Natto, a traditional Japanese food, is created by fermenting soybeans with the bacterium Bacillus subtilis var. natto. For individuals who are pregnant, the question of consuming natto often centers on balancing its considerable nutritional benefits with any potential food safety risks. Natto is generally considered safe and beneficial for maternal and fetal health, provided specific consumption guidelines are followed.
Key Nutritional Components Natto Offers During Pregnancy
The fermentation of soybeans transforms natto into a powerhouse of nutrients that directly support the physiological demands of pregnancy. It provides a source of high-quality, plant-based protein, with a 100-gram serving containing approximately 19 grams of protein, supporting fetal growth and maternal tissue repair. The process also increases the availability of dietary fiber, offering about 5.4 grams per 100-gram serving, which can aid in digestion and help alleviate common issues such as constipation.
Natto is also a valuable source of B vitamins, including folate, which is particularly significant during the first trimester. Adequate folate intake is strongly associated with a reduced risk of neural tube defects in the developing fetus. Beyond vitamins, natto contains a significant amount of iron, essential for preventing maternal anemia, and calcium, which supports the mineralization of the fetal skeleton while maintaining the mother’s bone density.
The food’s fermentation by Bacillus subtilis means natto is a natural source of probiotics, the beneficial bacteria that contribute to a healthy gut microbiome. A balanced gut environment is important for nutrient absorption and maternal immune function throughout pregnancy. This fermentation also produces an abundance of Vitamin K2, specifically menaquinone-7 (MK-7), a form that is highly bioavailable. Vitamin K2 plays a role in regulating calcium utilization in the body, which is important for both maternal and fetal bone health.
Safety Precautions and Potential Risks
While natto offers many nutritional advantages, pregnant individuals should be aware of certain considerations, particularly regarding its high concentration of Vitamin K2. The large amount of Vitamin K2 in natto can interfere with the effectiveness of certain prescription medications, such as anticoagulant or blood-thinning drugs like Warfarin. Vitamin K promotes blood clotting, and a sudden, large increase in its intake can counteract the medication designed to prevent clotting.
Individuals taking any form of anticoagulant medication must consult with their healthcare provider before introducing natto into their diet to manage this potential drug interaction. The high concentration of Vitamin K2 means that even small, regular portions can affect blood clotting parameters.
Another consideration is the sodium content, which can vary depending on the preparation and accompanying sauces. While plain natto may not be excessively high in sodium, the seasoning packets often included in commercial preparations can increase the overall intake. Those monitoring their blood pressure or managing pregnancy-related hypertension should be mindful of the added sodium from these condiments.
As a fermented food, natto is generally safe, but proper food handling is always a concern during pregnancy due to an altered immune response. The risk of contamination with foodborne bacteria like Listeria is present with any prepared food, emphasizing the need for careful sourcing and storage.
Practical Guidelines for Consumption
For pregnant individuals who have confirmed no contraindications with their healthcare provider, moderation is the best approach when first incorporating natto into the diet. Start with a small serving size, such as half a cup, a few times a week, to allow the digestive system to adjust to the high fiber and probiotic content. Monitoring the body’s reaction is helpful, especially in the early stages.
A popular traditional method of eating natto involves mixing it with a raw egg yolk, which must be avoided during pregnancy. Raw or undercooked eggs carry a risk of Salmonella contamination, which can lead to severe illness. Instead, mix natto with fully cooked accompaniments, such as cooked rice, chopped scallions, or cooked vegetables.
Always store natto in the refrigerator and consume it well before the expiration date. When purchasing, look for commercially packaged natto from trusted grocery stores, which ensures the product has been processed under controlled, hygienic conditions.