Calcium D-glucarate

What it is

Glucaric acid, also D-glucaric acid, is formed in human metabolism as the end product of the glucuronic acid pathway, in small amounts and entirely naturally. It is also found in many types of fruit and vegetables: in oranges, grapefruit, apples, broccoli and other cruciferous vegetables, spinach, carrots and potatoes. The amounts are small. In one analysis, broccoli and potatoes contained 1.12 to 1.73 mg per 100 g, and oranges were highest at 4.53 mg per 100 g.

Calcium D-glucarate is the commercial form, the calcium salt of this acid. According to Memorial Sloan Kettering Cancer Center, the glucarate component carries the effect, not the calcium. It is mostly sold in capsules, often also in combination products for so-called hormone balance, together with substances such as DIM or indole-3-carbinol. The accompanying narrative is estrogen detox or help with estrogen dominance.

How it is supposed to work

The liver makes many substances ready for excretion by attaching glucuronic acid to them. This applies to estrogens, but also to medicines and pollutants such as polycyclic aromatic hydrocarbons and nitrosamines. The substances packaged in this way reach the gut via the bile. There and in the tissues sits the enzyme beta-glucuronidase, which can cut the packaging off again. The released substance can then return to the circulation instead of leaving the body. The enzyme is also produced by gut bacteria.

This is where calcium D-glucarate comes in. In the stomach it gives rise to D-glucaro-1,4-lactone, a potent inhibitor of beta-glucuronidase. Less enzyme activity is supposed to mean that estrogens and pollutants stay packaged and are excreted. This pathway has been shown in rats. The lactone forms in the stomach, is absorbed, distributes into the organs and is excreted in the urine.

What users are looking for

Calcium D-glucarate is taken mainly by people who attribute their symptoms to an excess of estrogen, and in the detox and liver cleanse scene. According to Memorial Sloan Kettering Cancer Center, breast cancer patients also take it as self-medication after surgery or adjuvant therapy. There are no systematic user reports. Anyone who tries it has hardly any yardstick, because hormonal symptoms fluctuate anyway and no established lab value shows whether the product changes anything in their own body.

What the studies show

Rat breast cancer model

Rats received the carcinogen DMBA and then feed containing calcium D-glucarate. Tumor development was inhibited by more than 70%. At the same time, the body’s own levels of estradiol and of precursors of the 17-ketosteroids fell. This work is the basis of the estrogen detox narrative.

Initiation or promotion

In the same model, calcium glucarate was fed either during cancer initiation, during the growth phase or across both phases. Tumor incidence fell by 18%, 42% and 50%, and the number of tumors per animal by 28%, 42% and 63%. The glucarate thus acted mainly in the later phase, in which tumors spread.

The only human study

In humans there is only a 2004 conference abstract from the same research group. According to the summary by Memorial Sloan Kettering Cancer Center, calcium glucarate lowered beta-glucuronidase there, increased serum glucaric acid and was well tolerated. There is no full publication with the number of participants, duration and control group, and according to MSKCC, follow-up studies never appeared.

Where the data stop

The decisive step is missing: no one has measured in a published controlled study whether calcium D-glucarate lowers estrogen levels, relieves symptoms or reduces cancer risk in humans. MSKCC notes that no clinical studies have tested these effects in humans and that it does not consider calcium glucarate confirmed for either the treatment or the prevention of cancer. No study on its intake is registered at ClinicalTrials.gov. The only randomized trial that included calcium glucarate tested a combination product with indole-3-carbinol, lignan and plant extracts in 47 premenopausal and 49 postmenopausal women over 28 days, and the authors attribute the effect on estrogen metabolism to the other ingredients.

The mechanism is also less clear-cut than the marketing suggests. In one rat study, glucarate did not change beta-glucuronidase levels, and in cell culture glucarate possibly acted without the detour via the lactone. In humans it is unclear how strongly beta-glucuronidase can be influenced at all: a diet rich in citrus fruit, cruciferous vegetables and soy did not lower it in 63 healthy people. One rat study additionally reports a cholesterol reduction; the human data mentioned there could not be verified. The data are therefore sufficient for a hypothesis, not for a claim of efficacy.

Status, approval and legal

Calcium D-glucarate is not a medicine. It does not appear in the EU Novel Food Catalogue or in the Union list of authorized novel foods, and significant consumption in the EU before May 15, 1997, which would exempt it from the novel food requirement, has not been documented. Nor is it on the EU list of calcium compounds that may be added to foods as a nutrient source. Whether it is marketable as a dietary supplement is therefore unresolved, even though it is offered in Germany through mail-order pharmacies and online retailers. There are no official maximum amounts from EFSA or the BfR. It is not on the WADA 2026 Prohibited List.

Safety

Systematic safety data in humans are missing. In the only preliminary study it was well tolerated, no side effects were reported, and MSKCC lists no interactions. That does not mean it is safe, however, only that it has not been studied. An influence on medicines and hormones excreted via glucuronidation is theoretically conceivable, because in the laboratory the resulting lactone may also inhibit the enzymes that attach this packaging. Anyone receiving hormonal treatment, for example anti-hormone therapy after breast cancer, the contraceptive pill or hormone replacement therapy, should therefore discuss taking it with their doctor. There are no data for pregnancy, breastfeeding and children.

Sources

• Memorial Sloan Kettering Cancer Center, About Herbs: Calcium Glucarate (as of March 22, 2022)
• Walaszek et al., Carcinogenesis 1986 – calcium glucarate in the rat breast cancer model
• Abou-Issa et al., Anticancer Res 1995 – glucarate in initiation and promotion
• Dwivedi et al., Biochem Med Metab Biol 1990 – beta-glucuronidase inhibition and glucarate in foods
• Walaszek et al., Cancer Detect Prev 1997 – metabolism and excretion of D-glucarate
• Yoshimi et al., Int J Oncol 2000 – glucarate in the rat colon cancer model
• Abou-Issa et al., Anticancer Res 1993 – glucarate without effect on enzyme levels in rats
• Maruti et al., Cancer Epidemiol Biomarkers Prev 2008 – beta-glucuronidase on a fruit and vegetable diet
• Laidlaw et al., Breast Cancer 2010 – combination product with calcium glucarate, RCT
• European Commission, Novel Food Status Catalogue