Natto: A Nutritional Overview for Bone Health
Natto, the traditional Japanese fermented soybean dish, is often lauded as a superfood for its extensive nutritional benefits, which include its surprising role in promoting bone health. While the sticky texture and pungent aroma are an acquired taste for some, its rich nutrient profile makes it a compelling addition to any diet. Unfermented soybeans contain calcium, but the fermentation process with Bacillus subtilis natto bacteria elevates the nutritional value of the final product.
The Role of Calcium and Vitamin K2 in Bone Metabolism
Calcium is a fundamental mineral for building and maintaining strong bones, but it does not work in isolation. For calcium to be effectively integrated into bone tissue and kept out of soft tissues like arteries, it requires the assistance of other nutrients, primarily vitamin K2. Natto is a powerhouse of both.
The unique fermentation process of natto produces exceptional amounts of vitamin K2, specifically menaquinone-7 (MK-7), which is highly bioavailable. This nutrient activates two crucial proteins: osteocalcin and matrix Gla protein. Osteocalcin helps to bind calcium to the bone matrix, while matrix Gla protein prevents calcium from depositing in arteries and other soft tissues, preventing arterial stiffness. This synergistic relationship makes natto particularly effective for promoting overall skeletal and cardiovascular health.
Enhancing Calcium Absorption from Natto
While natto contains a significant amount of calcium, maximizing its absorption is key to reaping the full benefits. The fermentation process is pivotal in this regard. The action of Bacillus subtilis bacteria helps to break down proteins and anti-nutrients present in the raw soybeans, making the minerals easier for the body to absorb. Furthermore, studies indicate that the mucilage containing poly-gamma-glutamic acid (γ-PGA) produced during fermentation can increase calcium solubility in the small intestine, further boosting absorption.
To further enhance absorption, natto can be paired with foods rich in other supporting nutrients. Vitamin D, for example, is essential for calcium absorption in the gut. While natto is not a major source of vitamin D, combining it with foods like fatty fish or spending time in the sun can create a more comprehensive bone health strategy.
Natto Calcium vs. Other Fermented Foods
When comparing natto to other popular fermented foods, its unique nutritional profile, especially regarding calcium regulation, stands out. This table highlights some key differences in nutrient content related to bone health.
| Feature | Natto | Miso | Tempeh |
|---|---|---|---|
| Base Ingredient | Fermented Soybeans | Fermented Soybean Paste | Fermented Soybean Cake |
| Vitamin K2 (MK-7) | Exceptionally high content (richest plant source) | Very low to negligible | Low to moderate |
| Calcium Content | Significant source (approx. 217 mg per 100g) | Contains some calcium, but often high in sodium | Good source, similar to unfermented soybeans |
| Probiotics | Rich source of Bacillus subtilis natto | Contains various beneficial bacteria | Rich in beneficial bacteria like Rhizopus |
| Bioavailability | High absorption due to γ-PGA and fermentation | Absorption may be limited by high sodium | Good source of nutrients, but lacks natto's unique benefits |
This comparison demonstrates why natto is particularly prized for bone health. While miso and tempeh are healthy fermented soy products, they do not offer the same high level of vitamin K2 and unique compounds like γ-PGA that optimize calcium utilization.
Conclusion: Natto as a Complete Bone Health Package
In conclusion, the answer to "Is there calcium in natto?" is a definitive yes, but the real story lies in its complete nutritional package. Natto provides not only a good source of dietary calcium but, more importantly, a remarkable amount of vitamin K2 and other compounds that ensure this calcium is effectively utilized by the body. By promoting proper calcium deposition in bones and preventing its accumulation in arteries, natto offers a comprehensive approach to supporting both skeletal strength and cardiovascular wellness. For those seeking to boost their bone health through diet, incorporating this traditional Japanese food is a highly effective strategy.
Visit the National Institutes of Health for more information on calcium and health.
