What substance moderates blood pressure that both lowers if too high and raises it if too high?

Answer 1

Not sure exactly what you are asking regarding "substance". In the diet, salt would have alot to do with low/high pressure and it increases the volume of fluid/blood in your body the heart has to pump. If you want to lower pressure, decrease your salt intake and processed/fast foods; also no sodas. Increase water/fluids. Hope this helps.