Caffeine and Bone Health
After epidemiological findings linked cola consumption, but not the consumption of other carbonated beverages, to poorer bone health in adolescent girls, some people speculated that too much phosphorus (from phosphoric acid in cola drinks) or too much caffeine could weaken bones by “leaching” calcium from bones or blocking calcium absorption.
However, a series of studies conducted by scientific and patient advocacy organizations over the past fifteen years have concluded that as long as calcium intake is sufficient, sparkling beverages with phosphorus and/or caffeine do not weaken bones or cause osteoporosis in healthy individuals.
- In its 2010 update of calcium and vitamin D recommendations, the U.S. National Academy of Sciences’ Institute of Medicine (IOM) reviewed the existing research related to dietary factors that potentially could impact calcium balance in the body and found that, although caffeine modestly increases calcium excretion and reduces absorption, caffeine intake (equivalent to two to three or more cups of coffee per day) only results in bone loss in individuals with low milk or low total calcium intake. The IOM also found that dietary phosphorus has no negative impact of on calcium absorption, and noted that although several observational studies have suggested that the consumption of carbonated soft drinks with high levels of phosphate is associated with reduced bone mass and increased fracture risk, “it is likely that the effect is due to replacing milk with soda, rather than to phosphorus itself.”
- In 2006, the International Osteoporosis Foundation published a review of nutrition and bone health that addressed the concerns over carbonated soft drinks, notably cola drinks, and bone health. It stated “Although a few observational studies have shown an association between high carbonated beverage consumption and either decreased BMD (bone mineral density) or increased fracture rates in teenagers, there is no convincing evidence that these drinks adversely affect bone health.”
- In 2004, the U.S. Surgeon General’s Report on Bone Health and Osteoporosis acknowledged concerns had been raised about caffeine, phosphorus and carbonated beverages. However following a review of the scientific data, the report concluded that “as long as adequate levels of calcium intake are maintained, both carbonated and caffeinated beverages can be consumed in moderation.”
- In 2000, the NIH Consensus Development Conference Statement on Osteoporosis Prevention, Diagnosis and Therapy reaffirmed that dietary phosphorus/caffeine is not an important factor in osteoporosis for individuals consuming a balanced diet, noting that “high dietary protein, caffeine, phosphorus, and sodium can adversely affect calcium balance, but their effects appear not to be important in individuals with adequate calcium intakes.”
- In 1994, an independent bone and osteoporosis experts’ report on Optimal Calcium Intake developed for the U.S. National Institutes of Health (NIH) noted that “dietary components, including fat, phosphate, magnesium, and caffeine, have not been found to affect calcium absorption or excretion significantly. ” The American Medical Association reviewed the NIH experts’ statement and concluded that the effect of phosphate on calcium absorption was “physiologically trivial.”
As Dr. Robert P. Heaney, an internationally recognized bone health expert, noted in an editorial on soft drinks and bone health, “Not only is the seeming effect of low nutrient density beverages on the calcium economy relatively small, but, if as seems likely, the effect is mediated through milk displacement, the solution lies not in ‘viewing with alarm’ consumption of things that taste good, but with encouraging and promoting higher dairy intake.”
The phosphorus and caffeine content of sparking beverages:
Phosphorus is found widely in nature and is an essential nutrient in the diet for all living things. It plays an important role in energy metabolism in the body and is a major component of bones and teeth. In the United States, the Recommended Dietary Allowance (RDA) for phosphorus is 700 mg per day for all adults over age 18, including pregnant and lactating women.
When you consume phosphoric acid from a cola or any other sparkling beverage, it is digested in the stomach and absorbed by the body as phosphate. This is the same as for phosphorus from any other food. Phosphorus from meat, cheese, nuts, or grains also enters the body as phosphate following digestion.
Compared to other dietary sources of phosphorus, sparkling beverages contribute about two (2) percent of the total dietary phosphorus in the U.S. diet. The amount of phosphorus in 8 fluid ounces (240 milliliters) of Coca-Cola is about 41 mg., which comes from the small amount of phosphoric acid added to cola beverages to help provide their characteristic tangy taste. For comparison, 8 fluid ounces (240 milliliters) of milk contains 200 mg. of phosphorus. High protein foods like meats, cheeses, nuts and grains supply most of the dietary phosphorus.
The caffeine content of Coca-Cola is 23 mg/8 fluid ounces (240 milliliters), typically less than one-third the amount found in an equal amount of coffee. See our Caffeine Comparison Chart to compare the caffeine content of beverages.
The bottom line: Drinking sparkling beverages that contain caffeine and/or phosphoric acid does not weaken bones or cause osteoporosis. Authorities on bone health recommend good nutrition, adequate calcium and vitamin D, as well as physical activity that includes regular weight-bearing exercise, to build and maintain strong bones. Other nutrients, including vitamin K, vitamin A, magnesium, zinc, and protein, also play important roles in determining bone health.
Caloric sweeteners and bone health
In June 2008, a published review by Tsanzi et al. looked at the effect of caloric sweeteners, such as table sugar (sucrose) and high fructose corn syrup (HFCS), on bone health. The authors concluded that there is not enough scientific literature available to make any conclusions about any effect of caloric sweeteners on bone health. A 2003 publication stated that although sugars do increase urinary calcium excretion, the body adjusts and there is no net loss of calcium over time. But, it’s important to ensure you are eating a healthy diet, with adequate calcium, vitamin D, and vitamin K, and that you are engaged in physical activity that includes regular weight-bearing exercises.
Dietary Reference Intakes for Calcium and Vitamin D. Institute of Medicine, National Academy of Sciences. 2010.
Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. Institute of Medicine, National Academy of Sciences. 1997.
Dietary Supplement Fact Sheet: Calcium. Office of Dietary Supplements, National Institutes of Health.
Effect of consuming different caloric sweeteners on bone health and possible mechanisms. Tsanzi E, Fitch CW, and Tou JC. Nutr. Rev. 2008; 66(6):301-308.
Bone Appetit: The role of food and nutrition in building and maintaining strong bones. Dawson-Hughes B and the International Osteoporosis Foundation. 2006.
Dietary sources of nutrients among US adults, 1994 to 1996. Cotton PA, Subar AF, Friday JE, Cook A. J. Am. Diet. Assoc., 2004;104( 6): 921-930.
Got Soda? Editorial. Fitzpatrick L and Heaney RP. J. Bone Min. Res. 2003;18(9):1570-1572.
Bone Health and Osteoporosis: A Report of the Surgeon General. U.S. Surgeon General. 2004.
Osteoporosis Prevention, Diagnosis, and Therapy. National Institutes of Health Consensus Development Conference Statement, March 27-29, 2000.
[Note: This statement is more than five years old and is provided solely for historical purposes].
Optimal Calcium Intake. National Institutes of Health Consensus Development Conference Statement. June 6-8, 1994. [Note: This statement is more than five years old and is provided solely for historical purposes]
For an in-depth review of the science related to this topic, see:
IFIC Review: Physical Activity, Nutrition and Bone Health.