Nattō, a traditional Japanese dish of fermented soybeans, is seeing a surge in popularity across Western markets. While praised for its dense nutritional profile, medical professionals warn that the food poses risks for people with kidney issues or those taking blood-thinning medication.
Japan's tripled nattō exports since 2017
The global appetite for fermented foods has evolved beyond the mainstream popularity of Kombucha, Miso, and Matcha.. According to the report, trade data indicates that exports of nattō from Japan have tripled since 2017, driven in part by viral taste-test videos on social media platforms. In the United Kingdom, these fermented beans are now commonly found in Asian supermarkets or via online retailers, typically priced around £5 for 100g.
This trend reflects a broader Western pivot toward "functional foods"—ingredients that provide health benefits beyond basic nutrition. Nattō fits this mold perfectly, offering a polarizing sensory experience—characterized by a sticky texture and an ammonia-like scent—paired with a profile that appeals to the modern health-conscious consumer.
The role of nattokinase and the 10% stroke risk reduction
The health appeal of nattō is rooted in its unique fermentation process, which produces an enzyme called nattokinase. as reported, this enzyme is studied for its ability to break down fibrin, a protein involved in blood clots, which supports overall circulation. A long-term study published in the British Medical Journal in 2020 by the National Cancer Centre in Tokyo found that individuals who consumed fermented soy-based foods like nattō daily saw a 10 per cent reduction in the risk of death from heart attack or stroke.
Beyond cardiovascular health, the dish is a concentrated source of micronutrients. A standard 50g serving contains 110 calories, 10g of protein, and 5.4g of fiber. London-based dentist Dr. Soumaya Zinet notes that nattō is particularly rich in MK-7, a form of vitamin K2 essential for bone maintenance and blood clotting. This high conceentration of K2 is also linked to improved bone mineral density in postmenopausal women and better oral health.
From 8th-century origins to Edo period staples
Nattō is not a modern health fad but a culinary pillar with roots stretching back to the 700s in Japan. by the 1100s, the dish had become popular among warriors and aristocrats, and it later integrated into Buddhist vegetarian cuisine between the 1300s and 1500s. During the Edo period (1603-1867), nattō became a common household staple, frequently appearing in traditional cookbooks.
The traditional production method involved soaking, boiling, and fermenting soybeans with bacteria, often wrapping them in straw to regulate temperature. While modern consumers can buy ready-made containers from convenience stores, the core process remains a testament to ancient Japanese preservation techniques that are now being validated by modern science, such as a 2022 Pakistani study linking the beans to lower blood pressure.
The danger for kidney patients and blood-thinner users
Despite the benefits, nattō is not suitable for everyone. The report highlights significant risks for specific cohorts, particularly those with kidney disease or patients on blood-thinning medications. Because nattō is exceptionally rich in vitamin K2—which plays a critical role in blood clotting—it can potentially interfere with the efficacy of anticoagulant drugs.
However, several details remain unverified in the current reporting. While "experts" are cited regarding the risks to kidney patients, the specific biological mechanism causing this danger is not explained. Additionally, the source does not specify which types of blood thinners are most affected, nor does it provide guidance on safe consumption levels for those with mild health complications.
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