Vitamin K is one of many vitamins that comes in multiple forms, a situation that can get confusing fast. To help, here’s a simplified rundown of vitamin K's different forms and what they’re used for:

• Vitamin K1. Known as phylloquinone, this form of vitamin K is made by most plants and is found in high amounts in green leafy vegetables.
• Vitamin K2. Found in meat, cheese, and some other foods, this form of vitamin K is actually a group of fat-soluble vitamins known as menaquinones.

Some, but not all, research has shown that vitamin K1 and menaquinone-7 (a form of vitamin K2) are beneficial for preventing osteoporosis. In addition, menaquinone-4 (another form of vitamin K2) is approved as a prescription drug in Japan for preventing and treating osteoporosis; however, there’s evidence that its beneficial effect may be due to a component other than vitamin K. Vitamin K may also help promote normal blood clotting, though preliminary research suggests that menaquinone-7 is more potent than vitamin K1 and menaquinone-4. Of course, always consult your doctor before adding any new supplement to your regimen.

Source: Nutritional Medicine