Why electrolytes matter for immune health

Your immune system is like a specialized security force that protects your body from dangerous pathogens — tracking down viruses and removing damaged cells to keep your body healthy. But since your immune system is also created by your body, the strength of your immune system is inextricably tied to your health status.

Electrolytes are an integral contributor to your health status. Charged minerals like sodium, potassium, and magnesium may help prepare the immune system to fight infection or tamp down the friendly fire of chronic inflammation. In other words, electrolyte balance affects immune balance.

Today, you’ll learn some neat stuff about electrolytes and immunity. We’ll address some controversial research on sodium and cancer immunity, the anti-inflammatory roles of potassium and magnesium, and how infections and illnesses can influence your electrolyte needs.

Sodium and Immunity

It’s clear that the amount of sodium you consume can influence parts of your immune system. But will extra sodium bolster or weaken your defenses? The nature of that relationship is anything but straightforward. It depends on the particular infection or disease you’re dealing with, the affected tissues (skin, kidneys, stomach, etc.), and what type of immune cells are working to heal you.

To illustrate, let’s explore a few examples in three broad categories:

1. Infection and disease
2. Autoimmunity
3. Cancer

#1: Sodium, Infection, and Disease

High sodium intakes may protect against certain infections and diseases, but may exacerbate others. This can quickly get super complex — and this topic is mostly uncharted in humans — but I’ll simplify with a couple of examples.

A negative example: According to a comprehensive 2021 review, a high-salt diet keeps the hormone aldosterone low, which may result in reduced immune activity. How? Bear with me.

Aldosterone is a hormone designed to help you retain sodium. When you consume more sodium, you don’t produce as much aldosterone. But aldosterone may also play a role in stimulating two types of infection-fighting white blood cells: proinflammatory macrophages and neutrophils. So by consuming more sodium and reducing aldosterone, you may reduce the activity of these particular white blood cells. Lower aldosterone production may also increase glucocorticoids — steroid hormones that can suppress immune activity.

To summarize, high-salt diets may suppress immune activity by lowering aldosterone levels, a hormone partially responsible for stimulating some immune cells (macrophages and neutrophils), and other hormones involved in the immune system (glucocorticoids). The authors of this review conclude that a high-salt diet “may subsequently influence the outcome of a disease, or not” depending on the type of immune cells fighting the disease.

A positive example: Macrophages are a type of white blood cell known for engulfing pathogens. In mice, high-salt diets enhance macrophage activity against a skin parasite called Leishmania major. Higher salt intakes led to higher concentrations of salt in the skin, creating a microenvironment that protects against parasites. Since humans with greater salt intakes also have saltier skin, this benefit may apply across species.

The takeaway: We just covered two examples. In one, sodium downregulated immunity. In another, it upregulated immunity. What’s the bottom line on sodium, infection, and disease? At a minimum, sodium plays an indirect role in how immune cells respond to a threat. But the importance of that role is blurry at best, and depends greatly on the particular infection we’re battling. Let’s put acute infections aside now, and focus on autoimmunity.

#2: Sodium and Autoimmunity

People with autoimmune disorders — like multiple sclerosis or inflammatory bowel disease — have overactive immune systems, creating needless inflammation throughout the body. Their immune systems kick in unnecessarily and attack the body without cause. To reduce their symptoms, you need to reduce the inflammation.

Where does sodium come in? Some research has shown that people with average sodium intakes (compared to higher intakes) have lower counts of certain types of immune cells. That’s probably a good thing for folks with autoimmune conditions.

For example, one study on six healthy young men showed that consuming 3.6 grams of sodium per day (slightly above the American average) compared to 4.8 grams per day:

• Decreased monocytes (a type of white blood cell)
• Decreased some pro-inflammatory cytokines (proteins that signal other immune cells)
• Increased one anti-inflammatory cytokine

In other words, going from a high-salt to moderate-salt diet downregulated the immune system, shifting it to a less inflammatory state.

A 2019 Nature review also explored sodium’s influence on immune cells in excruciating detail. The authors explored test tube, animal, and human evidence suggesting that high-salt diets may:

• Increase pro-inflammatory activity of T_helper cells
• Decrease anti-inflammatory activity of T_reg cells
• Increase pro-inflammatory activity of M1 macrophages
• Decrease anti-inflammatory activity of M2 macrophages
• Possibly increase inflammation in the gut by reducing one beneficial gut bacteria

Rather than get a migraine trying to understand the various complex functions of each of these cells, just know this: Folks with autoimmune conditions typically want less pro-inflammatory activity and more anti-inflammatory activity. This study suggests that high-salt diets seem to drive the opposite trends.

The takeaway: A high-salt diet is probably not optimal for autoimmunity. Of course, salt is just one factor among many, but people with autoimmune issues should monitor symptoms at different salt intakes. Based on the first study above, around 3 grams of daily sodium seems to be a reasonable starting point.

#3: Sodium and Cancer

Much like with infection and disease, the research on dietary salt intake and cancer risk has both positive and negative theories. Both are in need of more research, but here’s what we know so far.

A positive example: To discuss how sodium relates to cancer, we must discuss myeloid-derived suppressor cells (MDSCs). These cells dwell near tumors, suppressing your anti-cancer immune response. Increased MDSC activity is linked to worse cancer outcomes. A 2019 mouse study suggests a high-salt diet may block MDSC activity, allowing the immune system to fight tumors better. A result in mice isn’t a result in humans, but it’s definitely an interesting mechanism to ponder.

A negative example: Some research specifically on gastric cancer falls on the opposite side of the fence. For instance, gerbils infected with H. pylori — a carcinogenic stomach pathogen — had higher rates of gastric cancer on a high-salt diet compared to those fed a regular diet.

Observational data in humans also correlated high salt intakes with higher rates of gastric cancer. However, it’s important to consider that both diet quality and exercise are important risk factors for cancer. Not only do processed and restaurant foods contribute more than 70% of sodium intake in the US, but people who eat a poor quality diet are also less likely to exercise. So my hunch is that the correlation between salt intake and gastric cancer has a lot to do with the diet and lifestyle choices of people who tend to consume the most salt — not the salt itself.

The takeaway: I can’t find a single scientific paper that suggests salt is carcinogenic on its own. The relationship between cancer and sodium intake appears to hinge on the simultaneous intake of the nitrates and nitrites found in highly processed foods. Remove the problem foods, and salt may be exonerated. Now, let’s move on to potassium!

Potassium and Immunity

Generally speaking, potassium may help cool the immune system down. For example, high potassium concentrations outside cells have been shown to inhibit an inflammatory complex called the NLRC4 inflammasome, reducing inflammation.

Going beyond anti-inflammatory properties, potassium deficiency seems to lead to more kidney infections in rats. And in humans, low blood serum potassium (hypokalemia) is linked to urinary tract infections, though it’s unclear which causes which. Higher potassium intakes have also been linked to a lower risk of colorectal cancer in humans.

The takeaway: Based on this limited data, it appears potassium deficiency is a bad thing for your immune system. It may not be the most important mineral for immune regulation, but let’s not forget that optimizing your potassium intake is all upside. Higher potassium intakes protect against heart disease (the leading cause of death globally), and have many other benefits as well. Time to talk magnesium.

Magnesium and Immunity

Around half of US adults consume less than the recommended amount of magnesium from food. This deficiency creates two interlinked problems:

1. It promotes chronic inflammation
2. It impairs many aspects of immunity

Let’s talk about chronic inflammation first. Chronic inflammation is an increase in immune response in the absence of a specific disease. This slow, simmering immune response is linked to heart disease, neurodegenerative disease, and many other chronic conditions. In the circulatory system, for instance, too much immune activity can lead to the development of atherosclerotic plaques, the defining feature of heart disease. Magnesium can help reduce inflammation, which may explain (in part) why good magnesium status is linked to better cardiovascular outcomes.

Magnesium deficiency also compromises your immune system in many ways. Here are some examples:

• Impaired apoptosis. Apoptosis (programmed cell death) is a crucial defense mechanism against cancer — which is basically when abnormal cells grow uncontrollably. When apoptosis works properly, cells self-destruct before they become cancerous. Magnesium deficiency can hinder this mechanism.
• Thymus shrinkage. The thymus gland resides between the lungs and produces disease-fighting T cells. The aptly named “killer T cells” are like the assassins of your immune system and are excellent at terminating cancerous cells. The thymus naturally shrinks with age, but magnesium deficiency can accelerate this process.
• Exercise-induced immunosuppression. Intense physical activity depletes magnesium (among other minerals) — exercise requires more magnesium for physiologic functions like heart and muscle contractions, and you also lose a bit of magnesium through sweat. This loss of magnesium can potentially impair immune function.
• Worse T cell performance. Getting enough magnesium may help certain T cells fight pathogens and cancer, and low blood serum magnesium levels are linked to worse results for cancer immunotherapy.
• Asthma symptoms. Asthma is an inflammatory condition that causes airway constriction, making breathing difficult. Nebulized magnesium appears to improve asthma symptoms, though it’s unclear if magnesium pills help.

The takeaway: Avoid magnesium deficiency by getting 400–600 mg daily through food and supplements. I take around 200 mg of magnesium malate daily and stuff my face with green vegetables like Popeye to hit my target.

Infection, Illness, and Electrolyte Depletion

When someone is critically ill, their medical team must pay close attention to fluid, sodium, and potassium levels. Fluid and electrolyte imbalances can seriously disrupt your body’s functioning on a normal day, and being sick can increase your risk of imbalances or exacerbate them. To support your body during a battle (and generally), getting enough electrolytes is key.

Let’s start with sodium. You can lose significant sodium through a feverish sweat, but that’s just one vector. Acute, infection-related inflammation may also increase antidiuretic hormone (ADH) secretion, preventing urination and increasing the risk of low blood sodium levels. For severe infections like the H1N1 influenza virus, sodium depletion can be fatal.

Illnesses can also deplete potassium. For example, cholera-related diarrhea can result in very serious fluid and electrolyte disturbances. With other illnesses, you may also lose potassium directly via vomit. Not to mention, expelling stomach acid increases your body’s PH. To re-acidify your body, you may excrete potassium (an alkaline mineral) at a faster rate. Thankfully, oral rehydration solutions can help restore balance to fluid and electrolyte levels.

And gut issues aren’t the sole root of all potassium problems during illness. In 175 patients with COVID-19, over half developed hypokalemia (low blood potassium) independent of gastrointestinal symptoms. Fortunately, they responded well to potassium supplementation.

The takeaway: Infections and illnesses can increase fluid and electrolyte needs in a variety of ways. Serious fluid and electrolyte disturbances are best handled by medical professionals — but if you’re just feeling unwell at home, it’s generally wise to provide your body with plenty of sodium, potassium, and water.

Recap and Practical Thoughts

Electrolytes matter for immune health. The right balance keeps your security force primed and ready without veering into chronic inflammation.

Today we covered how:

• High sodium intakes may protect against certain infections or exacerbate others.
• Moderate sodium intakes are probably more suitable for people with autoimmune disorders.
• Potassium has anti-inflammatory properties.
• Magnesium deficiency increases inflammation, shrinks the thymus, and impairs cancer defenses.
• Fluids and electrolytes are lost rapidly in the case of many illnesses, and should be replaced to help your body play defense.

Preventing electrolyte deficiency is an easy way to support immune health. Evidence-based targets are 4–6 grams of sodium, 3.5–5 grams of potassium, and 400–600 mg of magnesium daily. Determine your baseline intake and supplement as needed. Folks with autoimmune conditions might consider consuming a bit less sodium than is typical.

Of course, electrolytes are just a tiny piece of the immunity puzzle. For best results, combine your electrolyte strategy with adequate sleep, routine exercise, a nutrient-dense whole foods diet, and regular visits to a trusted healthcare provider. Take care of your immune system, and your immune system will take care of you.