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30-09-2010 | Bone health | Article

Vitamin K2 supplementation does not influence bone loss

Abstract

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MedWire News: Vitamin K2, taken in the form of menaquinone-7 (MK-7), as a dietary supplement does not influence the rate of bone loss among early postmenopausal women, Norwegian researchers report.

Large amounts of MK-7 are found in a traditional Japanese dish called Natto, which is prepared using soybeans fermented with Bacillus subtilis, note Nina Emaus (University of Tromsø) and colleagues.

A lower occurrence of fractures has been reported in Japanese regions with a high population intake of Natto, and some studies indicate that Natto may prevent osteoporosis in premenopausal Japanese women, say the researchers.

A relationship between vitamin K2 intake and bone strength has not been documented in Europeans, therefore Emaus and team assessed the effect of MK-7 on bone mineral density (BMD) changes in 334 Norwegian women aged between 50 and 60 years, who had not had a menstrual period for between 1 and 5 years.

The participants were randomly assigned to receive 360 µg MK-7 in the form of Natto capsules or the same amount of identical-looking placebo capsules containing olive oil.

The researchers report that, at 12 months, there were no significant differences in BMD loss between the groups at the total hip, femoral neck, lumbar spine, or total body. Specifically, bone loss at the total hip was 0.41% in the MK-7 group versus 0.35% in the placebo group.

Serum levels of carboxylated osteocalcin increased in both groups compared with baseline, but were significantly higher in the treatment group at 12 months compared with the placebo group, at 19.1 versus 14.9 ng/ml, respectively.

Conversely, under-carboxylated osteocalcin decreased in both groups compared with baseline, and was significantly lower in the treatment group at 12 months compared with the placebo group, at 2.2 versus 3.9 ng/ml, respectively.

These findings indicate that the participants took the medication, and that the medication was absorbed and active, but that BMD was not maintained despite improved of osteocalcin carboxylation, remark Emaus and co-authors in the journal Osteoporosis International.

They note that the relatively short 1-year follow-up period and a lower-than-expected mean bone loss among the participants were potential limitations of the study.

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

By Laura Dean

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