Borage oil, often marketed as starflower oil, is a dietary supplement derived from the seeds of the Borago officinalis plant. It is recognized for its unique fatty acid composition and traditional use in folk remedies. A frequent query centers on whether this supplement can influence the body’s endocrine system by raising estrogen levels. This article examines borage oil’s components and assesses the scientific evidence regarding its relationship with estrogen.
The Active Component: Gamma-Linolenic Acid
The therapeutic properties of borage oil are largely attributed to its high concentration of Gamma-Linolenic Acid (GLA), a polyunsaturated omega-6 fatty acid. Borage seed oil stands out as one of the richest plant-based sources of GLA, typically containing between 17% and 25% of this compound. Unlike the more common omega-6 fatty acids found in many vegetable oils, GLA has distinct biological actions once consumed.
GLA is an immediate precursor in a metabolic cascade that leads to the formation of signaling molecules called eicosanoids. The body converts GLA into dihomo-gamma-linolenic acid (DGLA) through an elongation process, bypassing a rate-limiting step often seen with other fatty acids. DGLA is then metabolized to create prostaglandin E1 (PGE1), a lipid mediator known for its potent anti-inflammatory effects. This pathway is the primary mechanism through which borage oil exerts its effects on the body’s physiological processes.
Investigating the Hormonal Link
Estrogen, a steroid hormone, triggers a biological response by binding directly to specific estrogen receptors (ERs) within cells. Borage oil and GLA are fatty acids, not steroid compounds, and they do not directly interact with these receptors.
Compounds that alter estrogen levels, such as phytoestrogens found in soy, possess a chemical structure allowing them to weakly bind to ERs. GLA does not share this characteristic, meaning it does not mimic estrogen’s action. Scientific investigations consistently show that borage oil does not function as a potent phytoestrogen.
Human research on borage oil’s impact on circulating estrogen levels is limited and often contradictory. Studies have shown varied results, including modest elevations in animals and decreases in postmenopausal women. Any influence on the endocrine system is thought to be indirect, possibly resulting from GLA’s role in modulating inflammatory responses. The current scientific consensus suggests that borage oil does not cause a notable increase in circulating estrogen levels.
The misconception about a hormonal link likely stems from borage oil’s traditional use in managing certain female health complaints. GLA’s anti-inflammatory metabolites can help alleviate symptoms associated with the menstrual cycle and menopause, such as breast pain or tenderness. These observed benefits are due to its inflammation-modulating properties rather than direct estrogen stimulation.
Established Uses and Benefits
The documented applications of borage oil are strongly linked to the anti-inflammatory effects generated by its GLA content. The production of the anti-inflammatory eicosanoid PGE1 helps to counteract pro-inflammatory compounds. This mechanism makes borage oil a subject of clinical interest for conditions characterized by chronic inflammation.
One recognized use is for inflammatory skin conditions, such as atopic dermatitis (eczema). The GLA is incorporated into skin cell membranes, helping to restore the skin’s barrier function and reduce associated redness and itching. Clinical trials have explored both oral and topical applications.
Borage oil has also shown potential in managing symptoms of rheumatoid arthritis (RA), an autoimmune condition involving joint inflammation. Studies indicate that daily supplementation can help reduce joint tenderness and swelling in individuals with RA. Its anti-inflammatory action is also utilized in managing cyclical mastalgia (breast pain), by moderating the inflammatory signals.
Safety Considerations and Contraindications
While borage seed oil is generally tolerated, users must be aware of potential safety concerns. The main concern revolves around naturally occurring pyrrolizidine alkaloids (PAs) in the borage plant. PAs are toxic to the liver and can cause serious damage, especially when consumed in high doses or over long periods.
Consumers should only use borage oil supplements certified as “PA-free” or “purified,” as the refinement process removes these harmful compounds. Purification is the best safeguard, even though standard borage seed oil typically contains negligible amounts of PAs. Common side effects, even with purified oil, can include mild gastrointestinal upset, such as bloating or nausea.
Borage oil may interact with certain medications due to its fatty acid components. Because GLA may prolong bleeding time, individuals taking anticoagulant or antiplatelet drugs (blood thinners) should consult a healthcare provider. There is also a theoretical concern regarding its use alongside medications that lower the seizure threshold. Borage oil is generally advised against for women who are pregnant or breastfeeding due to the potential for PA contamination and lack of comprehensive safety data.