What is Vitamin K?
Vitamin K is an essential fat soluble vitamin. It is not a single compound, but a group of chemically related compounds that serve the same purpose. Vitamin K naturally exists as vitamins K1 and K2, but synthetic forms are also available. The classic function of vitamin K is that it plays a major role in blood clotting. However, it is also needed for bone health, arterial health, and cell growth.
Where Does Vitamin K Come From?
Vitamin K can be synthesised within the gut by bacteria. It can also be found in a range of foods such as green vegetables. Kale, spinach, and collards are some of the best dietary sources of vitamin K.
Vitamin K Benefits
Although vitamin K is essential to life and there are many benefits with ensuring that your vitamin K levels are topped up, there is little direct relationship between vitamin K and bodybuilding or exercise.
One area to consider is the role of vitamin K in bone building. Female athletes in particular may benefit from vitamin K supplementation. This is because it is known that intensive exercise in women may result in decreased oestrogen levels which may have a negative impact on bone mass. This is obviously problematic for bone strength. The last thing you want is a fracture. It has been found that when elite female athletes were supplemented with vitamin K, there was evidence to show that they showed improvements in bone health (Craciun et al, 1998). Furthermore, it is known that people with higher vitamin K levels tend to have higher bone densities (UMMC, 2011). Despite the direct link between vitamin K and exercise performance, it is important to ensure that you have adequate vitamin K levels.
Vitamin K Negatives and Side Effects
At recommended doses, vitamin K has few side effects. It should be noted though, that if you are on blood thinning medication such as warfarin, taking vitamin K would not be recommended (UMMC, 2011).
Vitamin K Recommended Doses and Ingredient Timing
For adults, the total daily recommended intake of vitamin K is 120 micrograms for men and 90 micrograms for women. However, vitamin K intake should be increased for those who are using antibiotics (UMMC, 2011). This is because antibiotics will kill of the good bacteria that normally synthesise vitamin K within the gut. Therefore, it will be necessary to ensure you are eating enough vitamin K to make up for this loss. Secondly, groups of people who are fat blocker supplements may experience reduced absorption of vitamin K. This is because vitamin K is absorbed together with dietary fat. Thus, these people may benefit from a vitamin K supplement. Vitamin K can be taken with meals.
Vitamin K Supplements
Vitamin K can be found as a stand-alone vitamin supplement. It can also be found in multivitamins. If you are looking for vitamin K, be sure to look out for the different forms of vitamin K and alternative names. These include phylloquinone (K1), menaquinone (K2), menaphthone, and menadione (both synthetic forms of K3). Supplements containing chlorophyll are also a rich source of vitamin K, because vitamin K naturally occurs in this substance.
Stacking Vitamin K
Craciun et al (1998), Improved Bone Metabolism in Female Elite Athletes after Vitamin K Supplementation. Int J Sports Med, 19: 479-484
UMMC (2011), Vitamin K. University of Maryland Medical Center.