By Tiphanie Tueni, Naturopath in Paris 16, Passy - La Muette
Natto is a delicious nutty flavored superfood that has been eaten in Asia for over 2 000 years. It's made of soybeans that have been fermented with the bacteria Baxillus subtilis var. natto. According to a study published in 2017, natto is a factor of longevity of the Japanese population and arguably the healthiest way to eat soybeans.
One of the best plant based sources of protein and nutrients
Natto reigns supreme among plant based sources of protein : it provides 18 grams of protein for every 100 grams serving. Its fiber content make its protein easier to digest and more bioavailable than its animal based counterparts.
It’s also rich in vitamins and minerals such as manganese, iron, copper, vitamins B6, C & K1, magnesium, calcium, potassium, zinc, selenium, folate, pantothenic acid and antioxydants…
Why is natto traditionally fermented?
Through fermentation, natto contains less anti nutrients which can make legumes difficult to digest. Among the anti nutrients are lectins, phytates and oxalates. These are currently fueling debates and people have come up with lectin or oxalate free diets. However to eat natto wisely, one has to look at how it has traditionally been eaten for centuries: fermented. Indeed, the fermentation process greatly reduces anti nutrients!
It has a powerful enzyme called nattokinase
One of the key ingredients of natto was discovered by Dr Hiroyuki Sumi in 1987: the nattokinase enzyme. It’s a very powerful enzyme that has fibrinolytic, hypotensive, anti-atherosclerotic, anti-platelet, lipid-lowering and neuroprotective properties, amongst others.
Thanks to its fluidizing and proteolytic properties, nattokinase protects the cardiovascular system by helping to dissolve blood clots.
It's rich in probiotics
Natto is excellent for the gut microbiome : it is one of the richest fermented foods in probiotics and the only one containing the Bacillus subtilis species which promotes the development of other beneficial bacteria.
How to eat it?
In the land of the rising sun, it is traditionally eaten for breakfast as a topping on rice, with shoyu (soy sauce) and karashi (Japanese mustard). Dried bonito flakes, chives, green onions, shiso leaves or raw egg yolk may also be added.
Natto reigns supreme among plant based sources of protein
To get the most out of it, one needs to look at how it’s traditionally eaten - and not ingest large amounts on the pretext that it’s a health food! Thus Japanese people eat it in reasonable quantities, for example two to three teaspoons on a bowl of rice.
Its sweet hazelnut flavour is welcome in a salad or a plate of steamed vegetables. It can also be enjoyed in a delicious bowl of udon (natto-udon).
Where does one buy natto?
Natto can be found in Asian grocery stores. Prefer organic varieties and be creative when you eat it, natto is very versatile!
Do isoflavones (phytoestrogens) pose a risk?
The question of phyto-oestrogens in soy products is not yet clear-cut - indeed, their effects vary depending on several parameters such as age and hormonal impregnation, among others.
However, scientists agree that infants under six months of age and postmenopausal women with a family history of cancer should not be recommended. They recommend the consumption of fermented soya rather than industrial or non-fermented varieties of soya (yoghurt type, soya milk, etc.).
Finally, as previously mentioned, one can easily be tempted to be over-zealous when it comes to healthy foods. However as with everything else, moderation is the rule!
Dietary soy and natto intake and cardiovascular disease mortality in Japanese adults: the Takayama study. Nagata C, Wada K, Tamura T, Konishi K, Goto Y, Koda S, Kawachi T, Tsuji M, Nakamura K. Am J Clin Nutr. 2017 Feb; 105(2):426-431.
Sur le natto, protecteur cardio-vasculaire : Chen H, McGowan EM, Ren N, et al. Nattokinase: A Promising Alternative in Prevention and Treatment of Cardiovascular Diseases. Biomark Insights. 2018;13:1177271918785130. Published 2018 Jul 5. doi:10.1177/1177271918785130; voir lien : https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6043915/#bibr2-1177271918785130
Iwai, Kunihisa & Nakaya, Natsuko & Kawasaki, Yoshihiro & Matsue, Hajime. (2002): Antioxidative Functions of Natto, A Kind of Fermented Soybeans: Effect on LDL Oxidation and Lipid Metabolism in Cholesterol-Fed Rats. Journal of agricultural and food chemistry. 50. 3597-601. 10.1021/jf0117199.
Patisaul HB, Jefferson W. The pros and cons of phytoestrogens. Front Neuroendocrinol. 2010;31(4):400–419. doi:10.1016/j.yfrne.2010.03.003 ; article accessible sur https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3074428/