Health Benefits of GLA (Evening Primrose Oil)

Posted by Fruit Of Spirit on

Evening Primrose Oil (EPO) is a supplement that provides the health benefits of GLA (gamma-linolenic acid).

Native to the temperate and tropical climate regions of North America, the Evening Primrose (Oenothera biennis) plant is the most numerous species in Onagraceae. It is commonly known as "fever plant", "hogweed", "night willowherb", "King's cure-all", "scurvish", "German rampion", "sun cups", 'scabish", "sun drop" and many more.

The first people who used Evening Primrose oil came from several Native American tribes, including the Ojibwas, Cherokee, Potawatomi, and Iroquois. They used the plant for both food and medicinal purposes.

Evening Primroses flower from June to October. It has 2 to 4 bright yellow to gold colored petals and is biennial, which means that their flowers are open during the evening and are fully closed during the day. Evening Primroses can grow from 18 and up to 60 inches (1.5 to 5 feet) tall.

Evening Primrose Seeds and Oil

The most important and the pharmaceutical ingredient that the Evening Primrose produces is found in the seeds, which is called gamma-linoleic acid (GLA).

It is common to find 100 seed pods in a plant containing 300 – 400 tiny reddish-brown seeds. The seeds contain about 20 percent oil, wherein the amount depends on various factors such as growth conditions, cultivar, and the age of the grain.

The oil is extracted from the seed through the cold-pressing method. This method requires pressing the Evening Primrose seeds with high pressure.

Evening Primrose Oil (EPO) is highly constituted by linolenic acid (LA) by 70 to 74 percent and gamma-linolenic acid (GLA) by 2 to 15 percent.

Importance of Gamma-Linolenic Acid (GLA)

GLA is an omega-6 fatty acid, which is a polyunsaturated fat and is called an "essential fatty acid." This means that humans can only obtain this through diet consumption. Omega-6 fatty acids help with the function of all cells in the human body. They play a very crucial role in brain growth and function and usual growth and development.

The omega-6 fatty acids are primarily used for energy production regulation.

These fatty acids are also important structural components of the cell membranes. When fused into the phospholipids, they can affect the cell membrane's properties such as permeability, fluidity, flexibility, and the activity of membrane-bound enzymes and cell-signaling pathways.

Omega-6 fatty acids also influence the local production of bioactive lipid mediators, thus serving as precursors to the bioactive lipid mediators. Each precursor then leads to giving rise to a variety of molecules with a range of immune-modulating activities. These immune-modulating activities include inflammatory (Prostanoids and Leukotrienes), anti-inflammatory (Hydroxy fatty acids), and pro-resolving mediators (Lipoxins).

GLA and its metabolites can also affect immune system regulation, inflammation, and wound healing. It is also essential for stimulating skin and hair growth.

GLA can also affect gene regulation by interacting with the transcription factors within the cell’s nucleus.

It also has been said the GLA can lower the bad cholesterol (LDL) and increases an individual's excellent and protective cholesterol levels (HDL).

Without enough GLA, a deficient individual can reflect various physical and clinical signs. Physical signs include:

  • Dry, scaly rash
  • Dull or ‘lifeless’ hair
  • Dandruff
  • Excessive thirst
  • Follicular Keratosis (characterized by raised bumped on the skin),
  • Frequent urination, and
  • Soft or brittle nails.

Clinical signs exhibit such as:

  • Allergic or ‘atopic’ tendencies,
  • Attention problems,
  • Emotional sensitivity,
  • Sleeping problems, and,
  • Visual symptoms.

However, when an individual has consumed way too much omega-6 fatty acid, it can raise the blood pressure, which leads to blood clots that can cause strokes and heart attacks. Drinking too much omega-6 can also make your body retain water.

Benefits of GLA

All the research done to review the health benefits of GLA was done to animal models. Despite several studies done to expand knowledge on the benefits of GLA, it is still not fully understood.


Asthma is a condition wherein an affected individual's airways has inflammation, causing the inner linings to swell and produce mucus. This makes asthmatics have difficulty breathing and triggers coughing, wheezing, and shortness of breath.

There is data from various research showing that GLA lessens leukotriene production in a manner that is consistent with the reduction in inflammation. Leukotrienes are the ones responsible for the narrowing of airways.

GLA supports the lining of the lungs to work better and stay flexible.


GLA is known to have anti-inflammatory effects that can help individuals affected with Rheumatoid Arthritis (RA).

RA is a chronic autoimmune disorder that can affect one’s joints, heart, eyes, lungs, and blood vessels.

Some studies have shown that GLA appears to be effective due to its conversion to a hormone-like substance known to have a property to decrease inflammatory activity called prostaglandin E1.

Using EPO to help treat RA is a promising study.


Some countries have approved using Evening Primrose oil to decrease the symptoms of eczema.

Eczema is a dermatologic condition in which patches of skin become cracked, rough, and inflamed, causing redness and itch.

Individuals who have eczema do not have the average ability to process fatty acids, resulting in GLA deficiency.

Some trials have reported striking evidence that Evening primrose oil can reduce the itching.

Also, there is a study conducted in 2005 showing that using EPO helps improve skin moisture, elasticity, fatigue resistance, and firmness.


Sometimes acne and eczema go hand in hand together, but acne affects the oil glands under the skin.

GLA in EPO is thought to help acne by reducing inflammation in the skin and reducing both inflammatory and noninflammatory acne lesions. As mentioned in eczema, GLA may also help retain skin moisture.

Breast Conditions

Breast pain is common among women, especially during menstrual cycles. Some studies support the claim that EPO can alleviate breast pains.

EPO has demonstrated in a study that it reduces inflammation and helps inhibit prostaglandins that cause pain. It also showed that it lessened the severity of breast pain.

There also have been reports that continually show that EPO can reduce the symptoms of fibrocystic breast disease. Fibrocystic breast disease is a noncancerous condition where the breast feels lumpy.

Premenstrual Syndrome

Around the world, many women use EPO to relieve the symptoms of premenstrual syndrome (PMS).

However, most studies done to try and provide scientific evidence lacked to show benefits. Thus, it is still unclear since there is no conclusive experimental data to prove or support claims.

Despite this information, some people still believe that taking EPO is an effective treatment option. Some women have also reported that using GLA gives relief and improves PMS symptoms.


Similar to PMS, a lot of women have reported that GLA helps decrease the symptoms of menopause.

EPO has gained popularity in treating or reducing the severity of the hot flashes associated with menopause.


Some studies showed that GLA is possibly sufficient for nerve damage due to diabetes. It decreases the symptoms and prevents any or further nerve damage in affected individuals.

These symptoms include weakness, hot and cold sensitivity, tingling, and numbness.

GLA also seems to work better in individuals who have good blood sugar control.

Evening Primrose Oil Supplements

If omega-6 fatty acids are not obtained in the diet, there are supplements available at health food stores and sold in capsules.

The metabolism of LA to GLA is often an inefficient and rate-limiting step, so in taking GLA supplements, it is a means to avoid deficiency.

Generally, an oil of high quality is certified by an authorized and reputable third party that packages in light-resistant containers, refrigerated, and marked with a freshness date.

Safety Measures and Dosing

GLA supplements are said to be possibly safe for most adults when taken orally in amounts of no more than 2.8 grams per day. Also, avoid doses greater than 3,000 mg per day because high levels may further increase the inflammation in the body. Frequent doses of GLA intake range from 500 to 1000 mg daily.

Some sources cite that short-term use (up to 18 months) in recommended doses is likely to be safe. Long term use (up to 36 months) is possibly safe but has inconclusive data to support.

GLA supplements have been commonly used for over 20 years with no reports of serious events or effects. Despite no reports, it is wise to keep in mind that GLA is not thoroughly studied, and there are many still many unknown variables.

If you intend to use EPO, please ask and consult your doctor if they are safe for you to use and determine the most effective dose for your condition.

Side Effects

Individuals who already use GLA supplements feel the familiar and mild side effects that are well-tolerated.

The common side effects include:

  • Occasional headache
  • Nausea
  • Belching
  • Abdominal pain
  • Bloated stomach
  • Flatulence (gas)
  • Diarrhea (loose and soft stools)

In rare cases where intake of EPO may cause allergic reactions to an individual, symptoms include:

  • Rashes
  • Inflammation of both hands and feet
  • Difficulty breathing

Possible Interactions

When using EPO, its effectivity will be restricted when there is:

  • Use of alcohol
  • Smoking
  • Stress,
  • Magnesium (Mg) deficiency
  • Vitamin B6 (Pyridoxine) deficiency
  • Zinc (Zn) deficiency
  • Intake of saturated fatty acids
  • Intake of trans-fatty acids


EPO interactions with other drugs or medication are not well studied yet, so it is wise to be cautious in using EPO.

Drugs and medications that have possible interactions with EPOs include:

Blood-thinning medications

Blood-thinning medications, also called blood thinners, prevent the formation of blood clots. These can also prevent the enlargement of existing blood clots in an individual.

There are two types of blood thinners: anticoagulants and antiplatelets. There are some studies that GLA showed interactions with these medications.

GLA may interact with these:

  • Anticoagulants:
  • Warfarin – Coumadin, Jantove
  • Heparin – Fragmin, Lovenox. Innohep, etc.


  • Antiplatelets:
  • Aspirin
  • Clopidogrel – Plavix

EPO may increase bleeding and might slow blood clotting.

Nonsteroidal Anti-inflammatory Drugs (NSAIDs)

NSAIDs are medications to relieve pain and inflammation. GLA interacting with these drugs may also increase the risk of bleeding. Example of NSAIDs are:

  • Ibuprofen – Advil, Motrin, etc
  • Diclofenac – Voltaren, Cataflam, etc
  • Naproxen – Anaprox, Naprosyn, Aleve, etc.

Anti-cancer Treatments

GLA may increase and alter the effects that anti-cancer treatments offer. Anti-cancer treatments include:

  • Vinblastine
  • Doxorubicin
  • Vincristine
  • Cisplatin
  • Tamoxifen
  • Carboplatin
  • Mitoxantrone
  • Idarubicin


Phenothiazines are a class of medication to treat schizophrenia. Phenothiazines include:

  • Chlorpromazine – Thorazine
  • Fluphenazine – Prolixin
  • Perphenazine – Trilafon
  • Promethazine – Compazine
  • Thioridazine – Mellaril
  • Trifluoperazine – Stelazine

Taking EPO and the GLA in it may interact with these medications and may increase the risk of seizures. Do not take GLA if you have a seizure disorder.


Ceftazidime is an antibiotic in a class known as cephalosporins that acts by inhibiting the synthesis of bacterial cell walls against a variety of bacterial infections. Examples of ceftazidime drugs are Fortaz and Tazicef.

Intake of GLA may interact with this drug and might increase the effectiveness of the ceftazidime.


Cyclosporine belongs to the class of immunosuppressants. Cyclosporine is a medication used to prevent organ rejection and to suppress the immune system after an individual has undergone an organ transplant. This drug allows the new organ to function normally.

GLA may increase the immunosuppressive effects of this medication and may protect the individual against kidney damage, which is a side effect of cyclosporine.

Interactions with Herbs and Dietary Supplements

Ginkgo Biloba

Ginkgo Biloba, or maidenhair, is a popular supplement and is one of the top-selling herbal medicines.

Multiple studies have been reported that the use of GLA on top of the use of Ginkgo Biloba increases the risk of bleeding.

Natural Antioxidants

This might not be well studied or explored in humans, but natural antioxidants may inhibit GLA's specific effects.

Other Precautions and Warning

If you are going to have surgery soon, please avoid taking GLA at least two weeks before your schedule. GLA might increase the risk of bleeding and may decrease blood clotting.

Also, it is wise to keep in mind that the evening primrose oil is not monitored by the Food and Drug Administration (FDA).

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