What are amino acids and essential amino acids?
Amino acids are the fundamental building blocks of proteins, which play a critical role in almost every bodily function. There are 20 standard amino acids, and your body can synthesize 11 of them. The other nine are deemed 'essential' because they must be obtained through food. These essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. A food containing all nine essential amino acids in sufficient quantities is called a "complete protein".
Complete protein sources: Animal-based and plant-based
Many animal-based foods like meat, eggs, and dairy are considered complete proteins. However, several plant-based foods also contain a complete amino acid profile.
Animal-based complete proteins
- Meat and poultry: Lean meats like chicken and beef provide high-quality protein.
- Fish and seafood: Salmon, tuna, and shrimp offer complete protein and often omega-3 fatty acids.
- Eggs: Provide all nine essential amino acids.
- Dairy products: Milk, yogurt, and cheese are good sources of complete protein and calcium.
Plant-based complete proteins
- Soy products: Tofu, tempeh, and edamame are complete proteins.
- Quinoa: This grain is a complete protein source.
- Buckwheat: A pseudocereal that is a complete protein.
- Hemp seeds: Offer a full essential amino acid profile and healthy fats.
- Chia seeds: Another source of complete protein for plant-based diets.
- Spirulina: This blue-green algae is a nutrient-dense complete protein.
The myth of protein combining
It was once believed that vegetarians and vegans needed to combine different incomplete plant proteins at every meal to create a complete amino acid profile. However, this is a myth. The human body has an "amino acid pool" and can use amino acids from different foods eaten throughout the day. A varied intake of plant-based proteins over 24 hours provides all essential amino acids needed.
Ensuring adequate intake on a plant-based diet
A diverse plant-based diet is a practical approach for meeting amino acid requirements. Include a variety of the following:
- Legumes: Beans, lentils, and chickpeas are good protein and fiber sources.
- Grains: Whole grains like brown rice and oats contribute protein.
- Nuts and seeds: Almonds and pumpkin seeds offer protein and healthy fats.
- Vegetables: Many vegetables contain protein and nutrients.
Protein source comparison: Animal vs. Plant
Consider unique nutritional benefits and drawbacks when comparing protein sources. A varied diet provides a wider array of nutrients.
| Feature | Animal Protein | Plant Protein | Comments |
|---|---|---|---|
| Amino Acid Profile | Complete. | Can be complete or incomplete, but a varied diet provides all 9 EAAs. | Both types can fulfill requirements. |
| Digestibility | Generally higher. | Varies, can be lower due to fiber. | Cooking or sprouting can improve digestibility. |
| Fat Profile | Can be higher in saturated fat. | Typically low in saturated fat, may contain healthy fats. | Type of fat matters for heart health. |
| Fiber Content | No dietary fiber. | High in dietary fiber. | Fiber is a benefit of plant proteins. |
| Micronutrients | Often rich in Vitamin B12, Vitamin D, heme iron. | Often rich in antioxidants, phytonutrients, vitamins, and minerals. | Both are important, some nutrients may need supplementation in plant-based diets. |
Conclusion
Yes, certain foods are "complete proteins" containing all essential amino acids. Animal products and some plant-based options like soy and quinoa fall into this category. The need to combine complementary proteins in the same meal is a myth; the body effectively utilizes amino acids from a varied diet throughout the day. Focusing on dietary diversity is the most effective strategy for ensuring adequate intake of all essential amino acids.
Learn more about a balanced diet from authoritative sources, such as the Academy of Nutrition and Dietetics.
