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Carbonated beverages and urinary calcium excretion
1Creighton University Osteoporosis Research Center, Omaha, NE 68131, USA. rheaney@creighton.edu
The American Journal of Clinical Nutrition
|August 28, 2001
Summary
Carbonated beverages, especially caffeinated ones, increase urinary calcium temporarily. However, the overall impact on calcium balance is negligible, suggesting milk displacement is key to skeletal health concerns.
Area of Science:
- Nutritional Science
- Human Physiology
- Bone Metabolism
Background:
- Observational studies link carbonated beverage intake to increased fracture risk.
- A common hypothesis suggests constituents in these beverages elevate urinary calcium levels.
Purpose of the Study:
- To evaluate the acute effects of various carbonated beverages on urinary calcium excretion.
- To differentiate the impact of caffeine and acidulants on calcium metabolism.
Main Methods:
- A randomized block design study involving women aged 20-40 who regularly consumed carbonated drinks.
- Tested caffeinated and non-caffeinated beverages with phosphoric or citric acid, alongside water and milk controls.
- Measured urinary calcium, sodium, and creatinine in fasting and post-consumption urine samples.
Main Results:
- Urinary calcium significantly increased with milk and caffeinated beverages compared to water.
- Caffeine was the primary driver of increased urinary calcium, with an approximate 0.25 mmol excess.
- Phosphoric acid did not independently increase or potentiate caffeine-induced calciuria.
Conclusions:
- The acute increase in urinary calcium from carbonated beverages is primarily due to caffeine content.
- The type of acidulant (phosphoric or citric acid) has no immediate effect on urinary calcium.
- The net effect on calcium balance is minimal, with potential skeletal risks likely stemming from the displacement of calcium-rich beverages like milk.