World's Healthiest Foods rich in
vitamin K
FoodCalsDRI/DV
For serving size for specific foods see the
Nutrient Rating Chart.
Basic Description
There are few nutrients as closely identified with a specific food
source as vitamin K. We list ten foods and spices that contain more than
the adult male Adequate Intake (AI) for vitamin K, and each one is a
green vegetable. In fact, you'll need to go down to number 17 on our
list to find the first food—soybeans—that is not green.
Given the rich quantity of green vegetables in the World's
Healthiest Foods recipes, you'll get more than enough vitamin K to meet
your daily needs with our approach. This is good news because the health
benefits associated with diets rich in vitamin K have been expanding in
new and unexpected ways.
If you've read about vitamins A, B, C, D, and E, you might feel
like we've missed a few as we jump to vitamin K. But there are no
vitamins F through J (at least not yet). Vitamin K is named after the
German word for blood clotting (
koagulation). We'll explain the link as we talk about the role of vitamin K in health support below.
There are two types of vitamin K found in our diets. One type,
and by far the more important to human nutrition, is phylloquinone (or
vitamin K1). This type is found in plant foods only. The other type is
menaquinone (also known as vitamin K2). This type is produced in
bacteria, including the type of bacteria found in human and animal
intestines. Happily, both types of vitamin K appear to be sufficient to
prevent deficiency, although some believe that vitamin K2 may have some
unique effects at the far reaches of intake.
Of the World's Healthiest Foods, 21 are excellent sources of
vitamin K. Another seven WHFoods are very good sources, and 12 are good
sources. Five of the World's Healthiest Herbs and Spices are excellent
sources of vitamin K, as well. This list should provide you plenty of
choices to ensure a strong vitamin K intake.
Role in Health Support
Blood Clotting
The association between dietary vitamin K and blood clotting is
confusing, although this nutrient is very important in management of
this critical process. Blood clots are necessary to stop bleeding when
our skin gets cut, but inappropriate clotting of blood inside arteries
is an important step toward development of coronary artery disease.
It turns out that vitamin K plays a role both in the development
of blood clots and in the prevention of clotting. These both appear to
be true at intake levels that are routinely achieved through usual
diets.
Most famously, vitamin K is necessary for proper blood clots to
form. The clotting process is exceptionally complex, requiring at least
12 proteins to function before the process is complete. Four of these
clotting factors require vitamin K for their activity.
Luckily, we rarely see vitamin K deficiency lead to impairment in
the clotting process. We transiently see it in newborns because vitamin
K does not efficiently cross the placenta into a fetus, and it takes
several weeks to build up dietary stores. We also see it occasionally in
those with severe liver or gastrointestinal disease. But vitamin K
deficiency basically never causes clotting disorders in healthy adults.
On the other hand, we see a key role for vitamin K in slowing the
clotting process. This again occurs via multiple vitamin K-dependent
enzyme systems, most importantly one called matrix Gla protein.
It is currently somewhat of an open question how important
vitamin K is to the progression of clot formation and heart disease.
Researchers have sometimes, but not consistently, been able to correlate
low vitamin K intake with increased risk of heart disease.
One problem in interpreting this research, however, is separating
out the effect of healthy foods from the nutrients they contain. Even
casual readers of this site are probably aware that the same green leafy
vegetables that are our richest sources of vitamin K are also among the
best sources of many other heart-protecting nutrients.
Researchers have attempted to answer this question by giving
vitamin K in pill form at amounts similar to those found in the diet.
Over a three-year period, 500 mcg of vitamin K—about the amount found in
a serving of mustard greens—was associated with slightly slower
progression of hardening of the arteries of the heart.
Given the preliminary and often contradictory nature of this
research, we would characterize the association between diets high in
vitamin K and protection against coronary artery disease to be
plausible, but still unproven.
Bone Health
Vitamin K is necessary for the activation of a protein called
osteocalcin. This protein is used in the mineralization of bone, a
process by which calcium and other minerals are added to the structural
protein matrix.
Researchers are only now starting to see the critical ancillary
role vitamin K plays in bone metabolism. For example, low levels of
vitamin K are emerging as a potential risk factor for osteoporosis,
particularly in people with bowel disease. Additionally, researchers
have shown that increasing dietary vitamin K intake by 100 mcg per
day—roughly doubling the average American adult intake—led to a
significant increase in bone density in post-menopausal women over one
year.
Perhaps unexpectedly, low intakes of vitamin K have also been
correlated in multiple studies with arthritis. Drilling down,
researchers have found low activity of vitamin K dependent-proteins
inside arthritic joints, establishing a potentially causative
relationship.
Note that the same green leafy vegetables that are our best
sources of vitamin K are also very good to excellent sources of calcium
and magnesium, the two most important minerals for building strong
bones.
Summary of Food Sources
Understanding the best food sources of vitamin K is a pretty easy
process. You can be pretty confident that any green vegetable contains
10% or more of your Adequate Intake (AI) for vitamin K. If that green
vegetable is leafy, you should expect it contains close to 100% of the
AI, and could potentially contain several times that much.
The best sources of vitamin K are all plant foods. In addition to
green vegetable sources, many fruits and legumes contain significant
amounts of vitamin K. We see examples of both types of foods—blueberries
and soybeans, for instance—that provide up to one-third of the adult
male AI. Similarly, a number of non-green vegetables provide up to 20%
of the AI.
Surprisingly, some herbs and spices contain nutritionally
relevant amounts of vitamin K. For instance, just 2 tablespoons of
parsley contain the entire AI for this nutrient. A number of other
World's Healthiest Herbs and Spices also contain 5% or more of the AI
for vitamin K.
While the bacteria in our intestines do produce some absorbable
vitamin K, the amounts are not sufficient to meet our daily needs. So
you will always need to derive some vitamin K from your diet.
Understanding how to get enough vitamin K from your diet is
almost absurdly easy. If you eat two or three servings of green
vegetables per day, you'll probably get your AI or close to it. If you
make one of those green vegetables leafy, you'll probably approach the
AI with this single serving.
Adding fruits or legumes to your diet will help to add some extra
vitamin K, as well. Liberal use of fresh herbs and spices in the way
that we do in many of our recipes will also add significant vitamin K.
Nutrient Rating Chart
Introduction to Nutrient Rating System Chart
In order to better help you identify foods that feature a high
concentration of nutrients for the calories they contain, we created a
Food Rating System. This system allows us to highlight the foods that
are especially rich in particular nutrients. The following chart shows
the World's Healthiest Foods that are either an excellent, very good, or
good source of vitamin K. Next to each food name, you'll find the
serving size we used to calculate the food's nutrient composition, the
calories contained in the serving, the amount of vitamin K contained in
one serving size of the food, the percent Daily Value (DV%) that this
amount represents, the nutrient density that we calculated for this food
and nutrient, and the rating we established in our rating system. For
most of our nutrient ratings, we adopted the government standards for
food labeling that are found in the U.S. Food and Drug Administration's
"Reference Values for Nutrition Labeling."
Read more background information and details of our rating system.
World's Healthiest
Foods Rating | Rule |
|---|
| excellent |
DRI/DV>=75% OR
Density>=7.6 AND DRI/DV>=10% |
| very good |
DRI/DV>=50% OR
Density>=3.4 AND DRI/DV>=5% |
| good |
DRI/DV>=25% OR
Density>=1.5 AND DRI/DV>=2.5% |
Impact of Cooking, Storage and Processing
Vitamin K is a fairly stable nutrient to most types of processing.
Levels go down only slightly with common cooking techniques, and tend to
stay stable with storage.
Vitamin K in oils, but probably not in vegetables, is reduced by
exposure to light. This is one reason, but certainly not the only one,
that we recommend storing oils in dark areas and in opaque, sealed
containers.
The
hydrogenation process
that is used to stabilize and solidify liquid fats damages a
significant amount of the vitamin K content. This is just one of many
reasons why we believe that hydrogenated fats should be avoided.
Risk of Dietary Deficiency
For the most part, we don't see frank vitamin K deficiency symptoms
in the United States. In part because of this, we don't know
definitively what intake level of vitamin K is associated with problems
with blood clotting. Reflecting this, scientists talk more about an
Adequate Intake (AI) than a true deficiency.
By this AI standard, many age groups fail to meet vitamin K
recommendations on average. In particular, adolescents and young adults
are prone to sub-optimal dietary vitamin K intake. Also, males tend to
be less likely to meet AI goals than females.
This high risk of sub-optimal intake is almost certainly telling
us about our poor intake of vegetables in the U.S. For example, the
average American male in his 20s only obtains about 80 mcg of vitamin K
from his diet, an amount less than that found in a single serving of
broccoli.
As described above, it would be very easy to move from this
standard American diet marginal intake of vitamin K to a more optimal
level. Moving toward an approach that is based on the World's Healthiest
Foods would be an easy way to make this shift.
Other Circumstances that Might Contribute to Deficiency
The most common reason to see symptoms of vitamin K deficiency, at
least related to blood clotting, is use of medications that impair
vitamin K utilization. For people using these medications, the symptoms
of vitamin K deficiency are the goal, so you'll want to talk to your
doctor about how your diet fits into your treatment program.
Because vitamin K is a fat-soluble nutrient, you'll only obtain
it from foods that contain fat. For instance, the amount of vitamin K
found in a fat-free salad dressing is too low to measure. You don't need
much fat—turnip greens contain less than a gram of fat per 100 gram
serving, and are quite rich in vitamin K. It is theoretically possible,
although we can't find evidence that it is common, to eat a diet low
enough in fat to impair vitamin K nutrition.
There are a few disease states that can interfere with vitamin K
nutrition or utilization. For instance, any digestive disease that
impairs absorption of fat-soluble nutrients may impair vitamin K uptake
from foods. End-stage liver disease can also lead to symptoms of vitamin
K deficiency.
Relationship with Other Nutrients
Both vitamin A and vitamin E can compete for absorption with vitamin
K. To our knowledge, however, this has only been reported with mega-dose
supplementation, not with dietary intake. As such, you probably do not
need to eat in a certain pattern to protect your vitamin K nutrition.
Vitamin K works with the other nutrients important to bone
health—calcium, vitamin D, and magnesium—to ensure that your skeleton
stays strong. A deficiency of any of these nutrients can lead to
problems that cannot be fully undone by focusing on the other nutrients
on the list.
Risk of Dietary Toxicity
To our knowledge, there has never been a report of a person
developing an adverse reaction to vitamin K who was not on medications
that are influenced by this nutrient. Given the strong track record of
safety, the National Academy of Sciences did not choose to establish a
Tolerable Upper Intake Level (UL) for vitamin K. Further evidence for
the safety of dietary vitamin K comes from research studies where doses
of vitamin K at 500 times the Adequate Intake (AI) did not lead to
observable toxicity.
This is good news, as some of the WHFoods recipes contain close
to 20 times the adult male AI for vitamin K. This is unique among the
nutrients we profile on our website.
Please note that the UL is only meant to describe nutrient intake
for healthy adults. There are widely used medications that require
vitamin K restriction during treatment. If you are on one of these,
you'll need to work with your medical team to ensure proper vitamin K
intake.
Disease Checklist
- Blood clotting disorders
- Osteoporosis
- Coronary artery disease
- Cancer
- Liver disease
- Celiac disease
- Crohn's disease
- Ulcerative colitis
- Cystic fibrosis
Public Health Recommendations
In 2001, the Food and Nutrition Board (FNB) of the National Academy
of Sciences released a set of Dietary Reference Intakes (DRI) for
vitamin K. These included a set of age and gender specific Adequate
Intake Levels (AI) that are summarized in the following chart. The FNB
chose to establish an AI instead of a Recommended Dietary Allowance
because the existing research data are not currently strong enough to
determine a truly deficient level of intake. The AIs are as follows:
- 0-6 months: 2 mcg
- 6-12 months: 2.5 mcg
- 1-3 years: 30 mcg
- 4-8 years: 55 mcg
- 9-13 years: 60 mcg
- 14-18 years: 75 mcg
- 19+ years, female: 90 mcg
- 19+ years, male: 120 mcg
- Pregnant or lactating women, 14-18 years: 75 mcg
- Pregnant or lactating women, 19+ years: 90 mcg
The 2001 vitamin K DRI did not include an Upper Tolerable Intake
Level. We are not aware of any other authority who has suggested that
there is a toxic level of dietary vitamin K.
The Daily Value (DV) for vitamin K is 80 mcg. This is the value that you'll see on food and supplement labels.
References
- Ferland G, Sadowski JA. Vitamin K1 (phylloquinone) content of edible
oils: effects of heating and light exposure. J Agric Food Chem
1992;40:1869-73.
- Fisher L, Byrnes E, and Fisher AA. Prevalence of vitamin K and
vitamin D deficiency in patients with hepatobiliary and pancreatic
disorders. Nutr Res. 2009;29:676-83.
- Food and Nutrition Board, Institute of Medicine. Dietary
reference intakes for vitamin A, vitamin K, boron, chromium, copper,
iodine, iron, manganese, molybdenum, nickel, silicon, vanadium, and
zinc. Washington, DC: National Academy Press; 2001;394-419.
- Kanellakis S, Moschonis G, Tenta R, et al. Changes in
parameters of bone metabolism in postmenopausal women following a
12-month intervention period using dairy products enriched with calcium,
vitamin D, and phylloquinone (vitamin K1) or menaquinone-7 (vitamin
K2): the Postmenopausal Health Study II. Calcif Tissue Int
2012:90:251-62.
- Kuwabara A, Tanaka K, Tsugawa N, et al. High prevalence of
vitamin K and D deficiency and decreased BMD in inflammatory bowel
disease. Osteoporosis Int 2009;20:935-42.
- Neogi T, Booth SL, Zhang YQ, et al. Low vitamin K status is
associated with osteoarthritis in the hand and knee. Arthritis Rheum
2006;54:1255-61.
- Oka H, Akune T, Muraki S, et al. Association of low dietary
vitamin K intake with radiographic knee osteoarthritis in the Japanese
elderly population: dietary survey in a population-based cohort of the
ROAD study. J Orthop Sci 2009:14:687-92.
- Peterson JW, Muzzey KL, Haytowitz D, et al. Phylloquinone
(vitamin K1) and dihydrophylloquinone content of fats and oils. J Am Oil
Chem Soc 2002;79:641-6.
- Shea MK, Holden RM. Vitamin K status and vascular
calcification: evidence from observational and clinical studies. Adv
Nutr 2012;3:158-65.
- Shea MK, O'Donnell CJ, Hoffmann U, et al. Vitamin K
supplementation and progression of coronary artery calcium in older men
and women. Am J Clin Nutr 2009;89:1799-807.
The World's Heathiest Food
Adequate, lifelong dietary calcium intake is necessary to reduce the risk of osteoporosis.
Consuming adequate calcium and vitamin D and performing regular,
weight-bearing exercise are also important to build maximum bone density
and strength. With all the delicious substitutes for dairy products
these days, one can easily omit dairy from their diet. According to the
recommended guidelines for calcium, children 4-8 need 1000 mg and
children 9-13 need 1,300 mg and adults, including lactating mothers,
need 1,000 mg. There is a long list of plant foods that supply plenty of
calcium that is easily absorbed by the body: legumes, green leafy vegetables like kale , collards, mustard greens, turnip greens, bok choy, parsley, and broccoli, cabbage, oats, beans, sesame seeds, almonds, asparagus, as well as fortified plant milks, fortified juices, and firm tofu made with calcium-sulfate.
Seaweeds
are one of nature's true wonder foods! They are one of the most
nutritionally dense plants on the planet and also the most abundant
source of minerals in the plant kingdom as they have access to all the
nutrients in the ocean.
