Vitamin C is an essential nutrient known for strengthening immunity, enhancing skin health, and protecting the body from oxidative stress. While it is vital for connective tissue repair and iron absorption, experts warn that excessive vitamin C intake—particularly through high-dose supplements—may increase the risk of kidney stones in men. Research shows that men taking large doses of vitamin C are nearly twice as likely to develop kidney stones compared to those who don’t. Natural sources like citrus fruits and peppers are safe, but experts advise caution with supplements, especially for individuals with a history of stone formation, impaired kidney function, or existing urinary tract problems.
Understanding Vitamin C: Daily needs vs high doses
As published in
Harvard Health, the recommended daily intak e of vitamin C varies by gender:
- Men require about 90 mg per day
- Women require about 75 mg per day
This vital nutrient helps the body form and repair connective tissue, supports wound healing, strengthens bones, and improves iron absorption. Natural food sources such as citrus fruits, red bell peppers, and papaya typically provide sufficient amounts of vitamin C for most people.
However, many supplements far exceed the body’s needs, delivering 10 times or more the recommended daily allowance. While some individuals take large doses hoping to prevent colds, strengthen immunity, or fight chronic diseases, the scientific evidence supporting these claims remains weak.
Vitamin C intake in high doses doubles kidney stone chances: Study reveals
A major study published in JAMA Internal Medicine highlighted the connection between vitamin C supplements and kidney stone formation in men. The study followed over 23,000 Swedish men for 11 years, revealing that:
- Around 2% developed kidney stones during the study period.
- Men who took high-dose vitamin C supplements were twice as likely to develop stones compared to those who did not.
- Taking a standard multivitamin showed no increased risk.
These findings suggest that isolated, high-dose vitamin C supplements—not multivitamins or vitamin C-rich foods—pose a significant risk for kidney stone development in men.
Why does excess Vitamin C cause kidney stones
Kidney stones form when minerals and salts crystallize in the urinary tract. Several factors contribute to their development, including genetics, gender, obesity, and dietary choices.
The most common type of kidney stone is made of calcium oxalate. For some people, the body breaks down excess vitamin C into oxalate, which increases the likelihood of stone formation. This explains why high-dose supplementation, particularly in men, may lead to painful kidney stone episodes.
Kidney stones risk in men vs women: What studies show
Interestingly, the connection between vitamin C and kidney stones appears to be stronger in men than in women. A Harvard School of Public Health study led by Dr. Gary C. Curhan confirmed the increased risk in men.
However, an almost identical study in women found no significant link between vitamin C intake and kidney stones. This gender difference suggests that biological factors and metabolism may influence how vitamin C affects kidney stone risk.
Should men avoid high-dose Vitamin C
Health experts strongly advise caution. According to Dr. Curhan, men who have a history of calcium oxalate kidney stones should avoid high-dose vitamin C supplements altogether.
Similarly, Dr. Robert H. Fletcher of Harvard Medical School emphasized that if a cause-effect relationship exists, then approximately 1 in 680 men taking high-dose vitamin C could develop kidney stones. Fletcher raises an important question: Is this additional risk worth it if high-dose vitamin C offers no proven benefits?
Vitamin C supplements vs food sources: What’s safer
It is crucial to distinguish between vitamin C obtained from natural foods and from supplements.
Food sources such as citrus fruits, peppers, and berries provide vitamin C in safe, balanced amounts.
Supplements, especially high-dose formulations, may overwhelm the body’s metabolic capacity, leading to oxalate buildup and higher kidney stone risk.
Therefore, experts recommend fulfilling vitamin C needs through a balanced diet rather than relying on large-dose supplements.
Finding the right balance with Vitamin C
Vitamin C remains an essential nutrient for health, but more is not always better. While moderate intake from food supports immunity, skin, and bone health, high-dose supplementation—particularly in men—may double the risk of kidney stones.
The safest approach is to:
- Meet daily vitamin C needs through fruits and vegetables.
- Avoid high-dose supplements, especially if you have a history of kidney stones.
- Consult a healthcare provider before starting any supplement regimen.
The benefits of high-dose vitamin C remain unproven, but the risk of kidney stones is real—making moderation the wisest choice.
Disclaimer: This article is for informational purposes only and is not a substitute for professional medical advice. Always consult a qualified healthcare provider before making changes to your supplement or dietary routine, especially if you have a history of kidney stones or other health conditions.Also Read | Harvard-approved THIS ancient kitchen ingredient could be the surprising key to managing your weight and diabetes
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