An RD Explains the Different Types of Protein

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Ever wondered, “How much protein do I need?” It’s an essential question to address and then execute, but the quality of the protein source is just as important as meeting your daily protein requirements.

Confession time: I used to think high-quality protein was all about steak and chicken until my nutrition journey began. (I can’t be the only one, right?)

As a dietitian for almost a decade now, I’ve come to understand and value the different types of protein available. Protein is essential in your meals, and I’m here to guide you on high-quality choices for your diet (beyond steak and chicken)!

Medical disclaimer: This article is intended for educational and informational purposes only. It is not intended as a substitute for medical advice. For health advice, contact a licensed healthcare provider.

What Exactly Is Protein?

Protein is one of the three macronutrients, alongside carbohydrates and fats, needed in large amounts (macro = large). Its building blocks, amino acids¹, come in about 20 different types, forming all the proteins in our body.

These protein building blocks mostly fall into two amino acid categories: essential and non-essential amino acids. Branched-chain amino acids and conditionally essential amino acids are subcategories of amino acids.

Let it be known that non-essential doesn’t mean they aren’t essential, it’s just that our bodies can produce them if they are not consumed from our food. The 11 non-essential amino acids include:

Alanine
Arginine*
Asparagine
Aspartic acid
Cysteine*
Glutamic acid
Glutamine*
Glycine*
Proline*
Serine*
Tyrosine*

Conditional amino acids, marked with asterisks, are non-essential except in times of stress or inflammation when the body needs more than it can produce.

On the other hand, essential amino acids can’t be made by the body and must come from our diet. The nine essential amino acids include:

Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine

Branched-chain amino acids (BCAAs) are a subcategory of essential amino acids with protein anabolic properties. The three BCAAs include:

Isoleucine
Leucine
Valine

Essential and non-essential amino acids also dictate whether or not a protein is considered “complete” or “incomplete.”

RELATED: Best BCAA

Complete vs Incomplete Proteins

Complete proteins provide all nine essential amino acids for human growth and development. Animal sources—like red meat, poultry, fish, eggs, dairy, and a select few plants—are complete proteins.

Conversely, incomplete proteins lack one or more essential amino acids. Most plants, except for soy and a few others, are incomplete proteins.

Complete proteins are your all-star protein team, providing all essential amino acids, while incomplete proteins are like individual players. However, mixing different foods throughout the day can fill your daily protein roster, which is especially helpful for people following vegetarian diets².

What Are the Different Types of Protein Sources?

The different types of protein sources are often labeled complete or incomplete, but it’s simpler to classify high-protein foods as either animal (primarily complete) or plant proteins (mostly incomplete). This method is more approachable and user-friendly, reducing the constant need to Google questions like, “Are eggs a complete protein?”

Animal Proteins

Animal proteins, found in various sources, provide all essential amino acids and a blend of vital nutrients:

Red meats: Red meats—such as beef, pork, lamb, veal, and bison—are high in protein, iron, zinc, and vitamin B12.

White poultry meats: Chicken, turkey, duck, and other poultry meats³ provide highly digestible protein, iron, zinc, copper, and B vitamins, especially niacin.

Milk and dairy products: Milk and dairy products like cheese and yogurt are rich in protein and essential nutrients like calcium.

Eggs: The egg white holds the protein, but don’t fear the cholesterol-containing yolks, folks (unless instructed by a healthcare provider). Current research⁴ shows no clear link between dietary cholesterol and blood cholesterol levels, and the yolk contains essential nutrients (like choline) that support cognition and brain health⁵.

Fish: Whether fresh or saltwater, fish is an excellent source of protein. Fatty fish, like salmon and mackerel, also supply omega-3 fatty acids that support heart and brain health.

RELATED: Best Fish Oil Supplement

Although meats⁶ and animal products provide complete proteins and critical nutrients, tackling global deficiencies in iron and zinc, their higher saturated fat content than plant sources raises health concerns. This issue and a surge in animal protein demand⁷ drives interest in plant proteins.

Plant Proteins

Plant proteins, also known as vegetable proteins, often lack at least one essential amino acid. However, varying these plant proteins can create a more comprehensive amino acid profile:

Legumes: Bean varieties, chickpeas, lentils, and soy are excellent sources of protein and fiber.

Soy: Soy stands out among legumes, given the limited awareness of other plant proteins. Common dietary soy products include edamame (immature soybeans), tofu, and tempeh.

Nuts and seeds: While mostly healthy fat sources, nuts and seeds—like sunflower seeds—provide high-quality plant protein, fiber, and other beneficial nutrients.

Whole grains: Whole grains—such as oats, brown rice, and quinoa (technically a seed)—offer modest protein but excel in providing fiber, phosphorus, magnesium, and B vitamins like folate and thiamin.

While plants are a source of lean protein, they often don’t match the protein density of animal sources. For instance, 100 grams (3.5 ounces) of cooked chicken delivers 31 grams of protein, whereas you’d need to consume about 800 grams of canned chickpeas for the same amount of protein (which also brings a hefty 48 grams of fiber, potentially causing significant digestive discomfort).

RELATED: High-Protein Vegetables

Conversely, plant protein⁸ isolates and concentrates, which consist of 80 percent or more protein, offer a robust 10-20 grams of protein per serving with minimal carbs and fat. These concentrated protein sources are commonly available in protein shakes and powder mixes.

What Are the Different Types of Protein Powder?

Whole food sources should comprise most, if not all, of your daily protein needs. However, protein powder is a convenient option that caters to various lifestyles and dietary requirements, including health, environmental, and religious considerations. Let’s explore the many types of protein powder you can choose from.

Dairy-Based Protein Powders

Casein and whey, the two main proteins in cow’s milk, are isolated in the cheesemaking process. The milk is separated into solid curds (casein) and liquid (whey) and can be processed into dairy-based protein powders.

When comparing casein protein vs whey, one significant difference is their absorption rates. Whey protein is rapidly absorbed, making it ideal for post-exercise recovery. In contrast, casein digests slowly, making it the go-to protein before bed to support prolonged muscle protein synthesis during sleep.

It’s important to note that casein and whey proteins are beneficial any time of day. However, knowing their unique absorption rates and timing their consumption may maximize their effectiveness.

Plant-Based Protein Powders

Plant-based protein powders are sourced from high-protein plant sources with most of the carb and fat content removed. They are especially favored by those seeking dairy, lactose, and animal-free protein alternatives for dietary preferences and restrictions.

RELATED: Best Vegan Protein Powder

Common types of plant-based protein powders include:

Soy protein powder
Hemp protein powder
Pea protein powder
Chia protein powder
Pumpkin seed protein powder

Recall that plant-based proteins typically lack one or more essential amino acids. And while pea protein has all nine, it’s low in methionine and less bioavailable. Blends of plant proteins are often used for a complete amino acid profile for this reason. Still, verifying the label’s amino acid and protein content is wise when choosing a plant-based protein supplement.

Protein Benefits

Protein is more than beneficial—your body NEEDS protein. It fuels thousands of bodily processes as enzymes and supports every structure in our bodies, and that’s just scratching the surface. Let’s dive into the most intriguing benefits of protein.

Enhances Muscle Growth, Strength, and Recovery

A quick lesson on how to build muscle and strength: you must prioritize resistance exercise training and your diet. Resistance training causes tiny breakdowns in the muscle fibers, then protein steps in to prevent further breakdown and initiate muscle repair.

A systematic review⁹ suggests that post-workout protein may reduce muscle soreness and markers of muscle damage. When consistently training, applying progressive overload, and eating enough protein, muscle mass grows and takes shape, with greater strength likely to follow.

Improves Body Composition and Metabolism

Improving body composition typically involves a dual approach: increasing muscle mass and reducing body fat. Many essential factors are at play here, including a diet rich in high-protein meals.

Research, including a 2020 review¹⁰, supports that a high-protein diet increases muscle and fat loss when combined with exercise. Complementary research¹¹ suggests protein promotes weight loss and maintenance by influencing energy metabolism, controlling appetite, and regulating calorie intake.

Promotes Whole-Body Health

Protein plays a vital role in overall health, impacting most, if not all, body systems:

Bone health: Despite the debate about the effect of protein on bone health, research¹² proposes that protein is a crucial nutrient for bone health and helps prevent osteoporosis. Some evidence¹³ shows that high-protein diets can reduce hip fracture risk compared to low-protein diets.

Immune health: Proteins, particularly antibodies, are essential for a robust immune system. Insufficient protein or amino acids can weaken immunity and increase infection risks.

Hormone health: Proteins and amino acids are critical for regulating hormone production. For instance, adequate protein is necessary for proper thyroid function and maintaining insulin growth factor 1 (IGF-1) levels, vital for muscle growth.

Neurological health: Essential amino acids¹⁴ support the central nervous system and neurotransmitters, influencing mood and blood pressure. A 2022 review¹⁵ suggests higher protein intake, especially from sources like legumes, fish, and lean poultry, can reduce cognitive decline, unlike processed proteins like hot dogs.

Speaking of hot dogs, now’s an opportune time to reveal the potential drawbacks of protein.

Protein Drawbacks

While protein is crucial for health, its drawbacks stem from its source and overconsumption.

Processed vs Unprocessed Proteins

Processed meats¹⁶, preserved through smoking, curing, and salting (like hot dogs), are associated with cancer, heart disease, and higher mortality risk. The effects of unprocessed meats, only preserved by refrigeration or freezing, are mixed; some studies show varying health risks, and others¹⁷ suggest insufficient data for conclusive findings.

Processed plant proteins may lose essential nutrients, often replaced with additives like added sugar and sodium. Moreover, a 2021 study¹⁸ suggests vegetarians and vegans might consume more ultra-processed foods than meat eaters.

Red Meat Debate

Red meat raises concerns, mainly due to its saturated fat content, but the research is debatable. Some studies suggest a connection between red meat and health risks like heart disease¹⁹, while others, like those published in the American Journal of Clinical Nutrition²⁰, report no associations.

Excess Protein Intake Risks

You can have too much of a good thing, high-quality protein included. Be mindful of these high-protein diet side effects:

Nutrient deficiencies
Digestive distress
Weight gain
Kidney strain (particularly in those at risk of developing or currently managing a kidney condition)

Minimize these risks by varying minimally processed sources of protein to enrich your diet with essential nutrients like iron (red meat), calcium (dairy), and fiber (plant proteins). We also encourage consulting a healthcare professional for a diet tailored to your nutritional needs and preferences.

Different Types of Protein: Final Thoughts

Although different types of protein can be categorized as complete or incomplete based on their essential amino acid profiles, it’s more practical for everyday conversations to refer to them as either animal or plant proteins.

Animal proteins provide complete protein and all essential amino acids, whereas plant proteins often lack at least one essential amino acid. However, combining various protein-rich foods allows you to create a comprehensive amino acid profile, meet your daily protein needs, and obtain beneficial nutrients unique to each protein type—such as iron in beef and fiber in beans.

Remember, dietary protein is more than just a nutrient, it’s vital to a healthy life and life itself. So, explore beyond the traditional steak and chicken and embrace the different types of protein available to you.

Different Types of Protein: FAQs

What is the best protein type?

The optimal protein choice is a complete protein, rich in essential amino acids crucial for growth and repair, mainly found in animal products. However, combining different plant proteins helps obtain all essential amino acids for those following a plant-based diet.

What are the 2 main types of protein?

Proteins are generally classified as complete or incomplete based on their essential amino acid profiles. However, it’s often more practical to refer to them as animal (primarily complete) or plant (mostly incomplete) proteins.

What’s good protein for weight loss?

To effectively utilize high-protein foods for weight loss, choose lean options such as sirloin, skinless chicken, low-fat milk, and plant-based sources like beans. Just remember, achieving weight loss requires maintaining a calorie deficit.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any diseases.

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Sydney Lappe, R.D.

Sydney Lappe is a St. Louis-based Registered Dietitian with 6+ years of nutrition editing and writing experience. She holds a Master’s Degree in Nutrition and Dietetics and completed undergrad work in psychology. While fitness wasn’t in Sydney’s routine growing up, it quickly became a large part of her daily life while studying the facets of health and nutrition. Also managing chronic pain, she has come to fully realize movement is a special gift to never take for granted and hopes to inspire others to invest in their physical, mental, and emotional wellness while they can. Including her passion for all things health, Sydney enjoys spending time with her loved ones, being active in various capacities, drinking bottomless cups of coffee, eating a hearty bowl of oatmeal, and letting her creativity roam through writing and graphic design.

Different Types of Protein: An RD’s Simple Perspective and Practical Approach