Does Drinking Carbonated Water Cause Bone Loss?
Are carbonated water or seltzer water bad for your bones? Does carbonated water cause bone loss? This concern originally arose after results from a large cohort study showed decreased bone mineral density in women who drank cola sodas. Fortunately, those results were not reproduced in studies that examined the link between intake of seltzer or carbonated water and bone mineral density. The link seems to be limited to cola sodas, and not other carbonated beverages.
Phosphoric Acid in Colas and Carbonic Acid in Carbonated Water
Here is an explanation why. The connection between cola and bone mineralization is due to an ingredient in cola sodas rather than its carbonation. Cola sodas have phosphoric acid, an ingredient that is not found in seltzer or carbonated water. Phosphoric acid is linked to deterioration in bone mineralization.
You might ask about the carbonic acid found in seltzer or carbonated water. The carbonic acid in seltzer or carbonated water is not an added ingredient in the typical sense. It is a result of the carbon dioxide dissolving in the water, and the process of dissolving carbon dioxide in water causes the formation or carbonic acid, a weak acid. Does it do the same as phosphoric acid with causing bone loss or osteoporosis?
The answer is no. Phosphoric acid's bone damaging affects are understood to be due to the phosphorous in the phosphoric acid, not the fact that it is an acid. A diet that is high in phosphorous and low in calcium can trigger bone reabsorption, also know as bone breakdown, leading to weaker bones and osteoporosis.
Research on Carbonated Water and Bone Loss
It is important to point out that the highest quality studies on this topic are observational studies. There are no studies in humans that randomized people to drink cola sodas or carbonated water or a placebo and then examined bone mineralization after a long duration of intake. This allows for the suggestion that the phosphoric acid and bone mineralization link is only an association, not a causation. What that means is that people who drink a lot of cola sodas might also be doing other things that affect bone mineralization, and it is not the colas themselves with their phosphoric acid that leads to bone loss and osteoporosis.
In either case, understanding the link between the phosphoric acid in cola sodas and bone mineralization should not be the only reason to drink other beverages besides soda. High intake of cola sodas is linked to many other health concerns, and that link has been known since before the bone loss and osteoporosis links.
This always brings me back to how I present nutrition. A scary sounding headline about a food that we thought was healthy being dangerous is a great way to get clicks and readers. In most cases, nutrition recommendations are simple and unsurprising. If it sounds sensational, it is always a good idea to research further. If you are unsure about a news headline, you can ask a dietitian about how to understand what you read and incorporate it into your own life.