Re: What is the difference between Menatetrenone [MK-4] and Menaquinone [MK-7]?

Hello, Sue.

There are two naturally ocurring forms of Vitamin K-1, or phylloquinone, the major dietary source of Vitamin K. Also there's menaquinone -- the Vitamin K-2 forms of Vitamin K, which are synthesized in our intestines.

Menadione may be released from phyloquinone by catabolic activity, and is also known as Vitamin K-3. Now, MK-4, menatetranone is not produced in significant amounts by bacteria, but appears to be synthesized from phylloquinone. The exact mechanism of its metabolism is not entirely clear. However, Japanese researchers claim that MK-4 reduces the rate of bone loss better than other types of Vitamin K, although they used at least 50 times as much as the adequate intake for the vitamin.

The evidence to date is considered weak and needs to be further studied. Supplements of phyloquinone seem to be the best absorbed type of Vitamin K. Bacterial production of the Vitamin is now thought to be less than previously assumed.

Hope that helps,

P. Bosani.

Source: An Evidence-Based Approach to Vitamins abd Minerals - Jane Higdon Ph.D, 2003.