Nutrition for Bone Health

Special K

Vitamin K is an essential vitamin for growing bones. It comes in two forms, vitamin K1 (phylloquinone), which is found in green leafy vegetables, and vitamin K2 (menaquinone), primarily seen in fermented cheese or other foods.

In adult bone, vitamin K contributes as a co-factor in the carboxylation of osteocalcin, but in children, the significance of vitamin K in bone-mass acquisition is less known, according to a two-year study from the University Medical Centre Utrecht, Netherlands.⁷ The study followed 307 children with a mean age of 11.2 years and assessed their skeletal BMC. The researchers found those children with improved vitamin K status over the two-year period resulted in better BMC and improved bone mass of the whole body.

In a double blind, controlled trial, 452 men and women (60 to 80 years) were randomized to receive a multivitamin that contained either 500 mcg/d or no K1, plus a daily calcium (600 mg elemental calcium) and vitamin D (400 IU) supplement.⁸ Intent-to-treat analysis was used to compare change in measures in 401 participants who completed the trial. The researchers found no differences in changes in BMD measurements at any of the anatomical sites. The group that received the phylloquinone had significantly higher K1 levels and a significantly lower percent of undercarboxylated osteocalcin concentrations.

Another study supporting the theory that vitamin K helps maintain bone density was conducted at the University of Maastricht, Netherlands.⁹ In the three-year, placebo-controlled trial, researchers tested whether BMC and femoral neck width (FNW) in 325 postmenopausal women were affected by taking 45 mg/d of vitamin K2 (MK-4, menatetrenone). K2 did not affect BMD, but did increase BMC and FNW. In addition, the K2-treated women’s hip bone strength remained unchanged during the intervention period, whereas in the placebo group, bone strength decreased significantly.

Editor's Note: Looking for more information on vitamin K and bone health? Register for the free INSIDER Webinar, "Menaquinone-7 (MK): The Essential Vitamin K for Bone Health". Register for the Webinar by clicking here.

Impressive Ipriflavone

Ipriflavone, a synthetic isoflavone, is commonly used to maintain BMD and prevent osteoporosis, especially in postmenopausal women. Ipriflavone works by inhibiting bone resorption by osteoclasts and enhancing osteoblast bone formation activity. A study from Italy determined the safety and efficacy of ipriflavone (IP) in established osteoporosis.¹⁰ Researchers enrolled 149 elderly, osteoporotic women (65 to 79 years) with prevalent vertebral fractures in two multi-center, double blind, two-year studies. They received either oral IP (200 mg/tid at meals) or matching placebo, plus 1 g/d oral calcium. A significant increase in forearm BMD was obtained after IP treatment. Urinary hydroxyproline was significantly decreased in IP-treated patients, suggesting a reduction in bone turnover rate. Further, a reduction of incident vertebral fractures was observed in IP-treated women compared with control subjects. The study also suggests that IP may also improve bone pain and mobility, and the data shows long-term treatment with IP may be considered safe, and may increase bone density and possibly prevent fractures in elderly patients with established osteoporosis.

Another study using in vitro and in vivo legs looked at the effects of IP on caged layers’ (hens) bone metabolism.¹¹ IP was found to regulate the functional balance between osteoblasts and osteoclasts, enhancing bone formation. Based on these in vitro findings, researchers conducted a 70-day in vivo trial using 500 hens that were fed diets containing 0, 15, 25, 50 and 100 ppm of IP. Egg production increased in hens fed 25 ppm and decreased in hens fed 50 and 100 ppm, when compared with the controls and hens fed 15 ppm (P < 0.05). Egg weight, shell quality, BW, and serum P, Ca, estrogen and bone mineral content were not affected by inclusion of ipriflavone in the diet. Hens consuming 25 ppm of ipriflavone had greater serum alkaline phosphatase and bone gla protein levels than controls. Researchers stated that adding 25 ppm of ipriflavone to the feed "appears to be close to an ideal level for clinical treatment of osteoporosis because of improved egg production while maintaining bone mineral content."

Not all of the findings on IP have been universally positive. One randomized, placebo-controlled study evaluated the effect of IP (600 mg/d) against bone loss in premenopausal, ovariectomized women (n=37) and postmenopausal women (n=52).¹² In the early-stage group, the IP group showed a 6.7-percent decrease in BMD from baseline levels, whereas the placebo group showed a 10.7-percent decrease at 12 months of treatment, and 7.1-percent (IP) and 12.6-percent (placebo) decreases at 24 months of treatment. In the late-stage group, there was a 0.3-percent increase in BMD in the IP group and a 2.3-percent decrease in the placebo group at 6 months of treatment (P < 0.01), and similar changes were seen at 18 months (1.4 percent-increase and 3.9-percent decrease; P < 0.01). IP suppressed bone loss compared with placebo; however, it did not prevent acute bone loss in the early stage following ovariectomy.