The effect of chocolate on calcium absorption and its role in bone health is not clear. Chocolate contains compounds that have the potential to affect calcium absorption or excretion, including oxalate, caffeine and sugar. However, the Office of Dietary Supplements, or ODS, concludes that their effect is probably minimal as long as you regularly consume an adequate amount of calcium.
About Calcium
Along with vitamin D, phosphorus and magnesium, calcium is essential for healthy bones and teeth, where 99 percent of the body's calcium is stored. You also need calcium for vascular contraction and dilation, muscle function, nerve transmission and hormonal secretion. The Recommended Dietary Allowance for calcium depends on your age and gender: 700 mg for those 1 to 3 years old; 1,000 mg for those 4 to 8 years old; 1,300 mg for those 9 to 18 years old; 1,000 mg for women 19 to 50 years old and for 51-70 year-old men; and 1,200 mg for 51 to 70 year-old women and everyone over 71 years. Dairy products are rich sources of calcium, with 1 cup of 1 percent chocolate milk providing 290 mg calcium.
Oxalic Acid
Chocolate contains oxalic acid, a naturally occurring compound in cocoa beans. Oxalic acid binds to calcium in the intestines and inhibits its absorption. However, the Office of Dietary Supplements concludes that this interaction probably has little or no nutritional consequence if you eat a variety of foods. Spinach, collard greens, sweet potatoes, rhubarb and beans also contain oxalic acid. According to the National Dairy Council, chocolate milk contains only a small amount of oxalic acid, and calcium absorption from chocolate milk is similar to that from unflavored milk.
Caffeine
Chocolate contains caffeine, which can modestly increase calcium excretion and reduce absorption, according to the ODS. However, these effects are minimal. For example, one cup of regular coffee -- which contains 95 mg of caffeine -- causes a loss of only 2 to 3 mg of calcium. A 100-g portion of dark chocolate contains 80 mg of caffeine, while 1 cup of chocolate milk contains only 2 to 7 mg.
Sugar
Most chocolate products contain added sugar. An Australian study in the "American Journal of Clinical Nutrition" reported that a 100 g dose of dark chocolate increased calcium excretion by 147%. This may have been caused by sugar and increased insulin levels, which can both increase urinary calcium loss. Cocoa can also increase insulin levels.
Chocolate Milk
Milk is an important source of calcium and other nutrients that work together to build and strengthen bone. Most American adults and many children do not consume the recommended daily servings of dairy products. As children enter adolescence, their intake of milk often decreases, while their consumption of soft drinks increases. To encourage increased milk intake among children and adolescents, the American Academy of Pediatrics, the American Dietetic Association, the American Academy of Pediatric Dentistry and other public health groups have supported the use of chocolate and other flavored milks.
Bone Density in Elderly Women
As part of a larger study on calcium supplementation in women aged 70 to 85 years, Australian researchers examined chocolate consumption. They found that women who consumed chocolate milk once or more daily had lower bone density and strength than those who consumed the beverage less than once a week. They did not determine a cause for this effect and concluded only that further research is needed.
References
- Office of Dietary Supplements; Calcium; June 2011
- National Dairy Council; Flavored Milk in Perspective; 2009
- USDA National Nutrient Database
- American Journal of Clinical Nutrition; Chocolate Consumption and Bone Density in Older Women; Jonathan M. Hodgson et al.; January 2008
- Mayoclinic; Chocolate: Does it impair calcium absorption?; Katherine Zeratsky, RD; March 27 2010
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