Does Cola Weaken Bones? What the 2006 Study Really Shows
One 2006 study linked cola with lower bone density in women, but it did not show that cola causes bone loss. The short answer is that cola is not proven to weaken bones. A single observational analysis from the Framingham Osteoporosis Study found a link in women, and its authors said more research is needed. This guide gives that study its real weight, explains the two ideas behind it, and separates the bone question from the sugar and calorie question covered elsewhere.
At a glance
- The study: Tucker and colleagues, published in the American Journal of Clinical Nutrition in 2006, drawing on the Framingham Osteoporosis Study
- Who was measured: bone density was measured in 1,413 women and 1,125 men
- The finding: cola was linked with lower bone density at the hip sites in women, not at the spine, and not in men
- The limit: an observational study shows an association, not a cause
- Quotable line: one observational study is a reason to ask questions, not a verdict on a can of cola
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What did the 2006 study measure?
Researchers measured bone density at the spine and at three hip sites. The analysis adjusted for body mass index, height, age, energy intake, physical activity, smoking, alcohol, total calcium and vitamin D intake, caffeine from other sources, season and, in women, menopausal status and estrogen use. Diet in an observational study like this is an estimate rather than weighed food. The paper is indexed on PubMed under the identifier 17023723.
What did it find in women, men and other fizzy drinks?
In women, cola intake was linked with lower bone density at the hip sites, but not at the spine. In men, the link did not appear. The authors reported that diet cola showed similar results, and decaffeinated cola showed weaker associations. Other carbonated drinks showed no link. The title sums up the finding: colas, but not other carbonated beverages, were associated with low bone mineral density in older women. The authors wrote that additional research is needed to confirm these findings.
Why did the authors look at phosphoric acid?
The authors pointed to two things in colas: caffeine and phosphoric acid, which they said may adversely affect bone. They also looked at phosphorus. Total phosphorus intake was not significantly higher in daily cola consumers than in nonconsumers, but their calcium to phosphorus ratios were lower. That points to a balance question rather than a simple phosphorus overload, although the study cannot settle it on its own.
What are the two ideas behind the link?
The first idea is the calcium to phosphorus balance. Daily cola drinkers had lower calcium to phosphorus ratios, although their total phosphorus intake was not higher, and the study did not test whether that balance affects bone. The second idea is acid load, since the authors named phosphoric acid and caffeine as things that may adversely affect bone. The study did not prove either effect.
What are the honest limits?
The design is observational, so it can show a link but not a cause. The analysis adjusted for total calcium intake and other factors, but adjustment cannot rule out other differences between heavy and light cola drinkers. Diet in an observational study like this is an estimate. Diet cola gave similar results, which suggests sugar alone may not explain the pattern, though that is an inference from the comparison. The authors themselves said additional research is needed to confirm the findings.
The swap test for two weeks
If cola is a daily habit, swap one can a day for plain water or a glass of milk for two weeks. Note how often you still reach for cola and when the craving comes. This is a habit test, not a bone test, but it shows how much cola sits in your week, which is the useful starting point for a conversation with your doctor.
Where do kidney patients fit in?
Guy’s and St Thomas’ NHS trust says not everyone with chronic kidney disease has to follow a low phosphate diet, and that a doctor, nurse or dietitian explains whether it applies. If you have kidney disease, the phosphate plan is set by your team, not by a study or a headline. MedlinePlus adds that high levels of phosphorus in the blood occur only with severe kidney disease or severe problems regulating calcium, so a high blood phosphorus level is not what this study is about.
Bone pain does not settle, you have had a fracture from a minor fall, or you are worried about bone strength because of age, menopause or a family history of fractures. Ask your doctor about a bone health check rather than stopping or starting any medicine on your own. If you have kidney disease, do not change your phosphate or fluid plan because of a headline; your renal team decides.
Quick answers on cola and bones
Does cola weaken bones?
The evidence is not proven. A 2006 observational analysis linked cola with lower bone density in women, and its authors said more research is needed before a firm conclusion can be drawn.
Is cola bad for bones in women?
The link was seen in women at the hip sites in the 2006 analysis, which included older women. It is an association in a group, not a verdict on every woman who drinks cola.
Is diet cola better or worse for bones?
The analysis found diet cola gave results similar to regular cola, which suggests sugar alone may not explain the pattern. Decaffeinated cola showed weaker associations.
What is phosphoric acid, and does it affect bones?
It is the acid found in some colas. The authors named it, along with caffeine, as something that may adversely affect bone, but the study did not prove that effect.
Do other fizzy drinks weaken bones?
Other carbonated soft drinks showed no link in that analysis. The question was about cola specifically, which is one reason the finding should not be stretched to all fizzy drinks. For cola used as an upset stomach remedy, see the flat cola post, which is separate from the bone question.
Does cola cause calcium loss?
The study adjusted for total calcium intake, and it did not measure calcium loss directly, so it does not support a claim that cola causes calcium loss.
Does cola cause osteoporosis?
No study here shows that. Osteoporosis has many causes, and an observational link is a question to raise with a doctor, not a diagnosis. The calcium and osteoporosis post sets out the food side.
Should I stop drinking cola for bone health?
Not on the strength of this study alone. If you have bone risk factors, talk with your doctor about bone health, and decide with them rather than from a headline.
Is the phosphorus in cola a problem for healthy adults?
MedlinePlus says deficiency from diet is rare, and high blood phosphorus occurs only with severe kidney disease or severe problems regulating calcium. The 2006 study looked at bone density, not blood phosphorus levels, so it does not answer a blood question.
Bottom line
Cola is not proven to weaken bones. One 2006 observational study linked cola with lower bone density in women, and its adjustments for calcium, vitamin D, age and smoking do not rule out other differences between heavy and light cola drinkers. Sugar and calories are a different question, covered in the sugary drinks post. For more on the wider mineral and bone picture, see the Vitamins and Minerals hub.
Sources
- PubMed: Tucker KL, et al. Colas, but not other carbonated beverages, are associated with low bone mineral density in older women: the Framingham Osteoporosis Study, American Journal of Clinical Nutrition (2006)
- MedlinePlus: Phosphorus in diet
- Guy’s and St Thomas’ NHS Foundation Trust: Diet and chronic kidney disease