Protein power: a guide to both animal-based & plant-centric sources
Protein, one of three macronutrients crucial for overall health, is found in at least trace amounts in many foods. But which foods are the best sources? And what the heck does it even mean to be the “best protein” anyway?
Optimal choices vary when it comes to individual nutritional needs, which is why we’re not going to tell you which proteins are best. What you can expect is a breakdown of where to find protein, how to assess it, and how to strategically incorporate it into your nutrition.
What is protein?
Protein is a complex macronutrient composed of amino acids, which are essential for the structure and function of cells. It’s involved in everything from repairing tissues to creating enzymes and hormones and contributes to the overall growth, maintenance, and regulation of the body's intricate systems.
Why protein is important
The human body requires a diverse range of amino acids for optimal health, and proteins from various sources provide these essential components. Whether derived from animal-based or plant-based sources, proteins are integral to:
Muscle building: Regardless of your relative fitness, protein facilitates the growth and maintenance of muscle tissues.‚
Weight management: Protein’s high satiety factor helps regulate your appetite, and its thermogenic effect supports a healthy metabolism.
Immune system support: Protein aids your immune system in the production of antibodies and contributes to the overall resilience of the body against infections.
Hormonal regulation: From insulin to growth hormones, proper hormonal and biochemical relies on an adequate protein supply.
Considerations for protein sources
Grams per serving isn’t the only way to measure protein. When strategizing and informing your dietary choices, it’s important to get the full picture.
Amino acid composition
Amino acids are the building blocks of proteins, and the specific combination of these amino acids in a protein source determines its effectiveness in supporting various bodily functions.
Categorized as either essential or non-essential, a diverse range of amino acids is crucial for optimal health. When we talk about complete proteins, we’re referring to sources that contain all essential amino acids in sufficient amounts. Keep in mind that non-essential amino acids still carry plenty of value, such as supporting protein synthesis or regulating your mood.
Micronutrients
Protein sources also bring along essential micronutrients — red meat provides iron, for example, while dairy offers calcium. When choosing a protein source, considering the micronutrient content is crucial as it contributes to a balanced nutritional profile, bone health, immune function, and many other aspects of overall health.
Total macro picture
Protein is just one part of your nutritional profile, and balancing protein intake with fats and carbohydrates is key for a well-rounded diet.
That said, it’s worth looking at the overall composition of your protein sources if you want to get more specific about your macros. Some protein sources, such as eggs or certain cuts of meat, also contain similar amounts of fat, while certain plant-based sources tend to have more even carb to protein ratios.
These other macronutrients are just as important for your health, but if you’re looking for a source that packs a more focused punch, you may want a protein with different ratios. You can check out the other sections of this article for more specific breakdowns, but sources such as lean meats and fish, egg whites, and tofu typically have more concentrated amounts of protein.
Protein quality index
Protein quality is assessed through the Protein Digestibility-Corrected Amino Acid Score (PDCAAS), which is a widely-used method adopted by the World Health Organization. This index provides a comprehensive measure of a protein’s nutritional value by considering the following factors:
Amino acid composition: High-quality protein sources have a complete profile of essential amino acids in adequate proportions.
Digestibility: How effectively the body breaks down and absorbs the protein. Low digestibility diminishes the overall nutritional value.
Don’t get too caught up on the word “quality” — in this context, it refers to a source’s maximum benefit potential, but lower benefits don’t necessarily classify a protein source as poor or insufficient value. Protein is more complicated than that, but it’s still useful to consider how different sources land across the scoring pattern.
Other terms to note in this chart:
Protein efficiency ratio: The effectiveness of a protein through the measurement of animal growth. Any value beyond 2.7 is considered an excellent source.
Biological value: Calculates nitrogen used for tissue (muscle) formation divided by nitrogen absorbed by food to determine how efficiently the body utilizes the protein consumed, otherwise called bioavailability.
Net protein utilization: Similar to bio value, net protein utilization assesses the efficiency with which the human body utilizes the ingested (rather than absorbed) protein.
Protein digestibility corrected amino acid score: Evaluates the quality of a protein source by considering both its amino acid composition and digestibility, resulting in a score between 0 and 1, with 1 indicating optimal protein quality
Protein quality rankings
Source: U.S Dairy Export Council, Reference Manual for U.S. Whey Products 2nd
Edition, 1999 and Sarwar, 1997.
Animal-based protein
Commonly consumed animal-based proteins like meat, poultry, fish, eggs, and dairy products are considered complete proteins and provide a well-balanced array of essential amino acids.
Let's explore some common sources:
Meat
Red meat, whether beef, pork, or lamb, is an exceptional source of protein and a complete amino acid profile. Besides offering an array of savory flavors and a relatively high ranking according to the PDCAAS, meats also often deliver rich and diverse nutrients such as iron, zinc, and vitamin B12.
The composition and quality of meat can vary depending on its source and cut. Some cuts, such as a top sirloin beef steak or a pork tenderloin, are relatively lean and provide a high ratio of protein to fat.
To demonstrate the variety, here’s some average macro breakdowns:
Poultry
Poultry, which includes chicken, turkey, and several other less common options, is a lean and abundant source of protein with complete amino acid profiles. Similarly to red meat, poultry varies in macronutrient ratio and overall quality depending on the cut and source, but fat content generally stays relatively lower than red meat options. Skin-on poultry, generally referred to as bone-in, has higher fat content.
See the following macro breakdowns for common poultry cuts:
Fish and seafood
Fish and seafood not only supply lots of protein and rank highly on PDCAAS, but also bring omega-3 fatty acids to the table. It also offers an array of essential nutrients such as vitamin D, zinc, iodine, and selenium.
Compare the macros across various fish and seafood options:
Dairy
With the highest possible rating on the PDCAAS scale, milk, cheese, and yogurt provide a complete-profile protein boost as well as calcium, vitamin D, vitamin B12, and potassium. Yogurt and kefir in particular are excellent sources of probiotics, and some cheeses contain monounsaturated fats and omega-3 fatty acids. Lactose-free dairy options also deliver valuable nutrition, making them great for those with allergies or intolerances.
You’ll start to see more macronutrient ratio variation with dairy products as they contain lactose, a form of carbohydrates.
Whey
Whey, a byproduct of cheese production, is a popular supplement among athletes, gym rats, and general wellness enthusiasts. Combined with a high PDCAAS rating and its rapid absorption, whey is an ideal post-workout protein source. Whey protein falls in one of the following three categories:
Concentrate: Cost-effective and with varying amounts of fats and carbs.
Isolate: Typically has the highest protein percentage and fastest absorption.
Casein: Digested slowly, making it preferable for steady release over 6 to 8 hours.
Macronutrients vary depending on the brand, flavor, and other factors, but the approximate breakdowns are:
Eggs
Eggs are a nutritional powerhouse, offering a complete protein source with a rich mix of vitamins and minerals. Out of all protein sources, whole eggs rank only below whey in terms of overall quality.
Egg whites are a more concentrated source of protein, but whole eggs contain a lot more nutrients. Compare their macros:
Plant-based proteins
There are a number of reasons to seek out plant-based protein sources, such as vegetarianism/veganism, sustainability, ethics, and diversity. Plant-based proteins are abundantly available, but they often carry a few differences when compared to animal-based sources, such as higher fiber content and lower saturated fats.
The key difference is that, while most animal-based protein sources feature complete amino acid profiles and are highly bioavailable, many plant-based proteins are incomplete and contain compounds that affect absorption. By combining complementary plant sources, such as beans and rice, you can still achieve a complete amino acid profile. Fermenting, soaking, and cooking plant-based sources can also improve absorption efficiency.
With that, here are the macro breakdowns for your protein-packed plant friends:
Legumes
Legumes, encompassing a diverse family of plants such as beans, lentils, and chickpeas, are an exceptional source of protein and showcase an array of nutritional values that contribute to overall health and well-being. They’re not only rich in protein but also high in fiber, supporting digestive health, and also contain iron, folate, and potassium. Legumes aren’t complete proteins, but you can combine them with complementary proteins to achieve a complete amino acid profile.
In a shift from previous proteins, legumes bring a higher ratio of carbs to protein to the table. Here’s a macronutrient breakdown for common legumes:
Soy
Although technically under the legume category as it’s derived from soybeans, soy deserves its own category. Soy has a high PDCAAS rating that’s close behind animal-based sources, and it features a complete amino acid profile. It also features potential benefits such as antioxidant properties, high fiber, cholesterol management, and hormonal regulation.
Here's a macronutrient breakdown for common soy-based foods:
Grains
Grains, often relied on for starchy carbohydrates, also play a role as a source of protein and various other essential nutrients. Whole grains like quinoa and brown rice provide a complete protein boost alongside essential nutrients like fiber, magnesium and antioxidants. Quinoa, buckwheat, and certain other grains are also complete protein sources:
Nuts and Seeds
Almonds, chia seeds, and flaxseeds offer a closely balanced blend of healthy fats and protein, making them a nutritious snack or addition to meals. Certain nuts and seeds also boast high omega-3 fatty acid content, fiber, magnesium, vitamin E, and more.
And yes, we’re going to put peanuts in this category. Peanuts are seeds derived from legume plants, but they carry similar oil-based properties as nuts and seeds.
FAQs about protein sources
How much protein do I need daily?
The minimum guideline is about 0.8 grams of protein per kilogram of body weight or 3.5 grams per pound of bodyweight, but your needs may be higher depending on factors such as age, gender, and activity level.
Can I get enough protein on a plant-based diet?
While animal products are dense protein sources, a well-planned plant-based diet can provide all essential amino acids. Combining legumes, grains, nuts, and seeds ensures a diverse protein intake.
Are protein supplements necessary?
For most individuals, meeting protein needs through a balanced diet is sufficient. However, in specific cases, such as intense physical training, supplements can be a convenient way to reach protein goals.
