K is for (fermented) Kale and Vitamin K
In this letter we look at kale in regards to fermentation and demystify vitamin K (in the process proving again fermentation ads nutrition), a recipe for a pretty red Kale and Kraut Salad, and a 🐇🕳️
K is for Kale and for vitamin K. I have to say in keeping with the theme kale is also one of the vegetables that is a great source of vitamin K1. (Vitamin K itself is a generic name for a family of related molecules that can be broadly divided between Vitamin K1 (phylloquinone) and Vitamin K2 (menaquinone).) Interestingly, there are different forms of K2, most of which need some form of bacteria—enter fermentation—to be in the foods. Fermented vegetables are one of these foods. We will dig into vitamin K in a moment but let’s start with kale. In my mind, fermented kale must mean K1 plus K2 (double K for the win) but I couldn’t find a specific study that directly stated kale fermentation is a super source of vitamin K. However, this is a method that was tested and found successful to determine K in fermented foods, such as dark leafy greens.
Fermenting kale
I have found that fermenting kale (common to North American stores Red Russian, Redbor, Curly, Lacinato kale, and so on) is not as straightforward as most of the members of the brassica family. I have no idea why. Admittedly, I haven’t spent a whole lot of time researching that, as I would rather just keep playing around with it and seeing what it does and doesn’t do under the influence of microbes.
(See Down the Rabbit Hole at the bottom of this email for a few studies about Kale fermentation.)
I am all about flavor and ease of preparation because that is what makes the difference between creating a ferment, or not, in your kitchen. You must enjoy the ferment to want to eat and also spend the time to make it. In our first book Fermented Vegetables, I didn’t find a way to make kale taste good. In the last decade, I have had a lot more time to play around with kale. I knew it was safe, but I wasn’t as confident, or as experienced with my fermentation skills. I didn’t fully understand how to manipulate the vegetables in order to steer the microbes. I am going to also admit, I wasn’t completely sure back in 2012 when I wrote that book, that all vegetables could be fermented safely. I understood the basic principle of lactic acid fermentation—as in lactic acid eats carbohydrates, in doing so they create acid and CO2. For some reason, I didn’t make the connection that the microbes really didn’t care (or even know) the difference between a slice of carrot and a slice of cucumber. They are opportunistic sugar eaters, interested in how much and how accessible the simple sugars are. If there is sugar, they will make acid—acid is the superpower!
I think what really was at play is I couldn’t trust that there wasn’t an exception to fermentability based on the type of vegetable. It is hard to recall a time when any type of vegetable fermentation wasn’t a Google search away, but I spent hours using my son’s university library access trying to research different vegetables with no luck. Beyond the traditional vegetable ferments, I couldn’t find any reference for or against the more unusual (as far as being fermented) vegetables. As I continued to play around with possibility and take pH readings, I saw over and over again, that the safety as far as vegetable fermentation is concerned is very straightforward and safe.
K is for Kale and for vitamin K. I have to say in keeping with the theme kale is also one of the vegetables that is a great source of vitamin K1. (Vitamin K itself is a generic name for a family of related molecules that can be broadly divided between Vitamin K1 (phylloquinone) and Vitamin K2 (menaquinone).) Interestingly, there are different forms of K2, most of which need some form of bacteria—enter fermentation—to be in the foods. Fermented vegetables are one of these foods. We will dig into vitamin K in a moment but let’s start with kale. In my mind fermented kale must mean K1 plus K2 (double K for the win) but I couldn’t find a specific study that directly stated kale fermentation is a super source of vitamin K. However, this is a method that was tested and found successful to determine K in fermented foods, such as dark leafy greens.
Fermenting kale
I have found that fermenting kale (common to North American stores Red Russian, Redbor, Curly, Lacinato kale, and so on) is not as straight forward as most of the members of the brassica family. I have no idea why. Admittedly, I haven’t spent a whole lot of time researching that, as I would rather just keep playing around with it and seeing what it does and doesn’t do under the influence of microbes.
(See Down the Rabbit Hole at the bottom of this email for a few studies about Kale fermentation.)
I am all about flavor and ease of preparation because that is what makes the difference from creating a ferment, or not, in your kitchen. You must enjoy the ferment to want to eat and also spend the time to make it. In our first book Fermented Vegetables, I didn’t find a way to make kale taste good. In the last decade I have had a lot more time to play around with kale. I knew it was safe but I wasn’t as confident, or experinced with my fermenation skills. I didn’t fully understand how to manipulate the vegetables in order to steer the microbes. I am going to also admit, I wasn’t completely sure back in 2012 when I wrote that book, that all vegetables could be fermented safely. I understood the basic principle of lactic acid fermentation—as in lactic acid eats carbohydrates, in doing so they create acid and CO2. For some reason, I didn’t make the connection that the microbes really didn’t care (or even know) the difference between a slice of carrot and a slice of cucumber. They are opportunistic sugar eaters; they are interested in how much and how accessible the simple sugars are. As long as there is sugar they will make acid—acid is the super power!
I think what really was at play is I couldn’t trust that there wasn’t an exception to fermentability based on type of vegetable. It is hard to recall a time where any type of vegetable fermentation wasn’t a google search away, but I spent hours using my son’s university library access trying to research different vegetables with no luck. Beyond the traditional vegetable ferments, I couldn’t find any reference for or against the more unusual (as far as being fermented) vegetables. As I continued to play around with possibility and take pH readings, I saw over and over again, that the safety as far as vegetable fermentation is concerned is very straightforward and safe.
The more things that worked, or didn’t, the more I played. Most of my experiments are as “recipes” that start as a single inspiration, but occasionally I make a concentrated effort. I test many variables (ie same process, same salt ratio, different variety of kale) one jar at a time, changing the variables in different combinations and lining the jars up side by side. I have ended up with 16 jars side by side to figure out one element. In my kale fermentation trials, I learned a few things. The most surprising was that while cooked or steamed kale varieties often are interchangeable in a recipe as far as flavor is concerned, fermented I found that the green varieties finished brighter and tastier than the purple or red varieties. For example, curly kale, Siberian kale, or Lacinato (Dinosaur) kale produced clean, pleasing acid flavors while the Redbor and Scarlet kale fermented brought out the more bitter compounds. If I want to ferment a red variety, for example, I will use it as part of a mixed ingredient ferment where these compounds can add to the whole experience. I was also surprised that the hardy-textured Lacinato kale was not too tough to enjoy post-fermentation. In general, though the simplest way to add kale to your fermentation practice is to use it alongside other vegetables (like cabbage) as part of a ferment but not the only ingredient.
In this week’s paid subscriber post I will dig deeper into kale fermentation and how to make kale shine as the star, and even make a pure kale kraut. Meanwhile, I promised to look a little deeper into vitamin K.
What is Vitamin K?
We all have a sense that we need it but what is vitamin K. There is a lot of confusing information about Vitamin K. Some of this confusion occurs from the unclear nomenclature of Vitamin K and its different isoforms. Vitamin K gets a lot of attention in a singular sort of way but it is actually a group of chemically related fat-soluble compounds that includes vitamins K1, K2, and K3 (which we won’t discuss, as it is a synthetic compound). Lumping these together under one K leads us to believe the benefits of these compounds are the same, but they are different and play different roles in our bodies.
Vitamin K1 is all about liver health and maintaining healthy blood clotting; in fact, the origin of K comes from the German word koagulation. Vitamin K2’s role goes far beyond simple blood clotting in fact it appears to play a small part in blood clotting. K2 is best known to function in regulating calcium transport within the body. This reminds me of a story…
In 2019, our book Miso, Tempeh, Natto and other Tasty Ferments came out. We went on a book tour and found ourselves teaching miso-making in Ohio, in the middle of Amish country at Lehman’s Hardware. We began our class with introductions. When it was his turn, one of the participants, said, “I cut into people’s chests for a living.” Well-timed long pause. “I am a heart surgeon, and one of the first things I do is feel their veins, if it feels like there are eggshells inside I know that their calcium hasn’t stayed in their bones. I know this class is about miso, but I want to talk about natto. I want everyone to be eating natto.” And he sat down. The class looked at him wide-eyed. My eyes, likely lit up, and Christopher’s likely rolled, because he knows natto is one of my favorite topics.
So, circling back to the topic at hand, calcium transport. Nothing like visually eggshell-like shards of calcium running through your circulatory system to take notice. There is growing evidence that Vitamin K2 may be a critical element in the prevention of osteoporosis, cardiovascular and coronary disease, kidney disorders, diabetes, and cancer.
The best way for us to get K vitamins is through food as these are fat soluble essential nutrients we cannot make in our bodies. When you see recommendations for Vitamin K, it typically refers to K1 and K2 collectively. And because of the amount of K2 present in most foods such a minuscule amount of “Vitamin K content” likely is mostly K1 content. Vitamin K1 is found mostly in plants. (I am looking at you dark leafy greens!) Vitamin K1 deficiency is rare, especially if we are doing a fair job of eating those dark green veggies. K2 is more complicated. Humans are more likely to be deficient in K2, which I have to say is going to seem counterintuitive as you keep reading. Vitamin K2 (MKs or menaquinones) can be additionally divided into a family of related molecules that vary in the length of their side-chain structure. This is where my brain starts complaining that chemistry was too long ago but here goes.
The shortest of the menaquinones is MK-4, ranging up to MK-14. Among these MK isoforms of K2, MK-4 and MK-7 have been studied the most and are the only two that are available also in supplement form. In the supplements, MK-4 is a synthetic compound and MK-7 is commercially produced by purification from bacterial natto fermentation.
MK-4 is the K2 that is found in animal foods from egg yolks or butter (I never need an excuse to eat butter), to meat products. So, how is it that the Western diet that arguably doesn’t eat enough green vegetables and consumes too much of these animal foods is deficient in K2? (See what I mean about counterintuitive?!?)
It comes down to the industrialization and processing in our food systems. Historically we ate whole foods with minimal processing. The beasts that we ate, ate grass—green grass. As is true for many nutrients, the MK-4 content can be highly dependent on how the animals are raised and fed. Pastured and grass-fed animals will take in much more Vitamin K1 from all that plant matter, which is converted to MK-4. Given the vast majority of meat and dairy animals are factory farmed and grain-fed, they lose Vitamin K1 and therefore become deficient in Vitamin K2 MK-4 content.
Enter my favorite subject—Fermentation
Fermentation brings Vitamin K2 to the table, in the forms of MK-7, MK-8, and MK-9.
Yet another reason to eat your sauerkraut, drink your milk kefir and learn to love natto!
Fun fact: Natto has 15x more Vitamin K2 as the best cheese sources and somewhere around 200x as much as sauerkraut!
I will leave you with this easy K rich salad, someday soon I will devote some letters to natto, meanwhile this week’s paid subscribers will learn more tips and tricks for fermenting kale. Recipes included.In this recipe, I use kraut to soften and marinate the kale adding both flavor and probiotics. I made it for years before I realized how rich it is in vitamin K. I was always interested in the flavor and all the beautiful red vegetables involved. You will find on here. The Ruby Red Sauerkraut is a lovely combination of red cabbage, beets, dried cranberries, and apples. You will find that recipe here, do make it for this salad if you have a chance. If you don’t feel free to use any beet-based sauerkraut.
Kale and Kraut Salad
Serves 4 – 6
In this recipe I use kraut to soften and marinate the kale adding both flavor and probiotics. I made it for years before I realized how rich it is in vitamin K. I was always interested in the flavor and all the beautiful red vegetables involved. You will find on here. The Ruby Red Sauerkraut is a lovely combination of red cabbage and beets, plus dried cranberries, and apples. You will find that recipe here, do make it for this salad if you have a chance. If you don’t feel free to use any beet-based sauerkraut.
1 bunch Kale, (my favorite is Red Russian for this salad)
¼ (1.5 grams) teaspoon salt
½ cup Ruby Red Sauerkraut or any beet kraut
½ small red onion, finely diced
2 – 3 (28 – 40 ml) tablespoons balsamic vinegar*
¼ cup (118 ml) olive oil
½ cup (65 grams) fruit juice-sweetened dried cranberries, or substitute fruit juice-sweetened dried cherries
*note on balsamic: I prefer the long-aged, thick, syrupy type balsamic as it coats the kale and has mellow sour notes. If using regular thin balsamic use a little less.
Rinse the kale and cut into thin ribbons. Place in a bowl and sprinkle in the salt. Massage this salt into the kale until it is distributed throughout, and the kale is slightly wilted.
Add the sauerkraut and mix thoroughly. Allow this to sit for about 10 minutes.
Meanwhile dice the red onion finely.
Add the onion along with remaining ingredients and toss to mix thoroughly. Serve immediately, or if you have time, allow it to sit for a half hour to allow the flavors to continue to marinate. Store any leftovers in the fridge and it will still be tasty the next day.
🐇 Down the Rabbit Hole 🕳️
Here are two studies I looked at. One of the research projects used spontaneous fermentation for success, while the other needed to use starter cultures to obtain effective results. Different kind of brassicas, both with kale in their common name but likely different properties. And, as with most of these types of studies, nothing is mentioned about the sensory experience of the foods fermented—as in texture and flavor. Still, I do like to see what is being tested and discovered in the lab.
Fermented curly kale as a new source of gentisic and salicylic acids with antitumor potential
This study uses kale (Brassica oleracea var. sabellica) a common leafy green in North America and Europe as it is already known to be a food that helps lower the risk of cancer.
“Spontaneous fermentation with autochthonous LAB strains enriches curly kale with gentisic acid and decreases the amount of salicylic acid after this process. These compounds have confirmed immunomodulatory and anti-inflammatory properties which can cause anticancer effect. In this regard, the bioconversion of natural plant polyphenols by LAB enhances the biological functions of fermented curly kale, leading to improvement of nutraceutical properties.”
This study was done on African kale (Brassica carinata). The leafy green is a source of important micronutrients. As leafy vegetables are highly perishable the study aimed to see if fermentation was a good way to preserve the shelf life of this food. First, I wanted to know exactly this “kale” was compared to all the varieties of greens I think of as kale. Brassica carinata is a green but also is grown commercially for its oil, which falls into the category of rapeseed oil.
Interestingly, the researchers found that the fermentation was unreliable without the addition of starters. However, with starter cultures, it could be fermented without additional sugar as the strains L. plantarum and L. fermentum were able to use the simple sugars (fructose, glucose, and sucrose) in the kale.
When I read the study, my mind jumped to, that is what I had been feeling for many years. Kale is unreliable as a ferment, however, I never had trouble with the lowering of acid just unreliable flavor results. The other interesting thing they found was that the vitamin C decreased during fermentation, which also is unusual for vegetables. More to ponder.
A deep 🐇🕳️
I discovered this PDF when looking up African Kale…so many fun plants in this downloadable book.
Discovering Indigenous Treasures: Promising Indigenous Vegetables from Around the World. 2009. AVRDC – The World Vegetable Center.
Very timely since one of my relatives is about to undergo heart bypass surgery. Unfortunately they’re not the “let food be thy medicine types”, more of “let modern medicine be thy medicine and I’ll continue to eat and drink whatever I like.”
Sparked my interest again in natto, a friend gave me some spores and some left-overs so I’ll have to give it another try, maybe mixed in with our meals instead of on its own.
As an aside, speaking of the power of plants and the ability of the human body to heal itself, a friend of mine recently beat cancer with diet, exercise,meditation and a bunch of alternative therapies. Did you know that in scientific papers this is called “spontaneous remission”.
“Spontaneous” sure does a huge disservice to all the efforts that she and others put in to their health in order to heal themselves !!
I would love some posts about Natto! I put it in my smoothies. I make natto & then freeze it in individual servings. I’m still getting used to the texture, when eating it on its own but love the nuttiness & thickening it adds to my fruit smoothies. I also have congestive heart disease, like my dad did. Another reason I make it.