What is biological value (BV)?
Protein is a crucial macronutrient composed of amino acids, which are often called the building blocks of life. The human body requires 20 different amino acids to function, nine of which are considered "essential" because they cannot be produced by the body and must be obtained from food. Biological value (BV) is a metric that measures how efficiently the body absorbs and utilizes the protein from a food source. A protein source with a high BV is one that contains a complete and balanced profile of all nine essential amino acids. This means that the protein is well-suited for building and repairing body tissues, hormones, and enzymes.
The concept of completeness
Proteins can be categorized into two groups based on their amino acid profile:
- Complete Proteins: These foods contain all nine essential amino acids in sufficient quantities. Animal-based products are typically considered complete proteins due to their similarity to human protein composition.
- Incomplete Proteins: These foods are low in or missing one or more of the essential amino acids. Many plant-based proteins fall into this category, with legumes often being low in methionine and grains low in lysine.
Why is high biological value good?
Consuming proteins with a high BV is beneficial for several reasons, directly impacting everything from muscle development to immune health.
- Optimal Muscle Repair and Growth: For athletes and individuals engaged in strength training, high BV proteins provide the full spectrum of essential amino acids needed to efficiently repair muscle fibers and build lean muscle mass post-workout.
- Efficient Tissue Synthesis: Since high BV proteins contain all the necessary building blocks, the body can use them more readily for synthesizing new proteins for various bodily functions. This efficiency is particularly important during periods of rapid growth, pregnancy, and recovery from illness or injury.
- High Digestibility: Protein sources with a high BV are also typically highly digestible, meaning the body can break them down and absorb the amino acids with greater ease. This leads to less waste and better nutrient uptake.
High biological value vs. low biological value protein
To illustrate the differences, consider the table comparing the characteristics of high BV and low BV protein sources.
| Feature | High Biological Value Protein | Low Biological Value Protein |
|---|---|---|
| Amino Acid Profile | Contains all nine essential amino acids. | Lacks or is low in one or more essential amino acids. |
| Body Utilization | Very efficient for building and repairing body tissues. | Less efficient when consumed alone, as the limiting amino acid creates a bottleneck. |
| Common Sources | Meat, poultry, fish, eggs, dairy, and soy. | Most legumes, grains, nuts, and seeds (when consumed individually). |
| Digestibility | Generally highly digestible. | Can have lower digestibility due to factors like fiber and antinutrients. |
| Strategy for Optimal Intake | Consumed directly to provide all essential amino acids. | Combined with other protein sources to create a complete amino acid profile. |
How to get high biological value protein from any diet
While animal products are the most straightforward source of high BV protein, plant-based eaters can easily achieve the same quality through strategic food combinations. The key is understanding how different foods complement each other.
Complementary protein examples
- Grains and Legumes: Combining a legume (like beans or lentils) with a grain (like rice or wheat) creates a complete protein profile. For instance, rice and beans or lentil soup with whole-grain bread are classic complementary meals.
- Legumes with Nuts/Seeds: Pairing legumes with nuts or seeds can also create a complete protein. An example is hummus (made from chickpeas) served with sesame seeds or tahini.
- Grains with Dairy/Eggs (for vegetarians): Adding eggs or dairy to grains, like scrambled eggs with toast or yogurt with granola, ensures all essential amino acids are present in the meal.
Beyond biological value: Modern perspectives
While BV is a useful measure, newer metrics have emerged to provide a more comprehensive view of protein quality. The Digestible Indispensable Amino Acid Score (DIAAS) is now recommended by the Food and Agriculture Organization (FAO) as a superior method. DIAAS factors in the digestibility of individual amino acids, offering a more accurate reflection of how much of each essential amino acid is truly absorbed by the body. It accounts for the impact of food matrix effects, like fiber, which can affect digestibility. A varied diet, rich in different plant-based and/or animal protein sources, remains the best approach to ensuring a sufficient intake of all essential amino acids for most people. The overall nutritional 'package'—including fats, fiber, vitamins, and minerals—is also a critical consideration when choosing protein sources.
Conclusion
In summary, a high biological value is indeed good, as it signifies a protein source that provides all the essential amino acids your body needs to function optimally. High BV proteins are efficiently used for everything from muscle synthesis to immune function and tissue repair. While animal products are known for their high BV, vegetarians and vegans can effectively create complete proteins by combining complementary plant-based sources throughout the day, eliminating the need to combine them at every single meal. By understanding biological value, you can make informed dietary choices to ensure your body receives the highest quality protein possible, supporting robust health and wellness.
Best practices for consuming high-quality protein
- Prioritize Variety: Aim to consume a wide range of protein sources to maximize the spectrum of amino acids, vitamins, and minerals you receive.
- Combine Plant Proteins: For plant-based diets, intentionally pair different protein sources like legumes and grains to create complementary protein meals.
- Choose Lean Animal Sources: If consuming animal products, opt for lean meats, fish, eggs, and low-fat dairy to get high BV protein without excessive saturated fat.
- Read Labels: Be mindful of added sugars and unhealthy fats that can be present in some protein products or supplements.
- Timing is Key: Consume protein after exercise to aid in muscle repair and growth, especially high BV proteins like whey.
- Consult a Professional: A registered dietitian can provide personalized guidance to ensure your protein intake meets your specific health goals and needs.
