SCIENCE FRIDAY FOR ATHLETES: VITAMIN K

Taken by PKSenagore January 27, 2020. All rights reserved.

FOR BONE STRENGTH SPECIFIC DETAILS MATTER

THE HARVARD MEDICAL SCHOOL SPECIAL HEALTH REPORT, “OSTEOPOROSIS” that I recently purchased is more than 50 pages in length. The publication begins by explaining the “basics of bone”, then goes on to discuss the causes, risk factors, and consequences of the disease, among many other topics.  There are three sections that deal with bone protection: nutrition, exercise, and medication.

What surprised me is that, in addition to explaining the importance of consuming adequate amounts of calcium and Vitamin D each day to building and maintaining healthy bones, Vitamin K was included as a nutrient contributing to bone health. 

This vitamin has been of interest to me for almost 3 years, especially Vitamin K2.  I ‘discovered’ it while searching the scientific literature for ways to help my personal health situation, living with osteopenia and osteoporosis since the age of about 51 years.

In my understanding from reading on the topic, vitamin K1 (phylloquinone)and K2 (menaquinone) are different nutrients by several parameters:

1.     Dietary Sources:
Vit K1 -Green leafy plants (esp. spinach, cabbage, kale), vegetables (Brussel sprouts, asparagus, cabbage), some fruits (avocado, kiwi, grapes)

Vit K2 -Produced through bacterial conversion of Vit K1 in the gut of animals that consume plants containing Vit K1 where it is then converted to Vit K2
- Meats (esp. chicken), eggs, and dairy foods (esp. hard cheeses) of pasture animals (grass fed, not corn/grain fed goats, etc.)
- Foods fermented by bacteria that convert Vit K1 to Vit K2, like the fermented soybean product, natto, and sauerkraut

2.     Storage/Distribution within the body:
Vit K1          Stored inside the liver (site of coagulation factor production)
Vit K2         Distributed widely in tissues outside the liver (extra-hepatic tissues)


3.     Biological function in the human body:
Vit K1    
-Synthesis of blood coagulation/clotting factors II, VII, IX, X,
- and anti-coagulation proteins C, S, and Z

Vit K2              
-Protection against pathological inflammation
-Synthesis of osteocalcin and other proteins that protect against pathological calcification/mineralization of blood vessel (vascular) tissue and other soft (non-bone) tissues
-New roles being investigated: “anti-oxidant”, “promoter of cognition”, inhibitor of tumor progression, and regulator of bone-building genes

The Harvard report indicates that Vitamin K, which is present “in leafy greens”, may assist with strengthening bones by helping the body “produce osteocalcin, a protein that is instrumental in bone formation”, blocking substances that break it down, and regulating urinary calcium loss.  Not much effort is made to distinguish between Vitamin K1 and Vitamin K2 or it’s different dietary sources except in the instance noted below regarding fracture risk.

The report cites a) a review in which 7 of 13 studies on the subject, all involving Japanese people, showed reduced fracture risk in those taking Vitamin K2 , and b)  the Nurses’ Health Study and the Framingham Heart Study, both of which showed a decreased risk of hip fracture in those who consumed Vitamin K in greater amounts.  Readers are assured that most diets can adequately supply Vitamin K if they contain vegetables like raw spinach, cooked broccoli or Brussels sprouts, collard greens, scallion, asparagus, cabbage, and certain herbs (basil, thyme, sage). There is no mention of animal sources of K2.

Fortunately, the US National Institutes of Health Office of Dietary Supplements website also provides information on the role of Vitamin K in bone health but separately discusses K1 and K2 and their dietary sources, identified as leafy green vegetables (K1) and foods of animal origin and fermented foods (K2).

In spite of the erratic reporting on specific Vitamin K types in health information, there is a noticeable effort to raise awareness of the potential importance of this nutritional factor to bone health.  Some sources now make the effort to explain the differences in Vit K1 and Vit K2 and a few identify the different forms of K2 (usually MK-4 and MK-7).  Remarkably, research studies in the past have not always made the distinction either.

Future research will hopefully shed more light on the roles Vitamin K1 and K2 play in bone and other areas of health. Check out the linked/referenced articles if you wish to learn more. One thing is certain, although these two vitamins share similar chemical structures and names, they have different dietary sources for humans.

Earned Runs predicts that Vitamin K, especially Vit K2, will be the next big “new” health story to grab headlines in 2020 because of advances in understanding of certain aspects of cardiovascular disease, bone health and disease, cancer, and inflammation leading to aging-related conditions.
 
Last January (2019) a review article in the International Journal of Molecular Sciences, “Vitamin K: Double Bonds Beyond Coagulation Insights into Differences between Vitamin K1 and K2 In Health and Disease” identifies itself as “ the first to highlight differences between isoforms K1 and K2 by means of source, function and extra-hepatic activity.” The organ systems pictured at the article’s end, in which Vit K2 is identified as playing a protective role, include brain, bone, heart and blood vessels, kidney, liver, pancreas, and fat tissue. It further declares that “Vitamin K2, in the form of MK-7 has been shown to be a bioactive compound in regulating osteoporosis, atherosclerosis, cancer and inflammatory disease.
 
A scientific article in the November 2019 journal issue Gynecological Endocrinology, “Role of Vitamin K2 in Bone Metabolism: a Point of View and a Short Re-appraisal of the Literature” focuses on this nutrient’s potential role in limiting bone loss and in boosting existing therapies for osteoporosis, especially combined with adequate intakes of calcium and Vitamin D.

Most recently, in January 2020, the journal Nutrients published the article “Vitamin K as a Diet Supplement with Impact in Human Health: Current Evidence in Age-Related Diseases”. It discusses Vitamin K in general and Vitamins K1 and K2 separately, particularly in terms of absorption, bioavailability, storage and targets. The review article begins with an explanation of why the nutrient is worth investigating fully. “Vitamin K health benefits have been recently widely shown to extend beyond blood homeostasis and implicated in chronic low-grade inflammatory diseases such as cardiovascular disease, osteoarthritis, dementia, cognitive impairment, mobility disability, and frailty.

Excitement about Vit K and especially K2 may also be running rather high because, as the International Journal of Molecular Sciences piece (freely available for download) indicates, it has not been shown to cause toxicity, harmful side effects, or risk of overdosing.

Athletes might be excited about Vit K2 because of its potential impact on bone health, possibly helping to lessen or delay the onset of joint degeneration in osteoarthritis and bone loss in osteopenia/osteoporosis.  Another reason to take note of investigations into this nutrient is the possibility It may offer protection against abnormal coronary artery calcification that has been noted to occur in a subset of aging endurance athletes. 

With such encouraging news from the scientific community, we might expect to see Vitamin K receive more attention from popular media sources.  To be accurately informed, pay attention to the specifics.

RUN & MOVE HAPPY!

NOTE: Importantly, Vitamin K reports provide humans with additional reasons to fill their plates with dark -colored ‘greens’ that include collards, turnip greens, broccoli, and kale, and other vegetables and fruits that serve as good sources of Vitamin K1. AND we now have additional incentives to enjoy chicken, eggs, ground beef, ham, cheese, and milk as sources of Vitamin K2.

https://www.ncbi.nlm.nih.gov/pubmed/30791399

https://doi.org/10.1080/09513590.2019.1689554

https://www.ncbi.nlm.nih.gov/pubmed/31947821

https://www.ahajournals.org/doi/full/10.1161/circulationaha.117.028750

https://www.runnersworld.com/health-injuries/a20857967/heres-the-latest-on-whether-running-hardens-your-arteries/