Which is an example of a main source of protein? Discover Key Food Groups

January 1, 2026 •

4 min read

Protein is a crucial macronutrient, with the average adult's protein intake often exceeding the recommended daily amount from meat, cereals, and dairy. A single example of a main source of protein is chicken breast, which is a key part of many healthy diets.

Quick Summary

This guide provides examples of primary protein sources, from animal products like lean meats, eggs, and dairy, to diverse plant-based alternatives, including legumes, nuts, and soy products. It explores the different types and benefits of each.

Key Points

Which is an example of a main source of protein?: Chicken breast is a prime example of a main source of protein, along with eggs, fish, lentils, and soy products like tofu.
Complete vs. Incomplete Proteins: Animal-based sources like meat, eggs, and dairy are typically complete proteins, containing all nine essential amino acids. Most plant-based proteins are incomplete but can be combined to form a complete profile.
Diversify Your Sources: Eating a variety of protein sources, both animal and plant-based, ensures you receive a full range of essential amino acids and other important nutrients like fiber and omega-3s.
Prioritize Whole Foods: While supplements are an option, focusing on whole-food sources of protein like lean meats, eggs, dairy, legumes, and nuts provides a more complete nutritional package.
Plant-Based Options are Abundant: Plant sources like legumes, soy products (tofu, tempeh), nuts, and seeds offer excellent alternatives and can be combined to meet complete protein needs.
Protein for Health: A diet rich in protein is vital for muscle repair, immune function, hormone synthesis, and can assist with weight management.

Animal-Based Protein Sources

Animal products are well-known for being excellent, 'complete' sources of protein, meaning they contain all nine essential amino acids that the body cannot produce on its own. These sources are often highly bioavailable, allowing the body to easily digest and utilize the protein.

Meat and Poultry

Chicken and Turkey Breast: These are popular choices for lean protein, offering a high protein-to-calorie ratio. A 100g serving of cooked, skinless chicken breast contains approximately 27 grams of protein. They are also a good source of B vitamins, phosphorus, and selenium.
Beef: Cuts like sirloin, tenderloin, and ground beef (93% lean or higher) are rich in protein, iron, and zinc. A 3-ounce (85g) serving of 93% lean ground beef provides about 22 grams of protein.
Pork: Lean cuts of pork, such as tenderloin, are another solid protein option.

Fish and Seafood

Fish and seafood not only offer high-quality protein but are also often rich in heart-healthy omega-3 fatty acids.

Salmon: A fatty fish that is an excellent source of protein and anti-inflammatory omega-3s. A 3-ounce (85g) serving typically has around 19 grams of protein.
Tuna: Canned or fresh tuna is a convenient protein source. A 100g serving of drained, canned tuna can offer nearly 24 grams of protein.
Shellfish: Options like shrimp, clams, and scallops are packed with protein, healthy fats, and minerals like zinc and vitamin B12.

Eggs and Dairy

Eggs are a convenient and affordable protein source. A single large egg contains about 6 grams of high-quality, easily digestible protein. Dairy products are also fantastic protein sources, often paired with calcium for bone health.

Greek Yogurt: This is a particularly protein-dense dairy choice, with a 3/4-cup serving often containing around 15-20 grams of protein.
Cottage Cheese: Another dairy item known for its high protein content. A half-cup serving can provide about 12 grams of protein.
Milk: A single cup of milk can provide approximately 8 grams of protein.

Plant-Based Protein Sources

For vegetarians, vegans, or those simply diversifying their diet, plant-based proteins are abundant and offer additional benefits like fiber, vitamins, and minerals. While most are 'incomplete' on their own, combining a variety throughout the day ensures all essential amino acids are consumed.

Legumes and Soy Products

Lentils: Versatile and packed with protein and fiber. A single cup of cooked lentils can provide 18 grams of protein.
Beans: Varieties like black beans, kidney beans, and chickpeas are excellent plant-based options. A cup of cooked black beans has over 15 grams of protein.
Tofu and Tempeh: Made from soy, these are popular meat substitutes. Tempeh, a fermented soy product, often has a higher protein count than tofu, providing about 20.3 grams per 100g. Tofu offers around 8-10 grams per 100g.
Edamame: These young soybeans are rich in protein, with 11 grams per 100g.

Nuts and Seeds

Nuts and seeds are not only good protein sources but also provide healthy fats and fiber.

Almonds: Just one ounce of almonds contains about 6 grams of protein.
Peanut Butter: A popular and easy way to add plant protein. A two-tablespoon serving offers approximately 7 grams.
Pumpkin Seeds: These seeds are a protein powerhouse, containing nearly 30 grams per 100g.
Chia Seeds: Small yet mighty, offering fiber and omega-3s in addition to protein.

Whole Grains

Quinoa: A standout among grains as one of the few complete plant-based proteins.
Oats: A good source of protein, especially when paired with other protein-rich foods.

Protein Source Comparison Table


Food Source	Type	Protein Content (per 100g)	Other Notable Nutrients	Complete Protein?
Chicken Breast	Animal	~27g	B Vitamins, Phosphorus	Yes
Salmon	Animal	~25g	Omega-3 Fatty Acids, Vitamin D	Yes
Greek Yogurt	Animal (Dairy)	~10g	Calcium, Probiotics	Yes
Eggs	Animal	~14g	Omega-3s, B Vitamins	Yes
Tempeh	Plant (Soy)	~20g	Fiber, Vitamins, Minerals	Yes
Lentils	Plant (Legume)	~9g	Fiber, Iron, Folate	No (but can be complemented)
Almonds	Plant (Nut)	~21g	Healthy Fats, Fiber	No (but can be complemented)

Optimizing Your Protein Intake

Getting enough protein is vital for countless bodily functions, including muscle repair and growth, immune system support, and hormone production. While the occasional protein bar or supplement can be convenient, focusing on whole-food sources is generally recommended for a more comprehensive nutritional profile. For those following plant-based diets, consuming a variety of plant proteins throughout the day is key to ensuring you receive all essential amino acids. Combining foods like rice and beans or hummus with pita is a classic way to create a complete protein meal. Portion sizes are also important, and many sources provide simple visual guides, like a portion of meat being about the size of your palm.

Conclusion: Which is an example of a main source of protein?

An excellent example of a main source of protein is a skinless chicken breast, renowned for its high-quality, complete protein content and versatility in healthy cooking. However, the world of protein is vast and varied, encompassing a wide range of animal and plant-based foods. From lean meats and eggs to nutrient-dense legumes and nuts, diversifying your protein intake is the most effective strategy. This approach not only ensures you get all the necessary amino acids but also provides a broader spectrum of vitamins, minerals, and fiber essential for overall health. Whether you choose animal or plant sources, or a combination of both, a balanced intake is what truly matters.

Learn more about different protein sources and their benefits from The Nutrition Source at Harvard T.H. Chan School of Public Health: What should you eat? Protein

Frequently Asked Questions

Main protein sources for vegetarians include eggs, dairy products like Greek yogurt and cottage cheese, and plant-based options such as legumes, nuts, seeds, and soy products like tofu and tempeh.

While many animal proteins are considered 'complete' (containing all nine essential amino acids), plant-based proteins offer unique benefits like fiber and antioxidants. By eating a variety of plant-based protein sources, it is simple to get all the essential amino acids you need.

The amount of protein needed varies based on your weight, age, activity level, and health goals. However, a common recommendation is 0.8 grams of protein per kilogram of body weight, with higher amounts for athletes or those trying to lose weight.

Per 100 grams, chicken breast has significantly more protein (about 27g) than cooked lentils (about 9g). However, lentils are a budget-friendly source that also provides fiber.

Yes, protein can assist with weight loss by increasing feelings of fullness (satiety), which helps control calorie intake. High-protein diets can also help preserve muscle mass while losing fat.

A complete protein is a food that contains all nine essential amino acids in adequate amounts for the body's needs. These are typically found in animal products like meat, fish, eggs, and dairy, as well as some plant-based options like soy and quinoa.

For most people, it is best to get protein from a variety of whole foods, as these sources also provide other crucial nutrients. Supplements can be a convenient option for those with higher protein needs, like athletes, but are not a necessary replacement for a balanced diet.