Soda drinking has previously been associated with lower bone mineral density in women and children1,2, and a new study focuses specifically on the effects of diet soda on bone health. The authors commented that this research was sparked by the observation that diet soda drinking behaviors are often different than regular soda drinking behaviors – women often use diet sodas in an effort to avoid weight gain – either to stave off hunger between meals or as a replacement for calorie-containing beverages. Many women drink over 20 diet sodas per week.3
The average American drinks 216 liters of soda each year.4
These researchers discovered that parathyroid hormone (PTH) concentrations rise strongly following diet soda consumption. PTH functions to increase blood calcium concentrations by stimulating bone breakdown, and as a result release calcium from bone.
In the study, women aged 18-40 were given 24 ounces of either diet cola or water on two consecutive days, and urinary calcium content was measured for three hours. Women who drank diet cola did indeed excrete more calcium in their urine compared to women who drank water. The authors concluded that this calcium loss may underlie the observed connection between soda drinking and low bone mineral density.5
Although caffeine is known to increase calcium excretion and promote bone loss6, caffeine is likely not the only bone-harming ingredient in sodas. A 2006 study in the American Journal of Clinical Nutrition found consistent associations between low bone mineral density and caffeinated and non-caffeinated cola (both regular and diet), but not other carbonated beverages.7 One major difference between the two is the phosphoric acid in colas, absent from most other carbonated beverages.
In the Western diet, phosphorus is commonly consumed in excess – at about 3 times the recommended levels, whereas dietary calcium often low. Although phosphorus is an important component of bone mineral, a high dietary ratio of phosphorus to calcium can increase parathyroid hormone secretion, which is known to increase bone breakdown. Studies in which women were given increasing quantities of dietary phosphorus found increases in markers of bone breakdown and decreases in markers of bone formation.8,9 Therefore it is likely that the phosphorus content of colas, triggers calcium loss.
There is nothing healthy about diet soda. It is simply water with artificial sweeteners and other chemical additives, such as phosphoric acid. The safety of artificial sweeteners is questionable , and their intense sweetness disrupts the body’s natural connection between taste and nourishment, promoting weight gain.10 Diet sodas don’t just weaken our bones, they are linked to kidney dysfunction and promote obesity and other common medical problems.
1. McGartland C, Robson PJ, Murray L, et al. Carbonated soft drink consumption and bone mineral density in adolescence: the Northern Ireland Young Hearts project. J Bone Miner Res. 2003 Sep;18(9):1563-9.
Mahmood M, Saleh A, Al-Alawi F, Ahmed F. Health effects of soda drinking in adolescent girls in the United Arab Emirates. J Crit Care. 2008 Sep;23(3):434-40.
2. Tucker KL, Morita K, Qiao N, Hannan MT, Cupples LA, Kiel DP. Colas, but not other carbonated beverages, are associated with low bone mineral density in older women: The Framingham Osteoporosis Study. Am J Clin Nutr. 2006 Oct;84(4):936-42
Massey LK, Whiting SJ. Caffeine, urinary calcium, calcium metabolism and bone. J. Nutr. 19923 Sep;123 (9): 1611-14
7. Tucker KL, Morita K, Qiao N, et al. Colas, but not other carbonated beverages, are associated with low bone mineral density in older women: The Framingham Osteoporosis Study. Am J Clin Nutr. 2006 Oct;84(4):936-42.
8. Kemi VE, Kärkkäinen MU, Karp HJ, et al. Increased calcium intake does not completely counteract the effects of increased phosphorus intake on bone: an acute dose-response study in healthy females. Br J Nutr. 2008 Apr;99(4):832-9.
9. Kemi VE, Kärkkäinen MU, Lamberg-Allardt CJ. High phosphorus intakes acutely and negatively affect Ca and bone metabolism in a dose-dependent manner in healthy young females. Br J Nutr. 2006 Sep;96(3):545-52.
10. Swithers SE, Martin AA, Davidson TL. High-intensity sweeteners and energy balance. Physiol Behav. 2010 Apr 26;100(1):55-62.