The question "What are the amino acids of biological value?" is incomplete and should be rephrased to "What does biological value (BV) refer to regarding amino acids, and how is it determined?".
Biological Value (BV) is a metric used to assess the quality of protein sources based on how well the body can utilize the amino acids they contain. The higher the BV, the more efficiently the body can use the protein's amino acids for growth and repair. The BV represents the fraction of amino acids absorbed by the gut that is retained by the body. It is essential to note that BV ignores the portion of dietary protein that is not absorbed and appears in the feces.
Understanding Biological Value (BV)
BV is a key concept when discussing protein quality, particularly in the context of nutrition and supplementation. It is a valuable metric in dietary planning for those seeking to optimize their protein intake.
How is BV Determined?
BV is determined through a nitrogen balance study. In this study, the nitrogen intake (from protein) and the nitrogen excretion (in urine and feces) are measured. The amount of nitrogen retained by the body is the indicator of how effectively the body uses the amino acids in the protein.
The formula for calculating BV is:
BV = (Nitrogen Retained / Nitrogen Absorbed) x 100It is important to highlight:
- Absorption: BV focuses on how efficiently the absorbed amino acids are used, not on how much protein is absorbed in the gut.
- Retention: Higher retention translates to a higher BV, which signifies better protein quality.
- Practical Implications: While BV provides a useful theoretical framework, it may not be the only factor determining the best protein source for every individual or situation.
Key Factors that Affect BV
Several factors can influence the BV of a protein:
- Amino Acid Profile: A protein source that contains all essential amino acids in the right proportions for the body's needs will generally have a higher BV.
- Digestibility: How easily the protein is digested and its amino acids are absorbed.
- Individual Needs: The body's need for specific amino acids can vary based on age, activity level, health status, and other factors.
- Food Processing Methods: Heat treatments or other processing techniques can affect protein structure and digestibility, thus potentially affecting BV.
Common Protein Sources and their BV
Different protein sources vary in their BV. Some examples include:
| Protein Source | Biological Value |
|---|---|
| Whey Protein | 104 |
| Egg | 100 |
| Cow's Milk | 91 |
| Fish | 83 |
| Beef | 80 |
| Soybeans | 74 |
| Beans & Grains | Varies, but generally lower than animal protein sources |
Note: These are approximate values and can vary slightly depending on the source and preparation of the food.
Importance of BV
- Muscle Growth and Repair: Proteins with a higher BV are generally more effective at promoting muscle protein synthesis.
- Overall Health: Adequate intake of high BV proteins helps maintain various bodily functions, including enzyme production and hormone regulation.
- Dietary Planning: Understanding BV helps individuals and health professionals in crafting effective nutritional plans.
- Protein Supplementation: BV is one criterion considered when choosing protein supplements.
Considerations beyond BV
While BV is useful, it should not be the sole criterion for evaluating protein quality. Other factors such as:
- Digestibility (Protein Digestibility Corrected Amino Acid Score - PDCAAS)
- Complete vs Incomplete Proteins
- Food Matrix and Bioavailability
are also important.
In summary, biological value (BV) measures how efficiently the absorbed amino acids from a dietary protein are used by the body for protein synthesis. It is a valuable tool for assessing protein quality but should be considered along with other metrics.
