Calcium d-glucarate is a calcium salt of D-glucaric acid, a substance naturally found in some fruits and vegetables. It is commonly marketed as a dietary supplement for "detoxification" and colon health. The scientific rationale behind its use for supporting the large intestine (colon) centers on its potential ability to inhibit the enzyme beta-glucuronidase in the gut. Elevated beta-glucuronidase activity has been associated with increased reactivation of toxins and carcinogens in the colon, as this enzyme can deconjugate glucuronide-bound substances, making them more likely to be reabsorbed instead of excreted. Animal studies have suggested that calcium d-glucarate can lower beta-glucuronidase activity, thus possibly reducing the risk of colon carcinogenesis by enhancing the excretion of potentially harmful compounds.

However, direct clinical evidence in humans is limited. Most of the supportive data comes from laboratory and animal studies, with only a few small-scale human trials. No large, well-designed human studies have definitively shown that calcium d-glucarate supplementation reduces colon cancer risk or improves colon health. Therefore, while the mechanism is plausible and there is some experimental support, the evidence for its benefit in human colon health is weak and indirect. Its use is more scientifically reasoned than based on tradition, but robust clinical validation is lacking.