What’s So Special about Vitamin K?

The Importance of Vitamin K in The Bone Health of Athletes

Vitamin K comes in a few different forms and among other important functions, assists with Vitamin D absorption. It has been shown to help independently and collectively for bone health according to the European Food Safety Authority. Vitamin K1 form is found mainly in Green leafy vegetables such as kale and broccoli, along with plant oils, while the K2 form is found in small amounts in some dairy foods and to a greater amount in fermented foods such as sauerkraut, pickles, and kimchi. It can be produced by the bacteria found in the human intestines. This K2 form may improve bone density and prevent fracture risk. You may already be aware that Vitamin K is also involved in normal blood clotting, but it rarely reaches toxic levels because of the wide distribution throughout the body while being readily excreted.   Some vitamin D supplements have added small amounts of vitamin K to their products. Keep an eye out for vitamin K and COVID immune response as there is a correlation that is being considered. This is based on recent studies showing low levels may be involved in lung damage in some COVID cases that were admitted to hospitals.

The RDA values for Vitamin K are 120 mcg/day for males and 90 mcg/day for females age 19 and over. For those aged 9–13 years old, 60 mcg, and for ages 14-18, 75 mcg are the current standards.  The trend we are seeing is that athletes may demand higher levels. We are also seeing that as another fat-soluble vitamin, Vitamin K is stored in the adipose (fat) tissue and therefore has less bioavailability for use in cellular processes in obese people - less availability for bone and less availability for immune protection (Demeulemeester).

Back to the subject of bone health, one study in female elite athletes used 10 mg/day for a month because their subjects tested low on the calcium binding capacity of circulating bone protein osteocalcin. (Subjects either had amenorrhea due to decreased nutrition combined with vigorous training not being met by nutritional demands and/or adequate recovery affecting hormone levels, or they were on birth control pills). Regardless of the subject group, the researchers attributed the addition of vitamin K to the diet of all the athlete subjects to increased bone integrity (Craciun).  As a side note, this may help tie together some of the seemingly at odds reactions to COVID. If one is obese or even an elite athlete that is not properly meeting their nutritional demands, the lack of bioavailability/ uptake of Vitamin K and D, may explain certain severe reactions to COVID.

As stated in our articles about Vitamin D and Calcium, stay tuned,  as we hope to discover the proper intake amounts of Vitamin K that will benefit obese people, in addition to athletes who are shown to have higher nutritional demands in line with their increased metabolic requirements. 

- Dr. Goodbender

References

https://www.hsph.harvard.edu/nutritionsource/vitamin-k/

https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/

Rob Janssen, Margot P. J. Visser, Anton S. M. Dofferhoff, Cees Vermeer, Wim Jansssens, and Jona Walk. Vitamin K metabolism as the potential missing link between lung damage and thromboembolism in Coronavirus disease 2019. Br J Nutr. 2020 Oct 7. 

Craig Sale and Kristy Jayne Elliot-Sale. Nutrition and Athlete Bone Health. Sports Med. 2019; 49 (suppl 2): 139-151. 

A M Craciun, J Wolf, MH Knapen, F Brouns, C Vermeer. Improved Bone Metabolism in Female Elite Athletes after Vitamin K Supplementation. Int J Sports Med. 1998 Oct;19(7);479-84. 

Chad M. Kerksick, et al. ISSN exercise & sports nutrition review update; research & recommendations. J Int Soc Sports Nutr. 2018;15:38. 

Fien Demeulemeester, et al. Obesity as a risk factor for severe COVID-19 and Complications: A Review. Cells. 2021 Apr; 10(4):933.

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