Kimchi

Kimchi is Korean fermented veg, usually Chinese leaf or radish with chilli, garlic and ginger. Sour, hot and salty – often with fish sauce or shrimp.

What is kimchi? Korea's spicy national treasure

If one single food has reached cult status in modern microbiome research, it's kimchi. For centuries, this fiery, lacto-fermented vegetable mix (usually based on Chinese leaf and radish) has been the undisputed foundation of Korean cooking. The average Korean eats around 20 to 30 kilograms of kimchi a year. The traditional way of making it (kimjang) is so special that it has been added to UNESCO's list of intangible cultural heritage. During weeks of cold fermentation in special clay pots, ordinary vegetables turn into a living mix full of lactic acid bacteria.

Nutrition & micronutrients (per 100g)

Kimchi is very light in calories. What makes it interesting isn't the macros but the live cultures and plant compounds (phytonutrients):

• Energy: about 15–20 kcal
• Carbohydrate: about 2.5g (the bacteria eat most of the cabbage's natural sugars and turn them into lactic acid)
• Protein & fat: minimal (about 1g protein, hardly any fat).
• Vitamins: fermentation produces vitamin K2; kimchi also contains folate, vitamin C and various B vitamins.
• Live cultures: hundreds of millions of colony-forming units (CFU) of lactic acid bacteria, above all the strain Lactobacillus kimchii.

What studies have looked at: the lactic acid bacteria

Lactic acid bacteria and the gut

A large part of the body's defence tissue sits along the gut, in the gut-associated lymphoid tissue (GALT), which is in constant contact with bacteria. Kimchi brings a lot of live lactic acid bacteria with it. Gut bacteria produce short-chain fatty acids such as butyrate, which the cells of the gut lining use as fuel. Studies have looked at regular kimchi consumption in connection with respiratory infections, allergies and bowel movements.

Blood glucose and chilli heat

Interestingly, several studies by South Korea's World Institute of Kimchi (yes, it really exists) have measured blood lipids and fasting blood glucose in people who regularly ate fermented kimchi. Researchers are also looking at whether organic acids, especially lactic acid, slow how fast the stomach empties after a carb-heavy meal. Koreans traditionally eat kimchi alongside white rice. Other research looks at capsaicin – the heat in Korean chilli flakes (gochugaru) – and heat production in brown fat cells.

Vitamin K2

Fermented vegetables are one of the very few vegan sources of menaquinone (vitamin K2). Vitamin K2 activates osteocalcin, a protein that binds calcium into the bone matrix of your skeleton and teeth.

Everyday tip: skip pasteurised kimchi

The most common mistake: buying pasteurised kimchi from the ambient shelves in the supermarket. If kimchi is heated above 45 degrees – which jars on the shelf need for a shelf life of months – 100% of the lactic acid bacteria die. What's left is simply tasty, spicy cabbage. If you want live kimchi, buy it fresh and unpasteurised: you'll find it in the chiller cabinet of an Asian supermarket or organic shop. Look for a slightly domed lid – a sign that the bacteria are alive and busy producing CO2.