My HormonologyDread the irritability, depression, see-sawy moods and insomnia that are part of PMS in your premenstrual Week 4? The results of a recent 10-year study in the American Journal of Epidemiology reveal an easy way you can cut your risk of developing these and other PMS-related symptoms by 30 to 40 percent: Get 20 mg. daily of “non-heme” iron–the kind from plant foods (such as beans, tofu, lentils, spinach and iron-fortified cereal) and supplements–all cycle long. As the researchers explain, iron helps produce serotonin, a brain chemical that balances mood and improves sleep. And that’s key since serotonin production drops throughout your Week 4 as estrogen levels dip, triggering those unwanted PMS symptoms.