Evening Primrose Oil (Oenethera biennis)

Trish Morse January 30, 2001

What is it?

Evening primrose is one of my favorite flowers in the garden. It's bright yellow and blooms in the evening but it isn't really a primrose. It's actually related to willows, which isn't surprising since willows have a lot of medicinal uses.(5) The Native Americans used it externally for skin problems and internally for asthma, gastrointestinal problems, and gynecological problems. (5, 7) When the English took it to Europe in the 17th century, it became so popular it was called the King's Cure All.(4) These days, it's the oil from the seeds that's valued. It takes 5,000 seeds to get 500 mg of oil, so it's not surprising it isn't the cheapest supplement to take.(1) Borage oil and black currant oil can also supply some of the same things, but they are less bio-available and less studied, so evening primrose oil is preferred.(7, 11, 12, 44) The more I read the clearer it is that evening primrose oil can be a powerful force for health in the Hormone Jungle.

Signs that evening primrose oil might be for you

If you know that you have any of the following conditions, you might consider a trial of evening primrose oil: hair loss and brittle nails, eczema, cyclic mastitis, premenstrual syndrome, elevated cholesterol levels, autoimmune inflammation (like rheumatoid arthritis, allergies, etc.), diabetes and other blood sugar problems, or viral infections. If you eat high levels of saturated fat, cholesterol, and trans-fatty acids (anything that says hydrogenated or partially hydrogenated oil on the label), have deficiencies of b6, zinc, magnesium, C, biotin, or calcium, (11, 12, 15, 21, 29) drink a lot of alcohol, or are having radiation therapy, then evening primrose oil might make big improvements in how you feel. There may also be a special need if you have low thyroid (6).

Evening primrose oil is safe, so a trial can't do much harm (except of course to your pocketbook), but any trial has to be for four to six months. Evening primrose oil doesn't cure anything, but it relieves a lot of symptoms, and relief is a wonderful word.

Why evening primrose oil works

Evening primrose oil provides a pure dose of gamma linoleic acid (GLA), which has few sources in nature. But it's important to know how the GLA in evening primrose oil works so that you can decide whether you need it or whether lifestyle changes alone might be enough to help you. So here is the tale of the brambly thicket in the Hormone Jungle known as "prostaglandins," hormone-like chemicals that have very short lives and very large local effects.

To make prostaglandins, you need essential fatty acids--"essential" because our bodies don't make them so we have to eat them. There are two kinds of essential fatty acids that are important here--omega 6 fatty acids and omega 3 fatty acids. We need both kinds to be healthy. A lot has been written lately about omega 3 fatty acids, which come from fish, but omega 6's are even more important. The essential fatty acid in the omega 6 family is linoleic acid (LA). After we eat LA, an enzyme (delta 6 desaturase, for you biochemistry groupies) shows up and changes LA into a new form, GLA. That evolves into DGLA, which hovers in indecision, sniffing the bloodstream for omega 3 fatty acids. If it finds omega 3's, it becomes our hero, prostaglandin 1. If DGLA finds no omega 3's, it becomes arachidonic acid (AA), which becomes the villain--prostaglandin 2, which clots the blood, creates inflammation, makes stress reactions worse, and plays a role in causing endometriosis.(7, 10)

So, prostaglandin 1 is good because it prevents inflammation, stops cells from multiplying (as in endometriosis and cancer), and blocks prostaglandin 2 production(44). It also prevents blood clots, lowers cholesterol, reduces blood pressure, fixes defective T-lymphocyte immune cells (important for cancer , allergies, and infections), and maintains salt and water balance, nerve conduction, and gastrointestinal function.(3, 5)

Doctors have thought this was interesting as biochemistry but irrelevant for patients because an average American eats 10 times more LA than needed.(44) We couldn't possibly be deficient.

However, there are three big ways things can go wrong. The DGLA may decide to become AA because it can't find any omega 3 fatty acids in the bloodstream. Prostaglandin 1 constantly breaks down so it has to be replaced all the time.(4). (We can't replace prostaglandin 1 directly at this time because it breaks down so fast, though there is an experimental synthetic version).(44) The worst problem though is that the enzyme may not show up or it may be unable to do its job. Some people are born with limited ability to make the enzyme, some people don't give it the right kinds of fat to use, and some have a wide range of medical conditions that block it. There are two areas in our control.

Too much of the wrong stuff

Too much saturated fat substitutes for the LA so the enzyme do its thing. Hydrogenated or partially hydrogenated fats (also called trans-fatty acids)(6) seem to have LA, but their structure has been twisted so that they'll last longer on the grocery store shelf. However, with the structure twisted, the enzyme can't work, so nothing happens. Rancid oils also don't work, so they're no good either. The best fats to eat are cold-pressed, refrigerated oils available from health food stores or extra virgin olive oil,(6) which has good LA. Drinking less alcohol is a good idea too.

Not enough of the right stuff

The enzyme doesn't show up to do its thing if there aren't enough of the right nutrients: magnesium, zinc, selenium, and B vitamins, in particular(3, 6, 30). Since estrogen replacement blocks these same nutrients, the enzyme can't do its job. So, changing your diet and adding nutrients might be enough for your body to make its own GLA. Even if it's not, these are important changes to make.

Evening primrose oil comes to the rescue in this Hormone Jungle tale because it by-passes all the things that can go wrong with the enzyme by providing already made GLA. There are some particular areas that it might help a lot.

Cardiovascular problems

Preventing AA and prostaglandin 2 are important here, so taking both evening primrose oil (EPO) and fish oil is important. There are some studies that show a mixed picture for EPO alone, but in studies that included both fish oil and EPO the benefits were clear. (38) In a number of studies, cholesterol and particularly LDL, the bad cholesterol, are lowered by taking EPO. It seems to lower it somewhere between 9% with EPO alone(22) or 12% with EPO and fish oil.(22) EPO decreases platelet aggregation, clots, and strokes, especially if you take it with fish oil too.(22, 37). EPO is also a blood vessel dilator, opening them up(22), though some studies have not been as clear on that(28). EPO also decreased ventricular fibrillation and mortality in lab rats.(33) Because it helps with salt and water balance, EPO also seems to help with high blood pressure (2)

Cancer

This is some of the more interesting research to me. The GLA in EPO may discourage many cancers, and it helps minimize the side effects of radiation treatment.(32) GLA has inhibited the growth of melanoma cells (24) and some breast cancer cells (25, 42)(but not all (26) in test tubes and in rats. It suppressed human colon cancer cells in the test tube(44). Direct injections into tumors have even caused some regression of cancer in the few people tested.(27)

Premenstrual syndrome

A number of PMS symptoms are caused by prolactin. Our hero, prostaglandin 1, inhibits prolactin, so EPO might help against the bloating, breast pain, and irritability.(1) One fairly well-designed trial showed real benefits to taking EPO for PMS, but only after 6 months.(22) In other trials, the results weren't as clear, but the trials were shorter and the causes of PMS might have been other hormonal imbalances. However, anyone reading this who can still get pregnant should be cautious. EPO is the most popular supplement among American nurse midwives for inducing labor!(41)

Obesity

As always, the results are mixed,(20) awaiting that well-financed long-term study to really figure it out. However, scientists know that GLA deficiencies do lead to more calories being distributed to fat cells(22). And one small study showed that people who were over 10% of their ideal body weight did lose some weight and show some redistribution of calories(1). So, theoretically EPO might help and can't hurt.

Hair and nail problems

GLA helps to block the conversion of testosterone to dihydrotestosterone in the scalp and helps with the metabolism in skin and nails (and as it turns out, in fur and feathers too. Pet owners swear by EPO). Evening primrose oil can help these in a matter of weeks rather than months.(1) I found out about EPO because Mary Shomon, in her book on hypothyroidism, quotes both Stephen Langer, M.D., and the endocrinologist Kenneth Blanchard as endorsing evening primrose oil for these problems, particularly for people with hypothyroidism who have problems with the conversion. EPO is rumored to help dry eyes too, though I didn't find any research into it.

Eczema and itching skin problems

Eczema and pruritis (itching) is a known side effect of taking estrogen, which also causes deficiencies that affect the making of prostaglandin 1. EPO is an approved treatment for eczema in Great Britain, Ireland, Denmark, Germany, Spain, Greece, South aftica, Australia, and New Zealand.(2, 5) The most dramatic benefit in the studies (18) is in reducing the itching. However, if an eczema sufferer has already taken a lot of topical steroids over a period of time, there is less benefit or even no help.(10) Atopic dermatitis patients have been shown to have high levels of LA and low levels of GLA and it runs in families,(35) suggesting that they're born having trouble with the enzyme conversion. But evening primrose hasn't always helped all kinds of dermatitis. Still, it's worth a try. Another area where EPO has helped is with the painful itching that comes from kidney dialysis.(43)

Breast problems

EPO has become a medically accepted treatment for fibrocystic breast disease,(10) but studies have not shown a clear benefit on the reduction of cysts (10) or nodularity. (45) Still, breast pain is often associated with high prolactin levels and low prostaglandin 1, so EPO is worth a shot and is often prescribed.(22) A study of cyclical mastalgia in Hong Kong found that six months of EPO made a dramatic difference in pain and discomfort,(40) which backs up by a study in Wales, where 73 patients had their discomfort significantly reduced.(17) Women with cystic mastitis are known to have problems with fatty acid metabolism (15), so it seems as though evening primrose oil is also worth a try.

Emotional difficulties

Taking GLA in evening primrose oil for these problems hasn't been tested much, but there are a number of problems that it might help. People who are depressed seem to have very low levels of prostaglandin 1 (5) People with attention deficit disorder have a zinc deficiency, which indirectly affects dopamine metabolism. Some preliminary studies are finding that taking evening primrose oil compensates for the zinc deficiency in ADHD.(30) There's some speculation that this connection between depression and dopamine might be a cause of some alcoholism. Alcohol compensates for a missing link in the chain from LA to prostaglandin 1. Evening primrose oil is becoming a standard therapy for someone recovering from alcoholism. It relieves the depression and speeds up cell and nerve regeneration in the liver.(1)

Rheumatoid arthritis

Evening primrose oil decreases the inflammation (5, 2) and reduces the amount of toxic medication that needs to be taken for relief (10, 19). Here, too, it's crucial to take fish oil along with the EPO to prevent the AA from rearing its nasty head (36) and causing more inflammation.(14) The recommendation for rheumatoid arthritis is higher, 5 to 10 g of EPO daily.(36)

Other conditions

There are other areas being investigated for possible benefits because they have links to prostaglandin 1 deficiencies: diabetic nerve damage, multiple sclerosis, endometriosis, osteoporosis, irritable bowel syndrome, Raynaud's disease, chronic fatigue syndrome, Sjogren's disease, and other autoimmune problems. However, EPO seems to have no effect on hot flashes (22, 34)

Warnings

It's essentially very very safe. It's been in hundreds of controlled studies and it's prescribed to thousands of people in Europe. (5, 12) If you take too much, it can cause headaches, skin rashes, and nausea (2) that will go away as soon as you stop taking it. For the nausea, some take it with food. (5, 10)

There is a possibility that it might cause problems with someone with temporal lobe epilepsy (22) or schizophrenia, possibly by interfering with the phenothiazine epileptogenic drugs.(7) Diabetics might find a change in insulin requirements, and evening primrose oil can thin the blood, so, if you are taking a blood thinner, be sure to talk with your doctor before trying it.

Recommended dose

The recommendations if you're trying this therapy are to take

150-250 mg of GLA daily, or take 3 g or so of evening primrose oil with 7% to 9% GLA (depends how the label describes it)

Plus

400 IU of vitamin E to prevent the GLA from oxidizing into something bad (10, 12)

Plus

At least 1 g of fish oil for every gram of EPO to prevent the bad arachidonic acid from forming. Don't take flax seed oil in this case. The flax seed oil needs that same delta-6-desaturase enzyme to convert to the useful omega 6 fatty acids.

It's important to remember that evening primrose oil is not curative; it reduces symptoms and prevents further complications.(5) It also take 4 to 6 months to build up enough levels in the tissues to work well.(13) And don't forget to cut out those saturated and hydrogenated fats and get enough magnesium, zinc, B vitamins, calcium, and vitamin C.

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