Although lab studies suggest anticancer effects, calcium glucarate has not been shown to treat or prevent cancer in humans.
Calcium glucarate is absorbed in the intestine and converted into a molecule that inhibits beta-glucuronidase, to possibly increase elimination of toxic substances. For example, rats that were exposed to carcinogens and fed calcium glucarate had a slower onset of tumor development and a smaller number of tumors than rats that were not fed calcium glucarate. Calcium glucarate also increases estrogen elimination, which may reduce estrogen levels in the body. This explains its use as supportive care among estrogen-sensitive breast cancer patients. However, positive results in animal studies do not always mean a similar approach will work in humans. In addition, no clinical trials have tested whether calcium glucarate has these effects in humans.
To detoxify the body
Laboratory and animal studies suggest that calcium glucarate speeds up the elimination of carcinogens from the body. Human studies have not been conducted.
To prevent and treat cancer
A handful of animal studies show that calcium glucarate can slow the development and reduce the number of tumors in rats exposed to carcinogens, but human data are lacking. Only one small study in humans suggests that calcium glucarate supplementation might reduce cancer risk for some individuals. More well-designed studies are needed to confirm such effects.
D-Glucaric acid salt
Calcium glucarate is the salt and the commercial form of glucaric acid, which occurs naturally in a variety of foods including apples, oranges, broccoli, and spinach (1). Calcium glucarate and other derivatives have been used to prevent and treat cancer. Patients with breast cancer sometimes self-medicate with calcium glucarate supplements following surgery or adjunctive treatments. The glucarate component, not the calcium, is thought to account for its activity. Following administration, glucarate is converted to D-glucaro-1,4-lactone, which inhibits beta-glucuronidase (4).
In vitro and animal studies suggest that inhibition of beta-glucuronidase may prevent carcinogenesis (5), as well as initiation and promotion of cancer cells (3)(6). Increased elimination of carcinogens and hormones, including estrogen, has also been shown (2). In colon (7) and lung (8) cancer models, calcium glucarate administration exerted chemopreventive effects in the post-initiation phase of carcinogenesis. Dietary calcium glucarate also inhibited oral carcinogenesis (9). Topical calcium glucarate suppressed tumor development in murine skin tumors (6)(10)(11), and enhanced chemopreventive effects were achieved with a topical butyric acid, nicotinamide, and calcium glucarate combination (12)(13). A combination of topical ursolic acid and dietary calcium glucarate supplementation reduced skin tumor promotion and inflammatory signaling (14).
Preliminary findings from a human study suggest that low glucaric acid levels and/or high beta-glucuronidase levels are markers of detoxification system impairment, and that calcium glucarate supplementation might reduce the cancer risk of some individuals (15). Subsequent studies have not materialized and are needed to confirm such effects.
Cruciferous vegetables such as broccoli, cabbage, and Brussels sprouts; oranges, grapefruit, apples, spinach, carrots, potatoes, lettuce, bean sprouts, grapes (1)(4)(16)
Mechanism of Action
The glucarate component, not the calcium, accounts for the activity of calcium glucarate, which is absorbed from the gut as D-glucaric acid. This is further converted to D-glucaro-1,4-lactone, which is thought to inhibit beta-glucuronidase activity (4). Beta-glucuronidase has been shown to decrease the rate of elimination of estrogen and carcinogens such as polycyclic aromatic hydrocarbons and nitrosamines by deconjugation (3). Inhibition of beta-glucuronidase activity with calcium glucarate improves excretion of metabolized estrogen and carcinogens (2). D-glucarate can also be metabolized by gut bacteria, inhibit bacterial beta-glucuronidase, and potentially alter the enterohepatic cycle.
In animal studies, calcium glucarate reduced the quantity of benzo[a]pyrene-induced lung lesions with mutated K-ras and p53 genes in the post-initiation phase via DNA adduct removal, mutagenic suppression, and anti-inflammatory activity (8). Antitumorigenic effects of topical calcium glucarate may be due to stimulated differentiation via induction of transglutaminase activity and suppression of proliferation (6), as well as inhibition of thymidine kinase and aryl hydrocarbon hydroxylase activities, thus preventing carcinogen-DNA binding (10). Enhanced chemopreventive effects by a topical butyric acid, nicotinamide, and calcium glucarate combination used on murine skin tumors occurred via induced mitochondria-mediated apoptosis, upregulated p21, and downregulated Bcl-2, mut p53 (12). In another study this combination regulated miR-203 status through epigenetic or biogenetic modulations before and after tumor development to a greater degree than each of the individual compounds (13). Reduced epidermal hyperplasia with a combination of topical ursolic acid and dietary calcium glucarate supplementation caused a marked decrease in COX-2 and IL-6 expression (14).
In a preliminary human study, calcium glucarate supplementation suppressed beta-glucuronidase levels while increasing serum glucaric acid levels (15).
In a preliminary study, calcium glucarate was well-tolerated with no toxicity reported (15).