Natto is a traditional Japanese food made from soybeans fermented with the bacterium Bacillus subtilis natto. This process transforms the boiled soybeans into a sticky, stringy product known for its pungent aroma and unique flavor. Consumed for centuries in Japan, Natto is recognized for its dense nutritional value. Researchers are exploring how this fermented food may contribute to blood sugar management, given the global rise in diabetes.
Nutritional Profile and Glycemic Impact
Natto possesses a macronutrient composition favorable for blood sugar control. It is rich in plant-based protein, providing 7 to 19 grams per 100-gram portion. This high protein content promotes satiety, helping to reduce overall calorie intake and prevent overeating.
The food is also an excellent source of dietary fiber, offering 5 to 9 grams per serving. Soluble fiber helps slow the absorption of carbohydrates from the digestive tract, preventing rapid spikes in blood glucose after a meal. Consequently, Natto has a low glycemic load, meaning a typical serving size minimally impacts blood sugar levels.
Beyond macronutrients, Natto provides important micronutrients that support metabolic function. It contains significant amounts of magnesium, a mineral involved in the regulation of insulin and glucose metabolism. Manganese, another mineral found abundantly in Natto, also plays a role in enzyme function related to metabolism.
How Natto Supports Glucose and Insulin Regulation
The health benefits of Natto extend beyond its raw nutritional profile due to the fermentation process, which creates new bioactive compounds. The Bacillus subtilis natto bacteria act as powerful probiotics, improving the composition and function of the gut microbiota. A balanced gut microbiome is linked to improved insulin sensitivity throughout the body.
Studies show that consuming Natto as part of a meal can significantly suppress postprandial glucose and insulin responses. This effect is partly attributed to polyglutamic acid, a viscous substance produced during fermentation, which slows carbohydrate digestion. Regular intake of Natto has been observed to improve overall insulin sensitivity in individuals with impaired glucose tolerance.
Natto is a source of the potent enzyme Nattokinase, known for its fibrinolytic activity, meaning it helps to break down blood clots. Since cardiovascular disease is a major comorbidity for people with diabetes, this enzyme offers a protective benefit by improving blood flow and reducing heart-related risks.
The fermented product also exhibits anti-inflammatory and antioxidant properties. These are beneficial because chronic, low-grade inflammation can impair the body’s ability to utilize insulin effectively.
Dietary Guidelines and Safety for Diabetics
While Natto offers numerous metabolic advantages, individuals with diabetes must consider specific safety and consumption guidelines. The most important consideration is Natto’s high concentration of Vitamin K2, a nutrient necessary for blood clotting.
Anyone taking anticoagulant medications, such as warfarin, must consult a physician before consuming Natto. Inconsistent swings in Vitamin K intake can directly counteract the effect of these blood thinners, making the medication less effective. A medical professional can help manage this interaction by adjusting medication dosage or monitoring clotting factors.
Another practical consideration is the sodium content of packaged Natto products. Although the fermented soybeans are typically low in sodium, the included sauce packets often contain high levels of salt and sometimes sugar.
Diabetics, who are often advised to monitor blood pressure and sodium intake, should opt for low-sodium or unsalted varieties and use the included seasonings sparingly. Portion control remains important; a standard single-serving package of Natto is recommended as a moderate addition to a balanced meal plan.