There was a time when red meat was a luxury for ordinary Americans, or was at least something special: cooking a roast for Sunday dinner, ordering a steak at a restaurant. Not anymore. Meat consumption has more than doubled in the United States in the last 50 years. Now a new study of more than 500,000 Americans has provided the best evidence yet that our affinity for red meat has exacted a hefty price on our health and limited our longevity. The study found that, other things being equal, the men and women who consumed the most red and processed meat were likely to die sooner, especially from one of our two leading killers, heart disease and cancer, than people who consumed much smaller amounts of these foods. The number of excess deaths that could be attributed to high meat consumption is quite large given the size of the American population. Extrapolated to all Americans in the age group studied, the new findings suggest that over the course of a decade, the deaths of one million men and perhaps half a million women could be prevented just by eating less red and processed meats, according to estimates prepared by Dr. Barry Popkin, who wrote an editorial accompanying the report. In place of red meat, nonvegetarians might consider poultry and fish. In the study, the largest consumers of white" meat from poultry and fish had a slight survival advantage. Likewise, those who ate the most fruits and vegetables also tended to live longer.