Fish oil relieves pain associated with endometriosis

Endometriosis is a common chronic disease affecting women that is associated with debilitating pain, infertility, and other symptoms. However, evidence suggests that supplementation with omega-3 fatty acids, which are found in fish oil, may relieve pain and improve quality of life in patients with the condition, according to a study published in the journal Frontiers in Nutrition. According to the researchers, the beneficial effects of fish oil are primarily due to its ability to counteract inflammation and local muscle spasms. At the same time, modern diets often contain far too little omega-3 from oily fish and too much omega-6 from seed oils, corn oil, and other processed foods. This imbalance between omega-3 and omega-6 fatty acids increases the risk of endometriosis as well as many other chronic diseases.

Patients with endometriosis have a growth of estrogen-sensitive tissue resembling the uterine lining (endometrium). This hormone-sensitive tissue is primarily located in the muscular wall of the uterus, the ovaries, the fallopian tubes, and the vagina, but it may also occur in the peritoneum and other organs. Because this tissue responds to the same hormones as the uterus and follows the woman’s menstrual cycle, a wide range of symptoms may occur, including severe pain during menstruation, ovulation, urination, or bowel movements. Many women also experience chronic pain and fatigue, and around half become infertile.
Because endometriosis is influenced by the estrogen hormone estradiol, which is produced in the ovaries as part of female fertility, the disease typically begins during puberty and disappears after menopause. The condition is also characterized by chronic inflammation, which contributes to local muscle spasms and pain.
Endometriosis is treated with surgery and hormone therapies such as oral contraceptives and synthetic progestins. However, because many patients continue to suffer from severe pain, infertility, and reduced quality of life, there is a need for better treatment options. It is already well established that the omega-3 fatty acids EPA and DHA, found primarily in oily fish and fish oil, have anti-inflammatory properties. The researchers behind the new study therefore wanted to evaluate whether fish oil supplementation could improve pain, inflammatory biomarkers, and quality of life in patients with endometriosis.

Fish oil improves endometriosis on several parameters

The study included 289 patients with endometriosis, all of whom received conventional therapy. The patients’ pain levels, other symptoms, and quality of life were assessed using specialized questionnaires. In addition, 151 of the patients received fish oil supplements providing 600–1,200 mg of EPA and DHA daily. This corresponds to approximately 2–4 fish oil capsules per day. The control group consisted of 138 patients who received identical placebo capsules.
All participants also underwent blood testing to measure various pro-inflammatory markers. Compared with the control group, the patients who received fish oil experienced:

• A greater overall reduction in pain
• A greater decrease in the pro-inflammatory markers IL-6, TNF-α, and CRP
• A greater improvement in SF-36 PCS, a scale that measures physical quality of life and functional capacity based on several subcategories
• A greater improvement in MCS (Multiple Chemical Sensitivity), a form of sensitivity to fragrances and chemicals that often occurs alongside endometriosis and other inflammatory conditions

Overall, the patients who received the highest amounts of fish oil experienced the greatest improvements.
The researchers therefore conclude that patients with endometriosis who receive fish oil supplements in addition to conventional treatment can expect greater pain reduction, greater improvements in quality of life, and greater reductions in pro-inflammatory biomarkers in the blood. These benefits remained significant after adjusting for potential confounding factors such as BMI, age, smoking habits, alcohol consumption, and other variables.
According to the researchers, fish oil supplementation is therefore a relevant and promising therapy that can be combined with conventional treatment to help improve the well-being of patients with endometriosis.

Diet and the important balance between omega-3 and omega-6

The body must, of course, be able to initiate inflammation as part of its defense against infectious agents. However, inflammation must not become excessive or chronic, as it can then become highly damaging to health. Broadly speaking, the body’s inflammatory processes are regulated by omega-3 and omega-6 fatty acids. Omega-6 fatty acids generally promote inflammation, whereas omega-3 fatty acids generally help suppress it.
However, modern diets often contain excessive amounts of omega-6 from seed oils, corn oil, margarine, French fries, potato chips, mayonnaise, salad dressings, cakes, and processed foods. At the same time, modern diets provide far too little omega-3, largely because of insufficient consumption of oily fish and the widespread use of animal feed containing unnaturally high levels of omega-6.
This imbalance between the two types of fatty acids is a major contributor to chronic inflammation and a wide range of chronic diseases, including endometriosis.
For this reason, it may be beneficial to limit the intake of seed oils and other processed sources of omega-6 while increasing the intake of omega-3 from oily fish and, if appropriate, fish oil supplements.

Reference:

Ying Huang et al. Omega-3 polyunsaturated fatty acid intake and pain, inflammatory cytokines, and quality of life in endometriosis. Frontiers in Nutrition, 2026