subject: Salt and Sodium Intake – What Are the Risks and Do They Apply to You? [print this page] Salt and Sodium Intake What Are the Risks and Do They Apply to You?
Sodium intake has been a major issue in nutrition and public health for quite some time. The American diet (as well as those of many other nations) is notoriously high in sodium with staple foods like processed meat products, potato chips, and take-out food. It's been widely communicated to the public that high sodium intake can cause high blood pressure, also known as hypertension. However, this message has often failed to reach many people who don't currently suffer from hypertension and therefore believe that sodium reduction is not important to their health. Let's explore the mechanism behind the link between sodium and hypertension as well as some of the other risks associated with a high sodium intake level.
Salt is extremely hygroscopic, meaning its molecules attract water from the surrounding environment. High dietary salt intake causes an increase in the concentration of sodium in the blood. In order to dilute the blood back to an appropriate level, water is pulled out of other areas of the body and into the bloodstream. The increase in blood volume stresses blood vessels, which respond by thickening their walls. As the blood vessel walls thicken, the space through which blood can flow decreases. The heart is forced to pump harder in order to get enough blood around the body, leading to high blood pressure.
One consequence of chronic hypertension is left ventricular hypertrophy (LVH). LVH is an enlargement of a portion of the heart muscle due to an increase in the pressure it is required to pump against. Studies investigating the direct link between LVH and sodium intake have shown that in people who have already developed LVH, decreasing dietary sodium can significantly lower left ventricular mass within one year. In addition, those with more severe LVH show the greatest benefit from sodium reduction. Clearly, there is a causative relationship here that may be able to help those suffering from dietary sodium-induced LVH.
High sodium intake can also put your bones at risk. As dietary sodium increases, so does urinary calcium excretion. Sodium and calcium compete for the same reabsorption mechanism in the kidneys. As sodium output due to overconsumption goes up, less calcium is able to reabsorbed, leading to greater than normal losses in calcium. Though there are other nutrients that can affect urinary calcium output, it has been shown that sodium is the primary nutritional factor. Low dietary calcium also tends to exacerbate the problem, so it may be wise for those with higher sodium diets to keep an eye on their calcium intake.
Not only does increased urinary calcium excretion cause problems for bones, but it also increases the risk of kidney stones. In fact, high salt levels are even implicated in rising rates of childhood kidney stones! For anyone who's ever had a kidney stone can attest, it sucks. Don't let salty food be the cause of this excruciating disorder.
Another more direct risk to the kidneys exists, as well. High blood pressure can damage the kidneys' vascular system, resulting in what's known as hypertensive nephrosclerosis (HN). HN accounts for at least 25% of patients suffering from end-stage renal disease (ESRD). It is the second most common cause of ESRD in Caucasians and the leading cause in African-Americans.
Beyond the heart, bones, and kidneys, even more bad news awaits for the heavy sodium consumer. A high salt diet has been shown to assist Helicobacter pylori, the bacteria associated with 90% of duodenal ulcers and 80% of gastric ulcers. A high salt environment increases the expression of two genes in H. pylori that produce proteins associated with the bacteria's virulence. Essentially, your salt shaker lends a helping hand to the survival of the microorganism that's most likely responsible for punching holes in your gut.
Even worse, high dietary sodium levels have been shown to be significant risk factors for both gastric and colorectal cancers. Whether or not H. pylori plays a role in the increased incidence of the former cancer remains to be determined. However, it's clear that with or without the bacteria, chronically high salt intake will raise your chances of getting some very nasty cancers.
So, the upshot here is that sodium reduction is for pretty much everyone. Everyone, at least, who cares about their heart, bones, kidneys, stomach, or risk of getting cancer. There's more to the salt-reduction campaign that hypertension. So, whether your blood pressure is high, low, or just right, keep in mind the other risks of a high salt diet and look for alternatives to those foods in your diet that are loaded with sodium.
