As a doctor practicing integrative medicine, I find that education is as important to my patients as anything else I do. We focus on maintaining health and vitality of individuals instead of curing diseases, so dietary and lifestyle choices are often more effective than any medication I can prescribe. In a perfect world, making healthy choices would be simple. Unfortunately, the information that we have to guide these choices is often confusing, contradictory, incomplete, or flat-out wrong.
Advice about diet is probably the most confusing. Mainstream media seem to love telling us that whatever we thought we knew about eating is wrong. The only thing they seem to like more is telling us that whatever they told us yesterday is wrong today. The advice about osteoporosis is as confusing as anything else. Is protein good for bones or bad? Does taking calcium after menopause help or not? What about red clover and soybeans? Will soda leach calcium from my bones? It is so easy to lose track of what is and what is not good for maintaining healthy, strong bones.
But what makes bones healthy? You say, “calcium,” that is only part of the story. Bones are living tissue. Cells that maintain the bones are surrounded by non-living material. The part outside the cells is called matrix and it is made of protein strengthened by calcium. You can think of this matrix like reinforced concrete. The minerals act like the concrete resisting compression and the protein strands act like rebar resisting bending and tension.
It surprises most people, but bones never stop growing, not completely. They may stop getting longer and even shrink as we get older, but the body is constantly taking away old bone matrix and replacing it with new matrix. This is called normal bone turnover.
Bones also heal after being broken or other damage. The cells that take away old or damaged bone matrix are osteoclasts. The cells that put down new matrix to replace or heal are osteoblasts. When osteoblasts and osteoclasts are both working together, bone turnover is balanced and bones are healthy. When one type of cell is either stimulated or suppressed, then bones will either grow too much or waste away. The most common form of bone wasting is osteoporosis, which literally means “porous bones.”
Osteoporosis happens when the metabolism of bone turnover is disturbed. The density of the bones is decreased and their structure deteriorates. In both men and women, bones are strongest by the early 20’s and then are maintained at that level for approximately ten years. After this, bone density declines by about 0.4% a year. In men this decline is generally constant or slowly worsens. Women experience a sharp decline after menopause, when bone loss increases to 3% to 5% a year.
Osteoporosis has a number of impacts on the skeleton. Loss of bone strength at the neck of the femur makes a person vulnerable to hip fractures, which are very dangerous. Other fractures also become more common, as does the risk of falling. In addition to an increased fracture risk, loss of bone in the spine causes curvature and “dowager’s hump.” In extreme cases, a person can lose so much height and strength that their lower ribs come to rest on their hip bones.
One consequence of osteoporosis is that people who have it often reduce their activity. Whether from a fear of falling, pain from bone compression, or a general sense of fragility, osteoporosis makes people timid about movement. The irony of this is that when the bones have to bear our weight, they generate a signal to increase the activity of the osteoblasts. So if a person lets osteoporosis reduce their activity, they actually make the osteoporosis worse in a vicious spiral.
Instead of focusing on the negative things that can worsen osteoporosis, I want to focus on the positive things that can prevent or improve it. Cutting through the confusion about diet is possible. Adequate nutrient intake is, of course, important. Not just calcium, but also other minerals such as phosphate, boron and magnesium. Diet isn’t just a concern for women who have gone through menopause – it applies to men as well and throughout life. One could even say it also applies even further back than each person’s life, back to the health of the mother. Good maternal nutrition, not just in terms of vitamins and mineral but overall nutrition as well, increases bone growth in the child and lays a foundation that reduces fracture risk in later life[i].
Let’s look at the nutrients and foods that may help maintain bone health:
Calcium: You already know that calcium is vital for maintaining healthy bones, but you may not know the right amount or when it is most important. Although the general recommended daily intake for men and women is 1,000mg[ii], an intake of 1,200mg is now considered “ideal” by many experts[iii]. Even more important is having a good base of calcium in early adulthood – in young women 1,300mg a day is not unreasonable. Although supplements are one way of obtaining this level of calcium, calcium in food sources is more readily absorbed and used by the body, which means it is difficult to create a bone-healthy diet that does not include three servings of dairy a day[iv]. Obtaining dietary calcium from dairy products also means that you are also getting other important nutrients, like protein, potassium, and small amounts of vitamin D.
Vitamin D: While calcium is essential for building strong bones, vitamin D is vitally important for maintaining bone health. For example, in women after menopause given calcium supplements there are minimal changes in osteoporosis, but vitamin D supplements have been shown to reduce fracture risk[v]. Vitamin D promotes absorption of calcium in food and also helps regulate metabolic use of calcium. The recommended intake increases from 200IU (international units) between age 14 and 50 to 400IU for people 50 or older and 600IU over age 70[vi]. These recommendations were instituted to prevent rickets. However, recent population studies have demonstrated the inadequacy of these recommendations, since nearly 85% of the US population is currently estimated to be vitamin D deficient. Many experts now recommend 1000 to 2000IU daily and doses between 5000 and10,000IU have been used safely.
Other vitamins and minerals: Other vitamins that are necessary for healthy bones are vitamin K, vitamin C, and several B-vitamins[vii]. Vitamins K & C help cells make the protein that is part of the bone matrix. B-complex vitamins are necessary for the health of connective tissue. Minerals that are important include phosphate and magnesium. Phosphate has long been known as part of the bone matrix with calcium. Magnesium has recently been identified as increasing the number and activity of osteoblasts[viii]. A healthy, balanced diet should be able to provide all these nutrients in food, but most people can use the help of a multivitamin to ensure adequate levels. Commercial farming technologies have stripped the soil of its natural minerals content resulting in a dramatic drop in the nutritional content of most fruits and vegetables. According to USDA statistics, some vegetables have less than half the calcium and magnesium than they did in 1975[ix]
Alcohol: Long-term alcohol abuse has many negative effects, but in the last fifteen years we have been learning more about how it is a major risk factor for osteoporosis. Heavy drinking, especially during late adolescence and early adulthood, significantly compromises bone quality. As this is when we need to lay down as much bone strength as possible, this represents a loss of bone strength that can’t be made up for later[x]. Alcohol interferes with the metabolism of building bones and prevents proper formation of bone matrix, leading to higher fracture risk in later life[xi]. The body can compensate for moderate or occasional alcohol use, but chronic intake of large amounts of alcohol does not give the body the chance to repair the damage before more is done.
Soda: People that drink soda have a higher risk of osteoporosis, but the reason has been unclear. This has not stopped some authorities from telling women especially to avoid soda. On one hand, young women especially that displace dairy or other nutritious beverages with soda are laying down a smaller base level of bone strength, but most sodas are not by themselves damaging to bones. Colas, though, are definitely problematic because they have phosphoric acid and caffeine, both of which damage the ability of the body to put enough minerals into bone matrix[xii].
Soy and phytoestrogens: Japanese women have lower rates of breast cancer than Americans of European descent. When Japanese women come to the United States, however, and adopt an American diet, their cancer rates match the rest of the population. In Japan, most protein in the diet comes from soy products such as tofu instead of meat. Researchers suspected there were compounds in soy that were preventing cancer from growing as it otherwise would. They found a group of chemicals they named phytoestrogens (which means “plant estrogen”)[xiii]. Because estrogen in women helps protect bone before menopause, these phytoestrogens have also been suggested as remedies for osteoporosis. Similar phytoestrogens are also found in some other plants, notably red clover. A large number of studies about the effect of phytoestrogen on bone have been reported[xiv]. Generally positive effects have been seen in many of these studies[xv] but others show the extent of the effect is limited[xvi]. Clearly these chemicals do reduce bone loss, but the question seems to be whether this affects the risk of fractures or other negative consequences of osteoporosis[xvii]. Like the natural hormones they mimic, however, phytoestrogens have effects in many different systems, and we are just beginning to understand all of their effects.
Protein: As I said, the matrix of bone is protein that has been reinforced with minerals. It would be logical, then, to think that high protein in the diet would be good for bones. This has been disputed by some nutrition authorities. The fear was that a diet high in protein created an excess of “acidic ions” in the blood, which would leach minerals from the bones. Fortunately, recent studies have contradicted this idea[xviii], and there is no link between higher protein consumption and hip fractures[xix]. Elderly people who have higher protein intake have lower risks of hip fractures[xx]. People that do have hip fractures have more growth stimulation, greater bone density, and shorter recovery times when they take protein supplements during their recovery[xxi].
Vegetarianism: If protein is a good thing for bones, we would naturally wonder if a vegetarian diet would increase risk of osteoporosis and bone fractures. The answer depends on the exact type of vegetarian diet followed. The good news is that it is possible to have a well-balanced vegetarian diet that does not contribute to osteoporosis. As long as adequate protein and mineral content, whatever the source, is part of the diet, even strict vegetarians have no worse bone health than meat-eaters[xxii]. People on a balanced vegetarian diet have similar bone density to people of the same age on a non-vegetarian diet[xxiii]. A diet high in protein from vegetable sources compares well with meat diets in preventing fractures[xxiv]. Vegan diets, buy reducing the protein and calcium intake, apparently lower bone density, although without increasing fracture risk[xxv]. Vegetarianism on some extreme diets do show lower bone density, but they maintain healthy bone turnover[xxvi].
Once again we return to the basics of preventive wellness: eating a balanced healthy diet, adding high quality nutritional supplements, engaging in regular weight-bearing exercises and insuring proper hormone balance. Because there may be no symptoms associated with osteoporosis, far too many find out they have it after experiencing a fracture. Early screening for evidence of bone loss or an altered bone metabolism can reduce the chance that you will suffer the tragic consequences from this disease. For osteoporosis, like all chronic diseases, prevention is preferable to treatment.
[i]Session 2: Other diseases: Dietary management of osteoporosis throughout the life course. Earl S, Cole ZA, Holroyd C, et al. Proc Nutr Soc. 2010 Feb;69(1):25-33.
[ii] Dietary Supplement Fact Sheet: Calcium. Office of Dietary Supplements, National Institutes of Health, 2007 Oct 7, web resource at http://dietary-supplements.info.nih.gov/factsheets/calcium.asp accessed March 5, 2010
[iii] Nutritional therapies (including fosteum).Nieves JW. Curr Osteoporos Rep. 2009 Mar;7(1):5-11
[iv] Dairy and bone health. Heaney RP. J Am Coll Nutr. 2009 Feb;28 Suppl 1:82S-90S.
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[vi] Dietary Supplement Fact Sheet: Vitamin D. Office of Dietary Supplements, National Institutes of Health, 2007 Nov 13, web resource at http://dietary-supplements.info.nih.gov/factsheets/vitamind.asp accessed March 5, 2010
[vii] Nieves 2009
[viii] Skeletal and hormonal effects of magnesium deficiency. Rude RK, Singer FR, Gruber HE. J Am Coll Nutr. 2009 Apr;28(2):131-41.
[ix] Vegetables without Vitamins. Life Extension Magazine. March 2001
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[xii] Colas, but not other carbonated beverages, are associated with low bone mineral density in older women: The Framingham Osteoporosis Study. Tucker KL, Morita K, Qiao N, et al. Am J Clin Nutr. 2006 Oct;84(4):936-42
[xiii] Isoflavones–safe food additives or dangerous drugs? Wuttke W, Jarry H, Seidlová-Wuttke D. Ageing Res Rev. 2007 Aug;6(2):150-88
[xiv] Wuttke et al, 2007
[xv] Soy isoflavones and their bone protective effects. Zhang Y, Chen WF, Lai WP, Wong MS. Inflammopharmacology. 2008 Oct;16(5):213-5.
[xvi] The soy isoflavones for reducing bone loss (SIRBL) study: a 3-y randomized controlled trial in postmenopausal women. Alekel DL, Van Loan MD, Koehler KJ, et al. Am J Clin Nutr. 2010 Jan;91(1):218-30.
[xvii] Soy isoflavone intake increases bone mineral density in the spine of menopausal women: meta-analysis of randomized controlled trials. Ma DF, Qin LQ, Wang PY, Katoh R. Clin Nutr. 2008 Feb;27(1):57-64
[xviii] Phosphate decreases urine calcium and increases calcium balance: a meta-analysis of the osteoporosis acid-ash diet hypothesis. Fenton TR, Lyon AW, Eliasziw M, et al. Nutr J. 2009 Sep 15;8:41
[xix] Protein consumption and bone fractures in women. Feskanich D, Willett WC, Stampfer MJ, Colditz GA. Am J Epidemiol. 1996 Mar 1;143(5):472-9.
[xx] Dietary protein intake and risk of osteoporotic hip fracture in elderly residents of Utah. Wengreen HJ, Munger RG, West NA,et al. J Bone Miner Res. 2004 Apr;19(4):537-45
[xxi] Protein supplements increase serum insulin-like growth factor-I levels and attenuate proximal femur bone loss in patients with recent hip fracture. A randomized, double-blind, placebo-controlled trial. Schürch MA, Rizzoli R, Slosman D, et al. Ann Intern Med. 1998 May 15;128(10):801-9.
[xxii] Veganism, bone mineral density, and body composition: a study in Buddhist nuns.Ho-Pham LT, Nguyen PL, Le TT, Doan TA, Tran NT, Le TA, Nguyen TV. Osteoporos Int. 2009 Apr 7. [Epub ahead of print]
[xxiii] Bone mineral density of vegetarian and non-vegetarian adults in Taiwan. Wang YF, Chiu JS, Chuang MH, et al. Asia Pac J Clin Nutr. 2008;17(1):101-6.
[xxiv] Effects of meat consumption and vegetarian diet on risk of wrist fracture over 25 years in a cohort of peri- and postmenopausal women. Thorpe DL, Knutsen SF, Beeson WL, et al. Public Health Nutr. 2008 Jun;11(6):564-72.
[xxv] Effect of vegetarian diets on bone mineral density: a Bayesian meta-analysis .Ho-Pham LT, Nguyen ND, Nguyen TV. Am J Clin Nutr. 2009 Oct;90(4):943-50.
[xxvi] Low bone mass in subjects on a long-term raw vegetarian diet. Fontana L, Shew JL, Holloszy JO, Villareal DT. Arch Intern Med. 2005 Mar 28;165(6):684-9