Understanding Complete vs. Incomplete Proteins
Protein is a crucial macronutrient composed of smaller units called amino acids. The human body can produce 11 of the 20 common amino acids, known as non-essential amino acids. However, nine of these amino acids, called essential amino acids (EAAs), cannot be synthesized by the body and must be obtained from dietary sources.
A 'complete protein' is any food source that contains all nine of these essential amino acids in sufficient quantities. Animal products like meat, eggs, and dairy are classic examples of complete proteins. In contrast, an 'incomplete protein' is one that is low in or missing one or more of these essential amino acids. Many plant-based proteins, like those found in beans or grains, are incomplete on their own but can be combined to form a complete protein profile.
The Protein Digestibility Corrected Amino Acid Score (PDCAAS)
To standardize how protein quality is measured for nutrition labels, regulatory bodies like the FDA use scoring systems such as the Protein Digestibility Corrected Amino Acid Score (PDCAAS). This system evaluates a protein based on its amino acid profile and digestibility. A food receives a score, with 1.0 being the highest possible. If a protein source has a limiting amino acid—one that is present in insufficient quantity—its score is lowered. The "not a good source" label on Swanson's bone broth is a direct consequence of its score under this system.
The Collagen Connection in Bone Broth
The protein found in bone broth is primarily derived from collagen, a structural protein extracted from the simmering of animal bones, ligaments, and tendons. While collagen is a protein, its amino acid composition is not complete. It is especially rich in amino acids like glycine, proline, and hydroxyproline, which are beneficial for connective tissues. However, it is deficient in the essential amino acid tryptophan.
Amino Acid Profile of Collagen:
- High in glycine, proline, and hydroxyproline.
- Lacking the essential amino acid tryptophan.
- Lower in other essential amino acids like methionine and lysine.
Because of this imbalance, the protein in bone broth does not meet the criteria for a "good source" of protein according to nutritional standards. This is not a slight against the product but rather an accurate reflection of its amino acid profile, dictated by food labeling regulations.
Deciphering the Swanson Nutrition Label
When you read the nutrition facts on a Swanson chicken or beef bone broth carton, you will see a specific note: "Not a good source of protein". This is followed by the declared protein content, which can be 8 grams or more per serving. This is not a contradiction. The protein is present, but it's the quality* of the protein, not just the quantity, that is being labeled. The label is an honest disclosure to consumers that they cannot rely on the broth alone to meet their complete essential amino acid needs. Instead, the broth should be considered a nutritional supplement to a balanced diet.
Bone Broth vs. Complete Protein Sources
To better understand the nutritional difference, consider this comparison between Swanson bone broth and a complete protein source like whey protein.
| Feature | Swanson Bone Broth | Whey Protein | Soy Protein |
|---|---|---|---|
| Protein Source | Primarily collagen from bones | Whey, a milk byproduct | Soybeans |
| Amino Acid Profile | Incomplete, low in tryptophan | Complete, contains all EAAs | Complete, contains all EAAs |
| Primary Benefit | Supports joint health, gut lining, skin | Excellent for muscle building and repair | Versatile plant-based complete protein |
| Labeling | Labeled as "not a good source of protein" | Labeled as a protein source | Labeled as a complete protein source |
| Best Used As | A supplement or nutrient-dense cooking liquid | A post-workout shake or supplement | A primary protein source for meals |
The Role of Bone Broth in a Balanced Diet
Despite its "incomplete" protein status, bone broth still offers distinct health advantages. Its high concentration of collagen-related amino acids supports the health of connective tissues, skin, and the gut lining. It is a nourishing addition to meals, providing key nutrients and a savory flavor. For a well-rounded diet, it is important to include a variety of food sources to ensure you get all the essential amino acids you need. Combining bone broth with sources like meat, legumes, or whole grains throughout the day is a sound nutritional strategy.
What This Means for Your Health Goals
Your decision to consume bone broth depends on your personal health objectives. If your primary goal is to build muscle mass, a complete protein source like whey is likely more efficient. However, if you are focused on supporting joint health, skin elasticity, or gut integrity, bone broth's unique amino acid profile makes it a valuable dietary component. You can always use both supplements to achieve different benefits. The key is to recognize that not all proteins serve the same purpose and to understand what the labels are communicating. Bone broth is best viewed as a supplement for specific nutritional benefits rather than as a primary source for overall protein intake. For more information on protein in your diet, see this excellent resource from Harvard Health Publishing: Protein - The Nutrition Source.
Conclusion
In summary, the reason Swanson bone broth carries the label stating it is not a good source of protein is its incomplete amino acid profile, specifically its low level of tryptophan. The protein it contains is primarily from collagen, which is excellent for connective tissue health but does not contain all nine essential amino acids in the right proportions. This label is not an indication of a lack of protein but rather a declaration of its specific nutritional limitations, based on regulatory standards. By consuming a varied diet, you can reap the unique benefits of bone broth while still meeting your daily complete protein requirements.
