Days 1-3 will be on open diet but with dietary restrictions (no alcohol, cheese, fruits, ethnic foods such as Chinese and Indian food, grain legumes such as beans, lentils, peas and peanuts, and all kinds of sprouts (such as cress or alfalfa)). On day 2 a glass of orange juice (200ml) will be consumed in addition to the open diet. Urine collection will continue and stop on day 4 at 10 am.