Written by Martina Grace, RD
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Protein is one of the fundamental building blocks of life, playing a crucial role in numerous bodily functions. Whether you’re an athlete, a busy professional, or simply trying to maintain a healthy lifestyle, understanding protein—its types, roles, how much we need, and what is too much—can greatly enhance your overall well-being.

What Is Protein?

Proteins are complex molecules made up of long chains of amino acids. There are 20 different amino acids that combine to form proteins, but only 9 of these are essential, meaning our bodies cannot produce them in sufficient quantities. The 9 essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.

Why Do We Need Protein?

Protein is vital for several reasons:

Muscle Synthesis and Tissue Repair: Proteins are crucial for building and repairing muscles and other tissues.
Enzyme Production: Many enzymes, which facilitate biochemical reactions in the body and help digest foods, are proteins. For instance, amylase is an enzyme that breaks down starches into sugars.
Hormone Production: Many hormones in the body are proteins or peptides, and they play vital roles in regulating various physiological processes. Insulin, is a protein-based hormone that regulate blood sugar levels in the blood by facilitating the uptake of glucose into cells.
Immune Function: Antibodies that help defend against illness and infection are made out of proteins. For example, IgG (Immunoglobulin G) is the most abundant antibody in the blood and extracellular fluid; it provides long-term protection against pathogens and is important in immune response.
Energy Source: While carbohydrates and fats are the body’s primary energy sources, proteins can also provide energy when needed.

Types of Protein

Proteins can be categorized into two main sources:

1. Animal-Based Protein

Animal-based proteins are complete proteins, meaning they contain all nine essential amino acids. Common sources include:

Meat: Beef, pork, and lamb
Poultry: Chicken and turkey
Fish and Seafood: Salmon, tuna, shrimp, and other seafood
Eggs: A versatile protein source
Dairy Products: Milk, yogurt, and cheese

2. Plant-Based Protein

Plant-based proteins can be incomplete proteins, as they contain amino acids in lower amounts compared to animal proteins. However, combining different plant sources can provide a complete amino acid profile. You can read my full article The Best Plant-Based Protein Sources: Nutrition, Benefits, and Cooking Tips to learn everything about plant-based proteins. Key sources include:

Legumes: Beans, lentils, chickpeas, and peas
Tofu and Tempeh: Soy products rich in protein
Nuts and Seeds: Almonds, walnuts, chia seeds, and flaxseeds
Whole Grains: Quinoa, brown rice, and oats
Soy Milk: A dairy alternative with significant protein content

How Much Protein Do We Need?

The adequate protein intake varies based on age, activity level, weight and overall health. For the average sedentary adult, the recommended daily allowance (RDA) is 0.8g of protein per kilogram of body weight. For example, a person weighing 60 kg would need about 48g of protein daily.

For those who are more active and do endurance training like running, cycling and swimming, protein needs increase to 1.3 to 1.6g per kilogram of body weight. A person weighing 60 kg would then need about 78-96g of protein daily.

Athletes or individuals engaging in regular strength training, protein needs may increase to 1.6 to 2.2g per kilogram of body weight. In this case, a 60 kg person would require between 96-132g of protein per day.

For individuals looking to lose weight, protein intake should be at least 1.5 grams per kilogram of body weight. This is because protein is more satiating, requires more calories to digest, and excess protein is rarely stored as fat due to the inefficient conversion of protein to fat in the body.

Can Too Much Protein Can Be Harmful?

While protein is essential, consuming too much can lead to health issues. The upper limit is generally considered to be around 2.2g per kilogram of body weight. Exceeding this amount may increase the risk of:

Kidney Damage: Excess nitrogen from amino acids requires the kidneys to work harder, which can be harmful over time. As of today, there are no studies linking high protein intake to kidney damage in healthy individuals. However, excess protein can cause kidney damage in people with preexisting kidney disease. This is because damaged kidneys have to work harder to get rid of the extra nitrogen and waste products of protein metabolism. Consult your doctor to know if you have any health conditions such as kidney disease.
Kidney Stones: A high-protein diet can contribute to the formation of kidney stones, more specifically animal protein. Eating too much red meat, poultry, eggs, and seafood, is linked to an increased risk of developing kidney stones. This is because high animal protein content, either red or white meat, can cause a high purine load and increas uric acid load, which both are linked to an increased risk of having kidney stones.
Heart Disease and Cancer: Diets high in protein are often high in meat consumption, which are rich in saturated fats and cholesterol. These can elevate the risk of heart disease and certain types of cancer. It’s best to get your protein from healthy sources such as low-fat dairy products, fish, tofu, legumes, beans, nuts and seeds, lean chicken and turkey.
Dehydration: Increased protein intake may require additional water consumption to help flush out excess nitrogen. This can leave you dehydrated even though you may not feel more thirsty than usual. To avoid or minize this effect, it’s best to increase water intake, especially if you’re an active person.

CONCLUSION

Protein is an essential nutrient that plays a vital role in our health, supporting everything from muscle repair to immune function. By understanding the types of protein available, how much we need, and the potential risks associated with excessive intake, we can make informed dietary choices that enhance our overall health. Whether you prefer animal-based or plant-based protein sources, finding a balance that fits your lifestyle is key. Always consult with a healthcare provider like a registered dietitian for personalized dietary advice to ensure you're meeting your protein needs safely and effectively.

REFERENCE

Asoudeh, F., Talebi, S., Jayedi, A., Marx, W., Najafi, M. T., & Mohammadi, H. (2022). Associations of Total Protein or Animal Protein Intake and Animal Protein Sources with Risk of Kidney Stones: A Systematic Review and Dose-Response Meta-Analysis. Advances in Nutrition, 13(3), 821-832. https://doi.org/10.1093/advances/nmac013

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