Are carbonated sodas bad for your bones?

carbonated drink
©Jeff Gordon
Although many of the concerns raised in the media are not supported by scientific evidence, sodas do ‘displace’ milk in the diet and are not bone-healthy options.

Concerns have been raised that consumption of carbonated soft drinks, notably cola drinks, may adversely affect bone health. Although a few observational studies have shown an association between high carbonated beverage consumption and either lower bone mineral density or increased fracture rates in teenagers, there is no convincing evidence that these drinks negatively affect bone health.

It has been suggested that the phosphorus content may have a negative impact on calcium metabolism, but this has not been shown in any experimental studies. Along with calcium, phosphorus is a key component of bone mineral, and there is no evidence that phosphorus intake is bad for bone health or raises osteoporosis risk in healthy people.

Another argument that has been put forward is that cola beverages are acidic and dietary acidic load is detrimental to bone. To counterbalance the acidity in the blood, calcium or magnesium are taken either from the blood or, if not available, the body draws calcium from the bone. However, soda drinks have a moderate acid/alkaline balance and are essentially 'neutral' to the kidney. The acid in cola beverages is phosphoric acid, which is a biologically weak organic acid (as is citric acid, found in fruit juices).

The impact of caffeine

Colas and energy drinks do contain a lot of caffeine and high quantities of caffeine have been known to decrease the amount of calcium your body stores. However, studies in postmenopausal women showed that as long as calcium intake was sufficient (above 800 mg/day), caffeine intake had no detrimental effects. If on the other hand calcium intake was low, then the caffeine intake equivalent to about 3 cups of brewed coffee per day was associated with more bone loss. Therefore, ensuring that you have the recommended intake of calcium will help to offset potential calcium losses due to caffeine intake.

Try mineral waters instead of carbonated sodas

Finally, it should be noted that the carbonation is not the culprit. Many commercial mineral waters are carbonated, and some are rich in calcium and other minerals – as well as being free of calories. A study has shown that high calcium mineral waters were beneficial to skeletal metabolism in postmenopausal women with low dietary calcium intake (less than 700 mg/day). Check the labels of the mineral waters available in your supermarket and compare the calcium content – some can provide 150 mg or more of calcium per liter.

The displacement effect

Although there may be no firm evidence that carbonated soft drinks themselves adversely affect bone health, these drinks certainly do 'displace' milk in the diet – resulting in lower calcium intake. This is especially important to remember for children and adolescents. They should be drinking calcium-rich beverages such as milk or fortified soy beverage, with only limited intake of soft drinks. By getting enough calcium when the skeleton is still growing, children can build stronger bones which will give them a head start in preventing osteoporosis later in life.

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