Natto: Nutrition Facts and Health Benefits

Natto, the sticky, pungent, and stringy fermented soybean food from Japan, has long intrigued both culinary adventurers and health enthusiasts. But beyond its unique texture and acquired taste lies a nutritional powerhouse packed with bioactive compounds. Let's dive deep into what makes natto so special, both in terms of nutrition and its scientifically-backed health benefits.

Natto Nutrition Facts

Natto is not just another soy product—it’s a living, fermented food with a distinctive nutritional profile. Its fermentation process with Bacillus subtilis transforms the humble soybean into a source of rare nutrients and beneficial bioactives that set natto apart from tofu, miso, or tempeh.

Table 1: Core Nutritional Features of Natto

Protein and Amino Acids

Natto is an excellent source of plant-based protein, making it a valuable staple for vegetarians and vegans. Its fermentation does not diminish its amino acid profile; instead, certain peptides produced during fermentation may even have health-promoting effects 2.

Vitamin K2: Menaquinone-7

One of natto’s nutritional superpowers is its extraordinarily high content of menaquinone-7 (MK-7), a long-chain form of vitamin K2. In fact, natto contains up to 100 times more MK-7 than most cheeses or other fermented foods, providing upwards of 380 µg per serving (one pack, roughly 50g) 2 6. This far surpasses what’s found in other soy products or animal-based foods.

Nattokinase

Nattokinase is a unique enzyme produced only during natto fermentation by Bacillus subtilis. This enzyme has potent fibrinolytic (clot-dissolving) activity, making it a key reason behind many of natto’s cardiovascular benefits 2 5 7.

Isoflavones

Soy is renowned for its isoflavones, which are phytoestrogens with a range of health effects. In natto, fermentation increases the bioavailability of these compounds, meaning your body can absorb and use them more effectively than from raw soybeans or even tofu 2 3.

γ-Polyglutamic Acid (γ-PGA)

This sticky, viscous substance gives natto its characteristic stringiness. γ-PGA is a type of amino acid polymer that helps enhance the absorption of minerals, such as calcium, and may play a role in bone health 2.

Branched-Chain Fatty Acids (BCFA)

Natto is one of the few plant-based foods with significant levels of branched-chain fatty acids, typically found in dairy and beef. These BCFA types (C14–C17 iso- and anteiso-BCFA) are present in variable amounts, sometimes reaching levels comparable to those found in Western diets heavy in dairy 1.

Natto Health Benefits

The unique combination of nutrients and bioactives in natto doesn’t just look good on a label—it translates into real, measurable health benefits. Scientific studies have linked natto consumption to improved bone health, cardiovascular protection, antioxidant effects, and more.

Table 2: Major Health Benefits of Natto

Bone Health: The Vitamin K2 Effect

Perhaps the most robust evidence for natto’s health benefits comes from studies on bone health. Natto’s extraordinarily high vitamin K2 content is the cornerstone here.

• Postmenopausal Women: Large-scale observational studies in Japan have shown that women who eat natto regularly have higher bone mineral density (BMD) and experience less bone loss, especially in the hip and forearm, compared to those who eat little or no natto 3. This is not observed with tofu or other soy foods, highlighting natto’s unique role.
• Elderly Men: Similar findings have been reported among older Japanese men. The association between natto intake and higher BMD appears to be mediated almost entirely by its vitamin K2 content, as vitamin K is crucial for activating osteocalcin, a protein vital for bone mineralization 6.

Key Takeaway: Regular natto intake may help prevent osteoporosis and fractures, especially in populations at risk of bone loss 3 6.

Cardiovascular Health: Heart and Vessel Protection

Natto’s heart-protective properties stem from several synergistic factors:

• Nattokinase: This enzyme acts as a natural blood thinner, breaking down fibrin and potentially reducing the risk of blood clots, which can lead to heart attacks and strokes 5 7.
• Reduced CVD Mortality: Large population studies reveal that high natto intake correlates with a significant reduction in deaths from cardiovascular disease and stroke, even after accounting for other dietary and lifestyle factors 5.
• Lipid-Lowering Effects: Natto fractions have been shown to reduce blood triglycerides and total cholesterol in animal models, suggesting a favorable impact on lipid metabolism 4.
• Antihypertensive and Antiatherosclerotic Effects: Nattokinase also appears to help lower blood pressure and prevent the buildup of arterial plaque 7.

Key Takeaway: Natto may help protect the heart and blood vessels through multiple pathways, making it a unique food for cardiovascular wellness 5 7.

Antioxidant and Anti-Inflammatory Actions

Natto isn’t just about vitamins and enzymes—it also contains antioxidant compounds that can inhibit the oxidation of LDL cholesterol, a key step in the development of atherosclerosis.

• Animal Studies: Rats fed natto fractions showed reduced lipid peroxidation in the liver and arteries, and their LDL cholesterol was less prone to harmful oxidation 4.
• Human Implications: While further studies are needed, these findings suggest natto could help slow the development of cardiovascular disease by reducing oxidative damage 4.

Enhanced Isoflavone Bioavailability

Fermentation not only preserves but enhances the health effects of soy isoflavones. In natto, these phytoestrogens become more bioavailable, which may contribute to hormone balance, bone health, and possibly even reduced cancer risk, although more research is needed in humans 2 3.

Uniqueness Compared to Other Soy Foods

Not all soy products are created equal. While tofu, miso, and tempeh are healthy in their own right, only natto delivers high levels of vitamin K2 (as MK-7) and nattokinase. Studies consistently show that the health effects linked to natto are not found in consumers of other soy-based foods 3 5 6.

Conclusion

Natto stands out as a nutritional powerhouse and a functional food, thanks to its unique fermentation process and the resulting abundance of rare nutrients and bioactive compounds. Here’s a quick recap of why natto deserves a spot in your diet:

• Rich source of high-quality plant protein and bioactive peptides 2
• World’s highest food source of vitamin K2 (menaquinone-7), essential for bone health 2 3 6
• Contains nattokinase, a unique enzyme with potent heart-protective effects 2 5 7
• Delivers highly bioavailable isoflavones and γ-polyglutamic acid for added benefits 2 3
• Linked to reduced risk of bone loss, osteoporosis, cardiovascular disease, and stroke in population studies 3 5 6
• Provides antioxidant and lipid-lowering actions, supporting overall metabolic health 4 7
• Offers branched-chain fatty acids typically found in animal foods 1

While natto’s flavor and texture may be an acquired taste, its science-backed health benefits make it a food worth exploring for anyone seeking optimal nutrition and well-being.