Astaxanthin Shows Anti-Cancer Activity in Breast Cancer Models, Review Finds

Astaxanthin, the red xanthophyll carotenoid that gives salmon, shrimp and the microalga Haematococcus pluvialis their characteristic pigment, is drawing renewed attention as a candidate anti-cancer molecule. A narrative review published in Discover Pharmaceutical Sciences consolidates the preclinical evidence that this compound can suppress breast cancer cell proliferation, migration, angiogenesis and tumor growth in laboratory and animal models. The authors, Hashimji Hashim Akmal, Arathi Kollath, Tino Thamby and Vishnu Kalladathvalappil Venugopalan, emphasize that the evidence comes almost entirely from in vitro and in vivo work, and that clinical trials in breast cancer patients have not yet been carried out.

The review’s literature search covered PubMed, Scopus and Google Scholar, focusing on studies published between January 2015 and October 2025, with selectively included earlier foundational work. Inclusion criteria targeted original research providing preclinical evidence from cell culture and animal studies, including investigations of synergistic effects with conventional chemotherapeutic agents. The authors framed the review as a response to fragmented insights, since astaxanthin’s effects on breast cancer have typically appeared within broader anti-cancer discussions rather than dedicated analyses.

Astaxanthin is chemically defined as 3,3′-dihydroxy-β,β’-carotene-4,4′-dione, with a molecular mass of 596.84 g/mol and the formula C40H52O4. Its antioxidant activity has been reported as roughly ten times greater than that of zeaxanthin, lutein, canthaxanthin and beta-carotene, and about 100 times higher than alpha-tocopherol. Concerning lipid peroxidation, its capacity has been documented as exceeding vitamin E by more than 100-fold, with approximately 550-fold greater efficacy in quenching singlet oxygen. Natural astaxanthin from H. pluvialis reportedly shows about 50-fold stronger singlet oxygen quenching and roughly 20 times greater free radical elimination than the synthetic form, an advantage attributed in part to its esterified structure being more readily absorbed.

The compound’s molecular architecture underpins these properties. A chain of 13 conjugated double bonds provides delocalized electrons that neutralize free radicals and terminate radical chain reactions, while a polar-nonpolar-polar configuration allows astaxanthin to span the lipid bilayer of cell membranes, scavenging reactive oxygen and nitrogen species both in the hydrophobic core and at the hydrophilic interfaces. This membrane-spanning antioxidant behavior is central to the hypothesis that astaxanthin can limit oxidative damage, including DNA strand breaks and base modifications, that contributes to carcinogenesis.

In breast cancer cell lines, the review reports a consistent pattern of anti-proliferative and pro-apoptotic effects. Astaxanthin induced apoptosis in MCF-7 cells through a p53-dependent pathway and activated intrinsic apoptotic pathways in SKBR3 cells, evidenced by modulation of Bax/Bcl2 ratios and caspase activation. Reported IC50 values for apoptosis induction were 23 micromolar in MCF-7, 36 micromolar in SKBR3 and 37 micromolar in BT-474 cells. In T47D and BT20 cell lines, astaxanthin inhibited the expression of pontin and mutant p53 along with the cancer stemness genes Oct4 and Nanog, markers associated with tumor progression and treatment resistance. Comet assay results showed a dose-dependent decrease in DNA damage in breast cancer cells, alongside reduced viability of MDA-MB-231 and T47D cells and downregulation of Bcl-2.

Mechanistically, the review describes cell cycle arrest, most commonly at the G0/G1 phase, together with activation of the pro-apoptotic protein Bax, inhibition of Bcl-2, cleavage of caspase-3 and caspase-9, and phosphorylation of ERK1/2, JNK and p38 in SBR3 cells treated with astaxanthin. The compound also reduced intracellular ROS production and modulated superoxide dismutase expression. Beyond apoptosis, astaxanthin inhibited migration of both triple-negative and estrogen receptor-positive breast cancer cells, and appears to interfere with epithelial-mesenchymal transition by reducing inflammatory cytokines such as TNF-alpha and TGF-beta that promote EMT, potentially sensitizing cells to chemotherapy.

Animal studies reinforce these cellular findings. In female Sprague-Dawley rats in which mammary carcinogenesis was induced with N-methyl-N-nitrosourea, elevated dietary astaxanthin levels showed a notable inverse correlation with the occurrence of detectable mammary tumors, with a substantial decline in tumor manifestation in supplemented cohorts compared with controls. In mice bearing breast cancer xenografts, astaxanthin administration reduced tumor size, likely through modulation of the PI3K/Akt and NF-kappaB pathways. Additional animal work reported heightened caspase activity in tumor tissues, reduced vascular endothelial growth factor levels indicating suppressed angiogenesis, and elevated IgM and IgG antibody levels suggesting immune amplification.

The review also examines combination strategies. Astaxanthin combined with beta-carotene and lutein augmented cytotoxicity and oxidative stress in MCF-7 cells, inducing G0/G1 cell cycle arrest, outperformed individual treatments, and showed no adverse effects on normal breast epithelial MCF-10A cells. Combined with eugenol, astaxanthin amplified anticancer effects through enhanced histone acetylation and immune modulation, and significantly enhanced doxorubicin’s cytotoxicity, lowering its IC50. With melatonin, the combination showed markedly greater potency in T47D cells, which carry estrogen, progesterone and HER2 receptors, than in triple-negative MDA-MB-231 cells, underscoring how receptor expression shapes responses. Because doxorubicin’s cardiotoxicity is mediated by reactive oxygen species accumulation, the authors hypothesize that astaxanthin might offer cardioprotection by stabilizing mitochondrial membrane potential, though they caution that rigorous preclinical and translational research is needed to confirm any synergistic benefit in clinical settings.

Safety data appear favorable but come with caveats. Natural astaxanthin supplementation showed no safety concerns in human trials, with doses ranging from 2 to 24 mg per day used without adverse effects across at least 87 clinical trials, including 35 studies with doses of at least 12 mg per day. Doses up to 18 mg have been used clinically for up to 12 weeks, and the European Food Safety Authority has proposed an acceptable daily intake of 2 mg based on synthetic astaxanthin studies, noting that natural astaxanthin requires separate evaluation. Astaxanthin derived from H. pluvialis is considered the safest form. The compound was approved by the US Food and Drug Administration as a feed colorant in 1987 and as a dietary supplement ingredient in 1999.

Significant limitations temper the enthusiasm. The review acknowledges that no direct studies of astaxanthin in ER-positive, HER2-positive or triple-negative breast cancer subtypes have been carried out, that current literature often aggregates data across cell lines without stratification, and that apparent contradictions, such as reports of anti-apoptotic effects in aflatoxin-treated IPEC-J2 cells through the Nrf2 pathway, may reflect dose-dependent redox switching or differences in experimental conditions. The compound’s pronounced instability to light, oxygen, heat and pH extremes, together with its lipophilicity, poor aqueous solubility and low oral bioavailability, hampers both experimentation and clinical translation. The authors call for nano-based delivery systems such as liposomes and nanoemulsions, mechanistic studies within well-defined models integrating pharmacokinetic and therapeutic evaluation, and rigorous clinical trials stratified by breast cancer subtype before astaxanthin can be considered a viable chemopreventive or adjuvant agent.

Subject of Research: Preclinical evidence for astaxanthin as a potential therapeutic agent in breast cancer

Article Title: Anticancer efficacy and therapeutic potential of astaxanthin in breast cancer

Article References: Akmal, H. H., Kollath, A., Thamby, T., & Venugopalan, V. K. (2026). Anticancer efficacy and therapeutic potential of astaxanthin in breast cancer. Discover Pharmaceutical Sciences, 2(1), Article 7. https://doi.org/10.1007/s44395-026-00041-9

Image Credits: AI Generated

DOI: 10.1007/s44395-026-00041-9

Keywords: astaxanthin, breast cancer, carotenoids, preclinical studies, apoptosis, angiogenesis, oxidative stress, combination therapy, chemoprevention, triple-negative breast cancer, Anticancer, efficacy