6. Vitamin K

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Among vitamins, vitamin K certainly appears to be one of the lesser-known vitamins of the bunch. New discoveries may be starting to change that, however. Research indicates that vitamin K may be helpful in preventing heart attacks. Vitamin K can be found in found in leafy green vegetables, and is also available in supplement form. Unlike other vitamins like C, which are water soluble, vitamin K is fat soluble, which means it’s probably a good idea to take supplements with food that contains some fat.