Diet, Nutrition, & Low Salt

Why are my ankles swollen?

Have you heard of edema? It’s the medical term for fluid or water retention, which happens when the body has an abnormally high volume of fluid in the blood or tissues surrounding cells. How is fluid retention related to nutrition and salt? Although fluid retention can happen to anyone, it’s often caused by certain medications, pregnancy, an underlying condition, or a high-sodium diet from too much salt or other sources. People living with PAH are already at an increased risk for developing edema due to raised blood pressure, so regulating sodium becomes key to avoiding this irritating—and potentially dangerous—condition.

When fluid builds up, it may cause mild to severe swelling in different parts of the body. Many people with PAH notice that their ankles appear puffy, their hands tend to swell, or their tummy appears bloated. Excess fluid in the body’s tissues often accumulates in these areas. So, if you have fluid retention, you’ll probably notice one or more of these signs:

  • Puffy skin
  • Shiny skin
  • Bloated abdomen
  • Swollen ankles
  • Swollen hands
  • Pitting

Some signs of edema: Swollen ankles and pitting

Visual showing what some signs of edema look like on a PAH patient: swollen ankles and pitting

Pitting occurs when a small pit or dimple is left on the skin after pushing down on it for a few seconds. This is an indicator that the body is retaining too much water.

PAH Initiative’s diet, nutrition, and low salt article thumbnail

The science behind sodium and fluid retention

You’ve probably heard that your body is mostly made up of water. A little extra might seem like no big deal, right? In reality, your body works very hard to keep a precise balance of fluid and sodium, and even the slightest shift may affect your entire circulatory system. Here’s why:

Water is stored both inside and outside the cells, and your body automatically moves water in and out depending on where it is needed. How does your body decide where water is needed? The answer is largely based on sodium levels. When there is more sodium inside the cells, the body pulls water into the cells to balance it out. When there is more sodium outside the cells (often due to too much sodium/salt intake), the body pulls water out of the cells. Water outside the cells is stored in the blood plasma and fluid surrounding the cells.

Eating a diet that is high in sodium may cause the body's blood plasma levels to increase, causing higher blood volume, higher blood pressure, and swelling.

The added strain of high sodium on the heart

All that extra blood volume and higher pressure takes a toll on the heart—especially when it’s already working overtime due to PAH.

With PAH, the right side of the heart is already working hard to pump blood throughout the arteries and lungs, where it picks up oxygen. The blood vessels in the lungs have narrowed, making it harder for blood to pass through them.

Over time, the right side of the heart grows larger and weakens because of how hard it’s working. Higher sodium or fluid intake may increase the amount of blood in the right heart and force it to work even harder.

Limiting sodium and fluid intake may help reduce the strain on the right side of the heart.

What is the difference between salt and sodium?


Salt is what we add to our food

  • Salt is a chemical compound made up of sodium and chloride


Sodium is what’s already found in our food—especially in processed food containing preservatives—and may be listed on nutrition labels as

  • Salt
  • Baking soda
  • Sodium
  • Sodium nitrate
  • Sodium benzoate
  • Monosodium glutamate (MSG)

Reading nutrition labels with confidence

If you’ve ever felt overwhelmed at the grocery store trying to figure out which foods are actually good for you—you are not alone! There are tons of different versions of wording on food labels that infer something is “healthy,” but not all labeling is equal. Use the below table for a quick glimpse at what those nutrition labels really mean when it comes to sodium and salt content.

Chart discussing what nutrition labels say about salt and sodium verse what they really mean for PAH patients
Image Description

Sodium-free: <5 mg of sodium per serving; very low sodium: ≤35 mg of sodium per serving; low sodium: ≤140 mg of sodium per serving; healthy: <360 mg of sodium per serving/≤480 mg per meal for meal-type products; unsalted/no salt added/without salt added: No salt has been added to the food (however, sodium may still be present in some ingredients)

Should I reduce my sodium intake with PAH?

That depends. For many of us, hitting the daily recommended sodium limit can happen in just one meal. According to the FDA, Americans average about 3,400 mg of sodium per day—way over the Dietary Guidelines’ recommendation of less than 2,300 mg per day. For those with high blood pressure, the American Heart Association recommends even less sodium intake per day.

Recommended daily sodium intake

It’s always best to discuss your goals with your healthcare provider, including whether diet and nutrition changes will help you reach them. Your recommended sodium intake will be unique to you and aligned with your personal treatment goals. So, at your next visit, ask your healthcare provider what the recommended amount of sodium is for you.

Some healthcare providers might suggest following the American Heart Association guidelines, which recommend reducing salt and sodium intake to no more than 1,500 mg (about 3/4 teaspoons of salt) per day for most adults, especially if they have high blood pressure.

How can I improve my sodium intake?

Although you can’t control some of the causes of edema, you can control your sodium intake by closely monitoring your diet. Try these tips to start improving your sodium intake:

  • Read food labels for sodium content
  • Log your daily sodium intake in a journal or app
  • Speak with a dietitian about where to find low-sodium foods you enjoy
  • Ask a loved one to help prepare small portions of low-sodium meals for you to freeze and enjoy for several days
  • Avoid fast food, restaurant food, and processed food whenever possible

Learn more about PAH

PAH is a complicated disease that can be difficult to understand. We’ve broken it down for you with easy-to-understand information, simple graphics, and informative videos from a PAH specialist.

What Is PAH?

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