Nutrient strategies to enhance skeletal integrity
Clin Nutr. 2006 Oct 12; [Epub ahead of print] Picking a bone with contemporary osteoporosis management: Nutrient strategies to enhance skeletal integrity. Genuis SJ, Schwalfenberg GK. PMID: 17946114. This article is a very nice review of osteoporosis that includes an overview of osteoporosis, contemporary management of osteoporosis and nutrient strategies in the prevention and management of osteoporosis. It is the last item that I am going to highlight in this update. This particularly concerns the importance of four dietary nutrients in osteoporosis and bone health: vitamin D (VTD), strontium, vitamin K (VTK) and essential fatty acids.
Vitamin D. The authors note that “VTD is required at all phases of human development for the normal formation of skeletal tissue, the proper achievement of PBM (peak bone mass) and the maintenance of BMD (bone mineral density).” Sun exposure is a primary source of VTD as sunlight acts on 7-dehydrocholesterol in the skin to eventually form VTD. This is where the problem of low serum VTD develops as few foods have VTD and people often have limited sunlight exposure. The authors note that, although people often believe they can get adequate calcium and VTD from dairy products, the literature doesn't show this to be consistently true. It used to be thought that 600-800 I.U. of VTD daily was adequate. However more recent studies suggest that 1,000 I.U. may be more on the mark. See the calcium and VTD Update for details on this. The authors note that it is easy to monitor and manage VTD status via measuring 25-hydroxyvitamin-D (25[OH]D) in blood. When (25[OH]D) falls below 60 nmol/l in postmenopausal women, bone resorption markers are detectably elevated. However the authors suggest that a better minimally low (25[OH]D) level is 80 nmol/l. It is often thought that because excessive VTD can be harmful that one must be extra cautious not to take too much VTD. Toxicity is not seen below 250 nmol/l, so there is a wide margin of safety. The importance of adequate VTD levels is shown by a recent very large long-term Harvard School of Public Health study which showed that there was a 37% reduction in fracture risk in postmenopausal women consuming adequate amounts of VTD daily. Editor's comments: Knowing that you need to keep (25[OH]D) levels at or above 80 nmol/l gives everyone a good target to shoot for. Be sure to have your serum VTD checked occasionally to be sure you are getting adequate amounts daily from sunlight or dietary supplements.
Strontium: Strontium, especially strontium ranelate, has been shown in several recent studies to increase BMD and to reduce fractures. See the recent Update on this topic for details. One nice feature of strontium is that it increases bone formation while also decreasing bone resorption, thus improving BMD with two methods. Strontium doesn't have to taken in the ranelate form to be effective. The strontium gluconate, carbonate, lactate and chloride all seem to be effective. The authors note that “ . . .commercial foods grown on fields using synthetic fertilizers, pesticides and herbicides have appreciably lower levels of strontium than organic food counterparts.” This may mean that young people eating only commercially grown foods will never reach ideal PBM, and thus will be at higher risk of osteoporosis. The authors conclude: “In review, the findings from the medical literature suggest that judicious use of low dose stable strontium may be an effective and safe way of assisting patients to maintain and restore bone health.” Editor's comments: This would appear to be another reason to eat organically grown foods. Remember that high doses of strontium will affect the DXA results. See PMID: 10677790.
Vitamin K. There are two forms of the fat-soluble VTK: VTK-1 (phylloquinone) which is synthesized by plants and is abundantly found in green leafy vegetables and some vegetable oils; and VTK-2 (menaquinones) which collectively refers to a group of compounds that are commonly synthesized from bacteria that normally colonize the colon as well as enteric metabolism of VTK-1. VTK is important in blood coagulation and is a cofactor in many biochemical pathways associated with cell growth, brain development and bone health. Two large studies have shown that low VTK consumption led to dramatically increased hip fracture or that high VTK intakes led to a 35% relative risk of hip fracture compared to those on low intake. It appears that the VTK-2 form is the more important one for bone metabolism. The Japanese have done many studies on the oral VTK-2 form, menatetrenone (MK-4), and it relationship to osteoporosis, showing it to be an effective agent. Studies have shown VTK-2 to be well tolerated with the main concern being that it could counteract the effects of anticoagulant therapy or be dangerous to those with a history of thrombotic illness. Editor's comments: The main thing that people can do to maintain proper VTK levels is to eat adequate amounts of leafy green vegetables. There are supplements available, but I would suggest discussing this with your care provider before taking one, particularly the VTK-2 form. And be careful if you have a history of thrombotic disease or blood coagulation problems.
Essential fatty acids (EFAs). EFAs are those that we don't make naturally and that have to be consumed via food or supplements. A recent study has shown that animals deficient in EFAs develop severe osteoporosis which shows their importance for bone health. There are two categories of EFAs: omega-3 and omega-6 FFAs. Omega-6 EFAs are plentiful in foods such as cereal grains, processed foods, meat, milk, eggs and some vegetable oils. Omega-3 EFAs are found in only a few seeds and nuts and in fish oil. So omega-3's are the EFA normally needed in greater quantity. Problems develop when the ratio of intake of omega-6 to omega-3 EFAs gets too high. The authors note that there is an abundance of recent literature showing that a low omega-6/omega-3 ratio may be necessary for optimal health, normal development, and prevention of chronic disease. Two hundred years ago the omega-6/omega-3 ratio was about 1-2:1. It is now estimated to be 16:1. In Japan, where the ratio is about 4:1, the authors note osteoporotic hip fractures are greatly reduced compared to the U.S. The authors conclude, “In review, a low nutritional ratio of omega-6/omega-3 appears to enhance calcium absorption, reduce excretion, and increase calcium deposition in bone, which in turn decreases the risk of osteoporosis and resultant fragility fractures. Furthermore, by improving bone quality and BMD, in addition to reducing inflammatory cytokines, omega-3 FA supplementation has been shown to slow the rapid rate of postmenopausal bone loss. Accordingly, it may be prudent in clinical medicine to discuss EFA intake with patients and to supplement omega-3FAs as a routine aspect of care for individuals with compromised bone health.” Editor's comments: From everything I've read recently it appears that we need to be getting more omega-3 EFAs in our diet from foods or supplements. That is especially true for those of us with osteoporosis or osteopenia. But other studies show increased omega-3 FA intake decreases immune system inflammatory agents, improves heart health, decreases hypertension, benefits tender joints in rheumatoid arthritis, improves bipolar illness symptoms, gives a 60% less likely chance of developing Alzheimer's and lowers the risk of some cancers, especially breast and prostate cancers. Not mentioned in this study is whether to eat wild or farmed salmon. Most of what I've heard and read recently points to wild salmon as being the best source of omega-3 EFAs, so check this out for yourself if you are in doubt. You might want to get a copy of this article since it is a review article with 169 references. A good way to keep abreast of the latest in osteoporosis research, especially concerning nutritional factors.