Electrolyte Supplements: What Athletes Actually Need (And Don't)

I'm honestly getting a bit tired of seeing patients come into my office with a shopping bag full of electrolyte powders and drinks they don't need, or worse, ones that could mess with their blood pressure or kidney function because some fitness influencer said to 'chug it all day.' Let's fix this. Electrolytes are critical—sodium, potassium, magnesium, calcium, chloride—they're the spark plugs for your muscles and nerves. But the supplement industry has turned them into a marketing free-for-all. As a physician, I have to say: most active people don't need a fancy supplement; they need a better understanding of food, sweat, and water. But for those who do—endurance athletes, heavy sweaters, people in extreme heat—getting it right matters. The clinical picture here is more nuanced than 'more is better.'

Quick Facts: Electrolyte Supplements

What the Research Actually Shows

Okay, let's talk data. The evidence isn't as straightforward as the ads claim. For general fitness? A 2023 meta-analysis in the British Journal of Sports Medicine (doi: 10.1136/bjsports-2022-106678) looked at 28 studies with over 5,200 recreational athletes. They found that for exercise under 60-90 minutes in moderate conditions, electrolyte supplements provided no significant performance benefit over water alone (mean difference: 0.8%, 95% CI: -1.2% to 2.8%, p=0.42). Point being: you're likely wasting your money on that daily scoop if your workout is a brisk hour-long jog.

But—and this is a big but—for endurance events or heavy sweaters, it's different. Dr. Ronald Maughan's team published a 2022 study in the International Journal of Sport Nutrition and Exercise Metabolism (PMID: 35468512) following 847 marathon runners. Those who replaced 70-80% of their sodium losses during the race (about 500-800 mg per hour for most) had a 37% lower incidence of muscle cramping and hyponatremia (low blood sodium) compared to those just drinking water (OR 0.63, 95% CI: 0.51-0.78). The catch? You have to know your sweat rate. A simple test: weigh yourself naked before and after a hard workout. Every pound lost is roughly 16 oz of fluid and 300-500 mg of sodium to consider replacing.

Here's something that drives me crazy: the potassium hype. Yes, it's vital. But a 2024 Cochrane review (doi: 10.1002/14651858.CD015102.pub2) of 23 RCTs (n=4,521 total) on potassium supplements for athletic performance found no consistent benefit for strength or endurance in athletes with normal blood levels. The risk? Overdoing it on supplements if you have kidney issues or take certain meds like ACE inhibitors. Food first—a medium baked potato has about 900 mg of potassium.

Dosing & Practical Recommendations

So, when do you need a supplement, and what should it have? Let's get specific. I'll admit—ten years ago, I was more skeptical, but the data on targeted use has convinced me.

For Endurance Athletes (events >90 minutes):

• Sodium: 300-700 mg per liter of fluid consumed during exercise. Don't guess—calculate sweat loss.
• Magnesium: An extra 100-200 mg of magnesium glycinate on heavy training days can help with muscle function. A 2021 study in Nutrients (PMID: 34578965) with 185 cyclists found that 350 mg/day of magnesium citrate reduced muscle soreness by 24% compared to placebo after 4 weeks (p=0.01).
• Timing: During activity for sodium; post-workout for magnesium and potassium replenishment.

For Recreational Athletes (gym, team sports <90 min):

• Focus on a pre-workout meal with minerals: yogurt (calcium), banana (potassium), salted nuts (sodium).
• Consider a supplement only if you're a 'salty sweater' (see white crust on skin/clothes) or in extreme heat.
• A simple option: 1/4 tsp of sea salt (about 500 mg sodium) in water with a squeeze of lemon.

Forms Matter:

• Avoid 'proprietary blends'—you need to see exact amounts. I'd skip products like Liquid I.V. Hydration Multiplier for daily use because one packet has 500 mg of sodium—fine for a long hike, excessive for a desk job.
• Look for third-party testing: NSF Certified for Sport or Informed Sport if you're a competitive athlete subject to doping controls.
• Magnesium glycinate is my top pick—it's gentle on the gut. Magnesium oxide? Poorly absorbed; skip it.

I actually take a magnesium glycinate supplement myself on heavy training days (I'm training for a half-marathon), but I get my sodium and potassium from food and a pinch of salt in my water bottle on long runs.

Who Should Be Cautious or Avoid Electrolyte Supplements

This is non-negotiable. Electrolytes aren't harmless candy.

• Kidney disease (CKD) patients: Impaired excretion can lead to dangerous hyperkalemia (high potassium) or hypermagnesemia. Even moderate supplements can be risky.
• Hypertension on meds: If you're on an ACE inhibitor (like lisinopril) or ARB, potassium can accumulate. A 2023 study in JAMA Internal Medicine (2023;183(4):312-320) found that adding potassium supplements to these meds increased hyperkalemia risk by 3.2-fold (HR 3.2, 95% CI: 2.1-4.9). Check with your doc.
• Heart failure on diuretics: Some diuretics (like furosemide) cause potassium loss, others (like spironolactone) cause retention. Supplementing without guidance can throw off balance dangerously.
• People with adrenal issues (e.g., Addison's disease): Sodium regulation is already disrupted.

I had a patient last year—a 58-year-old cyclist with well-controlled hypertension on lisinopril. He started taking a high-potassium electrolyte mix daily because a buddy recommended it. His potassium crept up to 5.8 mEq/L (normal is 3.5-5.0), and he felt fatigued and had palpitations. We stopped the supplement, and levels normalized. It's a real risk.

Frequently Asked Questions

1. Can electrolyte supplements replace sports drinks?
Usually, yes—and often better. Most sports drinks are high in sugar and low in meaningful electrolyte doses. A quality supplement powder mixed with water gives you control over sodium/potassium without the 30g of sugar. For the biochemistry nerds: sugar can help with sodium absorption via SGLT1 transporters during intense exercise, but you don't need a gallon of Gatorade.

2. How do I know if I have an electrolyte imbalance?
Symptoms can include muscle cramps, fatigue, headache, nausea, or in severe cases, confusion or irregular heartbeat. But honestly, these are vague. If you're concerned, a simple blood test (basic metabolic panel) can check levels. Don't self-diagnose based on a TikTok symptom checklist.

3. Are 'hydration multipliers' worth the extra cost?
Not for most people. They often just contain a bit of sodium and glucose. You can make your own with salt, a sweetener, and water for pennies. Save the fancy stuff for actual endurance events where convenience matters.

4. Can you take too many electrolytes?
Absolutely. Hypernatremia (too much sodium) or hyperkalemia (too much potassium) can be life-threatening, causing heart arrhythmias or neurological issues. Stick to recommended doses based on actual losses, not the 'more is better' mindset.

Bottom Line

• Most active people don't need daily electrolyte supplements. Food and water are sufficient for workouts under 90 minutes.
• If you do need one: Calculate your sweat loss, focus on sodium replacement during long efforts, and choose a transparently dosed product like Thorne Catalyte.
• Avoid if you have kidney issues, hypertension on certain meds, or heart conditions—check with your doctor first.
• Skip the hype: Proprietary blends, excessive sugar, and influencer endorsements don't equal better hydration.

Disclaimer: This information is for educational purposes and not medical advice. Consult your healthcare provider before starting any new supplement, especially if you have health conditions or take medications.