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Pre-teens and Teens (9 to 19 years old) continued...

Calcium needs are higher now, too. From age 9 to 18, children require 1,300 mg of calcium daily, about the amount found in 32 ounces of milk. Children of all ages require 600 IU of vitamin D, which promotes calcium absorption in the body.

Iron requirements increase at age 14 to support increased blood volume and muscle mass. Teen girls need more iron than boys to make up for monthly losses due to menstruation. Inadequate iron intake can lead to anemia caused by iron deficiency, the most common nutrient shortfall for teen girls.

Teens who skimp on animal products run a greater risk for iron deficiency and insufficient intake of vitamin B12, calcium, and vitamin D, among others. A daily multivitamin helps to fill in small nutrient gaps in a teen’s diet.

Adults (19 to 50 years old)

Calorie needs decrease when you’re done growing. That means adults have less leeway for satisfying nutrient needs on a balanced diet that helps achieve and maintain a healthy weight.

A woman’s iron needs increase again in adulthood, to 18 mg daily. During pregnancy, iron requirements rise to 27 mg daily, which is difficult to satisfy with food alone.

Folic acid is another important nutrient during the childbearing years. This B vitamin helps to prevent birth defects during early pregnancy, when women may not know they have conceived. The Institute of Medicine encourages women who may become pregnant to consume 400 micrograms of folic acid daily from fortified foods, dietary supplements, or a combination of the two.

With the exception of pregnancy, calcium absorption starts decreasing during adulthood. Women, and men, should satisfy their daily calcium needs during this stage, which are 1,000 mg, to reduce the risk of bone fractures later on in life. 

Calcium and vitamin D supplements make sense if you don’t consume the recommended 24 ounces of low-fat (1%) milk or fat-free milk or yogurt, or a combination of these every day -- or if you don’t get the recommended calcium and vitamin D from other foods besides dairy.