Kids and Their Bones (page 2)

— National Institute of Mental Health
Updated on Apr 14, 2011

Factors Affecting Peak Bone Mass

Peak bone mass is influenced by a variety of factors: some that you can't change, like gender and race, and some that you can, like nutrition and physical activity.

Gender: Bone mass or density is generally higher in men than in women. Before puberty, boys and girls develop bone mass at similar rates. After puberty, however, boys tend to acquire greater bone mass than girls.

Race: For reasons still not well understood, African American girls tend to achieve higher peak bone mass than Caucasian girls, and African American women are at lower risk for osteoporosis later in life. More research is needed to understand the differences in bone density between the various racial and ethnic groups. However, because all women, regardless of race, are at significant risk for osteoporosis, girls of all races need to build as much bone as possible to protect themselves against this disease.

Hormonal factors: Sex hormones, including estrogen and testosterone, are essential for the development of bone mass. Girls who start to menstruate at an early age typically have greater bone density. Those who frequently miss their menstrual periods sometimes have lower bone density.

Nutritional status: Calcium is an essential nutrient for bone health. In fact, calcium deficiencies in young people can account for a 5 to10 percent lower peak bone mass and may increase the risk for bone fracture in later life. A well-balanced diet including adequate amounts of vitamins and minerals such as magnesium, zinc, and vitamin D is also important for bone health.

Physical activity: Important for building healthy bones, physical activity provides benefits that are most pronounced in the areas of the skeleton that bear the most weight. These areas include the hips during walking and running and the arms during gymnastics and weight lifting.

Calcium is found in many foods, but the most common source is milk and other dairy products. Drinking one 8-oz glass of milk provides 300 mg (milligrams) of calcium, which is about one-third of the recommended intake for younger children and about one-fourth of the recommended intake for teens. In addition, milk supplies other minerals and vitamins needed by the body. The chart on the next page lists the calcium content for several high-calcium foods and beverages. Your kids need several servings of these foods each day to meet their need for calcium.

How Can I Persuade My Daughter to Drink Milk Instead of Diet Soda? She Thinks Milk Will Make Her Fat.

Soft drinks tend to displace calcium-rich beverages in the diets of many children and adolescents. In fact, research has shown that girls who drink soft drinks consume much less calcium than those who do not.

It's important for your daughter to know that good sources of calcium don't have to be fattening. Skim milk, low-fat cheeses and yogurt, calcium-fortified juices and cereals, and green leafy vegetables can all fit easily into a healthy, low-fat diet. Replacing even one soda each day with milk or a milk-based fruit smoothie can significantly increase her calcium intake.

Selected Food Sources of Calcium
Food Calcium (mg) % DV *
Sardines, canned in oil, with bones, 3 oz. 324 32%
Cheddar cheese, 1 1/2 oz., shredded 306 31%
Milk, nonfat, 8 fl oz. 302 30%
Yogurt, plain, low fat, 8 oz. 300 30%
Milk, reduced fat (2% milk fat), no solids, 8 fl oz. 297 30%
Milk, whole (3.25% milk fat), 8 fl oz. 291 29%
Milk, buttermilk, 8 fl oz. 285 29%
Milk, lactose reduced, 8 fl oz.
(content varies slightly according to fat content; average=300 mg)
285 – 302 29 – 30%
Cottage cheese, 1% milk fat, 2 cups unpacked 276 28%
Mozarella, part skim, 1 ½ oz. 275 28%
Tofu, firm, with calcium, ½ cup** 204 20%
Orange juice, calcium fortified, 6 fl oz. 200 – 260 20 – 26%
Salmon, pink, canned, solids with bone, 3 oz. 181 18%
Pudding, chocolate, instant, made with 2% milk, ½ cup 153 15%
Tofu, soft, with calcium, ½ cup** 138 14%
Breakfast drink, orange flavor, powder prepared with water, 8 fl oz. 133 13%
Frozen yogurt, vanilla, soft serve, ½ cup 103 10%
Ready to eat cereal, calcium fortified, 1 cup 100 – 1000 10 – 100%
Turnip greens, boiled, ½ cup 99 10%
Kale, raw, 1 cup 90 9%
Kale, cooked, 1 cup 94 9%
Ice cream, vanilla, ½ cup 85 8.5%
Soy beverage, calcium fortified, 8 fl oz. 80 – 500 8 – 50%
Chinese cabbage, raw, 1 cup 74 7%
Tortilla, corn, ready to bake/fry, 1 medium 42 4%
Tortilla, flour, ready to bake/fry, one 6" diameter 37 4%
Sour cream, reduced fat, cultured, 2 tbsp 32 3%
Bread, white, 1 oz. 31 3%
Broccoli, raw, ½ cup 21 2%
Bread, whole wheat, 1 slice 20 2%
Cheese, cream, regular, 1 tbsp 12 1%

Source: USDA 2002, Heaney et al 2000.

* DV=Daily Value

* * Calcium values are only for tofu processed with a calcium salt. Tofu processed with a non-calcium salt will not contain significant amounts of calcium.

But my kids don't like milk.

Drinking milk isn't the only way to enjoy its benefits. For example, try making soup and oatmeal or other hot cereals with milk instead of water. Pour milk over cold cereal for breakfast or a snack. Incorporate milk into a fruit smoothie or milkshake. Chocolate milk and cocoa made with milk are also ways to increase the milk in your child's diet.

Sources of calcium also might include an ounce or two of cheese on pizza or a cheeseburger, a cup of calcium-enriched orange juice, or a small carton of yogurt. Your kids can also get calcium from dark green, leafy vegetables like kale or bok choy, or foods such as broccoli, almonds, tortillas, or tofu made with calcium. Many popular foods such as cereals, breads, and juices now have calcium added too. Check the Nutrition Facts label on the package to be sure.

My Teenage Son Loves Milk, But It Seems to Upset His Stomach. Could He Have Lactose Intolerance?

People with lactose intolerance have trouble digesting lactose, the sugar found in milk and dairy foods. Lactose intolerance is not common among infants and young children, but can occur in older children, adolescents, and adults. It is more common among people of African American, Hispanic, Asian, and American Indian descent.

Most kids with lactose intolerance are able to digest milk when it is served in small amounts, and combined with other foods like cereal. They may tolerate other dairy products such as cheese or yogurt even if milk is a problem. Lactose-free milk products are now available in most stores, and there are pills and drops you can add to milk and dairy products that make them easier to digest.

Be sure to include plenty of foods with calcium in the meals and snacks you plan for your kids. Almonds, calcium-fortified orange juice, tortillas, fortified cereals, soy beverages, and broccoli with dip are a few great choices. While it's best to get calcium from food, calcium supplements can also be helpful.

View Full Article
Add your own comment
DIY Worksheets
Make puzzles and printables that are educational, personal, and fun!
Matching Lists
Quickly create fun match-up worksheets using your own words.
Word Searches
Use your own word lists to create and print custom word searches.
Crossword Puzzles
Make custom crossword puzzles using your own words and clues.
See all Worksheet Generators