Calcium: “Getting enough calcium is important for all ages, but it's particularly important during adolescence and early adulthood, when bones are absorbing calcium,” says Heather Schwartz, MS, RD, a medical nutrition therapist at Stanford University Hospital and Clinics. Calcium and vitamin D are often paired in fortified foods such as milk. The reason: The body needs D in order to absorb calcium.
Iron: Essential for healthy blood cells, iron becomes especially important when girls begin to menstruate. With each period, a woman loses small amounts of iron. “About 10% of American women are iron deficient,” says Dorothy Klimis-Zacas, PhD, a professor of nutrition at the University of Maine and co-editor of Nutritional Concerns of Women (CRC Press, 2003). “About 5% have iron deficiency anemia.” Symptoms of low iron include fatigue, impaired immunity, and poor performance at school or work.
For once we're not talking about breakfast but rather the recovery meal after your workout. “So many women skip post-exercise nutrition because they don’t want to 'undo the calories they just burned,'” says Amanda Carlson-Phillips, vice president of nutrition and research for Athletes’ Performance and Core Performance. “But getting a combination of 10 to 15 grams of protein and 20 to 30 grams of carbohydrates within 30 minutes of your workout will help to refuel your body, promote muscle recovery, amp up your energy, and build a leaner physique.”
Fluids: Fluid needs increase as women age. The reason: Kidneys become less efficient at removing toxins. “Drinking more fluids helps kidneys do their job,” Schwartz says. “Unfortunately, thirst signals often become impaired with age, so people are less likely to drink enough water and other fluids.” Rather than fret about how many glasses to drink, Frechman says, check the color of your urine. "It should be clear or very pale colored. If it becomes darker, you need more fluid.”