Micronutrients for bone health

Bones make up the human skeleton and provide structure, mobility and support while protecting the various organs of the body. Although bones may seem like hard and lifeless structures, they are living tissues. During a person’s lifetime the body constantly breaks down old bone and builds up new bone. Any time old bone is broken down faster than new bone is made, net bone loss occurs.  

Even though it is mostly made of protein and minerals, bone is living, growing tissue. Throughout a person’s lifetime, old bone is broken down (‘resorption’) and new bone is added to the skeleton (formation). When more bone is broken down than is added to the skeleton, bone loss occurs. Many factors determine how much old bone is resorbed and how much new bone is made. People have control over certain factors (such as diet) whereas others factors are beyond their control (such as age).

Most new bone is added during childhood and teenage years. Bone formation continues until the peak bone mass (maximum solidness and strength) is reached. Peak bone mass (or bone density) is reached around the age of 30. After the age of 30, bone resorption slowly begins to exceed new bone formation, which leads to bone loss (1). Bone loss in women occurs fastest in the first few years after menopause, but continues into old age. In men, bone loss usually occurs later in life compared to women. By the age of 65, men catch up with women and lose bone mass at the same rate.

Factors that can contribute to bone loss include having a diet low in certain micronutrients such as calcium and vitamin D, not exercising, smoking, long-term use of certain medications (e.g., corticosteroids) and low sex hormone (estrogen or testosterone) levels. Proper nutritional choices can help to preserve bone health. As people’s lifestyles and eating habits have changed over the years, many no longer receive adequate amounts of the essential bone-building nutrients. Thus appropriate dietary supplements and fortified foods are used to ensure sufficient intakes.

Osteoporosis is not just an “old woman’s disease.” Although it is more common in white or Asian women over the age of 50, osteoporosis can occur in almost any person, women and men, at any age. In women, bone loss can begin as early as age 25 years. 45% of fractures in women aged 50 and over are due to underlying osteoporosis (3). In fact, about 75 million people are currently affected by osteoporosis in the EU, USA and Japan alone (4). The estimated global direct cost of osteoporotic fractures is US$ 50 billion per year (3).

Building strong bones and reaching peak bone density (maximum strength and solidness), especially before the age of 30, can be the best defense against developing osteoporosis. Furthermore, a healthy lifestyle can keep bones strong, especially for people over the age of 30. Osteoporosis is more or less preventable for most people. Prevention is very important because, while treatments for osteoporosis are in place, currently no cure exists. Prevention of osteoporosis involves several aspects, including nutrition (see below) and exercise. Loss of muscle strength and mass, especially in the absence of physical activity, can reduce bone strength and stability, increasing the risk of falling and breaking a bone.

Early detection of low bone mass (osteopenia) or osteoporosis is the most important step for prevention and treatment. The only way to accurately test the strength and solidness of the bones is with bone mineral density (BMD) tests. Bone mineral density tests measure the solidness and mass (bone density) of bones in the spine, hip and/or wrist, which are the most common sites of fractures due to osteoporosis.

Vitamin D deficiency and a lack of adequate calcium in diet may lead to rickets, a softening of bones in children, potentially leading to fractures and deformity. Rickets is among the most frequent childhood diseases in many developing regions but has resurged in developed countries as well (11-14). Achieving adequate dietary intakes of vitamin D in the key bone-building years is an urgent public health concern (15-17). Vitamin D is unique because it can be formed by the body with the right amount and intensity of sunlight on the skin. However, due to the use of sunscreens, dressing habits, indoor lifestyle and air pollution, vitamin D synthesis in skin is often severely limited. Several national pediatric associations now recommend that all infants consume at least 400 IU per day of vitamin D immediately after birth, continuing through adolescence, to make sure nutritional needs are met (18).

Bone fractures are not just due to brittle bones but also to falling. By minimizing the risk of falling, the fracture risk is reduced. Research indicates that vitamin D can help prevent fall-related fractures via its positive effect on muscle function and strength, which reduces loss of balance or swaying. Vitamin D plays a role in initiating protein synthesis in muscle fibers responsible for speed and strength – precisely those which help prevent a fall (24, 25). Muscle examined from people with vitamin D deficiency shows a breakdown in these fibers which can be reversed within a few weeks by increasing the amount of vitamin D in the body to sufficient levels (26). Furthermore, vitamin D helps maintain calcium levels in the blood, which is necessary for the normal functioning of muscles. Therefore vitamin D has a double impact on the prevention of osteoporotic fractures when the levels in the body are adequate: it strengthens bone and muscle at the same time, preventing osteoporosis, muscle weakness and fractures.

Vitamin C and vitamin B6 are needed to make collagen, an essential part of the organic material that holds bone together. Higher intakes of vitamin C may help to reduce bone loss (30).  A combination of vitamins B6, B12 and B9 (folic acid) may also help to decrease the risk of osteoporosis by reducing the concentration of homocysteine in the blood, which is thought to be associated with poor bone health (31).

The minerals magnesium and phosphorus as well as the trace element zinc are essential for building healthy bones. About half of all bone mineral is made up of phosphates, which forms a complex with calcium in the bone matrix. Both minerals have to be in balance because too much phosphate in the blood can lead to a removal of calcium from the bone (decalcification) and to a calcification of soft tissues, which can cause joint pain and skin alterations. Magnesium and zinc make up a minor part of bone minerals. Vitamins, minerals and trace elements work together to maintain healthy bones (1).
 
Emerging evidence suggests that fish consumption, or the long-chain omega-3 fatty acids it contains, may have bone-preserving properties (32). Oxidative stress can reduce the activity of cells responsible for bone building. Long-chain omega-3 fatty acids have been shown to have anti-inflammatory qualities and can potentially block the harmful effects of oxidative stress, which could increase bone formation.

1. Geissler C. and Powers H. ed. Human Nutrition, 11th, London: Elsevier, 2005:233.
2. Raisz L. G. Pathogenesis of osteoporosis: concepts, conflicts, and prospects. Journal of Clinical Investigation. 2005; 115(12):3318–3325.
3. Holroyd C. et al. Best Practice and Research: Clinical Endocrinology and Metabolism. 2008; 22(5):671–685.
4. EFFO and NOF. Who are candidates for prevention and treatment for osteoporosis? Osteoporos Int. 1997; 7(1).
5. Weaver C. M. The role of nutrition on optimizing peak bone mass. Asia Pac J Clin Nutr. 2008; 17(1):135–137.
6. Bonjour J. P. et al. Minerals and vitamins in bone health: the potential value of dietary enhancement. Br J Nutr. 2009; 101(11): 1581–1596.
7. Gaffney-Stomberg E. et al. Increasing dietary protein requirements in elderly people for optimal muscle and bone health. J Am Geriatr Soc. 2009; 57(6):1073–1079.
8. Vicente-Rodriguez G. et al. Independent and combined effect of nutrition and exercise on bone mass development. J Bone Miner Metab. 2008 ; 26(5):416–424.
9. Karlsson M. K. et al. Sustainability of exercise-induced increases in bone density and skeletal structure. Food Nutr Res. 2008; 52.
10. Gunter K. et al. Impact exercise increases BMC during growth: an 8-year longitudinal study. J Bone Miner Res. 2008. 23(7):986–993.
11. Fischer P. R. et al. Pediatric vitamin D and calcium nutrition in developing countries, Rev Endocr Metab Disord. 2008; 9(3):181–192.
12. Pettifor J. M. Vitamin D &/or calcium deficiency rickets in infants & children: a global perspective. Indian J Med Res. 2008; 127(3):245–249.
13. Holick M. F. and Chen T. C. Vitamin D deficiency: a worldwide problem with health consequences. Am J Clin Nutr. 2008; 87(4):1080–1086.
14. Bener A. et al. High prevalence of vitamin D deficiency in young children in a highly sunny humid country: a global health problem. Minerva Pediatr. 2009; 61(1):15–22.
15. Huh S. Y. and Gordon C. M. Vitamin D deficiency in children and adolescents: epidemiology, impact and treatment. Rev Endocr Metab Disord. 2008; 9(2):161–170.
16. Saintonge S. et al. Implications of a new definition of vitamin D deficiency in a multiracial US adolescent population: The National Health and Nutrition Examination Survey III. Pediatrics. 2009; 123(3):797–803.
17. Harkness L. S. and Bonny A. E. Calcium and vitamin D status in the adolescent: key roles for bone, body weight, glucose tolerance, and estrogen biosynthesis. J Pediatr Adolesc Gynecol. 2005; 18(5):305–311.
18. Wagner C. L. and Greer F. R. Prevention of rickets and vitamin d deficiency in infants, children, and adolescents. Pediatrics. 2008; 122(5):1142–1152.
19. IOM: Dietary Reference Intakes for Calcium and Vitamin D. http://www.iom.edu/Reports/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D.aspx 2010.
20. Dawson-Hughes B. et al. Estimates of optimal vitamin D status. Osteoporosis International. 2005; 16(7):713–716.
21. Bischoff-Ferrari H. A. et al. Prevention of nonvertebral fractures with oral vitamin D and dose dependency. Arch Intern Med. 2009; 169(6):551–561.
22. Dawson-Hughes B. et al. IOF position statement: vitamin D recommendations for older adults. Osteoporos Int. 2010; 21(7):1151–1154.
23. Vieth R. et al. The urgent need to recommend an intake of vitamin D that is effective. Am J Clin Nutr. 2007; 85(3):649–650.
24. Ceglia L. Vitamin D and skeletal muscle tissue and function. Mol Aspects Med. 2008; 29(6):407–414.
25. Bischoff-Ferrari H. A. et al. Fall prevention with supplemental and active forms of vitamin D: a meta-analysis of randomised controlled trials. Br Med J. 2009; 339:b3692.
26. Bischoff H. A. et al. Effects of vitamin D and calcium supplementation on falls: a randomized controlled trial. Journal of Bone and Mineral Research. 2003; 18(2):343–351.
27. Bolton-Smith C. et al. Two-year randomized controlled trial of vitamin K1 (phylloquinone) and vitamin D3 plus calcium on the bone health of older women. Journal of Bone and Mineral Research. 2007; 22(4):509–519.
28. Braam L. A. et al. Vitamin K1 supplementation retards bone loss in postmenopausal women between 50 and 60 years of age. Calcified Tissue International. 2003; 73(1):21–26.
29. Cheung A. M. et al. Vitamin K supplementation in postmenopausal women with osteopenia (ECKO trial): a randomized controlled trial. PLoS medicine. 2008; 5(10).
30. Sahni S. et al. Protective effect of total and supplemental vitamin C intake on the risk of hip fracture – a 17-year follow-up from the Framingham Osteoporosis Study. Osteoporos Int. 2009; 20(11):1853–1861.
31. McLean R. R. et al. Plasma B vitamins, homocysteine, and their relation with bone loss and hip fracture in elderly men and women. Journal of Clinical Endocrinology and Metabolism. 2008; 93(6):2206–2212.
32. Kontogianni M. D. et al. Association between dietary patterns and indices of bone mass in a sample of Mediterranean women. Nutrition. 2009 ; 25(2):165–171.