The Foundation: Understanding Protein and Amino Acids
Protein is an essential macronutrient vital for building and repairing body tissue, producing hormones and enzymes, and maintaining overall bodily function. Proteins are made up of smaller units called amino acids. The body can produce 11 of these, known as non-essential amino acids. However, nine are classified as essential amino acids (EAAs) because the body cannot produce them and must obtain them from food. These nine are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
Debunking the “Complete Protein” Myth
One of the most persistent myths in nutrition is the idea that plant proteins are "incomplete" and must be carefully combined at every meal to be useful. Early research led to this belief, but modern science has proven it to be outdated. While many individual plant proteins may be low in one or more EAAs, your body has an amino acid pool and can combine amino acids from different meals throughout the day. As long as you consume a variety of protein-rich plant foods over the course of a day, your body will obtain all the essential amino acids it needs. Furthermore, some plant foods are complete proteins on their own, such as soy (tofu, tempeh, edamame), quinoa, hemp seeds, and buckwheat.
Protein Quality: PDCAAS vs. DIAAS
Protein quality is often assessed using standardized scores. The Protein Digestibility Corrected Amino Acid Score (PDCAAS) and the newer Digestible Indispensable Amino Acid Score (DIAAS) are two common methods. PDCAAS compares a food's amino acid profile to a standard, while DIAAS is considered more accurate as it measures digestibility in the small intestine. While animal proteins often score highly, some plant proteins like soy also achieve high scores on PDCAAS. DIAAS can sometimes show a clearer distinction, but high scores are still possible with plant sources. Keep in mind that these scores evaluate protein in isolation, not within a varied diet.
How to Ensure Adequate Plant Protein Intake
Meeting your protein needs with plant-based sources is achievable with a little planning. Variety is key, ensuring you consume a range of plant foods with differing amino acid profiles throughout the day.
Complementary Protein Combinations By combining certain plant foods, you can create a complete amino acid profile, especially helpful for those with higher protein needs. Examples include pairing grains (often low in lysine) with legumes (often low in methionine), such as beans and rice, or combining nuts/seeds with legumes or grains.
Boosting Bioavailability and Absorption
Plant protein absorption can be slightly lower than animal protein due to antinutrients. However, this difference is minor for most people with sufficient total protein intake. Methods like cooking, soaking, sprouting, and fermenting can reduce antinutrient levels and improve digestibility.
Best Plant Protein Sources for Athletes
Athletes can meet their increased protein needs by focusing on a variety of protein-rich plant foods, such as soy products, quinoa, legumes, nuts and seeds, and plant-based protein powders.
Comparison of Common Protein Sources
{Link: Colorado State University website https://www.chhs.colostate.edu/krnc/monthly-blog/plant-based-protein-a-simple-guide-to-getting-enough/} provides a comparison of whey, soy, and pea protein, noting their source, completeness, typical protein per serving, amino acid profile, digestibility scores like PDCAAS, allergens, and other nutrients.
The Health and Environmental Benefits of Plant Protein
Choosing plant-based protein offers benefits like improved heart health, increased fiber intake, reduced chronic disease risk, and lower environmental impact. Replacing red and processed meat with plant sources may lower the risk of cardiovascular disease death.
Conclusion
Yes, plant protein counts towards protein intake and is a highly effective way to meet protein needs. A varied diet, including complete plant protein sources like soy and quinoa, and understanding complementary protein combinations, ensures individuals obtain all essential amino acids. Replacing animal protein with plant-based alternatives provides significant health and environmental benefits. Consuming enough calories from a varied, whole-foods diet generally meets protein needs. For further information, consult resources like Harvard Health Publishing.
