Key Takeaways
- Vitamin K refers to a collection of fat-soluble nutrients called phylloquinone (K1) and menaquinones (K2). Plant foods are higher in K1 while animal products have more K2.
- Vitamin K’s primary role is blood clotting, but it also assists with forming proteins needed for robust bones.
- Some of the best sources of vitamin K include leafy greens like spinach and kale, cruciferous vegetables such as broccoli and cauliflower, and natto.
Understanding Vitamin K
Vitamin K is a fat-soluble vitamin, but your body handles it differently than other fat-soluble vitamins like A, D, and E. Instead of storing excess K in fat tissue, your body metabolizes surplus quickly and removes it via urine. This makes toxicity less likely, but it also means you must regularly consume adequate K daily.
Vitamin K is abundant in leafy greens. In fact, one serving of certain leaves gives some people their entire recommended daily vitamin K. But other good sources can help you meet your needs too. Let’s explore further.
The Two Main Types: K1 and K2
While we refer to vitamin K as one nutrient, it’s actually several compounds divided into vitamin K1 and K2:
- Vitamin K1, aka phylloquinone, makes up most dietary K. It’s primarily in plant foods.
- Vitamin K2 refers to menaquinones. Animal products and fermented foods contain more K2, but gut bacteria also produce it – another reason to nourish healthy gut flora.
The Key Benefits of Vitamin K
Vitamin K is required to produce certain proteins critical for health. Key benefits include:
- Aiding proper blood clotting
- Supporting strong bones and potentially decreasing fractures
- Enhancing insulin sensitivity 2 hours after an oral glucose tolerance test when higher K1 intake precedes the test – more research is required
- Preventing artery calcification – scientists are investigating if K status impacts heart health
- Protecting cognitive function during aging – researchers believe nutrients in greens like K may help
11 Foods High in Vitamin K
Eating produce is one of the best ways to consume vitamin K. But other options can also provide what you need as part of a nutritious diet. Here are 11 foods loaded with vitamin K.
1. Leafy Greens
Leafy greens have some of the highest vitamin K levels. These include:
- Spinach
- Kale
- Collard greens
- Swiss chard
- Mustard greens
- Beet greens
- Arugula
Collards and turnip greens contain the most (420-530 mcg per 1⁄2 cup). But one cup of raw spinach has 145 mcg – more than an entire day’s K needs for most adults.
2. Cruciferous Vegetables
It’s not just leafy greens that deliver vitamin K. Other green veggies like broccoli, Brussels sprouts, cabbage, and cauliflower also supply substantial amounts. For example, one cup of Brussels sprouts provides 156 mcg. Broccoli has about half that with 77.5 mcg per cup.
3. Avocados
Avocados offer around 32 mcg vitamin K per average fruit. Their healthy fats help absorb the fat-soluble nutrient too. Add avocado slices to leafy green salads for an extra kick.
4. Vegetable Oils
While fish itself doesn’t provide much vitamin K, tuna canned in oil packs a punch thanks to the oil it’s packed in. One can has 12.3 mcg K – not huge but a nice addition to other K-rich foods.
5. Natto
Natto, a popular Japanese fermented soybean dish, is exceptionally high in K2. Just 3 ounces (about 1⁄2 cup) contains a whopping 850 mcg – over seven times the recommended daily amount for adults.
Research links natto consumption to slower bone loss in postmenopausal women. The K2 and soybean isoflavones likely contribute to the bone-protective effects.
6. Fruit
Although fruits have less vitamin K than many vegetables, they add up when combined with other sources. For example, one cup of blackberries or blueberries provides around 28.5 mcg. Dried figs have about 23 mcg per cup.
For better absorption, enjoy berries and nuts like walnuts together in yogurt.
7. Soybeans
Soybeans offer 47 mcg vitamin K per cooked cup. Stick to whole soybeans over oil for the fiber, protein, and other nutrients too.
8. Tree Nuts
Tree nuts like walnuts, almonds, and pistachios contain vitamin K. One ounce of walnuts (about 14 halves) has around 2.7 mcg. While not extremely high, nuts’ monounsaturated fats boost K absorption. Sprinkle them onto leafy salads.
9. Turkey Breast
While many meats provide vitamin K2, turkey breast specifically contains more than other poultry. Three ounces of roasted turkey has about 5 mcg K. Combine it with veggies for more.
10. Cheese
Vitamin K2 content varies based on the type and fat level. According to one study, hard cheeses like gouda and blue cheese offer around 43-65 mcg K2 per serving.
Full-fat versions tend to be higher than low-fat.
11. Eggs
Like other animal foods, eggs offer vitamin K2. Three large eggs have about 15 mcg. Though not extremely high, pair eggs with leafy greens to meet your daily target.
Signs and Causes of Vitamin K Deficiency
Symptoms of vitamin K deficiency relate to impaired blood clotting. These include easy bruising, bleeding gums, heavy menstrual bleeding, and blood in the urine or stool.
Deficiencies are uncommon, but some groups are at higher risk, like those with:
- Celiac disease
- Crohn’s disease
- Ulcerative colitis
- Liver disease
People who’ve undergone bariatric surgery may also need supplements. For most though, food sources of K are best.
How Much Vitamin K Do You Need Daily?
Recommended intakes vary by age and gender:
| Life Stage | Recommended Amount (mcg) |
|---|---|
| 0–6 months | 2 mcg |
| 7–12 months | 2.5 mcg |
| 1–3 years | 30 mcg |
| 4–8 years | 55 mcg |
| Children 9–13 years | 60 mcg |
| Teens 14–18 | 75 mcg |
| Pregnant teens | 75 mcg |
| Women 19+ years | 90 mcg |
| Breastfeeding women | 90 mcg |
| Men 19+ years | 120 mcg |
To illustrate, an adult woman could meet her RDA of 90 mcg by eating a cup of raw spinach (145 mcg) with half an avocado (32 mcg) for approximately 177 mcg total.
Is Too Much Vitamin K Harmful?
It’s possible to consume excess vitamin K, but overdose is very rare since surplus is excreted in urine. There is no established upper limit because toxicity risk is negligible.
However, if you take blood thinners like warfarin, avoid suddenly increasing or decreasing foods high in vitamin K, as this can impact medication effectiveness.
The Bottom Line
Vitamin K includes several compounds, primarily vitamin K1 from plants and K2 from animal foods. Leafy greens, cruciferous vegetables, avocados, natto, and other foods provide vitamin K to support blood clotting, bone health, heart health, and brain function. Eating a variety of foods high in this essential nutrient ensures you meet your daily needs.
Frequently Asked Questions
What foods provide the most vitamin K?
Leafy greens like kale, spinach, and Swiss chard are some of the richest sources. Other excellent sources include broccoli, cabbage, natto, avocados, soybeans, nuts, eggs, and cheese.
How much vitamin K should I get daily?
Most adults need at least 90-120 mcg per day. Pregnant and breastfeeding women need 90 mcg. Children need varying amounts between 2-75 mcg depending on age.
What are signs of vitamin K deficiency?
Deficiency symptoms relate to impaired blood clotting and include easy bruising, nosebleeds, bleeding gums, heavy menstrual bleeding, and blood in urine or stool. Underlying health conditions can increase deficiency risk.
Can you consume too much vitamin K?
Vitamin K overdose is very unlikely because excess is excreted in urine. There is no set tolerable upper limit due to its low toxicity risk when consumed through foods.
Does cooking destroy vitamin K?
Some vitamin K loss can occur when cooking greens and other plant foods. However, studies show good nutrient retention after cooking, so eating cooked greens and other vitamin K foods still provides what you need daily.
References
[1] FoodData Central. (2019). Blackberries, raw. U.S. Department of Agriculture.
[2] FoodData Central. (2019). Blueberries, raw. U.S. Department of Agriculture.