Enzyme from fermented soy food unravels protein fibrils associated with Alzheimer’s; those averse to the funky soybeans select natto supplements
by Craig Weatherby
When I enjoy Japanese food with old friend Chris Kilham—a renowned “medicine hunter” and inveterate strange-food adventurer—his order often includes the stringy clump of fermented soybeans known as natto (naht-toe).
Even some Japanese folk find its funky aroma and goopy nature off-putting, but Chris loves to nibble on natto.
I usually enjoy eating the similar, albeit less pungent fermented Javanese soybean food called tempeh. But when it comes to natto I can take it or leave it… usually the latter!
Dr. Andrew Weil recommends natto for its general benefits, and as an unsurpassed source of vitamin K, which plays a role in blood clotting but is increasingly seen as key to bone health.
In fact, natto contains a particular form of vitamin K called MK-7, which lasts longer and is more effective than the forms found in green vegetables and used in supplements (Schurgers LJ et al. 2007).
As well as loads of vitamin K, the bacteria used to ferment soy into natto—called Bacillus natto—produces enzymes, vitamins, amino acids, antibiotics, and other unique factors.
Now, results from Taiwan add to natto’s reputation as a highly healthful fermented food.
And fortunately, the active enzymatic elements are found in supplemental extracts, so you needn’t actually eat the rather pungent goo to get natto’s presumed brain benefits.
Natto digests brain plaqueAlzheimer’s is the most common form of dementia and currently affects more than 13 million people worldwide.
The beta-amyloid plaque deposits associated with Alzheimer's promote increased brain cell damage and death from oxidative stress (free radicals).
Enzymes in natto called nattokinase and pyrazine appear to dissolve the tiny fibers (fibrin) in blood clots… an effect believed largely responsible for correlations between regular natto consumption and a reduced risk of clot-related cardiovascular troubles.
Indeed, most natto research has focused on reducing blood pressure and preventing blood clots... with positive findings on both fronts fueling sales of nattokinase supplements.
Until now, no one had tested whether nattokinase can dissolve amyloid fibrils, which are resistant to normal protein-digesting enzymes (proteases) the body could otherwise use to help clear the brain of plaque.
New lab results from Taiwan indicate that natto enzymes may degrade the amyloid protein fibrils that form part of the beta-amyloid plaque linked to Alzheimer’s disease (Hsu RL et al. 2009).
Nattokinase and pyrazine appear able to prevent or resolve blood clots, and thereby help prevent heart attacks and strokes.
A team from Taiwanese colleges tested the enzyme against three types of fibrils: A-beta-40 fibrils, linked to Alzheimer's; insulin fibrils, linked to diabetic complications; and prion peptide fibrils, responsible for prion disorders such as “mad cow” disease and its human counterpart, called Creutzfeldt-Jakob disease.
Sure enough, the Taiwanese team witnessed nattokinase degrading all three different amyloid fibrils to very substantial degrees.
The researchers called for animal studies to explore the therapeutic potential of nattokinase, noting that the enzyme could be injected, or consumed either in natto or as purified nattokinase.
And they called for the obvious: “Since natto has been ingested by humans for a long time, it would be worthwhile to carry out an epidemiological study on the rate of occurrence of various amyloid-related diseases in a population regularly consuming natto” (Hsu RL et al. 2009).
Natto as a food and health tonic
Natto’s been eaten in Japan for more than 1,000 years, and its medical potential includes prevention of heart attacks, strokes, cancer, osteoporosis, obesity and serious infectious disease, including dysentery, typhoid, salmonella, and the deadly E. coli 0-157.
Some of the effects are attributed to soy’s own properties, but most are linked to the fermentation byproducts, which break down soybean nutrients difficult for humans to digest.
You can find frozen natto at Asian stores.
Many people like natto mixed with chopped green onion or leeks and minced garlic, or served over rice with a mustard and soy sauce mix.
Although it means missing out on some of whole natto’s benefits, I’d rather take nattokinase capsules and forgo this ancient food’s funky, fermented flavor.
- Hsu RL, Lee KT, Wang JH, Lee LY, Chen RP. Amyloid-degrading ability of nattokinase from Bacillus subtilis natto. J Agric Food Chem. 2009 Jan 28;57(2):503-8.
- Ko JH, Yan JP, Zhu L, Qi YP. Identification of two novel fibrinolytic enzymes from Bacillus subtilis QK02. Comp Biochem Physiol C Toxicol Pharmacol. 2004 Jan;137(1):65-74.
- Peng Y, Yang X, Zhang Y. Microbial fibrinolytic enzymes: an overview of source, production, properties, and thrombolytic activity in vivo. Appl Microbiol Biotechnol. 2005 Nov;69(2):126-32. Epub 2005 Nov 12. Review.
- Schurgers LJ, Teunissen KJ, Hamulyák K, Knapen MH, Vik H, Vermeer C. Vitamin K-containing dietary supplements: comparison of synthetic vitamin K1 and natto-derived menaquinone-7. Blood. 2007 Apr 15;109(8):3279-83. Epub 2006 Dec 7.
- Taniguchi A, Yamanaka-Okumura H, Nishida Y, Yamamoto H, Taketani Y, Takeda E. Natto and viscous vegetables in a Japanese style meal suppress postprandial glucose and insulin responses. Asia Pac J Clin Nutr. 2008;17(4):663-8.