Natto is gaining attention as a modern health food. The Japanese have some of the longest lifespans in the world today, and one of the secrets to their longevity is their consumption of natto.

A study published in the BMJ involving more than 90,000 Japanese participants found that those who regularly ate natto were more likely to live longer, particularly with a lower risk of cardiovascular disease mortality. Compared with those who did not eat natto, men and women who regularly ate it experienced a reduction in cardiovascular disease-related mortality by 24 percent and 21 percent, respectively.

Natto offers numerous health benefits, including:

• Prevention of arteriosclerosis, cerebral infarction, and myocardial infarction
• Anti-aging effects
• Improved memory
• Prevention of osteoporosis
• Prevention of cancer
• Enhanced skin health
• Protection against colds and food poisoning
• Support for digestive health
• Weight loss

Why does natto offer these health benefits, and what precautions should be taken when eating it?

Exceptional Health Food

Natto’s health benefits are closely tied to its unique production process. It is made by steaming soybeans and then wrapping them in straw, which maintains a specific temperature that allows the natural Bacillus natto bacteria in the straw to ferment the beans. The Japanese have been eating natto for more than 1,000 years. Its production method is similar to that of Chinese fermented soybeans (douchi), which are also known for their health benefits.

Natto’s most distinctive feature is its sticky strands, which are made of glutamic acid polymer synthesized by Bacillus natto from soybeans. These strands help protect the stomach lining, facilitate the smooth passage of food and waste through the gut, and promote the elimination of toxins from the body.

Bacillus natto can inhibit the activity of harmful bacteria, while simultaneously promoting the growth of beneficial bacteria.

A study published in Processes in 2020 found that natto contains antimicrobial substances that can inhibit pathogenic bacteria such as Escherichia coli, Helicobacter pylori, and Staphylococcus aureus. Additionally, research has shown that natto possesses antiviral properties, with nattokinase capable of disrupting the spike proteins on the SARS-CoV-2 virus. A study published in Nutrients showed that natto can increase the number of beneficial bacteria in the gut, such as bifidobacteria. Notably, a low count of bifidobacteria in the gut is linked to metabolic disorders such as hypertension and diabetes.

Given all these benefits, natto is indeed an exceptional health food.

6 Major Health Benefits

1. Promotes Digestion

Natto is beneficial for regulating digestive function and can help treat conditions such as dysentery, infections, gastrointestinal inflammation, bloating, indigestion, constipation, and incomplete bowel movements.

2. Prevents Osteoporosis

The vitamin K produced by microorganisms in natto, known as K2, differs from the K1 form found in vegetables. In the human body, vitamin K2 can also be biosynthesized by gut bacteria. In addition to promoting the formation of bone calcium, vitamin K2 helps prevent excessive calcium loss from bones, contributing to the prevention of osteoporosis.

3. Prevents Blood Clots

Nattokinase, produced during the fermentation of natto by Bacillus natto, is a natural substance with potent blood clot-dissolving properties found in the proteins of fermented natto. Animal studies have shown that nattokinase remains active as it passes through the acidic environment of the stomach and the alkaline conditions of the intestines.

Incorporating natto-fermented products, along with natural ingredients such as green onions and garlic, into your diet can effectively prevent blood clot formation, thereby reducing the risk of cerebral infarction, myocardial infarction, and other vascular diseases.

The risk of blood clotting or thrombosis increases during deep sleep from late night to dawn. Therefore, it is recommended to eat natto at dinner. Nattokinase remains in the bloodstream for four to 12 hours after consumption, potentially exerting its thrombolytic effects during this time.

4. Prevents Cancer

A study published in the Japanese Journal of Clinical Oncology suggested that regular consumption of natto may be associated with a lower risk of developing breast cancer in women.

5. Enhances Memory

Natto contains lecithin, which has been shown to enhance short-term memory. This is particularly beneficial for students and people with hectic work schedules.

6. Supports Weight Loss

A study published in the Journal of Functional Foods found that components in natto can promote fat metabolism, which may aid in weight loss.

Optimal Times for Consumption

Natto can be eaten every evening, but it is advisable not to eat it on an empty stomach, as its high fiber content may cause discomfort for those with digestive issues.

Natto is generally most beneficial when eaten in the evening. For most people, about 45 grams (1.59 ounces) per day is sufficient to obtain its health benefits. For those with cardiovascular disease or thrombosis, increasing the intake to about 90 grams (3.17 ounces) daily is recommended for enhanced benefits.

The growth of Bacillus natto and the activity of its enzymes are nearly halted when frozen, so it is best to freeze any unused natto to preserve its quality.

5 Groups of People Who Should Avoid Natto

For healthy individuals, moderate consumption of natto usually poses no side effects. However, people with the following conditions and situations should consult a doctor before eating natto:

• Impaired kidney function: Natto is made from soybeans, which are high in protein and can place an additional burden on the kidneys.
• Gastrointestinal diseases: People with stomach ulcers, dyspepsia, gastritis, or frequent stomach pain should limit their consumption of natto, as it contains a high amount of dietary fiber, which can place a significant burden on the stomach.
• Gout: Natto is a soybean product high in purines, which can exacerbate gout symptoms.
• Blood clotting disorders or taking anticoagulant medication: Natto is not recommended for people with bleeding wounds or those recovering from surgery. Additionally, it may interfere with the effectiveness of anticoagulant medications.
• On antihypertensive medication: Nattokinase can enhance the effects of blood pressure medications, potentially leading to excessively low blood pressure. Therefore, it is advisable to avoid eating natto concurrently with these medications. Individuals taking blood pressure medication should consult their primary care physicians before consumption.

Having learned about the Japanese secret to longevity—natto—consider incorporating it into your diet if you wish to combat aging and prevent blood clots.