What is the effect of sodium restriction on blood pressure?

Sodium restriction has a significant effect on blood pressure primarily through its influence on blood volume. When sodium intake is reduced, the body tends to retain less water because sodium plays a key role in regulating fluid balance. This reduction in sodium intake results in a decrease in blood volume, as less water is retained. Consequently, with lower blood volume, there is less pressure exerted on the arterial walls, leading to a decrease in blood pressure.

This understanding aligns well with the physiological responses of the body to changes in sodium levels. The kidneys play a critical role in this process, as they help regulate both sodium and fluid balance. When sodium is restricted, the kidneys excrete more water, which decreases blood volume and, therefore, lowers blood pressure.

Other options do not accurately capture the effects of sodium restriction on blood pressure, which is why they do not apply in this context.