’re otherwise known, also trigger and work with other immune system cells to destroy invaders to help prevent infection, disease and illness[10].
7. Balancing fluid
Water (or other solvent) always travels from an area of high concentration to one of a low concentration through a semipermeable membrane. Within the body, protein is a key factor in balancing fluid, or in other words maintaining the distribution of water in the body.
The most abundant protein in the blood is called albumin and it acts like a water magnet, pulling water from tissues into the blood vessels. Conversely, when there are low levels of albumin in the blood, the osmotic pressure is reduced and fluid moves into the tissue, a condition known as oedema, which can result in swelling and tissue damage[11, 12].
Stark examples of oedema can be seen in malnourished children whereby because they aren’t getting enough protein in their diet the liver can’t synthesis albumin, meaning there are low levels of albumin in the blood (hypoproteinaemia). This results in fluid accumulating in the peritoneal cavity[13], causing the bloated bellies which are often seen with cases of famine, part of a condition known as kwashiorkor.
8. pH balance
pH balance refers to how acidic a substance is. Most of the body works best at a neutral pH, around 7.36 and 7.4414, but many things which we encounter on a daily basis such as food and drink, pollution, etc can shift this balance slightly. If the hydrogen (H+) levels of the blood increases too much the resulting blood pH falls and becomes too acidic (acidosis)[7]. Whereas, if the H+ content falls, the blood becomes too alkaline (alkalosis)[7]. Both cases can negatively affect bodily functions.
In order to keep the body in equilibrium, the protein albumin can act as a buffer to keep pH level where it should be by either releasing H+ ions if the blood is too alkaline, or take H+ from the blood if it’s too acidic[15]. Thereby maintaining the status quo.
9. Structure & motion
Structural protein's function is to provide mechanical support for cells and tissues. Collagen is one of the most abundant and best known structural proteins in the body. It is a strong, fibrous protein found in connective tissues such as tendons and ligaments and makes up about 30% of bone tissue[15]. It is also abundant in the skin giving structure and is accompanied by the protein elastin which makes skin flexible, allowing for tissues to resume their shape after stretching or contracting[16]. Another well known structural and protective protein is keratin which is what skin, hair and nails are made of[17].
The contractile proteins, actin and myosin found in muscle are involved in movement. They are organised in a way that once stimulated by a nerve impulse they slide back and forth across each other causing a shortening or lengthening of the muscle, leading to movement[18].
It’s also worth noting that from about 50 years of age humans begin to gradually lose skeletal muscle and function, otherwise known as sarcopenia, which can result in an increased risk of experiencing falls, functional decline, frailty and mortality[19].
It is important to meet the daily recommended protein intake as well as regular activity as we age to maintain muscle mass, strength and mobility.
10. Wound healing, repair & adaptation
Proteins are incredibly important in the wound healing process which involves three key phases: inflammation, proliferation and remodeling. For example, if you cut your skin, the affected site will become red and inflamed which is a protective tissue response, coagulation will typically begin to stop the bleeding, and the remodelling process will involve laying down collagen to form a scar[20]. Specific proteins are involved in each of the three phases and if someone’s diet is protein deficient this can contribute to poor healing rates[21].
While wound healing only occurs following some form of physical trauma, the process of tissue regeneration is constantly ongoing. Tissue regeneration is the creation of new cells to replace old, dying tissue. Some tissues will have a faster turnover rate such as skin, hair and the lining of the intestine compared to others like nerve cells which are considerably slower[15]. Tissue regeneration requires lots of different types of proteins such as enzymes, transport proteins, hormones and structural proteins. This process is especially important during phases of growth and development such as pregnancy, childhood and adolescence, which is why children in particular require more protein per kilogram of body weight than adults[22].
How much protein do we need?
The recommended daily amount of protein for a sedentary individual is about 50g protein per day.
Or more specifically 0.8g protein per kilogram of body weight per day (/kg BW/d)[23]. However, if you are a more active person you’ll most likely require a greater amount of protein, between 1.2-2.0 g/kg BW/d, to support metabolic adaptations and repair and remodel skeletal muscle tissue[24, 25]. The specific amount of protein will depend on training modality, duration and volume of exercise[26].
How Huel can help support protein intake
All Huel products are good sources of protein.
If you’re looking for a high protein snack, Huel Complete Protein has 20g protein with just 105 calories per serve. Alternatively, if you’re looking for something a little more substantial – a high-protein meal – then Huel Black Edition, Powder v3.0 and Hot & Savoury all contain between 24 and 40g of protein. For a super-quick protein fix, Huel Bars and Huel Ready-to-drink drinks require zero prep time!
References
Voet D and Voet JG. Biochemistry Vol 1, 3rd ed. Wiley: Hoboken, NJ; 2004.
Freitas Jr and Robert A. Nanomedicine. Landes Bioscience: Georgetown, Texas; 1999.
Dhillon J, et al. The Effects of Increased Protein Intake on Fullness: A Meta-Analysis and Its Limitations. J Acad Nutr Diet. 2016; 116(6):968-83.
Batterham RL, et al. PYY modulation of cortical and hypothalamic brain areas predicts feeding behaviour in humans. Nature. 2007; 450(7166):106-9
Karra E, et al. The role of peptide YY in appetite regulation and obesity. J Physiol. 2009; 587(1):19-25.
Batterham RL, et al. Critical role for peptide YY in protein-mediated satiation and body-weight regulation. Cell Metabolism. 2006; 4(3):223-33.
Libretexts. Protein’s Functions in the Body. Date Accessed: 14th July 2021. [Available from: https://med.libretexts.org/@go/page/23867]
Hiller-Sturmhöfel S, et al. The endocrine system: an overview. Alcohol Health Res World. 1998; 22(3):153-64.
Kenneth R. Feingold, MD. Introduction to Lipids and Lipoproteins. Endotext: South Dartmouth, MA: 2000.
Libretexts. Antibody Proteins and Antigen Binding. Date Accessed: 14th July 2021. [Available from: https://bio.libretexts.org/@go/page/11785]
Scallan J, et al. Capillary Fluid Exchange: Regulation, Functions, and Pathology. Morgan & Claypool Life Science: San Rafael, CA; 2010.
Cardiovascular Physiology Concepts. Richard E. Klabunde, PhD. Hydrostatic and Oncotic Pressures. Date Accessed: 14/07/20 [Available from: https://www.cvphysiology.com/Microcirculation/M012]
London Health Sciences Centre. Albumin and Edema. Date Accessed: 14/07/20 [Available from: https://www.lhsc.on.ca/critical-care-trauma-centre/albumin-and-edema]
Hamm LL, et al. Acid-Base Homeostasis. Clin J Am Soc Nephrol. 2015; 10(12):2232-42.
Pennsylvania State University. Protein’s Functions in the Body. Date Accessed: 14/07/20 [Available from: https://psu.pb.unizin.org/nutr100/chapter/7-5-proteins-functions-in-the-body/]
Mithieux SM, et al. Elastin. Adv Protein Chem. 2005; 70:437-61.
Bragulla HH, et al. Structure and functions of keratin proteins in simple, stratified, keratinized and cornified epithelia. J Anat. 2009; 214(4):516-59.
Cooper GM. The Cell: A Molecular Approach. 2nd edition. Sunderland, MA; 2000.
Cruz-Jentoft AJ, et al. Sarcopenia. The Lancet. 2019; 393(10191):2636-46.
Gonzalez ACdO, et al. Wound healing - A literature review. An Bras Dermatol. 2016; 91(5):614-20.
Russell L. The importance of patients' nutritional status in wound healing. Br J Nurs. 2001; 10(6 Suppl):S42, s4-9.
Alles MS, et al. Nutritional challenges and opportunities during the weaning period and in young childhood. Ann Nutr Metab. 2014; 64(3-4):284-93.
Protein and amino acid requirements in human nutrition. World Health Organ Tech Rep Ser. 2007; (935):1-265, back cover.
Thomas DT, et al. American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance. Med Sci Sports Exerc. 2016; 48(3):543-68.
Jäger R, et al. International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition. 2017; 14(1):20.
Vliet SV, et al. Achieving Optimal Post-Exercise Muscle Protein Remodeling in Physically Active Adults through Whole Food Consumption. Nutrients. 2018; 10(2).
