Boron and Fish Oil Have Different Beneficial Effects on Strength and Trabecular Microarchitecture of Bone

Authors: Nielsen, Forrest - Frosty; STOECKER, BARBARA - Oklahoma State University

Submitted to: Journal of Trace Elements in Medicine and Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/18/2009
Publication Date: 7/1/2009
Citation: Nielsen, F.H., Stoecker, B.J. 2009. Boron and Fish Oil Have Different Beneficial Effects on Strength and Trabecular Microarchitecture of Bone. Journal of Trace Elements in Medicine and Biology. 28(3):195-203.

Interpretive Summary: Osteoporosis and associated fractures are major health problems in the United States. Estimates of incidence and economic burden are projected to increase markedly in the next 40 years in spite of numerous therapies for treating or preventing osteoporosis. Part of the reason that these therapies are not more effective is that their use is often inhibited by costs and adverse side effects. Establishing dietary factors, and identifying foods that contain them, would reduce drug therapy needs. High intakes of calcium and vitamin D are two factors that help in slowing the loss of bone, but have had only modest impact on the incidence of osteoporosis. This indicates the lack of other nutrients may be involved in bone loss leading to osteoporosis. Fruits and vegetables intakes have been associated with better bone health. These foods are rich in two nutrients, boron and omega-3 fatty acids, that have been suggested to be beneficial for bone formation and maintenance. Thus, an experiment with rats was performed to confirm the beneficial effects these two nutrients and to determine whether dietary fatty acid composition would affect changes in bone microarchitecture and strength induced by boron deprivation, or vice versa. Male rats were fed diets containing fish oil (high in omega-3 fatty acids) or safflower oil (high in omega-6 fatty acids), and either deficient or adequate in boron from pre-conception to maturity. Boron deficiency resulted in microarchitectural changes in vertebra bone that reduces bone strength. In addition, boron decreased the breaking strength of a long bone (femur). Feeding fish oil instead of safflower oil did not affect bone microarchitecture as markedly as boron, but did increase vertebral and femur bone strength. The findings indicate that boron and omega-3 fatty acids found in fish oil have beneficial effects on bone through different mechanisms, and the combination of the two nutrients was most beneficial for bone microarchitecture and strength. The findings suggest that boron and omega-3 fatty acids are two factors in fruits and vegetables providing some of the beneficial effects these foods have on bone health.

Technical Abstract: Recent findings suggest that boron and long-chain omega-3 polyunsaturated fatty acids have similar beneficial effects on bone strength and trabecular microarchitecture. Thus, an experiment was performed to confirm the beneficial effects and to determine whether dietary fatty acid composition would affect changes in bone microarchitecture, strength and mineral composition induced by boron deprivation, or vice versa. Female rats were fed diets containing 0.1 mg (9 umol) boron/kg in a factorial arrangement with variables of supplemental boron at 0 (boron-deficient) or 3 (boron-adequate) mg (278 umol)/kg and fat sources of 75 g safflower oil/kg or 65 g fish (menhaden) oil/kg plus 10 g linoleic acid/kg. After six weeks, six females per treatment were bred. Dams and pups continued on their respective diets through gestation, lactation, and after weaning. At age 21 weeks, the microarchitecture of the fourth lumbar vertebrae from 12 randomly selected pups from each treatment was determined by microcomputed tomography (uCT). The uCT findings indicated that boron is beneficial, if not essential, for trabecular microarchitecture that promotes bone strength. Boron deficiency decreased bone volume fraction and trabecular thickness, and increased trabecular separation and structural model index. Cortical bone findings also indicated that boron is beneficial to bone. Maximum force to break the femur (determined by a three-point bending test) was lower in boron-deficient than in boron-adequate rats. Boron deficiency decreased the femur concentrations of copper, iron, magnesium and zinc, which have functions contributing to bone strength and microarchitecture. Fish oil did not affect bone as markedly as boron. Feeding fish oil instead of safflower oil decreased connectivity density in vertebrae of boron-deficient but not in boron-adequate rats. Fish oil instead of safflower oil increased the force to compress the trabecular core from vertebra, especially in boron-adequate rats. Regardless of dietary boron, fish oil instead of safflower oil increased the maximum force to break and the bending moment, and decreased the iron concentration of the femur. Neither dietary boron nor oil affected femur calcium and phosphorus concentrations. Thus, dietary boron and fish oil have beneficial effects on bone apparently through affecting the organic matrix.