Vitamin K is a fat-soluble vitamin that exists in its vitamin K1 and K2 forms. Although both forms of vitamin K have different functions and are found in various foods, they have similar structures and some similar roles.
Vitamin K1 (phylloquinone) is an essential fat-soluble nutrient that makes up around 75-90% of all vitamin K consumed by humans. It is mainly found in green and leafy vegetables.
On the other hand, K2 (menaquinone) makes up the remaining 10 – 25% of vitamin K consumed by humans and can be found in fermented foods and animal products. Vitamin K2 is also made up of several subtypes of its own.
- What Does Vitamin K Do in Your Body?
- Vitamin K1 vs Vitamin K2
- Vitamin K Foods
- Vitamin K1 Recipes
- What Are the Symptoms of Vitamin K Deficiency?
- Vitamin K Toxicity
- Does Vitamin K Cause Blood Clots?
- Satiety Response to Vitamin K1 in Food
- Optimal Vitamin K1 Intake
- Synergistic Nutrients with Vitamin K1
- Nutrient Profile of High Vitamin K Foods
- How Do I Calculate My Vitamin K Intake?
What Does Vitamin K Do in Your Body?
- It’s interesting to note that we produce some vitamin K2 naturally with the help of the bacteria in our large intestine. However, it is poorly absorbed, given it’s in the lower bowel.
- Although both forms of vitamin K differ in function, they both play a vital role in blood clotting. Proteins that are involved in clotting are regulated by vitamins K1 and K2. Interestingly, the K comes from the Danish word “koagulation”.
- While Vitamin K1’s claim to fame is predominantly blood clotting, K2 has many other roles.
- Vitamin K2 has been shown to activate proteins that regulate inflammation, cell division, and soft tissue mineralisation.
- Vitamin K2 is crucial for bone health, and that this nutrient is critical for bone remodelling and calcium storage in the skeletal system (and not your joints or arteries). Vitamin K1 had little impact when studied.
- K2 is also helpful for calcium regulation in other parts of the body. The kidneys utilise K2 to remove excess calcium and prevent kidney stones.
- Vitamin K2 has also been shown to be helpful for heart disease as it helps prevent arterial calcification and stiffening.
- Adequate vitamin K levels have been linked to better reproductive health. Studies have specifically shown a connection between vitamin K and healthy sperm maturation.
- Vitamin K2 has been shown to regulate T-cells, a major component of the immune system and regulator of inflammation.
- K2 has a role in brain health, as myelinated regions of the brain seem to require high amounts of K2. Low levels of K2 are also linked to neurodegenerative conditions like Alzheimer’s.
- Speaking of inflammation, vitamin K has specific anti-inflammatory properties that have been shown to have cancer-protective, tumour-suppressive effects.
- Vitamin K2 also plays a role in maintaining insulin sensitivity.
- K2 has been shown to restore mitochondrial function, which is often damaged in chronic diseases like diabetes, autoimmunity, cancer, autism, and heart disease.
- Interestingly, your body efficiently recycles vitamin K. Although vitamin K is a fat-soluble vitamin that is reused readily, the body only holds onto small amounts of this nutrient. As a result, stores of vitamin K are depleted rather quickly if the diet does not replace them.
Vitamin K1 is said to have a lower absorption rate than vitamin K2, with estimates as low as 10% of the vitamin being absorbed. This could be because K2 foods are often rich in fat, whereas K1 sources are often leafy green vegetables. For best results, put some butter on that kale!
Vitamin K1 vs Vitamin K2
It’s important to note that K1 (phylloquinone) is found in plant foods, while K2 (menaquinone) is found in animal and fermented foods. Vitamin K2 is thought to be more critical for factors other than blood clotting.
Unfortunately, only Vitamin K1 is quantified in the various nutritional databases, so it’s hard to know if you’re getting sufficient K2 using Cronometer. However, Chris Masterjohn recommends getting 100 to 200 micrograms of K2 per day and has compiled The Ultimate Vitamin K2 Resource to help you determine if you are getting enough.
People on a strict vegan diet will get plenty of K1 but less K2. On the contrary, people on a carnivorous diet may get K2 and little K1. Although the conversion factor varies, most people can convert adequate K1 to K2. It’s not as clear if we can convert K2 to K1.
Vitamin K Foods
Although vitamins K1 and K2 look similar, they are found in different foods for the most part. For this reason, we’ve provided a vitamin K foods list to see foods that contain vitamin K1 and vitamin K2.
Vitamin K1 Foods
Some of the more popular foods that contain higher levels of vitamin K1 include:
- parsley
- kale
- spinach
- coriander (cilantro)
- mixed greens
- lettuce
- cabbage
- broccoli
- Brussels sprouts
- broccoli sprouts
- asparagus
- celery
- dill pickles
- sour pickles
- green beans
- cucumber
- sauerkraut
- kiwifruit
- black pepper
- cauliflower
- blackberries
- carrots
- green peppers
Plants readily produce vitamin K1. Subsequently, fresh fruits and vegetables are the best sources of vitamin K1.
See top foods high in vitamin K1 on Nutrient Optimiser for more detail.
Vitamin K2 Foods
Foods that are rich in vitamin K2 include:
- cheese
- yogurt
- kefir
- other dairy products
- natto
- sauerkraut
- kimchi
- eel
- liver
- egg yolks
- beef
- chicken
- pork
- butter
Bacteria can produce vitamin K2. As a result, foods that are fermented are rich in vitamin K2. Animal foods are also high in certain forms of K2.
Vitamin K1 Recipes
Some examples of our NutriBooster recipes rich in Vitamin K1:
- red cabbage & parsley salad (pictured below)
- cauliflower & spinach soup
- Sue’s salad
- sautéed radish & watercress
- puttanesca fish on silverbeet
What Are the Symptoms of Vitamin K Deficiency?
Inadequate vitamin K may cause bleeding, conditions of weakened bone density like osteoporosis, and potentially increase your risk of developing heart disease.
Other symptoms of vitamin K deficiency are:
- bruising easily
- bleeding excessively
- small blood clots under nails
- unexplained hemorrhaging
- bleeding in mucous membranes inside the body, and
- stools that are tar-coloured with some blood.
People at risk for vitamin K deficiency include:
- someone on anticoagulants
- people taking antibiotics
- someone diagnosed with a condition affecting nutrient absorption, like irritable bowel syndrome (IBS), celiac’s disease, inflammatory bowel disease (IBD), or a disorder affecting bile production (liver, gallbladder, bile duct diseases)
- someone diagnosed with cystic fibrosis
- have a diet deficient in vitamin K, and
- someone taking statins or osteoporosis medication (lowers conversion of K1 to K2).
Vitamin K is often given to counteract medications that thin the blood, like warfarin, and to newborns to protect from life-threatening bleeding in the skull.
Vitamin K Toxicity
Vitamin K toxicity is extremely rare and has mainly been reported from taking synthetic vitamin K forms. Toxicity has also been reported from the vitamin K shot delivered to newborns. Symptoms of vitamin K toxicity can look like jaundice, hemolytic anemia, and high bilirubin levels.
Does Vitamin K Cause Blood Clots?
Because of vitamin K’s role in blood clotting, many assume that the vitamin can prompt blood clots to occur. However, vitamin K is critical for synthesising proteins needed for blood clotting. Therefore, simply consuming more does not necessarily result in more clotting activity.
However, if someone is taking a medication like warfarin, vitamin K can counteract its effects–even if it’s sourced from food!
Satiety Response to Vitamin K1 in Food
Our satiety analysis indicates that Vitamin K from food has a moderate influence on satiety. People getting more Vitamin K1 in their food tend to consume 20% fewer calories than those consuming less vitamin K1. However, this lower food intake may simply correspond to a nutrient-dense, low-energy-density diet loaded with non-starchy green veggies and satiating protein.
Not enough is known about levels of vitamin K that contribute to deficiency to set the DRI. Subsequently, an Adequate Intake has been set based on the average Vitamin K intake in healthy populations.
The average intake of Optimisers is 533 micrograms (mcg) per 2000 calories, which is significantly higher than the ‘Adequate Intakes’ of 60 mcg per day for men and 50 micrograms per day for women.
Optimal Vitamin K1 Intake
Based on our satiety analysis, we have set a K1 stretch target of 1100 mcg for men and 880 mcg for women. Once you have started to get the hang of nutrient density, you could ‘level up’ by targeting these stretch targets to optimise your nutrition.
| nutrient | men | women |
| vitamin K1 (mcg) | 1100 | 880 |
Note: While difficult to track in tools like Cronometer, Chris Masterjohn suggests it could be helpful to aim for at least 100 to 200 mcg of vitamin K2.
Synergistic Nutrients with Vitamin K1
Vitamin K works synergistically with vitamins A, B3, B6, C, calcium, D, E, and manganese. In other words, vitamin K can’t carry out any of its fundamental processes without the help of these nutrients. For this reason, we recommend consuming vitamin K from a nutrient-dense diet to ensure you’re consuming the complete profile of all of these vitamins and minerals.
Nutrient Profile of High Vitamin K Foods
The nutrient fingerprint chart below shows that it is straightforward to obtain adequate Vitamin K1 from a nutrient-dense omnivorous diet. Because foods high in vitamin K1 are typically plant-based foods, they have plenty of protein and fibre and less fat.
How Do I Calculate My Vitamin K Intake?
If you’re interested in checking if you’re getting enough vitamin K in your diet, you can see your nutrient profile using our Free 7-Day Food Discovery Challenge.
After a week of tracking your current diet in Cronometer, Nutrient Optimiser will give you a prioritised list of foods and NutriBooster recipes that will help you plug your current nutritional gaps.
Level Up Your Nutrient Density
To help you level up your nutrient density, we’ve prepared a Nutritional Optimisation Starter Pack to ensure you are getting plenty of all the essential nutrients from the food you eat every day.
The free starter pack includes:
- Maximum Nutrient Density Food List
- Sample Maximum Nutrient Density Recipe Book
- Sample Maximum Nutrient Density Meal Plan.
To get started today, all you have to do is join our new Optimising Nutrition Group here.
Once you join, you will find the Nutritional Optimisation starter pack in the discovery section here.
Nutrient Density Index
Minerals
Vitamins
- Vitamin A
- Vitamin E
- Thiamine (B1)
- Riboflavin (B2)
- Niacin (B3)
- Pantothenic acid (B5)
- Vitamin B6
- Folate (B9)
- Vitamin B12
- Vitamin C
- Vitamin D
- Choline
- Vitamin K1