Vitamin K-2 is pretty
important for heart and bone health.
This is especially true if you already take extra calcium and/or vitamin
D supplementation.
In addition to heart and bone
health, vitamin K-2 may also play a role in preventing insulin resistance and
metabolic syndrome.
So what is vitamin K-2 and
how do we ensure we are getting an adequate amount?
Most people have heard of
vitamin K, but don’t realize there are several compounds that have vitamin K
activity in our body. The naturally occurring forms of vitamin K are
phylloquinone (K-1), isolated from plants; and menaquinones (K-2 or MK) synthesized
by bacteria and found in some animal foods.
My main focus for this article will be on vitamin k-2 and how it can
help maintain a healthy heart and bones.
This is not to negate or minimize the importance of other forms of
vitamin K, as all the naturally occurring vitamins and minerals work in concert
with each other and each on play a critical role in our health.
Vitamin K-3 (Menadione),
Vitamin K-4, and vitamin K-5 do not occur naturally and are synthetic forms of
the vitamin which I will not discuss in this article either.
Vitamin K-2 has several sub
types, each with a slightly different chemical structure. These are known as MK-4, MK-7, MK-8 etc., all
the way up to MK 11. The two most
studied forms of vitamin K-2 are MK-4 and MK-7.
MK-4 can be made from K-1 in
certain tissues of the body (testes, arterial walls, and pancreas). The MK-4 found in supplements is a synthetic
version of the naturally occurring MK-4.
Unlike MK-4, MK-7 can not be
produced from vitamin K-1 and it is dependent on bacteria in the digestive
tract for production or it can be obtained from eating foods high in vitamin
K-2.
How does this relate to Heart
and Bone Health?
Vitamin K-2 for Heart and
Bone Health
While vitamin K 1 is important
for proper blood clotting, vitamin K-2 has completely different functions in
the body. Vitamin K-2 is needed to properly metabolize calcium. Several studies have shown that women who
take calcium supplements, with or without Vitamin D, have 20-30% more heart
attacks and strokes than those who don’t take calcium supplementation. Could vitamin K-2 be the missing link? When calcium enters the blood, it is
transported to the tissues that need it, such as the heart, other muscles, or
bones under the direction of vitamin K-2.
If there is not enough vitamin K-2 to move calcium into the proper tissues,
calcium can be deposited into other tissues causing problems. For example, when excessive calcium is placed
in the arteries it makes them stiff (called hardening of the arteries or arthrosclerosis). Arthrosclerosis will eventually cause an
obstruction to the blood flow in the arteries.
Obstruction of blood flow to the brain can lead to a stroke, while
obstruction of blood flow to the heart may cause a heart attack. Excessive calcium can also be deposited into
other tissues causing such things as bone spurs or kidney stones. In the meantime we become deficient of
calcium in the bone because without vitamin K calcium cannot get into the bones
and this puts us at risk for developing osteoporosis. When calcium metabolism is properly regulated,
it does not get deposited into places such as the arteries or kidneys. Vitamin K-2 works with vitamin D to makes sure
calcium is in the proper place at the proper time. It does this by activating two different
proteins in our bodies. One of these
proteins function is to move calcium into the bones and teeth. The second protein helps find calcium that has
been deposited inappropriately, such as in the arteries, and then removes it
from these areas. Bone normally is not
static and is constantly breaking down and rebuilding. If this break down occurs more rapidly than
we can rebuild it, we end up with bone loss.
After menopause, with the loss of hormones, it is common to have
increased breakdown of bone. Some
observational studies have concluded that vitamin K-2 insufficiency may be responsible
for age-related bone loss.
Vitamin K-2 and Wrinkles
Excessive wrinkles are a
known symptom of K-2 deficiency. Without
sufficient vitamin K, excessive calcium is deposited in the skin, which causes
a loss of elasticity, the same way it causes stiffness in the arteries. K-2 helps remove this excessive build-up of
calcium in the skin.
Why K-2 May Be Lacking In
Your Diet?
According to Dr. Kate Rhéaume-Bleue, “Vitamin K-2 has become almost impossible to get in
the modern diet due to industrial farming techniques and confined animal
feeding.” In addition, the richest sources
of vitamin K-2 are not common foods in the American diet. Then there is the issue of over use of
antibiotics which destroy the good bacteria in our digestive system, and limit
the number of bacteria making vitamin K-2 for us. And even if you rarely take antibiotics,
they are so common in our food supply that we get them weather we realize it or
not. Lastly, low-fat diets interfere with the
amount of vitamin K we actually absorb. All
forms of vitamin K are fat soluble. As
such, absorption is enhanced when taken as part of a meal with some fat. Both bile salts (released in response to the
amount of fat in the meal) and pancreatic juice (dependent on good stomach acid
which naturally declines as we age and good pancreatic function) increase the amount
of vitamin K we absorb. Even if we do
consume adequate amounts of fat, many individuals have difficulty absorbing
dietary fats, which means we are not getting our fat soluble nutrients or
essential fatty acids into the blood where they are needed to get to all the
cells of our body. To paraphrase, absorption of vitamin K (and
many other nutrients) requires the presence of fat in a meal, good stomach
acid, adequate amount of bile from the gall bladder, and adequate pancreatic
function for digestive enzymes. Many of
these functions naturally decline with age.
Could this be why our risk of a heart attack increases as we get older?
As a nutritionist, I always
recommend food first, and then supplement with proper profession guidance if
needed.
So let’s discuss some ways to
ensure we do get adequate vitamin K-2 from our food.
- Eat 100% grass-fed meats. Grains-fed meats don’t have vitamin
K-2. Look for 100% grass-fed or grass-fed
and grass-finished on the label.
- Eat the yolks from truly free-range chicken eggs
of chickens eating a natural diet and that spend some time outdoors. Usually the eggs from healthy chickens have
a deep almost orange color yolk.
Farmers markets are a great source of healthy eggs. High omega-3 eggs are usually obtained
from chickens fed flax seeds.-3 fatty acids are a frequently a healthy
addition to the diet, flax seed does not provide vitamin K to the chickens
so their eggs won’t necessarily be a good source of vitamin K-2.
- Include Goose liver. Even when non-grass fed,
goose liver is high in vitamin K-2.
- Certain fermented foods are a source of vitamin
K-2. Gouda and Brie cheese are high in K-2. One serving of brie cheese contains
approximately 40-50 mcg vitamin K-2; this is about 50% of the daily
recommended intake according to Dr. Kate Rhéaume-Bleue.
- It is important to note that not all fermented
foods are a source of vitamin K-2, as only certain bacteria produce the
vitamin. K-2 is not in dairy
products, but the fermentation process used to make brie and gouda cheeses
introduce vitamin K-2.
- Natto. A
fermented soy beans dish that is common in some areas of Japan, is
the single highest food source of vitamin K-2. 1 serving of natto has ~ 300-400 mcg of
vitamin K-2 in the MK-7 form.
Toxicity
Concerns
Natural
source of vitamin K-2 when taken in balance with other nutrients has not been
shown to be toxic. Some synthetic forms
of vitamin K are toxic and should only be used under the direction of a health
care provider. Remember K-2 needs to be
balanced with vitamin D.
Drug
interaction/cautions
People
taking prescription anticoagulants, which intentionally interfere with the role
of vitamin K, need to monitor their dietary intake of vitamin K containing
foods closely, and should never take supplemental vitamin K without first
discussing it with their doctor.
Vitamin K supplementation during pregnancy (beyond normal dietary intake) may
increase the risk of jaundice in the newborn. Vitamin K ingested by breastfeeding mothers is
generally considered safe.
High doses of aspirin and quinine may
increase vitamin K requirements; antacids may decrease absorption of vitamin K,
and vitamin K may decrease the blood thinning effects of several herbs
including alfalfa, American ginseng, anise, celery, chamomile, horse chestnut, and red clover.
References:
Groff, James L. and Gropper,
Sareen S. “Advanced Nutrition and Human
Metabolism.” 3rd ed. Wadsworth: Australia;
2000. pg. 351-357.
Gundberg, Caren M. et al. “Vitamin K-Dependent Carboxylation of
Osteocalcin: Friend or Foe?” doi: 10.3945/an.112.001834Adv Nutr March 2012 Adv Nutr vol. 3: 149-157, 201.
Accessed July 31, 2016.
Inaba N, et Al.
“Low-Dose Daily Intake of Vitamin K (2) (Menaquinone-7) Improves
Osteocalcin y-Carboxylation: A Double-Blind, Randomized Controlled Trials.” J Nutr Sci Vitaminol (Tokyo). 2015;61(6):471-80. doi:
10.3177/jnsv.61.471. Assessed July 31,
2016.
Rhéaume-Bleue, Kate. “The Calcium Paradox. Lecture-The link between Osteoporosis and
Heart Disease.” Recorded April 25,
2012. https://www.youtube.com/watch?v=fYMExQNosTQ Accessed July 31, 2016.
Shearer MJ. “Vitamin K
metabolism and nutritive.” Blood Rev. 1992
Jun; 6(2):92-104. Accessed July 31, 2016
