I have found that taking kelp tablets have helped with excessive hair, painful periods and fluid retention. I have been quite surprised, I suddenly realised it was kelp tablets that I was taking that was making the difference. Only problem I have found is that, taking kelp or rather too much can tip the thyroid over the edge, i.e. hyperthyroidism.
Definetly help with painful/heavy periods ...but you must take care whilst taking kelp...and not take too much!
Please note this is how kelp has affected me, and I am merely relaying my experience here.