Who Cannot Eat Natto?

Are you a foodie who’s always seeking out new and exotic dishes to try? If so, you may have heard of natto – a traditional Japanese delicacy that’s making waves across the globe. This fermented soybean dish is known for its pungent aroma and distinct texture, and it’s often lauded for its numerous health benefits.

However, before you go ahead and dive into a plate of natto, it’s important to know that not everyone can enjoy this dish without consequences. In fact, there are certain people who cannot eat natto due to various health issues or dietary restrictions.

In this blog post, we’ll take a closer look at the reasons why some individuals should steer clear of natto. From those with soy allergies to people with digestive problems, we’ll explore who cannot eat natto and why.

By gaining a better understanding of who should avoid natto, you’ll be able to make more informed decisions about your diet and steer clear of any unwanted side effects. So if you’re curious about how this popular Japanese dish can impact your health, keep reading.

Who Should Avoid Eating Natto?

Natto, a fermented soybean dish originating from Japan, has become increasingly popular in recent years due to its unique flavor and numerous health benefits. However, not everyone can indulge in the goodness of natto. In this article, we will explore who should avoid eating natto and why.

Firstly, individuals who are allergic to soybeans should steer clear of natto. Soybean allergies are a common food allergy that can cause severe symptoms such as hives, swelling, and difficulty breathing. It is imperative for individuals with soybean allergies to be vigilant while reading food labels and avoid any foods containing soy products.

Secondly, people taking blood-thinning medication such as warfarin should limit their intake of natto or avoid it entirely. The high levels of vitamin K2 present in natto can interfere with the blood-thinning effects of warfarin. It is essential for individuals taking blood-thinning medication to consult their healthcare provider before incorporating natto into their diet.

Thirdly, individuals suffering from gastrointestinal issues such as irritable bowel syndrome (IBS) or inflammatory bowel disease (IBD) may want to avoid natto. The fermentation process used in making natto can produce histamines and other compounds that can irritate the gut lining, resulting in digestive symptoms such as bloating, gas, and diarrhea.

Lastly, pregnant women should exercise caution when consuming natto. Though there is no evidence suggesting that natto is harmful during pregnancy, it contains high levels of vitamin K2 that can interfere with blood clotting. Therefore, pregnant women should consult their healthcare provider before consuming natto or any other foods high in vitamin K2.

Soybean Allergy

Soybean allergies affect both children and adults and are one of the most common food allergies. For those with a soy allergy, consuming natto, the popular fermented soybean dish, may not be an option. This is because natto contains high levels of allergenic proteins that can trigger allergic reactions.

Symptoms of a soy allergy can range from mild to severe and may include hives, itching, swelling, vomiting, diarrhea, and difficulty breathing. In severe cases, anaphylaxis can occur, which is a severe and potentially life-threatening allergic reaction. Therefore, it’s crucial for individuals with a soy allergy to read food labels carefully and avoid any products containing soy or soy derivatives, including tofu, soy milk, edamame, and natto.

If you have a soy allergy and wish to consume natto, some alternative options are available on the market. However, it’s important to note that these alternatives may not have the same texture or taste as traditional soy-based natto. Some companies produce natto made from non-soy ingredients such as black beans or chickpeas.

It’s also essential to inform restaurants or other food establishments about your soy allergy to ensure that your food does not contain any soy products. This will help you avoid unexpected allergic reactions caused by accidental consumption of soy products.

Low Histamine Tolerance

If so, you may have low histamine tolerance. Histamines are organic compounds that trigger the body’s immune response to allergies and infections. However, for those with low histamine tolerance, their bodies cannot break down histamines efficiently.

Who Cannot Eat Natto-2

Foods that are high in histamines, such as natto, a traditional Japanese dish made from fermented soybeans, can cause adverse reactions in people with low histamine tolerance. Symptoms can range from mild discomfort to life-threatening anaphylaxis.

It’s important to note that low histamine tolerance is not the same as a histamine allergy. With an allergy, the immune system overreacts to histamines, but with low histamine tolerance, the body simply cannot break them down effectively. This condition can be caused by various factors such as genetics, medications, and underlying health conditions.

If you suspect you have low histamine tolerance, it’s crucial to avoid consuming high-histamine foods like natto. Consult with a healthcare professional to confirm your suspicions and get advice on how to manage your condition.

Here are some tips for managing low histamine tolerance:

  • Avoid high-histamine foods such as aged cheeses, smoked meats, and fermented foods like sauerkraut and kimchi.
  • Eat fresh foods that are low in histamines such as fresh vegetables and fruits.
  • Consider taking supplements such as DAO (diamine oxidase) enzyme or Vitamin B6 to help break down histamines.
  • Keep a food diary to track your symptoms and identify trigger foods.

Blood-Thinning Medications

Blood-thinning medications, also known as anticoagulants, are a medical marvel for people suffering from conditions like atrial fibrillation, deep vein thrombosis, or pulmonary embolism. These drugs work by preventing blood clots from forming and lowering the risk of life-threatening complications. However, it’s important to understand their limitations and avoid certain foods that can interfere with their effectiveness.

If you’re a fan of natto, a traditional Japanese dish made from fermented soybeans, it’s time to hit the pause button. Natto is high in vitamin K2, which has blood-clotting properties that can counteract the effect of blood thinners. Studies have shown that consuming natto while on blood thinners can increase the risk of bleeding and render the medication ineffective.

But natto isn’t the only food that people taking blood thinners should avoid. Other high-vitamin K2 foods like spinach, kale, collard greens, broccoli, Brussels sprouts, and liver can also interfere with blood thinners’ effectiveness. Therefore, it’s crucial to consult with your healthcare provider before making any significant dietary changes while on these medications.

Your healthcare provider can help you navigate appropriate dietary modifications and monitor the effectiveness of your medication. They may recommend reducing or eliminating high-vitamin K2 foods from your diet or adjusting your medication dosage accordingly.

Pregnant and Nursing Women

As a specialist in this field, I’m here to share some vital information about the consumption of natto during pregnancy and breastfeeding. While natto is a popular dish in Japan renowned for its health benefits, there are some significant considerations to bear in mind before adding it to your diet.

Firstly, natto contains high levels of vitamin K2, which can interfere with blood-thinning medications that are often prescribed during pregnancy and breastfeeding. If you’re taking any blood-thinning medication, it’s best to limit your consumption of natto and other vitamin K2-rich foods like broccoli, spinach, kale, and liver. However, always consult with your healthcare provider before making any changes to your medication regimen.

In addition to potential medication interactions, some pregnant women may experience gastrointestinal discomfort when consuming natto due to its strong smell and taste. This can lead to nausea, vomiting, and other digestive issues that could potentially harm both the mother and developing baby. So if you’re not accustomed to the taste or smell of natto, it may be best to avoid it altogether.

For nursing mothers, it’s crucial to note that certain flavors or seasonings added to natto may cause an allergic reaction in some infants who are sensitive to soy products. Therefore, it’s essential to pay close attention to your baby’s reactions after consuming natto and seek advice from your healthcare professional if you observe any adverse effects.

Overall, while natto is generally considered safe for consumption by pregnant and nursing women, it’s important to exercise caution and moderation to ensure that both mother and baby remain healthy. Here are some additional tips to keep in mind:

  • Stick with reputable brands of natto that have been prepared safely.
  • Avoid eating raw or undercooked natto as it may contain harmful bacteria.
  • Incorporate a diverse range of nutrient-dense foods into your diet to support optimal health for both you and your baby.

Symptoms of Soybean Allergy

Soy products are a common ingredient in many foods, but for some people, they can cause a serious allergic reaction. Soybean allergy is one of the most prevalent food allergies and can affect people of all ages. It’s essential to know the symptoms of soybean allergy to identify it quickly and seek medical attention if necessary.

The symptoms of soybean allergy can vary in severity from mild to life-threatening. They can occur within minutes or even hours after consuming soy products. Some of the most common symptoms include hives, itching, swelling of the lips, tongue, or throat, coughing, wheezing, difficulty breathing, abdominal pain, diarrhea, vomiting, and anaphylaxis.

Anaphylaxis is a severe allergic reaction that can cause a drop in blood pressure, breathing difficulties, loss of consciousness, and even death. Not everyone experiences all these symptoms; some may only have mild reactions like itching or hives. However, some people may experience more severe symptoms like anaphylaxis.

If you or someone you know experiences any symptoms after consuming soy products, seek medical attention immediately. An allergist can perform a skin prick test or blood test to determine whether you have a soybean allergy. If diagnosed with this allergy, it’s crucial to avoid all soy products and carry an epinephrine auto-injector at all times in case of an emergency.

In summary, soybean allergy is a serious condition that can cause mild to severe symptoms and life-threatening reactions. Here are some key takeaways:

  • Soybean allergy can affect people of all ages.
  • Symptoms range from mild to severe and can occur within minutes or hours after consuming soy products.
  • Anaphylaxis is a severe allergic reaction that requires immediate medical attention.
  • If diagnosed with a soybean allergy, avoid all soy products and carry an epinephrine auto-injector at all times.

Effects of High Histamine Levels in Natto

This traditional Japanese food is packed with nutrients and has a reputation for its health benefits. However, it’s important to be aware of the potential risks associated with consuming natto, particularly in relation to high histamine levels.

Histamine is a naturally occurring chemical that plays a crucial role in regulating various bodily functions, including the immune system and digestion. In most cases, the body can break down histamine without issue. However, excessive histamine levels can lead to histamine intolerance, which occurs when the body cannot break down excess histamine. This can result in a range of symptoms such as headaches, hives, nausea, and digestive issues.

Unfortunately, natto is known to be particularly high in histamine, which means individuals who are prone to histamine intolerance should exercise caution when consuming this food. This includes individuals with mast cell disorders or allergies, as well as those taking certain medications that interfere with histamine breakdown.

Interaction between Vitamin K2 and Blood-Thinning Medications

While natto is an excellent source of vitamin K2, individuals who take blood-thinning medications such as warfarin or Coumadin should be cautious about consuming it. Vitamin K is essential for blood clotting, which can interfere with the effectiveness of these medications.

Vitamin K2 is a fat-soluble vitamin that plays a crucial role in bone and cardiovascular health. It activates proteins that help to transport calcium throughout the body, ensuring that it is deposited in the bones where it belongs and not in the arteries where it can cause damage. However, its interaction with blood-thinning medications is complex and depends on the type and dosage of medication.

Therefore, individuals who are taking blood-thinning medications should consult their healthcare provider before adding natto to their diet. The healthcare provider will advise on the appropriate intake of vitamin K2 to maintain good cardiovascular and bone health while ensuring that the medication’s effectiveness remains intact.

However, not everyone can safely consume vitamin KPeople with bleeding disorders or those undergoing surgery should avoid consuming natto or any other high vitamin K foods. Vitamin K can increase the risk of bleeding and interfere with blood clotting during surgery or in individuals with a history of bleeding disorders.


In summary, natto is a beloved Japanese dish that has captured the hearts and taste buds of people around the world. However, it’s important to note that not everyone can indulge in this fermented soybean delicacy without consequences.

For instance, individuals with soy allergies should steer clear of natto as it can cause severe symptoms such as hives, swelling, and difficulty breathing. Meanwhile, those with gastrointestinal issues like IBS or IBD may experience discomfort after consuming natto due to its high fiber content.

Furthermore, people who are on blood-thinning medication like warfarin should be cautious when eating natto as it contains high levels of vitamin K2 that can interfere with the medication’s effectiveness. Similarly, pregnant or nursing women should consult their healthcare provider before incorporating natto into their diet.

It’s also worth noting that low histamine tolerance can lead to adverse reactions when consuming high-histamine foods like natto. Therefore, individuals who experience such symptoms should avoid this dish altogether.

By understanding who cannot eat natto and why, people can make informed decisions about their diet and avoid any unwanted side effects. If you have concerns about consuming natto or any other food products, it’s crucial to consult with a healthcare professional.