The best swimmers among female Ironman triathletes complete the swimming portion of the event in 50 minutes to an hour. At the World Championship, the cutoff time for all competitors is two hours, 20 minutes. Any participant who fails to complete the 2.2-mile swim within that time is eliminated from the competition.
There are two sources of this essential vitamin, including vitamin K1, or phylloquinone which is primarily found in green leafy vegetables and vitamin K2 or menaquinone which is synthesized by certain intestinal bacteria.
Vitamin K is unique among the vitamins in several respects. It is the only vitamin that can be produced within the human body, but not by the body (to be defined as a vitamin, a substance cannot be produced by human tissue). 7 Beneficial bacteria in the human intestine produce about 75% of the vitamin K the body absorbs each day, with the other 25% coming from dietary sources. 8 The amount of vitamin K absorbed each day from both sources usually is equal to the minimum amount required for normal bodily function. 9.