The most effective way to lower blood sodium levels depends on whether you’re dealing with a clinical condition (hypernatremia, where blood sodium exceeds 145 mmol/L) or simply trying to reduce the sodium load in your diet to protect your heart and kidneys. For most people searching this topic, the answer involves drinking more water, eating fewer processed foods, and increasing potassium-rich foods. Normal blood sodium falls between 136 and 145 mmol/L, and your kidneys do most of the heavy lifting to keep it there.
Why Blood Sodium Gets Too High
Your kidneys are the central regulators of sodium balance. They use a network of specialized channels and transporters to fine-tune how much sodium and water your body retains or excretes. A hormone called vasopressin (also known as antidiuretic hormone) tells the kidneys when to hold onto water, which dilutes sodium in the blood. Another hormone, aldosterone, controls how much sodium the kidneys reabsorb versus flush out.
When this system works properly, your body keeps blood sodium in a tight range. Problems arise when you lose too much water (from dehydration, vomiting, diarrhea, or heavy sweating), take in too much sodium without enough fluid, or have a medical condition that disrupts hormone signaling. Certain medications, particularly lithium and some diuretics, can also impair the kidneys’ ability to concentrate urine, leading to water loss and rising sodium levels.
Symptoms of High Blood Sodium
Mild elevations in blood sodium often produce intense thirst and reduced urine output. As levels climb, symptoms become neurological: confusion, irritability, muscle twitching, and restlessness. When sodium exceeds 160 mmol/L (classified as severe hypernatremia), seizures, loss of consciousness, and brain damage become real risks. Extreme hypernatremia, above 190 mmol/L, is life-threatening. If you or someone you’re with shows confusion, lethargy, or seizures alongside dehydration, that warrants emergency care.
Drink More Water (the Simplest Fix)
For mild cases and general prevention, water is the most direct tool you have. When you drink plain water, it dilutes the sodium concentration in your blood. Your kidneys then have an easier time excreting the excess. Most healthy adults can lower mildly elevated sodium simply by increasing fluid intake over several hours. Sipping water consistently throughout the day is more effective than drinking large amounts at once, since your kidneys can only process fluid at a certain rate.
If you exercise heavily or live in a hot climate, you lose both water and sodium through sweat. Sweat sodium concentrations vary widely between individuals, ranging from about 10 to 70 mmol/L for whole-body sweat. More vigorous exercise and hotter conditions push sweat sodium higher. For most people trying to lower blood sodium, replacing lost fluids with plain water rather than sports drinks is the better choice.
Cut Back on Dietary Sodium
The average adult globally consumes about 4,310 mg of sodium per day. That’s more than double the World Health Organization’s recommendation of less than 2,000 mg per day (roughly one teaspoon of table salt). Reducing dietary sodium gives your kidneys less work to do and helps bring blood levels down over time.
The challenge is that most dietary sodium doesn’t come from the salt shaker. It’s hidden in processed and packaged foods. The differences between unprocessed and processed versions of the same food are striking:
- Beef: Plain roasted beef contains about 48 mg of sodium per 100 grams. Canned corned beef contains 950 mg.
- Peanuts: Plain peanuts have 2 mg per 100 grams. Dry roasted peanuts have 790 mg.
- Sweet corn: Corn on the cob boiled in unsalted water has just 1 mg per 100 grams. Canned corn has 270 mg.
- Salmon: Raw or steamed salmon has about 110 mg per 100 grams. Smoked salmon has 1,880 mg.
- Wheat bran: Plain wheat bran has 28 mg per 100 grams. Bran flakes cereal has 1,000 mg.
Condiments and flavor enhancers are some of the worst offenders. Soy sauce contains roughly 7,000 mg of sodium per 100 grams. Bouillon cubes and powdered broths can reach 20,000 mg per 100 grams. Snack foods like pretzels and cheese puffs average around 1,500 mg, and bacon sits at the same level. Reading nutrition labels and cooking with whole ingredients are the two most practical steps you can take.
Eat More Potassium-Rich Foods
Potassium and sodium have an inverse relationship in the body. When you eat more potassium, your kidneys excrete more sodium. This process is regulated by aldosterone, which acts as a master switch for both minerals. Increasing potassium intake through food is one of the most reliable ways to help your body clear excess sodium naturally.
Good sources include bananas, potatoes, spinach, beans, avocados, yogurt, and oranges. The DASH diet (Dietary Approaches to Stop Hypertension) is built around this principle, emphasizing fruits, vegetables, whole grains, and lean proteins while limiting sodium and processed foods.
The DASH Diet Approach
The DASH diet is the most studied dietary pattern for sodium-related health problems. In the DASH-Sodium trial, people who followed the diet with low sodium intake saw their systolic blood pressure drop by 7.1 mmHg if they didn’t have hypertension and by 11.5 mmHg if they did. A meta-analysis of 17 randomized controlled trials involving over 2,500 participants found the DASH diet reduced systolic blood pressure by an average of 6.74 mmHg and diastolic by 3.54 mmHg.
Combining the DASH diet with exercise and weight loss amplifies the effect. In the ENCORE study, overweight participants with above-normal blood pressure who combined the DASH diet with a weight management program saw systolic blood pressure drop by 16.1 mmHg, compared to just 3.4 mmHg in the control group eating their usual diet. The DASH diet alone produced an 11.2 mmHg reduction. These are meaningful differences that, for many people, rival the effect of a first-line blood pressure medication.
How Hospitals Treat High Sodium
When blood sodium is dangerously elevated and can’t be corrected by simply drinking water, treatment happens in a hospital setting. The core principle is restoring lost water without dropping sodium levels too fast. Lowering sodium more than 12 mmol/L per day (or more than 0.5 mmol/L per hour) can cause the brain to swell, a condition called cerebral edema. This is why correction is done slowly and with close monitoring.
For patients who can’t drink enough on their own, doctors use intravenous fluids that contain less sodium than the blood. Regular saline (which matches the body’s sodium concentration) isn’t useful for this purpose since it won’t dilute the excess. Instead, fluids with lower sodium concentrations or sugar water solutions are used to gradually bring levels down. If a medication is causing the problem, stopping or switching that medication is part of the treatment plan.
Practical Steps to Start Today
If your blood work shows sodium at the high end of normal or slightly above, the lifestyle approach is straightforward. Aim for less than 2,000 mg of sodium per day by cooking more meals from scratch and avoiding the processed foods listed above. Increase your water intake, especially if you tend to drink less than you should or if you’re physically active. Add potassium-rich fruits and vegetables to every meal.
Track your sodium intake for a few days using a food diary or app. Most people are surprised to find they’re consuming two to three times the recommended amount without realizing it. A single restaurant meal can easily contain an entire day’s worth of sodium. Making even moderate reductions, like swapping canned vegetables for fresh or frozen, choosing unsalted nuts, and cutting back on condiments, can meaningfully shift your sodium balance within weeks.