Which supplements cause kidney stones? A Nutrition Guide

October 8, 2025 •

4 min read

According to the National Kidney Foundation, more than half a million people seek emergency care for kidney stones every year. While most dietary supplements are safe when used responsibly, some, particularly at high doses, can significantly increase your risk of developing kidney stones. This guide explores which supplements cause kidney stones and how to mitigate the risk.

Quick Summary

An overview of dietary supplements that can contribute to kidney stone formation, including high-dose Vitamin C, specific calcium supplements, and high-protein powders. Learn how these supplements affect urinary chemistry and increase risk, along with practical strategies for safe supplementation.

Key Points

High-Dose Vitamin C: Supplements containing 1,000 mg or more of Vitamin C, or ascorbic acid, increase kidney stone risk by converting to oxalate.
Calcium Timing Matters: Taking calcium supplements between meals can elevate urinary calcium, but consuming dietary calcium with food is protective.
Excess Protein: High-protein diets, particularly from animal sources, increase kidney acid load and urinary calcium excretion, raising stone risk.
Vitamin D Risk: High-dose Vitamin D supplements, especially when combined with calcium, can raise blood calcium levels and promote stone formation.
Creatine is Safe: In healthy individuals, creatine supplements are generally safe and do not cause kidney stones, contrary to popular myth.
Hydration is Key: The best prevention strategy, even when supplementing, is to drink plenty of fluids (2-3 liters daily) to flush the kidneys.
Consult a Professional: Always talk to your doctor before starting supplements, particularly if you have a history of kidney stones.

Understanding Kidney Stones and Supplement Risk

Kidney stones are hard deposits made of minerals and salts that form inside your kidneys. The most common type is a calcium oxalate stone, formed when calcium combines with oxalate. While factors like dehydration and diet play a significant role, some dietary supplements can alter the delicate balance of substances in your urine, creating an environment ripe for stone formation. Being mindful of how and when you take supplements is crucial for prevention, especially if you have a history of stones.

The Main Culprits: Supplements Linked to Increased Risk

High-Dose Vitamin C (Ascorbic Acid)

For those with a history of calcium oxalate stones, high-dose Vitamin C supplements are a notable risk factor. This is because the body can convert excess Vitamin C into oxalate, which is then excreted in the urine.

How much is too much? A dose-dependent increase in risk has been observed, with studies showing an elevated risk for men taking 1,000 mg or more per day. Interestingly, the Vitamin C obtained from food is not associated with this increased risk.
Safe Alternatives: For immune support, it is better to obtain Vitamin C from whole foods like oranges and bell peppers.

Calcium Supplements

There is a common misconception that since most stones are calcium oxalate, one should avoid calcium. The opposite is true for dietary calcium, which binds with oxalate in the gut and prevents its absorption. However, the story is different for supplements.

The Risk Factor: Large doses of supplemental calcium, particularly when taken between meals, can increase urinary calcium levels and contribute to stone formation.
Mitigation Strategy: If calcium supplementation is necessary, it is best to take it with a meal. Some experts also recommend taking calcium citrate instead of calcium carbonate. Total daily intake should not exceed 1,200 mg.

High-Protein Supplements (Protein Powder)

High protein intake, especially from animal sources, creates an acid load that can increase urinary calcium excretion and lower urinary citrate, a natural stone inhibitor.

Protein Powder Specifics: While research specifically on protein powder and stone formation is limited, caution is warranted with excessive use, especially for those with existing risk factors.
The Role of Hydration: Adequate hydration is vital when taking protein supplements to help flush the kidneys and reduce crystal formation.

High-Dose Vitamin D

Vitamin D is crucial for bone health, but supplementation, especially in high doses and when combined with calcium, can elevate blood calcium levels. This can subsequently increase the amount of calcium in the urine, raising the risk of stone formation. It is particularly a concern for individuals with pre-existing hypercalciuria (high urinary calcium).

Certain Herbal Supplements

Some herbal products have been associated with kidney damage, which could indirectly contribute to the risk of stones. Specific examples include Ephedra and St. John’s Wort. It is critical to exercise caution with any herbal remedy and to consult a doctor, as regulations are not as strict as for conventional medicine.

Dispelling a Common Myth: Creatine and Kidney Stones

Creatine, a popular supplement for athletes, has often been associated with kidney stone concerns. This stems from creatine's metabolism, which slightly increases creatinine levels, a waste product filtered by the kidneys. However, multiple studies have shown that creatine is generally safe for healthy individuals at recommended doses and does not cause kidney stones. Some research even suggests it might reduce urinary oxalate, a key component of stones.

Mitigating Risk: How to Supplement Wisely

Stay Hydrated: Drinking plenty of water (2-3 liters per day) is the most effective way to prevent kidney stones, regardless of supplementation.
Timing Your Supplements: If you need calcium, take it with a meal to aid binding with oxalate in the gut. Avoid taking large doses of any supplement at once.
Get Nutrients from Food: Prioritize getting your vitamins and minerals from whole foods. For example, get Vitamin C from fruits and vegetables instead of high-dose pills.
Avoid Excessive Intake: Stick to the recommended daily amounts for all supplements. More is not always better and can be detrimental to kidney health.
Consult a Healthcare Professional: Always speak with a doctor or registered dietitian before starting a new supplement, especially if you have a history of kidney stones or other kidney issues.

Supplement Risks: At a Glance


Supplement	Primary Mechanism of Risk	Risk Level	Prevention Tips
High-Dose Vitamin C	Converted to oxalate, a key stone component.	High, especially >1000mg/day.	Get from food, avoid high-dose supplements.
Calcium Supplements	Large doses increase urinary calcium, especially between meals.	Moderate to High, depends on dosage/timing.	Take with meals, consider calcium citrate, stay within limits.
High-Protein Powder	Increases acid load, urinary calcium, and lowers citrate.	Moderate, with excessive intake.	Limit animal protein, stay well-hydrated.
High-Dose Vitamin D	Elevates blood and urinary calcium levels.	Moderate, especially with calcium.	Adhere to daily limits, balance with overall diet.
Creatine	Misconception about creatinine; no direct evidence linking to stones.	Minimal/None for healthy individuals.	Safe at recommended doses; ensure hydration.

Conclusion

While supplements can play a valuable role in a nutritional plan, they are not a substitute for a balanced diet and responsible health practices. Understanding which supplements cause kidney stones is the first step toward informed choices. High doses of Vitamin C, poorly timed calcium supplements, and excessive protein intake pose the highest risk. By prioritizing whole foods, staying well-hydrated, and consulting a healthcare professional, you can reduce your risk of developing kidney stones and support your overall kidney health.

For more information on preventing kidney stones through diet, consider exploring resources from reputable health institutions like the National Institutes of Health (NIH).

Frequently Asked Questions

High doses of supplemental Vitamin C (ascorbic acid) can be converted into oxalate in the body, which is then excreted in urine. This increases the risk of forming calcium oxalate kidney stones, especially for men taking 1,000 mg or more per day.

You should not avoid dietary calcium, as it is protective. However, large doses of supplemental calcium, especially when taken on an empty stomach, can increase your risk. Taking calcium supplements with food is a safer approach.

Excessive intake of animal protein, which is often found in protein powders, can increase acid load and urinary calcium, potentially increasing kidney stone risk. Staying well-hydrated is crucial if you use protein supplements.

Yes, for healthy individuals using recommended doses, creatine is generally considered safe. Concerns are largely based on misinformation, and modern research does not link creatine to kidney stone formation.

High doses of Vitamin D can increase calcium levels in the blood and urine, which elevates the risk of stones, particularly if you are also taking calcium supplements. This risk should be managed under the guidance of a healthcare provider.

The safest way is to obtain Vitamin C from food sources like oranges, strawberries, and bell peppers. This minimizes the high-dose intake associated with supplements that increases oxalate excretion.

Staying well-hydrated is the most important preventive measure. High fluid intake helps dilute urine, preventing the concentration of minerals and salts that form stones.