Cheonggukjang vs Natto: Key Differences, Taste, and Health Benefits
Featured image: AI-generated illustration (not a photograph).
Is Cheonggukjang the Same as Natto?
No, although they are close relatives. Both are whole soybeans fermented by Bacillus subtilis, but natto uses a specific strain (B. subtilis var. natto) and ferments for about a day, while cheonggukjang usually ferments for two to three days with a mixed group of Bacillus bacteria. The biggest practical difference is how they are eaten: natto is eaten raw, stirred into sticky threads and served over rice, while cheonggukjang is mashed and cooked into a pungent stew. Cheonggukjang also smells much stronger.
The sections below cover the microbiology, the history, a side-by-side table, and a cheonggukjang stew recipe.
The Science Behind the Fermentation: Meet Bacillus subtilis
Bacillus subtilis is the engine driving both ferments. In Korean and Chinese traditions, it’s called gochogyun (枯草菌), which translates roughly to “dried grass bacterium” — a nod to the fact that it naturally colonizes rice straw. This is no fragile organism. It forms endospores that can survive temperatures above 100°C for a significant period of time, making it one of the toughest bacteria found in traditional food fermentation.
When Bacillus subtilis encounters soybean protein, it releases powerful proteases — enzymes that break complex proteins down into amino acids. One of those amino acids is glutamic acid, the compound responsible for deep, savory umami flavor. The fermentation also produces poly-γ-glutamic acid (PGA), a sticky biopolymer that gives natto its signature stringy threads and cheonggukjang its thick, viscous texture. The sweet spot for fermentation is around 40–42°C, and the bacteria thrive under aerobic conditions rather than anaerobic ones.
History and Culture: The Same Root, Two Very Different Paths
The Story of Cheonggukjang
Cheonggukjang’s origins are debated, but the most popular legend traces it back to the Goguryeo Kingdom and the battlefield. Soldiers reportedly carried cooked soybeans tucked under their horse saddles. The horse’s body heat — naturally around 38–39°C — combined with Bacillus subtilis living in the straw beneath the saddle created the perfect fermentation environment. According to the legend, the resulting food was called jeongukjang (戰國醬), meaning “wartime paste,” and the name later became cheonggukjang. This is a folk etymology rather than documented history: no historical source is known for where cheonggukjang actually began.
Written records come later. The 1766 Korean text Jeungbo Sallim Gyeongje (增補山林經濟) is often cited as describing how to make cheonggukjang, which suggests it was an established food by the Joseon Dynasty. In Korea, cheonggukjang is consumed almost exclusively as a cooked stew. Its intense smell is famously polarizing — people either love it or avoid it completely — but it has been a beloved winter dish for centuries. Today, odor-reduced powder and pill supplements have made it far more accessible to those who want the benefits without the smell.
The Story of Natto
Natto’s origin story is strikingly similar. During the Heian period (794–1185 CE), soldiers under the commander Minamoto no Yoshiie reportedly discovered that cooked soybeans wrapped in rice straw had transformed into something sticky and pungent during a military campaign. Whether or not that story is entirely accurate, natto spread through Japan’s Edo period (1603–1868) as an affordable, protein-rich food for ordinary people, particularly in the Kanto region.
Today natto is a familiar breakfast food across Japan. Unlike cheonggukjang, which is always cooked before eating, natto is almost always eaten raw, stirred vigorously with soy sauce and mustard, then served over rice. That single difference in preparation has significant implications for nutrition, which we will get to shortly.
Cheonggukjang vs. Natto: A Scientific Comparison
| Category | Cheonggukjang | Natto |
|---|---|---|
| Primary strain | Bacillus subtilis and related Bacillus species (varies by batch) | Bacillus subtilis var. natto |
| Fermentation temperature | 40–45°C | 40–42°C |
| Fermentation time | 2–3 days | 18–24 hours |
| How it’s eaten | Cooked (usually as stew) | Raw |
| Sodium per 100g | Varies widely; salted products are high in sodium (check the label) | Low in plain natto; the included sauce packets add sodium |
| Vitamin K2 (menaquinone) | Present (amount varies by product) | Very high; commonly cited around 870 µg per 100 g (varies by product) |
| Nattokinase | Present (activity reduced by heat) | Present (preserved when raw) |
| Poly-γ-glutamic acid (PGA) | Present | Present (more pronounced stringiness) |
Note: Sodium varies a lot with the recipe and brand. Always check nutrition labels for packaged products.
Nattokinase and Vitamin K2
Two compounds have made natto a darling of the wellness world. The first is nattokinase, a serine protease produced by Bacillus subtilis var. natto. It was first described in 1987 by Dr. Hiroyuki Sumi and colleagues, and it has been shown in laboratory and animal studies to break down fibrin, a key structural component of blood clots. Whether eating natto does the same in people has not been established. The second is vitamin K2 in the form of menaquinone-7 (MK-7). Natto is one of the most concentrated dietary sources of vitamin K2, with commonly cited values around 870 µg per 100 g, though it varies by product. Vitamin K2 is involved in calcium metabolism, but the evidence that K2 intake prevents fractures or heart disease is mixed.
Important: The research on nattokinase and vitamin K2 is ongoing. This article is not medical advice. If you are on blood-thinning medications or have a health condition, speak with your doctor before adding natto or cheonggukjang supplements to your diet.
Cheonggukjang typically ferments longer than natto, and ammonia is part of its sharp smell as proteins break down further. Cooking the paste into a stew reduces heat-sensitive enzyme activity, including nattokinase. That said, the amino acids, isoflavones, and dietary fiber largely survive the heat. It’s a trade-off between convenience and raw nutritional potency.
Recipe: Homemade Cheonggukjang Jjigae (Fermented Soybean Stew)
This is a classic Korean winter stew — deeply savory, warming, and satisfying. Serves 2.
Ingredients
- 4 tablespoons cheonggukjang paste (about 80g)
- ½ block firm tofu (about 150g)
- 100g Korean radish (daikon), sliced
- ¼ zucchini, sliced
- ⅓ stalk green onion, sliced on the diagonal
- 1 cheongyang (Korean green) chili pepper, sliced (optional, for heat)
- 1 teaspoon minced garlic
- 400ml anchovy broth or water
- 1 teaspoon doenjang (Korean soybean paste) — optional, for extra depth
- 1 teaspoon gochugaru (Korean red pepper flakes) — optional
Instructions
- Step 1: Place the radish slices in a pot and pour in the anchovy broth. Bring to a medium heat and cook for about 5 minutes. Starting with the radish is key — it takes longer to soften and its starch gives the broth body and sweetness.
- Step 2: Once the radish turns slightly translucent, add the tofu cut into 2cm cubes and the zucchini cut into half-moon slices.
- Step 3: Add the cheonggukjang paste and stir it into the broth until fully dissolved. Leave the lid off — this lets some of the strong aroma cook off.
- Step 4: Stir in the minced garlic and gochugaru. Let everything simmer together for 3–4 minutes. If you want a rounder, more complex flavor, add the optional teaspoon of doenjang at this point.
- Step 5: Add the sliced green onion and chili pepper. Let the stew come to one more boil, then turn off the heat. Adding the green onion at the very end preserves its fresh fragrance.
- Step 6: Ladle into a stone pot (dolsot) or earthenware bowl if you have one. The heat-retaining properties of a stone pot keep the stew bubbling at the table, which is part of the experience.
Cook’s tip: The longer you simmer cheonggukjang, the milder the smell gets, but heat also inactivates enzymes such as nattokinase. If you want to preserve more of the heat-sensitive enzymes, add the paste near the end and keep the cooking time short; the trade-off is a stronger smell.
Two Traditions, One Future
From a fermentation science perspective, cheonggukjang and natto are siblings. Both break soybean protein into smaller peptides and amino acids. Both generate compounds during fermentation that were not present in the raw soybeans. And both represent something rare: an ancient food technology that modern science keeps finding new questions about.
These two fermented foods evolved independently in neighboring countries over hundreds of years, shaped by different climates, cuisines, and cultures. Now, as interest in fermented foods grows globally, both are finding their way onto shelves and into kitchens far beyond Northeast Asia. Cooking a stew kills many of the microbes in the paste, but the flavor they built stays in the bowl.
About This Article
The author, Hoon Kwak, has worked in food distribution for about 20 years, and his family made meju and looked after jang crocks. The recipe above uses ready-made cheonggukjang paste and follows common Korean home practice; it is not a laboratory-tested formula. For more on the Korean side, see the science behind the smell and doenjang jjigae. For the microbes involved, see fermentation molds.
Frequently Asked Questions
Is it exactly the same bacterium in both foods?
The same species, Bacillus subtilis, is central to both, but the strains differ, and cheonggukjang can involve other Bacillus species as well.
I take warfarin. Can I eat natto or cheonggukjang?
Ask your prescriber first. Natto is very high in vitamin K, and the U.S. National Institutes of Health advises people taking warfarin to keep their vitamin K intake about the same every day, because sudden changes can affect clotting.
Does cooking destroy nattokinase?
Heat inactivates enzymes, and how much is lost depends on temperature and time. That is why raw natto and cooked cheonggukjang differ.
How do I know it is spoiled and not just smelly?
A sharp ammonia smell and sticky threads are normal. Fuzzy colored mold, pink or black growth, or a rotten smell that differs from the usual pungency means you should throw it away.
Sources
- Wikipedia. Cheonggukjang.
- National Institutes of Health, Office of Dietary Supplements. Vitamin K: Fact Sheet for Consumers.
- World Health Organization. Salt reduction fact sheet.
