Products are independently selected by our editors. We may earn an affiliate commission from links.
If you count broccoli, cauliflower, and Brussels sprouts as among your most-frequently eaten foods, congratulations—you may already be consuming sufficient levels of vitamin K.
Though vitamin K may be less well-known than vitamins C or D, it is no less vital. The vitamin is essential for proper blood clotting, bone health, prevention of osteoporosis, heart health, and proper assimilation of vitamin D—which we all know is extremely important, especially in those dark winter months.
Unfortunately, according to the National Library of Medicine, vitamin K deficiency “may be commonly observed in 8% to 31% of typically healthy adults.” Here’s what to know about this essential nutrient and how to ensure your levels of vitamin K stay optimal, including information on what to eat.
What is vitamin K?
The term vitamin K refers to a set of fat-soluble vitamins, which can be divided into two groups:
- Vitamin K1 or phylloquinone, found mainly in green leafy vegetables
- Vitamin K2 or menaquinone, which is found in animal foods and fermented foods, but can also be produced by gut bacteria
Vitamin K is essential for helping the blood to clot and for preventing excess bleeding. Additionally, vitamin K helps strengthen bones, and may prevent osteoporosis and fractures after menopause. Recent studies have indicated that vitamin K may also assist in preventing Alzheimer’s disease.
Vitamin K2, in particular, is also essential for enhancing the efficacy and safety of vitamin D as it minimizes the risk of raising calcium levels in the body to unhealthy levels.
Why should vitamin D be taken with vitamin K?
When vitamin D intake is recommended due to deficiency, your doctor may suggest taking vitamin K alongside your vitamin D supplement as well. Both are essential for bone and cardiovascular health and each is indispensable for the other. Vitamin D should be taken with vitamin K because the latter helps boost the effectiveness of the former. Specifically, vitamin D synthesizes proteins, which can only be activated by vitamin K— both are needed for activation and accumulation.
Foods that are high in vitamin K
Eating a varied diet of natural, whole foods should provide you with sufficient amounts of vitamin K to meet the daily recommended requirements of 90 to 120 mcg. In addition, vitamin K can be produced by the gut flora; when we consume too much, the excess is stored in the liver, and then released as needed.
Foods that contain high levels of vitamin K are:
- Green leafy vegetables such as spinach, chard, turnip greens, or kale
- Cauliflower, broccoli, and Brussels sprouts
- Vegetable oils such as olive oil and soybean oil
- Fermented foods such as sauerkraut, kimchi, and kefir
- Natto, or Japanese fermented beans (an outstanding source of vitamin K)
- Eggs
- Butter
- Chicken
- Gorgonzola and other blue cheeses that contain molds
- Blueberries
- Figs
How much vitamin K do you need per day?
As mentioned above, the recommended dose is 90 mcg for women and 120 mcg for men. Vitamin K should be taken after a meal that contains fat to optimize the vitamin’s absorption, as vitamin K is fat soluble.
It’s important to note that vitamin K can interfere with some medications, especially anticoagulants. Speak to a doctor or health care professional if you are on this type of medication and plan to take a vitamin K supplement.
Who should take a vitamin K supplement?
- Those who suffer from conditions such as celiac disease and inflammatory bowel disease, which can impede the absorption of vitamin K
- Those who follow prolonged treatment with antibiotics that destroy vitamin K-producing bacteria
- Those who have inadequate levels of prothrombin, a protein involved in blood clotting