What are amino acids and why do you need them?
Amino acids are the fundamental building blocks of protein, which is an essential macronutrient for virtually every function in the human body, including repairing tissues, building muscle, and creating enzymes and hormones. Of the 20 amino acids the body uses, nine are classified as 'essential' because our bodies cannot produce them and must obtain them from food. The essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
The truth about 'complete' and 'incomplete' proteins
For decades, a pervasive myth suggested that plant proteins were "incomplete" because they might be low in one or more of the essential amino acids. This led to the belief that you needed to carefully combine different plant foods at each meal to form a "complete" protein. However, this advice is now considered outdated. The human body maintains an amino acid 'pool' that it can draw from throughout the day. As long as you consume a variety of protein-rich plant foods over the course of the day, your body will get all the amino acids it needs.
Are some plant proteins complete?
Yes, some plant foods naturally contain all nine essential amino acids in sufficient amounts and are therefore considered complete proteins. These include:
- Soy products: Tofu, tempeh, and edamame
- Quinoa: A pseudo-grain that serves as a complete protein source
- Buckwheat: Another pseudo-grain with a complete amino acid profile
- Hemp seeds: A great source of protein, healthy fats, and fiber
- Spirulina: A type of blue-green algae with a very high protein content
How to ensure you get enough amino acids from plants
Meeting your amino acid needs on a plant-based diet is simple and does not require complex meal planning. The key is to focus on variety and consuming enough calories to meet your energy needs.
The importance of variety
By incorporating a wide range of protein-rich plant foods into your diet, you naturally ensure you are getting a full spectrum of amino acids. Since different plant groups have varying amino acid profiles, eating a mix ensures any deficiencies in one food are compensated for by another. For example, grains are often lower in lysine, but legumes are rich in it. Conversely, legumes are often lower in methionine, which is abundant in grains. This is how traditional pairings like rice and beans became dietary staples in many cultures.
Key plant protein sources
To create a balanced plant-based diet, focus on incorporating a mix of these protein sources:
- Legumes: Lentils, chickpeas, and all types of beans (black, kidney, pinto)
- Nuts and Seeds: Almonds, walnuts, chia seeds, hemp seeds, and pumpkin seeds
- Whole Grains: Quinoa, buckwheat, oats, and whole-wheat bread
- Soy Products: Tofu, tempeh, and edamame
- Vegetables: Many vegetables, like broccoli and spinach, contain meaningful amounts of protein
Addressing protein bioavailability
One valid consideration is the bioavailability of plant protein, which refers to how effectively the body can absorb and use the amino acids. Some plant proteins have lower digestibility due to factors like fiber and antinutrients. However, a few key strategies can help maximize absorption:
- Cooking and Processing: Heat treatment, fermentation, and sprouting can improve the digestibility and bioavailability of plant proteins. For example, fermented soybeans in tempeh are easier to digest than raw soybeans.
- Consuming Variety: The sheer variety of a plant-based diet, combined with sufficient caloric intake, often makes up for any minor differences in bioavailability.
- Isolation: Plant protein isolates, commonly found in protein powders (e.g., soy, pea, rice protein), have significantly improved digestibility and are a great option for those with higher protein needs.
Plant-based protein comparison table
| Food (per 100g) | Protein (g) | Complete? | Notes |
|---|---|---|---|
| Hemp Seeds | ~30 | Yes | Excellent source of omega-3 and omega-6 fatty acids |
| Tempeh | ~20 | Yes | Fermented soy, rich in probiotics |
| Lentils (boiled) | ~9 | No | High in lysine, good fiber source |
| Quinoa (cooked) | ~4.4 | Yes | Versatile pseudo-grain, good fiber source |
| Chickpeas (canned) | ~7 | No | High in lysine, can be paired with grains |
| Tofu | ~16 | Yes | Versatile soy product |
| Pumpkin Seeds | ~24 | No | High in protein but low in lysine |
Special considerations for specific populations
While meeting amino acid needs is achievable for most people on a plant-based diet, some groups have higher protein requirements that need extra attention.
Athletes and muscle growth
For those engaging in heavy resistance training, higher protein intake is required to facilitate muscle repair and growth. A daily intake of around 1.6 grams of protein per kilogram of body weight is often recommended. Plant-based athletes can successfully achieve this by increasing their overall food intake and focusing on protein-dense foods and supplements, such as soy protein or pea protein isolates. Studies have shown that with adequate training and sufficient protein intake, muscle growth is comparable whether the protein comes from plant or animal sources. For more detailed information on protein for athletes, see the resources at VeganHealth.org.
Older adults
Older adults may experience age-related anabolic resistance, requiring a higher relative protein intake to maintain muscle mass and prevent sarcopenia. Combining consistent resistance exercise with a diet rich in high-quality plant proteins, such as soy, can help mitigate this effect. Spreading protein intake throughout the day is a useful strategy.
Conclusion: Thriving on a plant-based diet
In summary, it is absolutely possible to get enough amino acids from plants. The key lies not in obsessively combining specific foods at each meal, but in consuming a wide variety of protein-rich plant foods over the course of a day. By focusing on legumes, whole grains, nuts, seeds, and soy products, and ensuring adequate overall energy intake, anyone can thrive on a plant-based diet and meet all their amino acid requirements. Whether you are a vegan athlete or simply looking to add more plants to your plate, a well-balanced plant-based diet provides a complete and wholesome nutritional package, supporting overall health and well-being.
