Nutritional supplements haven't been proven to be THE miracle PMDD treatment. Although quite a few have been studied and shown to partially relieve premenstrual and PMDD symptoms. Calcium supplements look to be the best bet, but others are worth considering - especially if you don't eat a well-balanced, healthy and varied diet.
What you eat greatly affects your health. Nutrients in food are what create your cells and enable every little bodily function to work correctly. If you don't provide the right fuel, your body can't work right. Fuel for your body is made up of vitamins, minerals, fats, carbohydrates, protein and water.
These are the vitamins and minerals that have been shown to have a positive effect on PMDD symptoms and your mood:
If you aren't eating a healthy diet made up of varied foods, herbs and spices (and many people don't), it may be a good idea to take a multivitamin. That way you'll have the basics down for overall, good health, and you can build from there. If you decide to try a supplement mentioned above, then you can take into account what you're already getting from the multivitamin, and add an extra supplement. If you start with a basic multivitamin, then you may end up taking less pills everyday, which is kind of nice.
If you decide to start taking a multivitamin and a supplement for PMDD treatment, then choose a good quality brand. Research it if you need to. Just keep in mind, a lot of times you get what you pay for. If one brand is really cheap, that doesn't necessarily mean it's poor quality, but just take the time to look into the company and supplement sources.
I tend to choose things that are as natural as possible, preferably organic. Your health is your most precious resource, so you need to take care of it.
One last thing I want to repeat. I am not a doctor and not trying to give anyone medical advice. I think it's best if you work with your own doctor to create a treatment plan that's right for you, although I know not everyone will. I've had PMDD and just want to help others with treatment options with what I've learned and researched.