Children's Bone Health

The baby steps toward building strong bones begin in childhood. It is in childhood that you lay down the foundation for strong bones. It is said that osteoporosis is a pediatric disease with geriatric consequences, says Melissa Dobbins, M.S., R.D., C.D.E., nutrition expert, National Dairy Council, Rosemont, IL. Osteoporosis, a condition marked by gradually weakened bones, affects an estimated 10 million Americans each year. As bones lose mineral density over time they become porous and prone to fractures.

Bone super nutrients

The key nutrients for developing strong bones are calcium and vitamin D, according to The 2004 U.S. Surgeon Generals Report on Bone Health and Osteoporosis. In a 2008 study published in Bone (43(2):312-21), researchers evaluated data from 21 randomized clinical trials, including more than 3,800 children, to look at dietary calcium intake and bone mineral content. Children with low baseline intakes of calcium experienced significantly increased bone mineral content when their dietary calcium and/or dairy product intake was increased. The calcium recommendations for children are 500 mg for 1 to 3 years of age; 800 mg for 4 to 8 years; and 1,300 mg for 9 to 18 years. The absorption of dietary calcium in foods and supplements is also a critical factor in determining its availability for bone development and maintenance. Three sources of calciumcalcium carbonate, calcium citromalate, and milkappear to ensure efficient absorption, retention and use for bone mineralization.

Its about more than calcium, says Dobbins. Vitamin D helps the body absorb and use calcium. The adequate intake for vitamin D from birth to 18 years of age is 200 IU per day, but there has been discussion about increasing this recommendation. The major source of vitamin D is sunlight, as ultraviolet B radiation penetrates uncovered skin and converts 7-dehydrocholesterol to previtamin D3, which then becomes vitamin D3. Vitamin D can also be found in fortified milk, fortified foods, fatty fish, beef liver, cheese and eggs.

A number of macronutrients and micronutrients are involved in bone health, including magnesium, phosphorus, potassium and vitamin K. The RDA for magnesium, recognized as a shortfall nutrient for school-aged children, is 80 mg per day for ages 1 to 3; 130 mg for ages 4 to 8; and 240 mg for ages 9 to 13. The RDA for phosphorus is 460 mg per day for ages 1 to 3; 500 mg for ages 4 to 8; and 1,250 mg for ages 9 to 13. The adequate intake for vitamin K is 30 mcg per day for ages 1 to 3; 55 mcg for ages 4 to 8; and 60 mcg for ages 9 to 13. Magnesium and phosphorus are essential for the metabolism of bone mineral. Short-term studies have found that potassium may reduce calcium excretion and bone turnover. Vitamin K appears to be involved in bone density. In a 2008 study published in Clinical and Experimental Rheumatology (26(3):484-91), researchers reported that high vitamin K status in healthy children and children with juvenile idiopathic arthritis was positively correlated with better bone properties, and poor vitamin K status was associated with significant impairment in bone quality.

An area of emerging interest is nondigestible oligosaccharides, as some studies have shown that they increase the absorption of minerals like calcium, magnesium and phosphorus. Inulin-type fructans, including oligofructose, fructooligosaccharides (FOS) and short-chain fructooligosaccharides (scFOS), may show promise in bone health. This effect is attributed to increased fermentation of intestinal bacteria and subsequent production of short-chain fatty acids. This makes the environment more acidic, which increases the mineral solubility.

Dairy builds strong bones

Milk is a veritable all-in-one package for delivering key nutrients linked with bone health. An 8-oz. glass of milk provides 30% of the DV of calcium, 25% of the DV for vitamin D, and 25% of the DV for phosphorus, says Sharon Gerdes, senior account manager, Dairy Management, Inc., Rosemont, IL.

Dairy products such as cheese and yogurt are excellent substrates for adding nutrients for bone health, according to Gerdes, as some calcium is already bound in the casein micelle, and this calcium is more stable than added calcium. Other dairy ingredients that can boost calcium include nonfat dry milk powder and acid whey. In addition, milk calcium complex, derived from whey products, includes the actual minerals from milk in a balanced mineral profile.

Sharon Palmer is a registered dietitian with 16 years of experience in health-care and foodservice management. She writes on food and nutrition for newspapers, magazines, websites and books. Palmer makes her home in Southern California and can be reached at [email protected] .