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.
Not getting enough fiber can lead to constipation and can raise your risk for other health problems. Part of healthy eating is choosing fiber-rich foods, including beans, berries, and dark green leafy vegetables, every day. Fiber helps lower your risk for diseases that affect many women, such as heart disease, diabetes, irritable bowel syndrome, and colon cancer. Fiber also helps you feel full, so it can help you reach and maintain a healthy weight.
The tiny gender differences in minerals other than calcium and iron depend on body size. But while the dietary requirements for selenium fit this rule, men may benefit from supplements of about 200 micrograms a day, a level about four times above the RDA. That's because both a clinical trial and an observational study suggest that selenium may reduce the risk of prostate cancer. It's far from proven, but it's something for men to consider.
Weighing yourself too often can cause you to obsess over every pound. Penner recommends stepping on the scale or putting on a pair of well-fitting (i.e. not a size too small) pants once a week. “Both can be used as an early warning system for preventing weight gain, and the pants may be a better way to gauge if those workouts are helping you tone up and slim down.” [Tweet this tip!]
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.”