Another aspect of the "DASH" diet that was found to be a potential contributing factor was magnesium. Magnesium has a relaxing effect on the arterial and vascular systems, so that was one of the proposed mechanisms as to how the "DASH" diet had that reduced pressure effect. That makes sense, because if we look at this tube again, we see that stretching this out, and putting that tension within the system; now when you try to add more tension to it it's going to be that much harder to stretch the arterial system out; thus the pressure is going to increase that much more. Remember; when we're talking about the mechanisms for blood pressure, it's the volume and tension relationship. These are some of the foods; mostly grains; that are high in magnesium. Again; we're talking about actual foods, and not nutrient supplementation. In addition to having an affect on the actual arteries of the arterial system, it has an affect on the heart muscle tissue, as well.