The effects of two vitamin K-forms on carboxylation of the vitamin K-dependent proteins osteocalcin and matrix-gla protein will be compared after supplementing these vitamins in a nutritional dose range.

The investigators hypothesized that MK-7 is more effective than K1 at a dose comparable to the RDA of vitamin K.

Vitamin K is a group name for the naturally occurring phylloquinone (K1) and menaquinones (MK-n; K2). The latter can be subdivided into the short-chain (e.g. MK-4) and the long-chain (e.g. MK-7, MK-8, and MK-9) menaquinones. Earlier studies have shown that high vitamin K intake leads to improved bone and vascular health by increased carboxylation of vitamin K-dependent proteins in these tissues. In the dietary range, MK-7 has been suggested to be the most effective cofactor for the carboxylation of Gla-proteins, such as osteocalcin (OC) and matrix-Gla protein (MGP).Until now, no randomized controlled trial has compared the efficacy of K1 versus MK-7 in a nutritional dose range. The investigators are therefore interested to compare the effects of K1 and MK-7 on OC and MGP carboxylation after supplementing these vitamins at a dose not exceeding the RDA.

Inclusion Criteria:

• Healthy men and women, aged between 20-80 years
• Normal body weight and height (18.5 kg/m2 < BMI < 30 kg/m2)
• Stable body weight (weight gain or loss < 3 kg in past 3 mo)
• Written consent to take part in the study
• Agreement to adhere to dietary restrictions required by the protocol

Exclusion Criteria:

• Abuse of drugs and/or alcohol
• Use of vitamin supplements containing vitamin K
• Pregnancy
• (a history of) metabolic or gastrointestinal diseases, e.g. hepatic or renal disorders, osteoporosis
• Chronic degenerative and/or inflammatory diseases, e.g. diabetes mellitus, cancer, cardiovascular disease
• Use of oral anticoagulants, drugs or hormones that influence bone metabolism
• Corticoid treatment
• Subjects with anaemia or subjects who recently donated blood or plasma
• Systemic treatment or topical treatment likely to interfere with coagulation metabolism (salicylates, antibiotics)