Protein and its major significance in Human body
Proteins are large chains of amino acids linked by alpha peptide bonds (Watford & Wu, 2018). In the human body, there are 20 amino acids that function as the building blocks of protein. Nine of these amino acids are considered essential amino acids (Must be consumed in the diet) while five of them are considered non-essential (synthesized by the human body). The remaining six amino acids are considered conditionally essential in the human diet as their synthesis might be limited in certain life stages or in pathological conditions.
Essential amino acids include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, valine, tryptophan, and threonine.
Non-essential amino acids include asparagine, alanine, aspartic acid, glutamic acid, and serine while the conditionally essential amino acids include arginine, glutamine, glycine, cysteine, proline, and tyrosine.
Deficiency
Deficiency of this nutrient can be classified as:
Marasmus- Severely underweight and thin due to a deficiency of macronutrients: carbohydrates, protein, and fat (Titi-Lartey & Gupta, 2020).
Kwashiorkor- Characterized by distinctive edema due to the deficiency of both the quality and quantity of protein (Benjamin & Lappin, 2019).
Recommended daily intake (RDI)
The recommended daily intake of protein for a healthy individual with minimum physical activity is 0.8 g/kg of body weight (Lonnie et al., 2018). To meet functional needs such as promoting skeletal muscle synthesis, protein consumption ranging from 1-2 g/kg of body weight depending upon the amount of physical activity is suggested (Wu, 2016).
Long-term high intake of protein (more than 2g/kg of body weight) may result in gut, kidney, and vascular abnormalities and should be strictly avoided (Wu, 2016).
Why is protein important?
a) Growth and repair of the Human tissue
Protein is required for the growth and maintenance of Human tissue. In normal conditions, the body breaks the same amount of protein that is required from the tissue.
The demand for protein is high in the state of illness, pregnancy, lactation, and injury (Yeung et al., 2017).
b) Helps facilitate a chemical reaction.
Enzymes are proteins comprised of amino acids which aid in thousands of biochemical reactions that occur in the human body. Functions such as digestion, energy production, blood clotting, and muscle contraction depend upon enzymes (Cooper, 2000).
c) Functions as a hormone
Insulin, glucagon, human growth hormone, antidiuretic hormone, adrenocorticotropic hormone, etc. are some examples of protein-based hormones in the human body.
Insulin and glucagon play a role in the maintenance of blood glucose levels (Cooper, 2013).
d) Act as buffer to maintain pH
Protein regulates the concentrations of acids and bases in your blood and other bodily fluids (Lamanda et al., 2007).
e) Act as Transporter
Albumin aid in the transport of bilirubin, hormones, metals, vitamins and drugs in the body. proteins transport substances throughout your bloodstream, into, out of, and within cells (Busher, 1990).
f) Protein as a source of energy
Each gram of protein contains four calories. In normal state, protein provides only few amount of energy, however, it can be a great source of energy in the state of Calorie deficit. Our body breaks down skeletal muscle when the energy intake is less than the energy expenditure for energy (Carbone et al., 2014).
Suggestions to increase protein in the diet
Here are some recommendations to help you enhance your protein intake in your diet:
- Include a protein source in each meal: Aim to have a protein source with every meal. Good options include lean meats (chicken, turkey, beef), fish, eggs, dairy products (milk, yogurt, cheese), legumes (beans, lentils), tofu, and tempeh.
- Prioritize lean protein sources: Opt for lean cuts of meat, skinless poultry, and low-fat dairy products to minimize saturated fat intake while maximizing protein content.
- Incorporate plant-based protein sources: Include plant-based protein sources like legumes, lentils, chickpeas, black beans, quinoa, tofu, tempeh, and edamame. These are not only rich in protein but also provide additional nutrients and dietary fiber.
- Snack on protein-rich foods: Choose protein-rich snacks to keep you satiated and support muscle recovery. Examples include Greek yogurt, cottage cheese, hard-boiled eggs, protein bars or shakes, nuts, and seeds.
- Make use of dairy products: Dairy products like milk, yogurt, and cheese are not only good sources of protein but also contain essential nutrients like calcium. Choose low-fat or non-fat options if watching your calorie and fat intake.
- Add protein to your breakfast: Start your day with a protein-packed breakfast. Include eggs, Greek yogurt, cottage cheese, or protein-rich smoothies to fuel your body and keep you satisfied throughout the morning.
- Experiment with protein-rich recipes: Explore recipes that focus on protein-rich ingredients. Look for new ways to incorporate lean meats, fish, legumes, and plant-based protein sources into your meals.
- Plan meals and snacks in advance: Plan your meals and snacks ahead of time to ensure you have protein-rich options readily available. This can help you make healthier choices and prevent relying on convenient but less nutritious options.
- Consider protein supplementation if needed: If you struggle to meet your protein needs through food alone, protein supplements like whey protein, casein protein, or plant-based protein powders can be convenient options. Consult with a healthcare professional or registered dietitian for guidance.
Remember, it’s essential to maintain a balanced diet that includes a variety of nutrients, not just protein. Consult with a registered dietitian or healthcare professional to determine the appropriate protein intake for your specific goals and need.
References
Benjamin, O., & Lappin, S. L. (2019, March 21). Kwashiorkor. Nih.gov; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK507876/
Busher, J. T. (1990). Serum Albumin and Globulin. Nih.gov; Butterworths. https://www.ncbi.nlm.nih.gov/books/NBK204/
Carbone, J. W., Pasiakos, S. M., Vislocky, L. M., Anderson, J. M., & Rodriguez, N. R. (2014). Effects of short-term energy deficit on muscle protein breakdown and intramuscular proteolysis in normal-weight young adults. Applied Physiology, Nutrition, and Metabolism, 39(8), 960–968. https://doi.org/10.1139/apnm-2013-0433
Cooper, G. M. (2000). The Central Role of Enzymes as Biological Catalysts. National Library of Medicine; Sinauer Associates. https://www.ncbi.nlm.nih.gov/books/NBK9921/
Cooper, G. M. (2013). Signaling Molecules and Their Receptors. Nih.gov; Sinauer Associates. https://www.ncbi.nlm.nih.gov/books/NBK9924/
Lamanda, A., Cheaib, Z., Turgut, M. D., & Lussi, A. (2007). Protein Buffering in Model Systems and in Whole Human Saliva. PLoS ONE, 2(2). https://doi.org/10.1371/journal.pone.0000263
Lonnie, M., Hooker, E., Brunstrom, J., Corfe, B., Green, M., Watson, A., Williams, E., Stevenson, E., Penson, S., & Johnstone, A. (2018). Protein for Life: Review of Optimal Protein Intake, Sustainable Dietary Sources and the Effect on Appetite in Ageing Adults. Nutrients, 10(3), 360. https://doi.org/10.3390/nu10030360
Titi-Lartey, O. A., & Gupta, V. (2020). Marasmus. PubMed; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK559224/
Watford, M., & Wu, G. (2018). Protein. Advances in Nutrition, 9(5), 651–653. https://doi.org/10.1093/advances/nmy027
Wu, G. (2016). Dietary protein intake and human health. Food & Function, 7(3), 1251–1265. https://doi.org/10.1039/c5fo01530h
yeubaan. (2022, December 8). Balanced Diet And Plate Portioning – Yeu Baan. Yeubaan.com. https://yeubaan.com/balanced-diet-and-plate-portioning/
Yeung, S. E., Hilkewich, L., Gillis, C., Heine, J. A., & Fenton, Tanis R. (2017). Protein intakes are associated with reduced length of stay: a comparison between Enhanced Recovery After Surgery (ERAS) and conventional care after elective colorectal surgery. The American Journal of Clinical Nutrition, 106(1), 44–51. https://doi.org/10.3945/ajcn.116.148619
