Natto, a traditional Japanese food, is created by fermenting soybeans with Bacillus subtilis bacteria. This fermentation process gives natto its distinct sticky, stringy texture and pungent aroma, characteristics that make it an acquired taste for many outside Japan. Despite its unique qualities, natto is gaining global recognition for its health properties.
Natto’s Nutritional Composition
Natto provides a range of beneficial nutrients. A 100-gram portion offers around 19.4 grams of protein, making it a plant-based source. It also contains approximately 5.4 grams of fiber, which contributes to digestive health. The fermentation process enhances digestibility and nutrient absorption, introducing probiotics that support gut health.
Natto is particularly rich in Vitamin K2 (menaquinone-7), with 100 grams providing about 23.1 micrograms, which is involved in bone metabolism and calcium regulation. It also supplies various B vitamins, including B6, folate, pantothenic acid, thiamin, and riboflavin, which play roles in energy production and cellular function. Moreover, it contains minerals such as iron (8.6 mg), manganese (1.53 mg), copper (0.667 mg), calcium (217 mg), magnesium (115 mg), potassium (729 mg), zinc (3.03 mg), and selenium (8.8 mcg) per 100 grams.
Daily Consumption Guidelines
While there isn’t a single strict universal guideline for daily natto consumption, common practices in Japan and nutritional insights offer practical recommendations. A typical serving in Japan is one small pack, weighing between 40 to 50 grams. Many sources suggest that one to two such packs per day is a moderate and beneficial amount for regular intake.
This quantity provides a meaningful dose of beneficial compounds, such as nattokinase. The Japan Nattokinase Association suggests a daily intake of 2000 FU (fibrinolytic units) of nattokinase, which is typically found in one to two 50-gram packs of natto. For individuals new to natto, starting with smaller portions, perhaps a teaspoon to a tablespoon, can help the palate adjust to its unique taste and texture and gradually introduce its components to the digestive system. Consistency in consumption, even in smaller amounts, may be more impactful than consuming large quantities infrequently.
Specific Health Considerations
While natto offers nutritional advantages, certain considerations are important for some individuals. Natto contains a high amount of Vitamin K2, which plays a role in blood clotting. Individuals taking blood-thinning medications, such as warfarin, should consult a healthcare provider before regular consumption, as the Vitamin K2 content could interfere with their medication’s effectiveness.
For some, natto may cause digestive issues like bloating or gas, especially when first introduced into the diet, due to its high fiber and probiotic content. As natto is made from soybeans, individuals with a soy allergy should avoid it. Additionally, soybeans contain goitrogens, which may affect thyroid function in individuals with pre-existing thyroid conditions. Always consult a healthcare professional for personalized advice, particularly if you have existing medical conditions or concerns.