If you’ve been following the news about salt, you probably know that the debate has gone back and forth about how it affects blood pressure. Early studies indicated that eating a diet that contained a lot of salt increased both risk of high blood pressure and actual blood pressure numbers in those who already had high blood pressure. But subsequent studies found that the picture may not be so clear-cut and cast doubt on whether individuals should really worry about salt when it came to their pressure. Fortunately, a new review of all the research on the effects of high salt on the body has found that blood pressure isn’t the only factor when it comes to deciding how salt to eat.
How does salt affect blood pressure?
While no research has confirmed exactly how a high-salt diet increases blood pressure, most doctors and scientists agree that there are several factors at play. All that salt first gets dumped in the bloodstream. When one area has higher amount of salt than another, the high-salt area tends to pull water out of the low-salt area to balance out the concentration of salt. In the case of blood, high amounts of circulating salt pull water out of surrounding areas of the body as blood courses through blood vessels. More water means more blood, which leads to higher blood pressure if nothing else changes.
It also seems that salt affects the hormones that regulate the kidneys. One role of the kidneys is to decide how much water to hold on to and how much to release to be excreted as urine. Salt can affect the kidneys so that they hold on to more water, which leads to a larger amount of blood and higher blood pressure. Some studies show salt also affects blood vessels and may prevent them from relaxing and opening up to allow for that increased amount of blood.
Does everyone’s blood pressure respond to salt?
Researchers have found that only some people with high blood pressure are sensitive to changes in salt. If someone’s blood pressure changes when they either increase or decrease their salt consumption, they’re called salt-sensitive. If blood pressure doesn’t change with changes in salt, those people are called salt-resistant. This led some physicians to conclude that salt limits shouldn’t be applied to everyone since not all people are salt-sensitive.
What did this new review find?
This team of researchers wanted to know whether there were other reasons to be concerned about consuming too much salt. To do this, they looked at all of the research they could find on how eating lots of salt could affect other parts of the body. They found that high salt levels affected several organs of the body.
- Blood vessels: Salt seems to decrease the ability of blood vessels to shrink and expand in response to the needs of the body. This size changing is essential in regulating blood pressure and in ensuring that the body’s organs get the blood they need.
- Heart: Salt seems to increase the thickness of the heart’s walls. That increased thickness makes it harder for the heart to fill properly, which in turn makes it harder for the heart to pump blood effectively and get blood to organs in need.
- Kidneys: Salt has been found to worsen kidney function. Outside of its role in blood pressure, the kidney also helps to filter the blood. Studies indicate that high salt makes this filtration less effective and makes the kidneys more susceptible to damage.
- Brain: Salt acts on different parts of the brain and seems to change how the body regulates blood pressure and other functions associated with the “fight or flight” response. Even if blood pressure isn’t increased overall, this increased sensitivity makes it jump dramatically with minimal provocation. That rapid variability in blood pressure can damage organs.
What should I do?
This research shows us that it really is important to lower the amount of salt in our diet. Even if your blood pressure isn’t affected by your salt consumption, chances are good other parts of your body are. The authors point out most of the salt we get isn’t salt we add ourselves. About 70% of the salt in your diet comes from processed foods, often in things like bread, breakfast cereals or soups. To lower your dietary sodium, always check the nutritional information for high sodium content and buy low salt alternatives. Making your own food when possible from fresh ingredients can also make a big difference.