Vitamin K2 (menaquinone) is a fat-soluble vitamin. One main function is to support blood clotting by being involved in the activation of certain clotting factors. This helps stop bleeding and promote wound healing. Vitamin K2 also contributes to bone health. It helps transport calcium from the blood into the bones and deposit it there. This can reduce the risk of osteoporosis.
Vitamin K2 is synthesized by bacteria in the intestine. However, there is controversy about how much the long-chain menaquinones produced by gut bacteria can contribute to daily vitamin K supply. Although gut bacteria produce a significant amount, the body has difficulty effectively absorbing them in the digestive tract. Relying solely on menaquinone production by the intestinal flora may not be sufficient (source).
There are several types of vitamin K2, which differ depending on the length of the carbon chain. The two most well-known types are:
- Menachinone-4 (MK-4)
- Menachinone-7 (MK-7)
To a limited extent, the body can convert vitamin K1 (phylloquinone) into vitamin K2. However, the exact conversion rate is not well-researched and can vary from person to person. It is believed that the conversion efficiency is limited and may not be sufficient to meet the entire vitamin K2 requirement. Here is the table of vitamin K1 foods.
Vitamin K2 is predominantly found in animal products. However, there are a few plant-based vitamin K2 foods that we will discuss in more detail below.
Who Should Ensure Adequate Vitamin K2 Intake?
Specifically, the following groups of people should pay attention to sufficient vitamin K2 intake:
- Individuals with impaired vitamin K absorption in the intestine due to diseases or medical procedures.
- Individuals at increased risk of osteoporosis or cardiovascular diseases.
- Individuals with an unbalanced diet who may not receive enough vitamin K2 from food. This can also include a vegan diet since vitamin K2 is mainly found in animal products and fermented foods.
- Individuals taking anticoagulant medications.
- The production of bile acids is important for the absorption of fat-soluble vitamins. If bile acid production is impaired, the absorption of vitamin K2 may also be reduced.
- The pancreas plays a role in the production of enzymes necessary for fat digestion. Impaired pancreatic function can hinder the absorption of fat-soluble vitamin K2.
- In certain life stages or with additional medical conditions, there may be an increased need for vitamin K2. These include pregnancy, breastfeeding, menopause, and liver diseases.
Symptoms of vitamin K2 deficiency may include increased incidence of bone fractures, muscle weakness, dental problems, or excessive bleeding.
Vitamin K2 Foods
Vitamin K2 is produced by bacteria and therefore naturally occurs only in fermented foods. Some plant-based foods that provide vitamin K2 include:
- Fermented soy products can contain a significant amount of vitamin K2. This includes the traditional Japanese dish called Natto, made from fermented soybeans. Natto is considered the best plant-based source of vitamin K2. A 100g serving of Natto can contain more than ten times the daily requirement of vitamin K2. The form present is menaquinone-7 (MK-7), which is produced through fermentation with a specific strain of Bacillus subtilis. Natto has a distinctive strong smell and sticky texture, which makes it a unique culinary experience. Miso (traditional Japanese seasoning paste) and tempeh also contain small amounts of vitamin K2 in the form of MK-7.
- Fermented vegetables such as sauerkraut (fermented cabbage) and kimchi (fermented vegetable mix) contain small amounts of vitamin K2. However, the vitamin K2 content is also very low.
- Some types of seaweed such as nori, kombu, and wakame can contain small amounts of vitamin K2.
- Shiitake mushrooms can also be a potential plant-based source of vitamin K2.
- Plant oils may contain traces of vitamin K2. Natto oil, rapeseed oil, soybean oil, and olive oil may have low levels.
- The fermented tea beverage called kombucha contains small amounts of vitamin K2.
Eat Vitamin K2 With Fat
The body can better absorb vitamin K2 when consumed simultaneously with fat. Foods rich in vitamin K2 should be combined with healthy fats found in nuts, seeds, and avocados to enhance absorption.
What Does A Vegan Vitamin K2 Diet Look Like?
Since there are very few vegan sources of vitamin K2, it can be challenging to obtain sufficient amounts through a purely plant-based diet. Nevertheless, here are some vegan recipe suggestions:
- Tofu-Natto Salad: Mix diced tofu with fermented natto, vegetables, and your choice of nuts or seeds.
- Natto Rice Bowl: Serve warm rice with a serving of natto on top. Add vegetables, avocado, and spices to taste.
- Natto Miso Soup: Prepare a miso soup with natto as a topping. Add vegetables, tofu, and spring onions to the soup.
- Natto Salad: Combine natto with chopped cucumbers, tomatoes, spring onions, and a dressing made with soy sauce, rice vinegar, and sesame oil.
- Vegan Miso Soup: Miso is a good base for a vegan soup with vegetables and tofu.
- Sauerkraut Burger: Prepare vegan burger patties using beans, oats, and spices. Serve them on a whole-grain burger bun with sauerkraut, vegan mayo, and fresh vegetables.
- Sauerkraut Taco: Fill soft tortillas with seasoned and fried tofu, avocado, sauerkraut, and a delicious vegan sauce.
- Sauerkraut Sandwich: Layer your favorite bread with vegan deli slices, vegan cheese, sauerkraut, and mustard or vegan mayonnaise.
- Vegan Sushi Rolls: Make vegan sushi rolls with avocado, cucumber, carrot strips, and romaine lettuce.
- Seaweed Salad: Combine various types of seaweed such as wakame, dulse, and hijiki with cucumbers, carrots, and a flavorful dressing for a tasty and healthy salad.
- Seaweed Pesto Pasta: Prepare a delicious pesto using seaweed, basil, garlic, pine nuts, and olive oil, and serve it over your choice of pasta.