Nattō, a fermented soybean dish originating in Japan, is gaining international attention as a potential superfood, with proponents citing its nutritional benefits and possible cardiovascular advantages. Historically significant in Japanese cuisine, nattō's unique characteristics—a strong ammonia-like smell and sticky, slimy texture—make it a polarizing food.
Origins and Preparation
First introduced to Japan around the 8th century, nattō became more widespread by the 12th century and was incorporated into Buddhist vegetarian diets. By the Edo period (1603–1867), it was a common household staple. Traditionally, nattō is made by soaking soybeans, boiling or steaming them, and then fermenting them with Bacillus subtilis var. natto. Historically, this fermentation occurred naturally when soybeans were wrapped in straw; today, it is often produced commercially.
Nutritional Profile and Health Benefits
A 50-gram serving of nattō is low in calories (approximately 110) and sodium, while being rich in protein (around 10 grams) and fiber (5.4 grams). It is also a significant source of micronutrients, including calcium, potassium, iron, manganese, vitamin K2, vitamin B6, and vitamin E. These components are linked to improved bone health, blood circulation, skin elasticity, and oral health.
Nattō's reputation as a nutritional powerhouse is attributed to its high concentration of vitamin K2, specifically the MK-7 form, which is essential for normal blood clotting and maintaining bone health. Additionally, the fermentation process yields nattokinase, an enzyme studied for its potential role in breaking down fibrin, a protein involved in blood clots.
Research suggests that nattō may contribute to cardiovascular health. Studies indicate that nattokinase can support healthy blood circulation and potentially help manage high blood pressure. A long-term study published in the British Medical Journal found that daily consumption of fermented soy foods like nattō was associated with a 10% reduced risk of death from stroke or heart attack among men and women.
The high vitamin K2 content also benefits bone health, with studies showing improvements in bone mineral density and a reduction in fracture risk, particularly in postmenopausal women. The presence of calcium and phosphorus further supports both bone and tooth health, as healthy bone structure is crucial for supporting teeth.
Risks and Considerations
Despite its purported benefits, nattō is not suitable for everyone. Individuals with soy allergies should avoid it. Like other beans, it can cause temporary bloating or gas, especially for those unaccustomed to it.
The primary medical concern involves individuals taking anticoagulant medications, such as warfarin, which are vitamin K antagonists. Due to nattō's very high vitamin K content, people on these medications must consult their doctor before significantly increasing their nattō consumption. Excessive vitamin K can lead to liver problems, breathing difficulties, and complications with blood clotting.
Furthermore, nattō's sticky consistency can make it challenging to clean from dental appliances like braces. Rinsing with water and thorough brushing after consumption can help mitigate this.