<p>THE secret to longevity lies in the supermarket. According to "SuperFoods Rx: Fourteen Foods That Will Change Your Life" (William Morrow, $24.95), some foods will not only improve your life - but may well extend it.</p>
<p>Beans, blueberries, broccoli, oats, oranges, pumpkin, salmon, soy, spinach, tea, tomatoes, turkey, walnuts and yogurt - all rich in nutrients and relatively low in calories - are all credited with preventing, and in some cases even reversing, heart disease, diabetes, certain cancers and dementia.</p>