While calcium plus vitamin D-enriched dairy did enhance bone mineral density, only dairy that included vitamin K1 or K2 in the formulation led to changes in levels of osteocalcin, a vitamin K-dependent protein and is essential for the body to utilize calcium in bone tissue. Without adequate vitamin K, the osteocalcin remains inactive, and thus not effective.
Results published in Calcified Tissue International indicated that only the dairy products fortified with K1 or K2, and calcium and vitamin D produced improvements in the ration of undercarboxylated osteocalcin (ucOC – inactive osteocalcin) to carboxylated osteocalcin (cOC).
“The present study revealed more favorable changes in bone metabolism and bone mass indices for the two vitamin K-supplemented groups, mainly reflected in the suppression of serum levels of bone remodeling indices and in the more positive changes in lumbar spine BMD for these two study groups,” report researchers from Harokopio University in Greece.
The study adds to the ever-growing body of potential health benefits of vitamin K intakes. Despite the positive impacts, vitamin K deficiency may be more common than previously thought, according to findings from a Dutch study in 2007 (Thrombosis and Haemostasis, Vol. 98, pp. 120-125).
There are two main forms of vitamin K: phylloquinone, also known as phytonadione, (vitamin K1) which is found in green leafy vegetables such as lettuce, broccoli and spinach, and makes up about 90 per cent of the vitamin K in a typical Western diet; and menaquinones (vitamins K2), which make up about 10 per cent of Western vitamin K consumption and can be synthesised in the gut by microflora.
Menaquinones (MK-n: with the n determined by the number of prenyl side chains) can also be found in the diet; MK-4 can be found in animal meat, MK-7, MK-8, and MK-9 are found in fermented food products like cheese, and natto is a rich source of MK-7.
Concerns over deficiency, coupled with increased consumer awareness of the potential benefits, have led to an upsurge in vitamin K formulations as supplements and functional foods. According to Francis Foley from Xsto, the US distributor of Kappa’s K2Vital Vitamin K Product Line, the current K market in the US is valued at $10 million in raw material sales (vs finished product sales). “What is really impressive is the growth in vitamin K supplementation, estimated to be (my personal estimate) over 15% year. We feel the K2 market can double to $20 million in less than five years,” he said.
The new study investigated the effects of dairy enriched providing 800 mg per day of calcium and 10 micrograms (400 IU) per day of vitamin D3, with or without the addition of 100 micrograms per day of either phylloquinone or menaquinone-7.
Results showed that, after 12 months of supplementation, bone mineral density (BMD) in the enriched groups, but only women consuming the vitamin K-enriched products had significant increases in BMD in vertebrae in the lower back (lumbar spine).
In addition, only the vitamin K groups displayed improvements in the ratio of undercarboxylated osteocalcin to osteocalcin.
75 million affected
The results show potential for reducing the risk of osteoporosis in postmenopausal women. Osteoporosis is characterized by low bone mass, which leads to an increase risk of fractures, especially the hips, spine and wrists. An estimated 75 million people suffer from osteoporosis in Europe, the USA and Japan.
Women are four times more likely to develop osteoporosis than men.
Source: Calcified Tissue International
Volume 90, Number 4, 251-262, DOI: 10.1007/s00223-012-9571-z
“Changes in Parameters of Bone Metabolism in Postmenopausal Women Following a 12-Month Intervention Period Using Dairy Products Enriched with Calcium, Vitamin D, and Phylloquinone (Vitamin K1) or Menaquinone-7 (Vitamin K2): The Postmenopausal Health Study II”
Authors: S. Kanellakis, G. Moschonis, R. Tenta, A. Schaafsma, E.G.H.M. van den Heuvel, N. Papaioannou, G. Lyritis, Y. Manios