Healthy Bones

There are 206 bones in the human body and the skeleton comprises 20 percent of total body weight. The human skeleton is strong yet light, and almost perfectly adapted for the movement, protection and manipulative functions it performs. Maintaining strong, healthy bones can be accomplished by getting the recommended amount of calcium and vitamin D daily, being physically active and maintaining body weight in a healthy range.

Kids/Teen Fractures

Fracture incidence has increased by one-third in boys and one-half in girls compared to a generation ago.¹ This can be attributed to the increase in childhood obesity, replacement of milk with other beverages such as soda and juice and a decrease in physical activity due to increased "screen time" such as playing video games or being on the computer

Dietary calcium, a key nutrient in milk, has been shown to be a major factor associated with fracture risk. A multitude of studies has shown that increasing dairy or calcium intakes during childhood and adolescence enhances bone health at various skeletal sites,² particularly in those populations with low calcium intakes.³ Physical activity is another key determinant in bone health. Activities that are specifically good for bone health include weight-bearing activities such as jogging, walking and dancing. Teens can assess their level of physical activity by completing the Teen BEAT, Basic Exercise & Activity Tracker.

During the teenage and young-adult years, it is important to achieve the highest peak bone mass (PBM) possible to reduce the likelihood of breaking a bone and developing osteoporosis later in life. PBM is attained at about 30 years of age, however, during the years of rapid growth during adolescence, 40 percent of total lifetime bone mass is accumulated.⁴ Calcium is deposited in the bones at the greatest rate around age 12 for girls and age 14 for boys.⁵

Unfortunately, dietary intake surveys repeatedly show that many children fail to meet the dietary recommendations for calcium. Nine out of 10 girls and 6 out of 10 boys aged 12-19 do not consume adequate calcium in their diet.⁶ According to one study, children who had inadequate calcium consumption increased their bone mineral content (BMC) 25 times more than children who consumed enough calcium, when intake was increased to the amounts recommended in the Dietary Guidelines.⁷ Calcium and Kids offers realistic suggestions for increasing calcium in the diet during these critical years.

Overweight children break more bones than normal-weight children, and children who break a bone at an early age have more future broken bones.⁸ A study in boys found that high body fatness and low BMC were linked to more forearm fractures.⁹ Body weight may contribute to fracture risk by placing extra burden on bones during falls. Lack of physical activity—common in overweight children—may also play a role in fracture risk, as physical activity is associated with stronger bones.

The younger a child gets his or her first fracture, the more likely it is that he or she will have a future fractures. Children who consume three cups of milk and dairy foods daily and are physically active for one hour on most days are likely to maintain strong bones and good health.¹⁰

Osteoporosis

Osteoporosis is a bone disease common in older adults, marked by lower than normal bone mineral levels that lead to increased fracture risk. This disease affects millions of Americans every year, especially women. Women are twice as likely to develop osteoporosis as men due to the sudden drop in estrogen at menopause and their tendency to live longer. Some other risk factors for osteoporosis are smoking, old age, ethnicity (whites or Asians have a higher risk than blacks or Hispanics), family history, being very thin, early menstruation and/or late menopause, eating disorders, alcoholism, excess caffeine, low calcium intake and a sedentary lifestyle.¹¹ Keeping calcium levels high, making physical activity a habit and minimizing controllable risk factors (such as smoking or drinking) will help prevent the disease.

Vitamin D

Vitamin D is often referred to as the "sunshine" vitamin because our bodies can make it when our skin is exposed to the sun. About 10 to 15 minutes of sun exposure per day on our face, hands and arms—without sunscreen—is enough to meet our needs. Children and adults up to age 70 years need 600 International Units (IU) of vitamin D per day. With age, we lose some ability to make the vitamin from sunlight exposure and to turn it into its active form, so the recommendation increases to 800 IU per day for those over 70 years. Vitamin D is essential to good health because it helps with dietary absorption of calcium. Deficiency in vitamin D in children can cause rickets and in older adults could cause muscle weakness that may lead to falls. Recent research suggests that having enough vitamin D increases cognitive performance, immune function and protects against some cancers and periodontal disease.¹²

The benefits of consuming adequate calcium, especially from dairy foods, are numerous and include bone health, nerve and muscle function and effectively treating mild hypertension. Current research investigating the link between dairy products, calcium and vitamin D, and cancer prevention are listed.

Learn more about the relationship between low-fat milk and cancer prevention.

More about vitamin D: Vitamin D: What You Need to Know About the Sunshine Vitamin.

Return to Dairy Facts Overview page.

¹Khosla S et al. JAMA 2003;17;290(11):1479-85.
²Miller GD, Jarvis JK, McBean LD. Handbook of dairy foods and nutrition, 3rd ed. CRC Press, 2007.
³Wosje KS, Specker BL. Nutr Rev 2000;58:253.
⁴Greer FR, Krebs NF and Committee on Nutrition. Pediatrics 2006;117:578-585.
⁵Bailey DA et al. J Bone Miner Res 2000;15:2245-2250.
⁶What We Eat in America. NHANES 2005-06. USDA, ARS.
⁷Huncharek M, et al. Bone 2008; 43(2):219-410.
⁸Taylor et al. Pediatrics 2006;117(6):2167-2174.
⁹Goulding A et al. J Bone Miner Res 2005;20(12):2090-6.
¹⁰Dietary Guidelines for Americans 2010, 7th ed. 2010: www.healthierus.gov/dietaryguidelines.
¹¹Mayo Clinic (2007) Osteoporosis risk factors. Retrieved Aug 13, 2008, from Mayo Clinic website: http://www.mayoclinic.com/health/osteoporosis/DS00128/DSECTION=risk-factors.
¹²Vitamin D: A new look at an old vitamin. http://www.dairycouncilofca.org/PDFs/vitaminD_2010.pdf