Hi there. There's no foods that make your periods lighter. What we expel during our period is the built up lining of our uterus that washes away each cycle when pregnancy doesn't occur. Hormones cause it to build up IN CASE we have intercourse and fertilize an egg, an embryo attaches to that thickened lining. But when we don't have a fertilized egg, our hormones trigger to release that lining and then it starts all over again with your next cycle. So, there is no food that can do anything about that, it's a natural process. Even if you bleed a good deal during your period, it is most likely not enough to make you anemic or low in iron. When women have periods for very long periods (over 7 to 10 days), anemia can happen. Eating a balanced diet can make sure you have the right balance of nutrients and you can always take a good multi vitamin to be safe. But you should not be low in iron. That is something a doctor can diagnose though if you think you are--- they check your blood levels or you can tell him your symptoms that make you think you are low in iron (it comes with symptoms).
In the old days, my grandma at liver. :>) And iron rich foods include green vegis such as spinach beans, lima beans, cereal fortified with iron, most meats (go lean though), fish, sweet potatoes, broccoli, etc.
good luck