The defense against sniffles and sore throats is going natural. Since last year, use of herbal remedies has increased for every age group, reports the Food Marketing Institute in "Shopping for Health 1999: The Growing Self-Care Movement." Roughly 36 percent of Gen Xers say they take natural remedies, as do nearly one-third of mature consumers aged 54 and over. While over-the-counter medications are still used most frequently by consumers today (76 percent), that's down from 85 percent in 1998. Shoppers are also incorporating specific foods into their diet to stay healthy. Two out of three respondents in the FMI study say they consume fortified foods, beating out prescriptions (61 percent overall) and organic foods (34 percent).