Hyaluronic acid (HA) is a popular ingredient in personal care and supplements, celebrated for its exceptional ability to hydrate the skin and lubricate joints. Despite its widespread use, persistent questions remain about its safety, specifically concerning a potential link to cancer growth. This concern arises from observations regarding HA’s behavior in the presence of malignant cells. Understanding the true risk requires separating the molecule’s natural role in the body from its use in consumer products and carefully examining the complex scientific evidence.
What is Hyaluronic Acid
Hyaluronic acid (HA), also called hyaluronan, is a large, naturally occurring sugar molecule known as a glycosaminoglycan. It is found in nearly all body tissues and consists of repeating units that allow it to bind and retain vast amounts of water. HA is a major component of the extracellular matrix, the structural scaffold surrounding cells.
Its primary physiological role is maintaining tissue hydration, with roughly half of the body’s HA content located in the skin. HA also acts as a shock absorber and lubricant in the joints, where it is a component of synovial fluid. Furthermore, HA plays a functional role in tissue repair, helping to regulate inflammation and promote cell migration during wound healing. The natural, high molecular weight form of HA is associated with healthy tissue function and stability.
The Role of HA in Tumor Progression
The link between HA and cancer is not that HA causes tumors, but that existing tumors produce and exploit high levels of HA to accelerate growth and spread. High concentrations of HA are frequently found within the tumor microenvironment, the area surrounding the cancer cells, and this is often a sign of more advanced malignancy. This endogenous HA creates a structural network that aids in tumor cell proliferation, survival, and movement through the body, a process called metastasis.
Cancer cells often overexpress the CD44 protein receptor on their surface, which acts as the main binding partner for HA. When HA binds to CD44, it activates internal signaling pathways that essentially give the cancer cell a biological advantage. This interaction promotes cancer stem cell characteristics and can contribute to drug resistance, making tumors harder to treat.
Molecular Weight Matters
The size of the HA molecule, or its molecular weight, is a significant factor in its biological effect. The large, native form, High Molecular Weight HA (HMW-HA), is generally associated with tissue maintenance. HMW-HA can even inhibit tumor progression in some models by increasing the density of the extracellular matrix.
Conversely, when HMW-HA is broken down by hyaluronidase enzymes, it creates smaller fragments called Low Molecular Weight HA (LMW-HA). These smaller fragments are strongly associated with inflammation. LMW-HA is thought to promote pro-cancer activities, such as cell proliferation and the formation of new blood vessels (angiogenesis) that feed the tumor.
Assessing the Safety of External HA Use
Assessing the risk of external HA use centers on the difference between the body’s internal, pathological processes and the bioavailability of consumer products. For topical products like serums and creams, the risk is considered negligible. The HA molecule is relatively large, and when applied to the skin, it primarily remains on the surface or in the upper layers of the epidermis, providing hydration without significantly entering the systemic circulation.
The safety profile for topical HA is well-established, with regulatory bodies concluding that it is safe for cosmetic use. For oral supplements, HA is absorbed through the intestine, though some degradation occurs during digestion, and its fate depends on its molecular weight. Studies confirm that orally ingested HA, even in its high molecular weight form, can be absorbed and distributed to tissues like the skin and joints.
Despite this systemic absorption, there is no evidence that standard doses of oral or topical HA products trigger the formation of new cancers in healthy individuals. The concern is theoretical: if a person had an undiagnosed microscopic tumor, a large systemic dose might potentially provide a growth advantage. This is why medical injections, such as joint viscosupplementation, which deliver high local concentrations, carry a note of caution for individuals with a history of cancer. Scientific consensus distinguishes between the high-concentration HA environment produced internally during disease and the low systemic exposure from external cosmetic or supplemental use.