Is it safe to take 300 mg of potassium (K+) as a supplement three times a week?

Safety of 300 mg Potassium Supplementation Three Times Weekly

Taking 300 mg of potassium three times per week (900 mg total weekly) is safe for most adults without kidney disease or those not taking potassium-sparing medications, though this dose is far below therapeutic levels and unlikely to provide meaningful health benefits.

Context: Recommended Potassium Intake

The dose you're considering is extremely low compared to standard recommendations:

• Daily dietary potassium targets range from 3,510 mg/day (WHO) to 4,700 mg/day (US Dietary Guidelines) 1
• Your proposed supplementation of 300 mg three times weekly equals only 128 mg per day on average—representing just 2.7% of the recommended daily intake 1
• Even a single medium banana contains approximately 450 mg of potassium, exceeding your proposed daily average 1, 2

Safety Assessment

For Most Healthy Adults

This dose poses minimal to no safety risk for individuals without the following conditions:

• Normal kidney function (no moderate-to-advanced chronic kidney disease) 1
• Not taking potassium-sparing medications including:
  • ACE inhibitors or angiotensin receptor blockers (ARBs) 1, 2
  • Potassium-sparing diuretics (spironolactone, amiloride, triamterene) 2, 3
  • Combination of these medications 2

Why This Dose Is Exceptionally Safe

• Therapeutic potassium supplementation typically starts at 20-60 mEq/day (780-2,340 mg/day) for treating deficiency 3
• Your proposed 300 mg three times weekly is approximately 1/18th of the minimum therapeutic starting dose 3
• The 2024 ESC guidelines recommend increasing potassium intake by 500-1,000 mg daily for blood pressure benefits—far exceeding your proposed regimen 1

Clinical Effectiveness Considerations

While safe, this supplementation strategy has no evidence base for clinical benefit:

• Blood pressure reduction requires potassium increases of 1,380 mg/day or more 1
• Cardiovascular risk reduction demonstrated in trials used potassium-enriched salt substitutes (25% potassium chloride) consumed daily, not intermittent low-dose supplements 1
• Studies showing benefit used daily supplementation, not intermittent weekly dosing 1

Practical Recommendations

If Your Goal Is General Health

Increase dietary potassium through food rather than supplements 1, 2:

• 4-5 servings of fruits and vegetables daily provide 1,500-3,000 mg potassium 1, 2
• Good sources include: avocados (710 mg/cup mashed), spinach (840 mg/cup boiled), bananas (450 mg each) 1, 2
• Low-fat dairy products, fish, nuts, and legumes are also excellent sources 1

If You Have Specific Medical Reasons

• For hypokalemia treatment: Therapeutic doses start at 20 mEq/day (780 mg) divided into 2-4 doses daily, not weekly 3
• For blood pressure management: Aim for 3,510-4,700 mg daily through diet or salt substitutes 1

Monitoring Requirements

Even at this low dose, monitor serum potassium if you have 1:

• Any degree of chronic kidney disease
• Take ACE inhibitors, ARBs, or potassium-sparing diuretics
• History of hyperkalemia

Bottom Line

Your proposed regimen of 300 mg three times weekly carries virtually no safety risk for healthy adults but also provides no meaningful clinical benefit 1, 3. This dose is approximately equivalent to eating one extra banana per week. If you're seeking health benefits from potassium, focus on consuming 4-5 daily servings of potassium-rich fruits and vegetables instead 1, 2.