IF WOMEN want to drink coffee, they would be wise to make it cafe au lait, in order to avoid osteoporosis, according to research from California. Women in the town of Rancho Bernardo who had a lifetime's intake of caffeinated coffee had lower bone mineral density, in both the hip and spine, than non-coffee drinkers. But the effect, reported in the Journal of the American Medical Association, was offset among women who drank at least one pint of milk a day throughout their adult life.