Food sources of vitamin D are very limited. They include fatty fish, such as cod, mackerel, salmon, and sardines, and egg yolks. Fortified food sources of vitamin D include dairy milk, soy milk, butter, margarine, and many cereals. If you spend a considerable amount of time in direct sunlight this summer when exercising or enjoying other outdoor activities, you could make adequate vitamin D from sunlight. Sunscreen, however, blocks vitamin D production, and safe sun exposure without sunscreen is estimated to be ten minutes in lighter skinned persons and up to 30 minutes in darkerskinned persons. Our ability to make vitamin D from sunlight also decreases as we age. Most dermatologists would recommend no sun exposure without sunscreen and recommend that you reapply sunscreen when outside for longer periods of time.