How Does Caffeine Affect Calcium Levels and Bone Health?

January 8, 2026 •

4 min read

According to a 2021 University of South Australia study, consuming 800mg of caffeine over a six-hour period can significantly increase urinary calcium excretion. This highlights the complex question: how does caffeine affect calcium levels in the human body, and what are the implications for long-term bone health?

Quick Summary

This article explores the mechanisms by which caffeine influences calcium metabolism, including its effects on absorption, excretion, and hormonal regulation. It addresses the conflicting research on caffeine's impact on bone health and explains how adequate dietary calcium intake can mitigate potential risks, providing practical advice for health-conscious consumers.

Key Points

Caffeine Increases Urinary Calcium Excretion: High doses of caffeine can significantly increase the amount of calcium the body excretes through urine, a temporary effect that is less pronounced with moderate intake.
Impact on Calcium Absorption is Minimal: Research shows a very small, short-term reduction in intestinal calcium absorption, which is not a significant concern for most healthy individuals.
Adequate Calcium Intake Mitigates Risk: The potential negative effects of caffeine on calcium balance are largely offset when a person consumes the recommended daily allowance of calcium.
High-Risk Groups Should Be Cautious: Vulnerable populations, such as postmenopausal women with low calcium intake, may experience accelerated bone loss with excessive caffeine consumption.
The Net Effect is Compensated: For those with moderate caffeine habits and a healthy diet, the body effectively compensates for any minor calcium shifts, resulting in no long-term damage to bone health.
Long-Term Effects are Conflicting: Studies on the long-term relationship between caffeine and bone mineral density have produced conflicting results, suggesting other lifestyle factors are more influential.

The Dual Impact of Caffeine on Calcium Metabolism

Caffeine is one of the world's most widely consumed psychoactive substances, found in coffee, tea, energy drinks, and many sodas. For decades, researchers have investigated how this stimulant influences the body's mineral balance, with a particular focus on calcium. The relationship is multifaceted, involving a small, short-term impact on calcium absorption and a more significant, temporary increase in calcium excretion through urine.

How Caffeine Influences Calcium Excretion

One of the most direct effects of caffeine on calcium levels is its mild diuretic property, which increases urination. As the kidneys process more fluid, they also excrete more calcium. Studies have shown that consuming a high dose of caffeine (800mg) over a short period can significantly increase the amount of calcium flushed out of the body through urine. However, a moderate intake of caffeine results in a minimal, temporary increase in urinary calcium, which the body often compensates for shortly after. The risk of a negative calcium balance becomes more pronounced with high caffeine consumption, especially when coupled with an inadequate dietary calcium intake.

Caffeine's Effect on Calcium Absorption

Beyond affecting urinary excretion, caffeine can also interfere with the body's ability to absorb calcium from food. Research suggests that caffeine may:

Interfere with Vitamin D receptors: Vitamin D is crucial for helping the intestines absorb calcium. Caffeine has been shown in some studies to decrease the expression of vitamin D receptor proteins in osteoblast cells, potentially hindering calcium absorption.
Reduce Intestinal Absorption: Some studies suggest a direct, albeit small, depressant effect of caffeine on the efficiency of intestinal calcium absorption.
Alter Other Metabolic Factors: Caffeine can decrease levels of inositol, a protein involved in calcium metabolism. Lower levels of inositol may lead to less intestinal calcium absorption.

Conflicting Research and Long-Term Effects

While the mechanisms for how caffeine could negatively affect calcium balance are understood, the actual long-term impact on bone mineral density (BMD) and fracture risk is a topic of conflicting research. Many studies show no significant correlation, particularly in individuals with adequate calcium intake. However, for specific high-risk populations, excess caffeine could compound existing issues.

For example, studies on postmenopausal women with low calcium intake have found that high caffeine consumption can accelerate bone loss. In contrast, a 2025 meta-analysis published in Frontiers in Nutrition suggested that moderate, long-term coffee and tea consumption could be associated with a reduced risk of osteoporosis. The discrepancy in findings is likely due to varying methodologies, population groups, and the dietary habits of participants.

Mitigating the Effects of Caffeine on Calcium

For most healthy adults, the effect of moderate caffeine consumption on calcium levels is negligible. The small amount of calcium lost can be easily replaced. However, for those with pre-existing bone health concerns, a simple adjustment can help. Adding a splash of milk to your coffee or ensuring a calcium-rich diet is a straightforward strategy. For example, the small calcium loss from one cup of coffee can be entirely offset by just 1–2 tablespoons of milk.

How to Minimize Caffeine's Impact on Your Calcium Balance

Consume Dairy with Your Coffee: Add milk or a dairy-based creamer to your caffeinated beverages to directly offset the minimal calcium loss.
Prioritize Calcium-Rich Foods: Ensure your daily diet includes adequate sources of calcium such as dairy products, fortified plant-based milk, leafy greens, and sardines.
Monitor Your Intake: Stay mindful of your total caffeine intake from all sources (coffee, tea, soda, energy drinks) to avoid excessive amounts.
Consider Timing: While minimal, avoiding excessive caffeine intake alongside calcium supplements or meals specifically designed to boost calcium may be beneficial.

Comparison of Effects on Calcium: Moderate vs. High Caffeine Intake


Feature	Moderate Caffeine Intake (<400mg/day)	High Caffeine Intake (>800mg/day)
Calcium Excretion	Minimal, temporary increase in urinary calcium.	Substantial, temporary increase in urinary calcium (up to 77%).
Intestinal Absorption	Small, negligible effect on absorption efficiency.	Potentially greater interference with absorption, especially if dietary intake is low.
Bone Health Risk	No significant risk for healthy adults with adequate calcium intake.	Increased risk for vulnerable groups (e.g., elderly women with low calcium intake).
Overall Impact	Any negative effect is easily offset by a balanced diet.	Could lead to a negative calcium balance if not paired with sufficient intake.

Conclusion

Ultimately, the science surrounding how does caffeine affect calcium levels indicates that for the majority of healthy people, the impact is minimal and easily manageable. The small increases in calcium excretion can be offset by a balanced diet rich in calcium. Concerns primarily arise with high-dose, frequent caffeine consumption, especially in individuals who already have low dietary calcium or other risk factors for osteoporosis. Maintaining a moderate caffeine habit and prioritizing adequate daily calcium intake are the most effective ways to support long-term bone health. For those with specific health risks, consulting a healthcare provider is recommended for personalized dietary advice.

Frequently Asked Questions

No, for the majority of healthy adults with adequate calcium intake, moderate coffee consumption does not cause osteoporosis. The small amount of calcium loss can be easily replaced through diet.

The calcium loss from one standard cup of coffee (60-120mg caffeine) is very small and considered negligible. It can be easily offset by adding a tablespoon or two of milk to the coffee.

Yes, you can easily prevent or counteract the effects by ensuring adequate daily calcium intake through your diet. Adding milk to your coffee is a simple and effective way to do this.

Tea also contains caffeine and has a similar effect on calcium excretion. However, some research suggests that other compounds in tea, like polyphenols, may have a positive effect on bone health, though more research is needed.

Individuals with consistently low dietary calcium, postmenopausal women, and the elderly should be most mindful of high caffeine intake, as they are already at higher risk for bone loss.

Research has indicated that high-dose consumption, such as 800mg of caffeine over a few hours, can have a more pronounced effect on urinary calcium excretion. This is significantly more than a typical daily intake.

No, for most people, there is no need to stop drinking coffee. Instead, focus on consuming adequate calcium and vitamin D, and practice moderation with your caffeine intake.