The close relationship between hypertension and dietary sodium intake is widely recognized and supported by several studies. A reduction in dietary sodium not only decreases the blood pressure and the incidence of hypertension, but is also associated with a reduction in morbidity and mortality from cardiovascular diseases. Prolonged modest reduction in salt intake induces a relevant fall in blood pressure in both hypertensive and normotensive individuals, irrespective of sex and ethnic group, with larger falls in systolic blood pressure for larger reductions in dietary salt. The high sodium intake and the increase in blood pressure levels are related to water retention, increase in systemic peripheral resistance, alterations in the endothelial function, changes in the structure and function of large elastic arteries, modification in sympathetic activity, and in the autonomic neuronal modulation of the cardiovascular system. In this review, we have focused on the effects of sodium intake on vascular hemodynamics and their implication in the pathogenesis of hypertension.
Salt vs. sodium equivalents
Sodium chloride or table salt is approximately 40 percent sodium. It’s important to understand just how much sodium is in salt so you can take measures to control your intake. These amounts are approximate.
- 1/4 teaspoon salt = 575 mg sodium
- 1/2 teaspoon salt = 1,150 mg sodium
- 3/4 teaspoon salt = 1,725 mg sodium
- 1 teaspoon salt = 2,300 mg sodium
Sodium can be sneaky! Taking control of your sodium means checking labels and reducing preservatives. Other foods to be aware of include:
- Processed foods
- Natural foods with a higher-than-average sodium content, including cheese, seafood, olives and some legumes
- Table salt, sea salt and kosher salt (sodium chloride)
- Some over-the-counter drugs
- Some prescription medications
The cycle of damage: How your heart is affected
Over time, excessive salt intake can lead to high blood pressure (hypertension), which stiffens and narrows the blood vessels. Blood and oxygen flow to key organs decreases. So the heart tries harder to pump blood throughout the body, which further increases blood pressure.
Elevated blood pressure, particularly over a long period of time, puts an incredible strain on the heart. It can enlarge the heart’s left pumping chamber and weaken the heart muscle (heart failure).
Unchecked hypertension can also damage the artery walls, which begin to collect fat, leading to heart disease and potentially heart attack or stroke.
The best way to prevent a heart attack is to stop the arteries from becoming damaged.
What hypertension does to your kidneys?
You can see this chicken-or-egg effect with high blood pressure and kidney disease as well. Hypertension puts extra pressure on the kidneys’ filtering units, which can lead to scarring. This impairs the kidneys’ ability to regulate fluid, which increases blood pressure.
If this cycle is not stopped, it can lead to kidney disease and kidney failure.
“High blood pressure and uncontrolled diabetes are the most common causes of kidney disease.”
Unfortunately, the vast majority of people with kidney disease don’t realize they have it. The signs and symptoms may be attributed to other conditions and usually appear when the kidneys have already begun to fail. Here are symptoms to watch for:
- Unusual fatigue.
- Sleep troubles.
- Itchy skin.
- Decreased urination.
- Blood or foam in the urine.
- Swelling in the ankles, feet or around the eyes.
- Lack of appetite, nausea or vomiting.
- Muscle cramps.
- Taste abnormality.
If you are experiencing any of these symptoms — particularly if you are at risk of kidney disease because you’re over age 60, have high blood pressure, have diabetes or have a family history of kidney failure — talk to your doctor about your kidney health and salt intake.
The question of salt sensitivity
Salt affects people differently. Some people can consume sodium with no effect on their blood pressure. But for others who are ‘salt sensitive,’ even a slight increase in sodium intake wreaks havoc on the kidneys’ ability to regulate fluid, and increases blood pressure.
Salt sensitivity is most prevalent among people who are middle-aged or elderly, overweight or obese, and African-American. It also tends to become more prevalent as we age.
Lifestyle changes can help
One of the first things your doctor will recommend is modifying your lifestyle by:
- Eating a low-sodium diet (the American Heart Association recommends no more than 1,500 mg/day for most adults), especially if you’re at risk.
- Limiting alcohol.
- Exercising regularly.
- Maintaining a healthy weight.
Even with salt restriction and lifestyle changes, blood pressure may remain elevated. Medications, in addition to lifestyle changes, are oftentimes also needed to lower your blood pressure. Examples of medications include:
- Diuretics, or water pills, which increase urination to help discharge excess fluid.
- Angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers (ARBs), which help to relax blood vessels.
Besides encouraging you to keep hypertension and diabetes under control, your doctor may test you annually for kidney disease.
Working with your doctor to ensure that salt intake is not raising your blood pressure and impacting your heart and kidneys can have a dramatic impact on your health and longevity.