Saturday, February 21, 2009

Calcium needs of children

Calcium is the most abundant mineral in the body. More than 99% of total body calcium is stored in the bones and teeth and the remaining 1% is found throughout the body in blood, muscle, and the fluid between cells.

Calcium has several important functions, for example
  • It is vital in the construction, formation and maintenance of bone and teeth.
  • It is an essential component in the production of enzymes and hormones that regulate digestion, energy, and fat metabolism.
  • It maintains all cells and connective tissues in the body.
  • It is a vital component in blood clotting systems, helps in wound healing and may prevent gum disease.
  • It is involved in blood pressure control, nerve transmission, and release of neurotransmitters.
  • It is essential for muscle contraction.
In the US, more than 60% of dietary calcium comes from milk and dairy products. Adequate dietary calcium intake during growing years is critical for the accretion of peak bone mass, which protects against osteoporosis later in life. The U.S. Department of Agriculture's Food Guide Pyramid ( recommends that children two years and older eat 2-3 servings of dairy products per day. A serving is equal to:
1 cup (8 fl oz) of milk
8 oz of yogurt
1.5 oz of natural cheese (such as Cheddar)
2.0 oz of processed cheese (such as American)
Dairy products are the most concentrated food sources of calcium (e.g. one cup of milk contains approximately 271 mg of calcium). But what if your child/adolescent doesn't drink milk or is lactose intolerant, how do they meet their calcium needs ? In this case you need to consider other sources of calcium, for instance:
Calcium-fortified orange juice is a very good source of calcium, however because the calcium settles on the bottom of the carton, you need to ensure you shake it before pouring. Since most children require more vitamin D in their diet, choose an orange juice that is fortified with vitamin D as this will help improve calcium absorption. You may be inclined to think that giving your child several servings of juice is the solution to their calcium needs. As parents we need to keep in mind that excess juice intake may provide excess calories in the diet of our children. The American Academy of Pediatrics' recommendation is that children over the age of 7 years limit their juice consumption to 2 servings per day. So while calcium-fortified juice provides a useful alternative to dairy as a calcium source, drinking too much orange juice is not recommended.

Canned fish,
such as salmon and sardines, are excellent sources of calcium. A single sardine contains 92 mg calcium, while a 3 ounces can of salmon (with the bones) contains 181 mg calcium. OK, this is great except I can't imagine too many children eat sardines. Perhaps we will have better luck with salmon, hmm.....not so sure they'll eat the bones !

Next idea...

Calcium fortified soy milk, (note, natural soy milk is not a good source of calcium, it needs to be calcium-fortified), is an alternative to dairy milk. Again, sedimentation of the calcium occurs so you need to make sure to shake the carton. One report (1) found that unshaken samples of soy beverages had only 31% of the expected calcium and there is some concern regarding whether the absorption of calcium in these products is the same as that of dairy milk. But it is a good alternative to dairy if your child does not drink milk.

Processed foods such as ready-to-eat breakfast cereals contain calcium. If the food label states the product contains 10% of calcium on the label - this is equivalent to approximately 100 mg of calcium.

Other foods that contain modest amounts of calcium include citrus fruit, dark-green leafy vegetables (chinese cabbage, kale, collard greens and broccoli), nuts/seeds and peanut butter.
If your child doesn't eat dairy products, will they have an adequate intake (AI) for calcium?"

First of all, lets review the AI for calcium:
500 mg for children aged 1 to 3 years
800 mg for children aged 4 to 8 years
1,300 mg for children aged 9 to 18 years.
One study (2) conducted in children aged 9 to 15 years found that an adequate intake (AI) of calcium could not be met if the child was eating a dairy-free diet and so they recommended that calcium-fortified foods should to be included in the diet. Ideally, calcium fortified juice or soy milk should not be a substitute for dairy milk. However, given that only 25% of boys and 10% of girls are getting enough calcium in their diet, its a welcomed solution for parents.

(1) Heaney, R. (2006). Journal of the American Dietetic Association; 106 (11); 1753-1754.
(2) Gao et al. (2006) Journal of the American Dietetic Association; 106 (11); 1759-66.

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