Does chocolate impair calcium absorption?

It is unclear to what extent chocolate, which comes in many different forms, impairs calcium absorption. According to a 2019 evidence review in Nutrition, the bone effects of chocolate vary based on the type of chocolate consumed, and more laboratory and human studies are needed to tease out how or if chocolate impacts the minerals you consume significantly.

Chocolate does contain a compound that is known to get in the way of mineral absorption called oxalate. Oxalate is abundant in chocolate and can range from 500 to 900 milligrams per 100 grams. Studies have also pointed toward other components in chocolate that may inhibit mineral absorption or affect bone health, such as:

• Added cocoa butter
• Sugar
• Methylxanthines

What gets complicated is that chocolate also contains compounds such as flavonoids and antioxidants that support bone health.

The largest study to date published in The American Journal of Clinical Nutrition in 2008 found that elderly women who ate chocolate more than one time each day had thinner bones (less bone density) than women who ate chocolate less than once per week. The researchers concluded that daily chocolate eating may interfere with the absorption of calcium needed for maintaining bone density, but that more studies would be needed to confirm the findings.

Since the 2008 study, there has not been enough large-scale research to warn women at risk for osteoporosis to avoid chocolate. The Bone Health & Osteoporosis Foundation warns that legumes, some beans, spinach, rhubarb, beet greens and caffeine may interfere with calcium absorption, but it does not mention chocolate.

Based on the current limited evidence, the researchers in Nutrition note that cocoa powder, followed by dark chocolate with high cocoa content, were the least likely to affect bone health negatively, but that more research is needed.

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Current guidelines for bone health

According to the 2020-2025 Dietary Guidelines for Americans, most people should be able to get enough calcium from a healthy diet that includes healthy dairy products and protein from seafood, lean meats, poultry and eggs. The guidelines say that tofu made with calcium salts and fish with edible bones like canned salmon or sardines are good sources of calcium. Although the guidelines do not mention avoiding chocolate, they do suggest avoiding foods high in added sugar and saturated fat.