Dosages of nutritional supplements vary widely, depending on the product and individual needs. For vitamins and minerals, U.S. RDA's are essential guidelines. For other products, manufacturers' guidelines, consumer information sources such as nutritional books and magazines, and practitioners including nutritionists and naturopathic physicians may be consulted.
A spokesperson for optimal nutritional intake is the well-known biochemist Bruce Ames, who proposed the "triage theory of nutrients," in which enzymes responsible for cell maintenance functions evolved to have lower affinity for the essential vitamin and mineral cofactors than the enzymes responsible for short-term survival, to preserve life during times of famine. 
Trying to balance the demands of family and work or school—and coping with media pressure to look and eat a certain way—can make it difficult for any woman to maintain a healthy diet. But the right food can not only support your mood, boost your energy, and help you maintain a healthy weight, it can also be a huge support through the different stages in a woman’s life. Healthy food can help reduce PMS, boost fertility, make pregnancy and nursing easier, ease symptoms of menopause, and keep your bones strong. Whatever your age or situation, committing to a healthy, nutritious diet will help you look and feel your best and get the most out of life.
In addition to diet, exercise and other lifestyle factors can also play an important role in bone health. Smoking and drinking too much alcohol can increase your chances of developing osteoporosis, while weight-bearing exercise (such as walking, dancing, yoga, or lifting weights) can lower your risk. Strength or resistance training—using machines, free weights, elastic bands, or your own body weight—can be especially effective in helping to prevent loss of bone mass as you age.