Last updated: Jun 14, 2016

You've probably been told your entire life that too much sodium is bad for you. Now, new research suggests that a diet low in sodium may actually be harmful.

The collection of four studies, published in the journal The Lancet, followed more than 100,000 participants—some with high blood pressure, some without—from nearly 50 countries for almost four years. The researchers found that people with a low sodium intake (less than 3,000 mg) experienced a higher risk of heart attack, stroke, or heart failure, compared to people who consumed between 3,000 mg and 6,000 mg a day. That’s well above the current recommendations by the USDA of 2,300 mg for healthy adults, and 1,500 mg for those with hypertension or increased risk of high blood pressure.

The study has come under some scrutiny because the researchers assessed the participants' sodium levels via a single urine sample that was collected when the participants enrolled. Also, the data did not reveal a direct cause and effect; it simply showed an association between lower sodium diets and increased risk of heart problems, leaving many questions unanswered.

In any case, the findings have fueled the ongoing sodium controversy. Just a few years ago, for example, a panel of top experts concluded that while Americans are consuming excess amounts of sodium, cutting back too much may do more harm than good. Meanwhile New York City is requiring restaurant chains to post sodium warning labels next to certain menu items. The USDA and American Heart Association continue to stand by the current sodium guidelines.

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Clearly sodium isn't a cut and dry subject, and it can be challenging to sort through the latest info. Some of my clients are even confused about the basics, like what sodium is and why we need it. If you're in the same boat, here are seven things you should know, including my advice for determining how to get just the right amount.

Sodium is a mineral

Sodium is an essential mineral, which means your body doesn't make enough of its own supply naturally, so you must meet your needs with food.

It helps your body operate

Sodium performs several critical functions, such as allowing muscles and nerves to work properly. It also regulates the delicate balance of fluids in your body, helping to maintain a proper blood volume and blood pressure.

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Sodium is found in salt

Many people use the words salt and sodium interchangeably, but they aren’t the same. Sodium is a mineral that occurs naturally in some foods, and is added to most processed foods. It’s also a component of salt, which is technically called sodium chloride because it's made up of 40% sodium and 60% chloride. To put that into perceptive, one level teaspoon of salt contains about 2,300 mg of sodium.

Most sodium doesn’t come from salt

Data shows that roughly 70% of an average American’s sodium intake comes from processed foods. And if you start looking at the mg of sodium per serving on nutrition labels, you'll see why. One cup of canned soup (not the whole can) can contain more than 900 mg. A quarter cup of bottled salad dressing or a frozen low-cal entrée can each contain nearly 700 mg, while a whole frozen pizza typically has more than 1,600 mg. Even foods that don’t seem salty can pack a lot of sodium. A blueberry scone, for example, may contain more than 750 mg. However, fresh whole foods tend to be low in sodium. Raw spinach only provides 24 mg per cup, and a cup of chopped raw celery packs 81 mg.

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Excess amounts of sodium are probably bad for everyone

One concern about sodium is that it causes your body to retain excess fluid. This leads to an increase in blood pressure, which then ups your risk of heart disease, stroke, kidney damage, and other serious health problems. It is estimated that reducing the average amount of sodium people eat to the current recommended level could result in 11 million fewer cases of high blood pressure each year, which might have a significant impact on a number of related health risks.

Hypertension, or abnormally high blood pressure, is often called the “silent killer” because the condition has no obvious warning signs. That’s why it’s important to keep tabs on your blood pressure throughout your life. A healthy reading is less than 120 systolic (the upper number) and 80 diastolic (the lower number). Even prehypertension can put too much stress on your heart, and damage the muscle. So if you have no idea what your blood pressure is, start getting it checked now.

When you sweat you need more sodium

We lose sodium through sweat. So whether it's because of humid weather or exercise, if you're perspiring a lot, it's important to replace lost sodium. Not doing so can be dangerous and even deadly. Keep in mind that plain water won't cut it, since it's naturally low in the mineral. Instead, reach for a sports drink or another electrolyte replacement (electrolyte is a term for minerals like sodium that carry an electric charge).

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It's best to get your sodium from whole foods and salt

I think it goes without saying that cutting back (or cutting out) processed foods is important for a number of reasons. It will slash your sodium intake considerably, and improve your overall diet. While many fresh, whole foods do contain some sodium, it’s okay to use a few shakes or a small pinch of sea salt after cooking, especially if you’re concerned about reaching your body's sodium needs.

That said, try to be consistent. An erratic intake of sodium may cause water retention, which can trigger bloating. And even if you use some salt for flavor, keep on seasoning your food with natural herbs and spices, which add extra antioxidants to your meals.

Bottom line: Balance is best, so avoid the extremes of gobbling up too much processed food or being sodium-phobic. Instead, work on developing a healthy eating pattern you can stick to for the long haul.

Do you have a question about nutrition? Chat with us on Twitter by mentioning @goodhealth and @CynthiaSass

Cynthia Sass is a nutritionist and registered dietitian with master’s degrees in both nutrition science and public health. Frequently seen on national TV, she’s Health’s contributing nutrition editor, and privately counsels clients in New York, Los Angeles, and long distance. Cynthia is currently the sports nutrition consultant to the New York Yankees, previously consulted for three other professional sports teams, and is board certified as a specialist in sports dietetics. Sass is a three-time New York Times best-selling author, and her newest book is Slim Down Now: Shed Pounds and Inches with Real Food, Real Fast. Connect with her on FacebookTwitter and Pinterest.