Be careful not to overeat. Once your digestive system becomes familiar with new intestinal flora, you can try new foods. It's wise to drink bottled spring water, available everywhere. Go easy on tea and coffee, which can contribute to dehydration and sleeplessness, and can aggravate digestive problems. If you use alcoholic beverages, do so sparingly, if at all.
Alcohol increases the risk of dehydration and stomach upset.
There is an American-operated hospital in Istanbul. Luxury hotels often provide North American-style 110 volts as well. Turkey is on Eastern European time, seven hours ahead of New York. When it's noon in Turkey, it's 5 am in New York and 2 am in Los Angeles. Turkish clocks are turned ahead one hour from late March to late September for daylight saving time.