What is Vitamin K?

Vitamin K?  “I didn’t even know there was a Vitamin K?” This is usually the answer I get when I start talking about this amazing Vitamin.  Who knew there was a Vitamin K?  Well, to be honest…you should know.   Vitamin K, although discovered back in 1929, has gained new press these days because of its association with increased bone density and decreased artery calcification.  In fact, Vitamin K could be the missing link scientists have been looking for, in solving the Calcium Paradox.  (The Calcium Paradox is the simultaneous excess of calcium in one part of the body, arteries, and lack in another, bones, which may occur regardless of calcium supplementation.)  So are you eating enough foods with Vitamin K?  Do you even know what foods contain Vitamin K?  No?  Well, good thing you are reading this blog…

First:  what is Vitamin K?

Vitamin K is a group of fat-soluble Vitamins needed for blood coagulation (blood clotting) increasing metabolic pathways of bone generation and decreasing arterial calcification.  There are two main natural forms of Vitamin K; K1 and K2.

We will discuss both since they have significantly different functions.

Vitamin K1.

Vitamin K1 (also known as Phylloquinone or phytomenadione) was discovered in 1929 by Danish scientist Henrick Dam, and was referred to as Koagulationsvitamin.  As its name implies, Vitamin K1 is involved in blood coagulation.  Without K1 we could bleed to death from a simple paper cut.  Unlike your other fat-soluble vitamins (Vitamin A, D, and E) your body does not store high levels of Vitamin K1 in your tissue.  Luckily your body has a special mechanism that recycles the vitamin, so dietary requirements of Vitamin K1 are minimal.

The best sources of Vitamin K1 are green leafy plants like kale, spinach, collards, chard and broccoli.  There are also smaller amounts of K1 in roots vegetables and fruits.  My personal recommendation for someone in need of more Vitamin K1, is to drink a mineral broth.  Essentially you cook kale spinach, lettuce, chard and any other leafy greens in a pot of filtered water.  After the water turns a pretty green, you remove the vegetables and drink the broth (about a1-3 once a day).  As some of you know I am not a big fan of eating lots of above ground vegetables, especially leafy greens.  Drinking only the mineral broth and not eating the vegetable fibers will protect you from the polyunsaturated fats, vegetable toxins and cellulose found in the vegetables.  For more on this topic refer to my blog Leafy Greens- Essential or toxic?

 Vitamin K2

Vitamin K2, the main storage form in animals, is primarily used to move Calcium around the body.  To be more specific, Vitamin K2 helps Calcium move into the bones and out of the arteries—which is pretty important, right?  Vitamin K2 is sometimes referred to as the “grass-fed” Vitamin.  Westin A. Price, the dentist who discovered Vitamin K2 back in the 1940’s (Yet, he didn’t realize this and termed the Vitamin, “activator x”), noticed a huge correlation between Vitamin K2 levels and the amount of grass an animal ate.  What he realized was the more green leafy plants (grass) these animals ate the higher the Vitamin K2 content was in their milk, egg yolks, organs, and butter.  You see, K2 can be created from K1 in the testes, pancreas and arterial walls of certain animals.   And since we know there are high levels of K1 in leafy green plants (refer back to reading about K1 if I lost you here), it would make sense that this would produce more K2 levels.

Now, I know my vegetarian friends are already thinking, “If animals can produce K2 from K1, can humans do this as well?  Can humans produce our own K2, thus making eating animal foods unnecessary?”  Well, kind of…Humans can produce very small amounts of K2 by the bacteria in our intestinal tract from K1.  However, these very small amounts are not nearly enough to prevent a Vitamin K2 deficiency.  In fact, Vitamin K2 is now being looked at as an essential nutrient; since we now know we cannot produce adequate amounts by our intestinal flora.  In addition, unlike Vitamin K1, K2 is not recycled in the body, creating a daily need for this nutrient.   This means we have to get Vitamin K2 directly from our foods.

What foods contain Vitamin K2?

Vitamin K2 is primarily located in the milk fat of animals and in their organs and fatty tissue.  Good sources are foie gras (goose liver), butter, ghee, egg yolks, and grass-fed meats and organs.  Vitamin K2 can also be synthesized via fermentation in certain foods.  Dutch Gouda cheese, French brie and other cheeses are good sources of fermented foods with high Vitamin K2 levels.  Natto, or fermented soy, is also a great source of Vitamin K2.  As long as you understand the negative effects of soy, this may be the way to go if you are a vegetarian and need more K2.  The only BIG problem with natto is it taste like an old shoe and has the texture of stringy, gooey, slimy cheese…yum.

It wasn’t until 2006 that the US Department of Agriculture along with Tufts University determined the K2 content in most foods.  It has taken years of current research for scientist to realize how different K1 and K2 actually are, and that K2 needs its own daily requirements outside of K1.

The Science behind Vitamin K2.

Bone Health

Current research is linking Vitamin K2 to increased bone calcification and decrease arterial calcification.  In 2000, the team of M. Shiraki studied 241 osteoporotic patients for 2 years.   After 2 years the treated group that ingested 45mg of oral K2 had far lower incidents of repeat fractures. In 2004 another group of Japanese researchers found that vitamin K2 sustains the lumbar bone mineral density (BMD), prevented osteoporotic fractures in patients with age-related osteoporosis, and vertebral fractures in patients with glucocorticoid-induced osteoporosis.  They concluded that K2 not only increases bone formation but also suppresses bone re-absorption.  Based on these and many others studies Vitamin K2 is already used in Japan as a way to treat osteoporosis.

As I stated in my Calcium blog, there is much more to increasing bone density than just Calcium.  No nutrient works without its “team”.  Just like you cannot play football with only a quarterback, you cannot build healthy bone with only Calcium.  Your team–Magnesium, Vitamin A, Vitamin D, Vitamin E, fats, proteins, sugars and the newest member to this bone building team, Vitamin K2 –are all essential.

Cardiovascular Health

In 2004 the Rotterdam study reported that after following 4,800 individual for 10 years, those who ingested higher levels of Vitamin K2 had lower levels of cardiovascular disease and mortality.  In 2009, a team of researchers from the Netherlands analyzed research from the Prospect-EPIC cohort of over 16,000 women.  They concluded that those who ingested higher levels of K2 had far lower chances of cardiovascular heart disease (CVD).

For years people have tried to understand how the French can eat a diet rich in saturated fats and cholesterol and maintain lower levels of heart disease.  Well, the fact that the French love foie gras, butter and cheese may actually prove to their favor.  These foods are high in saturated fats, proteins, Vitamin A, D, E and Vitamin K2.  Since we now know saturated fat and cholesterol are not the bad guys we were all lead to believe – these foods may be just what the doctor ordered when it comes to the health of your heart and bones.

In addition to helping with osteoporosis and CVD, Vitamin K2 has also been linked to:

Treating Alzheimers patients;

Protecting against certain types of cancers including liver, lung, prostate and Non-Hodgkin Lymphoma;

Improving insulin sensitivity in diabetics;

Preventing joint damage; and

Increasing elasticity in skin improving wrinkles and varicose veins.

How much Vitamin K2? 

Most scientific research says we should be consuming around 45mcg of K2/day.  This is equal to about 2 ounces of raw Gouda cheese. In supplement form, 15 mg- 45 mg. of liquid K2 is recommended.  Personally, I use a combination of both: the days I eat more cheese and liver, I use less liquid K2.  The days I eat less Vitamin K2 enriched foods the more I supplement with liquid Vitamin K2.  Every person will be different, but for most people adding in a Vitamin K2 supplement should prove to be beneficial.  I prefer liquid K2 by Thorn research.

There are no known toxicity levels with Vitamin K2.  However, Vitamin K2 foods and supplements can interfere with the activity of oral anticoagulants (blood thinners) such as warfarin  (Coumadin). Patients who are using warfarin should only use vitamin K2 supplements with the knowledge of the prescribing physician.  In addition, if you are pregnant or nursing please consult your physician before adding in a Vitamin K2 supplement.

Although, Vitamin K2 research is still in its infancy, it has already proven to be a big player in your bone and cardiovascular health.  As always the best source of all vitamins and minerals is a real food diet.   However, proper supplementation of Vitamin K2 can prove to be beneficial.  If you are concerned about your bone or heart health please consult your physician.

Your Optimal Health Coach,

Kate

Disclaimer:

“I am an exercise physiologist, personal trainer, nutritional and lifestyle coach, not a medical doctor.  I do not diagnose, prescribe for, treat or claim to prevent, mitigate or cure any human disease or physical problem. I do not provide diagnosis, care treatment or rehabilitation of individuals, nor apply medical, mental health or human development principles.  I do not prescribe prescription drugs nor do I tell you to discontinue them.  I provide physical and dietary suggestions to improve health and wellness and to nourish and support normal function and structure of the body.  If you suspect any disease please consult your physician.”

References:

1.  Pearson DA.  “Bone health and osteoporosis: the role of vitamin K and potential antagonism by anticoagulants”. Nutr Clin Pract. 2007 Oct; 22(5):517-44.

2.  Vermeer C.  “Vitamin K: the effect on health beyond coagulation – an overview”.
Food Nutr Res. 2012 Apr 2.

3.  Vermeer C, Theuwissen E.
Vitamin K, osteoporosis and degenerative diseases of aging”.
Menopause Int. 2011 Mar; 17(1):19-23.

4.  Jie KS, Bots ML, Vermeer C, Witteman JC, Grobbee DE.
Vitamin K intake and osteocalcin levels in women with and without aortic atherosclerosis: a population-based study”.
Atherosclerosis. 1995 Jul; 116(1):117-23.

5.  Yoshida T, Miyazawa K, Kasuga I, Yokoyama T, Minemura K, Ustumi K, Aoshima M, Ohyashiki K. “Apoptosis induction of vitamin K2 in lung carcinoma cell lines: the possibility of vitamin K2 therapy for lung cancer”. Int J Oncol. 2003 Sep;23(3):627-32.

6.  Iwamoto J, Takeda T, Sato Y. “Role of vitamin K2 in the treatment of postmenopausal osteoporosis”. Curr Drug Saf. 2006 Jan;1(1):87-97.

7.  Wallin R, Schurgers L, Wajih N.  “Effects of the blood coagulation vitamin K as an inhibitor of arterial calcification”.
Thromb Res. 2008;122(3):411-7.

8.  Iwamoto J, Takeda T, Sato Y. “Effects of vitamin K2 on osteoporosis”. Curr Pharm Des. 2004;10(21):2557-76.

9.  Gast GC, de Roos NM, Sluijs I, Bots ML, Beulens JW, Geleijnse JM, Witteman JC, Grobbee DE, Peeters PH, van der Schouw YT. “A high menaquinone intake reduces the incidence of coronary heart disease”. Nutr Metab Cardiovasc Dis. 2009 Sep;19(7):504-10.

10.  Weijs B, Blaauw Y, Rennenberg RJ, Schurgers LJ, Timmermans CC, Pison L, Nieuwlaat R, Hofstra L, Kroon AA, Wildberger J, Crijns HJ.  “Patients using vitamin K antagonists show increased levels of coronary calcification: an observational study in low-risk atrial fibrillation patients”.
Eur Heart J. 2011 Oct;32(20):2555-62.

11.  Schurgers LJ, Vermeer C. “Determination of Phylloquinone and Menaquinones in Food. Haemostasis”. 2000; 30: 298-307

12.  Price, Weston A. “Nutrition and Physical Degeneration”. Self-published, 1945

13.  Couvreur S, Hurtaud C, Lopez C, Delaby L, Peyraud JL.  “The linear relationship between the proportion of fresh grass in the cow diet, milk fatty acid composition, and butter properties”.  J Dairy Sci. 2006 Jun; 89(6):1956-69.

14. Chris Masterson, On the Trail of the Exclusive X factor: A 60 year old mystery finally solved. Thurs, 14, 2008

15. Orimo H, Shiraki M, Tomita A, Morii H, Fujita T, Ohata M (1998) “Effects of menatetrenone on the bone and calcium metabolism in osteoporosis: a double-blind placebo-controlled study”. J Bone Miner Metab 16:106–112

16. Shiraki M, Shiraki Y, Aoki C, Miura M (2000) “Vitamin K2 (menatetrenone) effectively prevents fractures and sustains lumbar bone mineral density in osteoporosis”. J Bone Miner Res 15: 515–521

17.  “Vitamin K found to protect against liver cancer”

http://www.nutraingredients.com/Research/Vitamin-K-found-to-protect-against-liver-cancer

18.  Allison (2001). “The possible role of vitamin K deficiency in the pathogenesis of Alzheimer’s disease and in augmenting brain damage associated with cardiovascular disease”. Medical hypotheses 57 (2): 151–5.

19.  Nimptsch K, Rohrmann S, Linseisen J (April 2008). “Dietary intake of vitamin K and risk of prostate cancer in the Heidelberg cohort of the European Prospective Investigation into Cancer and Nutrition. (EPIC-Heidelberg)”. Am. J. Clin. Nutr. 87 (4): 985–92.

20.  “Vitamin K May Protect Against Developing Non-Hodgkin’s Lymphoma, Say Mayo Clinic Researchers”. 201, Science Daily

21. Dr. Kate Rheaume-Bleue, ND. “Vitamin K2 and the Calcium Paradox –How a Little-Known Vitamin Could Save Your Life”.  Pub. Wiley, 2012

22. Dr. Ray Peat.  Calcium and Disease: Hypertension, organ calcification, & shock, vs. respiratory energy. www.ray peat.com

Calcium Supplements…Do you need them?

Calcium supplements… Do you need them?

I think this is a very important question to ask since it seems everyone I encounter these days — primarily women — are on some sort of Calcium supplement. Whether it was their doctor, last nutritionist, trainer, or the latest magazine article that told them to take it, most believe their Calcium supplements are necessary. And yes, for some this may be true. Especially since so many people these days are scared of dairy (the best source of Calcium) for one reason or another.

Still the question stands, “do you really need it?” And if you do, is the supplement you are taking really working?

Most of us know we need Calcium for bone health. Many of us know we need it for proper cell and nerve function. Yet, few of us really understand how Calcium works in the body and what other cofactors are needed for proper absorption and utilization.

To really understand if we need to supplement our diets with Calcium and to understand if it is working in our body, we need understand so much more… only then can we make an educated decision on if we actually need a supplement.

First, what is the role of Calcium in the body?

*Bone and teeth structure

*Blood clotting

*Nerve and cell function

*Muscular contraction

*Regulates the heart beat

*Lowers blood pressure by down-regulating parathyroid hormone (PTH)

99% of Calcium is stored in the skeletal system (the bones are referred to as Calcium banks). The other 1% is located in the soft tissue and blood. Every day there is a transfer of Calcium among the bones, cells, and blood. Thus, since we do not make our own Calcium within the body, a constant intake of dietary Calcium is needed. Without proper intake, the body will pull Calcium from our Calcium banks (bones) and use it for cellular function. This is one big reason why we need to be ingesting an adequate level of Calcium every day. Ok, so it does make sense for doctors to prescribe Calcium supplements, right? Well, maybe…

The Calcium paradox

Although there are many paradox’s surrounding Calcium, a big one is this. Why do some nations like the US, who supplement with more Calcium than most other nations, have a higher level of osteoporosis (bone breakdown)? In a 1992 study between the US and Japan, the US showed almost 3 times as many hip fractures than the Japanese, even though on average the Japanese ingested far less Calcium on a daily basis. In fact, in a nation where people are trying to consume the recommended daily allowance of Calcium, some 10 million Americans have osteoporosis, while another 34 million have low bone mass. Why is this happening? If Americans are consuming more Calcium, shouldn’t we have less osteoporosis?

Another factor to consider is a 2010 study published by the British Medical Journal concerning Calcium supplementation and cardiovascular risks. In a meta-analysis (compiled results of several studies that address a related research hypotheses) of 12,000 individuals, it was concluded that taking Calcium supplements increased the chance of a heart attack by 30%.

Kate! Are you saying increased Calcium supplementing may NOT prevent osteoporosis AND it may also increase my chance of a heart attack? In some respects, yes… in others, no. Huh? Have I confused you yet?

You see, for Calcium to work properly, there are so many other factors to consider. Calcium needs many helpers and a certain gut environment for proper absorption and utilization. If these helpers or conditions are unavailable, Calcium may be excreted through the urine… or worse — calcified in tissues and arteries. Obviously, over time, this could lead to bone breakdown and stiff, blocked arteries.

So, before popping your next Calcium supplement, let’s look at what really needs to be occurring in your diet and body for proper Calcium absorption and utilization.

1. Adequate levels of Vitamin D (specifically D3). Vitamin D helps Calcium to be absorbed through the small intestine by increasing the number of Calcium-binding proteins. Without enough Vitamin D, the absorption of Calcium decreases significantly. Know anyone with a Vitamin D deficiency? It seems just about everyone these days. Best source of Vitamin D — the sun. Other sources are milk, butter, eggs, shellfish, and white fish.

*In the British 2010 meta-analysis, it was shown that those supplementing with Calcium plus Vitamin D did not show an increase in heart attacks ONLY those taking Calcium alone.

2. Adequate levels of Vitamin A. Vitamin A is a fat-soluble vitamin required in proper Calcium metabolism. Good sources are liver, milk, cheese, and eggs.

3. Adequate levels of Vitamin E. Vitamin E is a fat-soluble vitamin needed for proper Calcium metabolism. Good sources are milk, blueberries, blackberries, butternut squash, olive oil, crab, nectarines, and papaya.

4. Adequate levels of Vitamin K (more specifically K2). Vitamin K is a fat-soluble vitamin. Increased levels of vitamin K are showing a decrease in calcification of tissue and arteries and increase in bone development. In a clinical study from Rotterdam, Holland: “When Vitamin K2 is lacking, the Calcium remains in the blood and ends up getting deposited in the walls of arteries and other sites, which is very undesirable.” Good sources of vitamin K2 are foie gras, Gouda, and Edam cheese.  Good sources of K1 are green leafy vegetables. Bacteria in the small intestine can convert K1 to K2.

5. Adequate levels of Magnesium. Magnesium is needed for Calcium absorption and retention. According to Dr Ray Peat, “Magnesium deficiency and Calcium deficiency have some similar symptoms (such as cramping). But Magnesium is antagonistic to Calcium in many systems. It is the basic protective Calcium-blocker. G. Jasmin, showed that Magnesium deficiency causes inflammation. A deficiency of either Calcium or Magnesium can stimulate the parathyroid glands to produce more hormone (parathyroid hormone, PTH), which increases Calcium absorption, but also removes Calcium from the bones. This hormone, responding to a dietary Calcium or Magnesium deficiency, is an important factor in causing cells to take up too much Calcium. And its excess is associated with many inflammatory and degenerative diseases.”

Good sources of Magnesium are Epson salt baths, tropical fruits, coffee, dark chocolate, bone broth, squash, spinach, some nuts.

6. Stomach health. Calcium is an alkaline mineral. However, it needs an acidic environment to break down to allow for proper absorption. If your stomach does not produce enough hydrochloric acid (HCl), Calcium will not be able to break down and be absorbed in the small intestine. HCl naturally decreases with age.

7. Adequate levels of protein. Too much or not enough protein can interfere with Calcium metabolism. According to Dr Ray Peat, “Traditional meat-eating cultures efficiently use the whole animal, including blood, skin, bones, and the various organs, rather than just the muscles. That diet is favorable for Calcium regulation, because it provides more vitamin A, D, E, and K, Calcium, and gelatin, and less of the pro-inflammatory amino acids — tryptophan and cysteine.”

8. Adequate levels of fat. Fats contain all the fat-soluble vitamins (A, D, E, and K) that are needed for proper Calcium metabolism.

9. Adequate levels of sugar (carbohydrates). As I told you in my Milk blog, lactose or other sugars are necessary to help increase Calcium absorption.

10. Small intestine health. Calcium is absorbed into your body through your small intestine. If you have intestinal inflammation (due to stress, processed foods, PUFA’s, alcohol, drugs, food additives, etc.) all your minerals, including Calcium, have a hard time entering your system. The unabsorbed Calcium ends up being excreted through the urine.

11. Stress. Parathyroid hormone (PTH) increases under stress. PTH is a hormone produced by the pituitary gland and acts to increase levels of Calcium in the blood. Under stress, PTH pulls Calcium from the bones and kidneys to increase blood Calcium levels. This is needed to keep blood Calcium levels within the normal range. However, like all stress hormones, chronic high levels will cause damage. Chronic elevated levels of PTH will lead to bone breakdown and calcification of soft tissues.

12. The quality of the supplement. Most supplements these days are filled with additives, fillers, and binders. Due to the binders, these supplements can be hard for your system to break down and absorb. And the additives and fillers can cause an allergic reaction. The end result may be an expensive pill that creates intestinal inflammation or is just excreted in your urine or feces.

13. Other influences. Smoking, caffeine, corticosteroids, drugs, oxalates, insoluble fiber, and Phosphorus all inhibit the absorption of Calcium.

Holy cow! Can you see why taking a Calcium supplement might not be doing you any good?

So then what is the answer to, “Do I really need to take Calcium supplement?”

Well, here is my take… Are you ready?

My theory is really complex….

Eat REAL food and remove the CRAP!

You should always try to get your Calcium from food first. Why? Because the right Calcium-enriched foods usually will contain a lot of the other nutrients to help with proper Calcium absorption and utilization. This is why food should be your supplement…

Best sources of Calcium.

1. Milk. An 8oz (1 cup) serving of milk contains about 300mg of Calcium. In addition, milk contains proteins, sugars, fats, Vitamins A, D, and E, plus Magnesium. Do you see why I like real milk so much? *Remember there is a BIG difference between conventionally farmed milk and grass-fed organic milk. So choose wisely!

2. Cheese. One ounce of cheese contains about 200mg of Calcium. Cheese, in addition to milk, contains Vitamins A, D, E, and Magnesium. Most cheese contains only fat and protein (no sugar or carbs). Once again, where the cheese comes from makes a difference. Grass-fed organic is always best. Try to find cheese that is void of fillers and additives.

3. Yogurt. One cup of plain Greek yogurt contains about 230 mg of Calcium. It contains, fat, protein, and sugars, plus Vitamin A, D, and E. Fage Greek yogurt is a good option.

4. Ice cream. ½ cup of vanilla ice cream contains about 100mg of Calcium. Ice cream also contains fats, sugars, and proteins, plus Vitamin A, D, and E. I only use Hagan Daz (no fillers or additives — just milk, sugar, eggs, and cream).

Other good sources of Calcium are sardines, salmon, almonds, and *egg shells.

Although many other sources (spinach, chard, berries, and nuts) contain adequate levels of Calcium, these sources also contain oxalates. Oxalates bind with Calcium and increase Calcium excretion from the body. This just means less Calcium absorption.

*Ground up, boiled eggshells are a great way to get your Calcium if you have a hard time getting Calcium via food. One eggshell equals about 800mg of Calcium without added fillers and binders.

How much do you need?

The RDA recommends anywhere from 1200-1500mg a day. The exact amount for you may depend on your activity, your gut health, stress, age, sex, and the source from where you are getting it. Each of these may increase your need for Calcium while also increasing your need for other minerals and nutrients.

It is also recommended to take Calcium throughout the day. But no more than 500mg is recommended at one serving/meal. Too much at once will not be absorbed and will be excreted from the body.

We must remember that there is a reason real food is designed the way it is…it is a perfectly designed energy source. Real, unaltered food provides all the nutrients we need without having to become a nutritional scientist and concocting a supplemental cocktail.

In a world of genetically modified foods, environmental toxins, pesticides, processed foods, fast-food, herbicides, fertilizers, additives, preservatives, fillers, emulsifiers, hormones, and antibiotics, it does seem to make sense that we would need to supplement our food. However, doesn’t it make more sense to just eat well? Yes, it may cost more NOW, but in the long run, it will cost far less.

Pay NOW or pay LATER… The choice is yours.

Your Optimal Health Coach,
Kate

“Disclaimer:  I am an exercise physiologist, personal trainer, nutritional and lifestyle coach, not a medical doctor.  I do not diagnose, prescribe for, treat or claim to prevent, mitigate or cure any human disease or physical problem. I do not provide diagnosis, care treatment or rehabilitation of individuals, nor apply medical, mental health or human development principles.  I do not prescribe prescription drugs nor do I tell you to discontinue them.  I provide physical and dietary suggestions to improve health and wellness and to nourish and support normal function and structure of the body.  If you suspect any disease please consult your physician.”References:

1. Fujita T, Fukase M. Comparison of osteoporosis and Calcium intake between Japan and the United States. Proc Soc Exp Biol Med. 1992 Jun;200(2):149-52.

2. Cees Vermeer, Laviena Braam et al. Vitamin K supplementation: A simple way to bone and cardiovascular health, AgroFOOD industry hi-tech, Nov/Dec 2003 17-20

3. Cranney, A; Horsley, T, O’Donnell, S, Weiler, H, Puil, L, Ooi, D, Atkinson, S, Ward, L, Moher, D, Hanley, D, Fang, M, Yazdi, F, Garritty, C, Sampson, M, Barrowman, N, Tsertsvadze, A, Mamaladze, V (2007 Aug). “Effectiveness and safety of vitamin D in relation to bone health”. Evidence report/technology assessment (158): 1–235. PMID 18088161

4. Feskanich D, Weber P, Willett WC, Rockett H, Booth SL, Colditz GA. Vitamin K intake and hip fractures in women: a prospective study. Am J Clin Nutr. 1999; 69:74–79.

5. R. Bowen. Endocrine control of Calcium and Phosphate Homeostasis. 2003

6. Dr Ray Peat. “Calcium and Disease: Hypertension, organ calcification, & shock, vs. respiratory energy”

7. Effect of Calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. BMJ 2010; 341 doi: 10.1136/bmj.c3691 (Published 29 July 2010) Cite this as: BMJ 2010;341:c3691

8. Iwamoto J, Takeda T, Sato Y. “Effects of vitamin K2 on the development of osteopenia in rats as the models of osteoporosis.” Department of Sports Medicine, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan. jiwamoto@sc.itc.keio.ac.jp

9. Wallin R, Schurgers L, Wajih N. “Effects of the blood coagulation vitamin K as an inhibitor of arterial calcification.” Department of Internal Medicine, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina 27157, USA. rwallin@wfubmc.edu. Thromb Res. 2008;122(3):411-7. Epub 2008 Jan 30

10. Heaney RP (2000) “Calcium, dairy products and osteoporosis.” Journal Am Coll Nutr 19 (2 Suppl) : 835-995 PMID 1075913

11. Rude RK, Singer FR, Gruber HE.  “Skeletal and hormonal effects of magnesium deficiency.”  J Am Coll Nutr. 2009 Apr;28(2):131-41.