Evening primrose oil
Evening primrose oil (EPO) is a North American native biennial
plant, but now found all over the world. The medicinal product is
derived from the plant’s seeds. It’s also known as tree primrose,
fever plant, night willowherb, King’s-cure-all, scabish, scurvish,
sun drop and suncups.
EPO is rich in polyunsaturated omega-6 fatty acids that can help
in the regulation of pain and inflammation with no major safety
problems. EPO is a rich source of two types of polyunsaturated
omega-6 essential fatty acids: linolenic acid (LA; 70 per cent;
converted in the body to GLA) and gamma-linolenic acid (GLA; two–15
per cent).
GLA is a vital precursor of hormone-like molecules in the body
called prostaglandins which are important for the regulation of
pain and inflammation. GLA might also suppress inflammatory
responses by directly acting on some inflammatory cells. Sunflower
oil and other oils generally used in normal diet contain only LA.
Several factors can interfere with the production of GLA from LA in
the body. These include aging, dietary deficiencies, viral
infections and some diseases. EPO is one of the richest sources of
pure GLA.
EPO is formulated in capsules (500–1,300 mg) or oil (150 ml) and
these products are available in most pharmacies, health food shops
and supermarkets. No recommended safe doses have been established
for the use in musculoskeletal conditions. A dose of 6 g per day
(540 mg GLA per day) has been used in previous trials.
Effectiveness
Evidence for the effectiveness of EPO in reducing joint pain in
rheumatoid arthritis patients isn’t conclusive. However, there is
some evidence for effectiveness in improving morning stiffness. EPO
doesn’t seem to modify long-term disease activity, so, if used,
should be taken along with conventional therapy.
Safety
The compound, if taken in the correct dose, has no major safety
problems. Common side-effects include nausea, diarrhoea and skin
rash. Patients with epilepsy or seizure disorder shouldn’t take
this product as it can induce seizures.
Interactions with other medications haven’t been well studied,
but interactions with anti-inflammatory drugs (e.g. cortisone) and
other medications that affect blood clotting (e.g. aspirin,
warfarin) are possible.