Evening primrose

Latin name: Oenothera biennis L. [Onagraceae]
Plant part: Seed

Evening primrose seeds contain up to 25 percent oil. Evening
primrose oil (EPO) contains two types of omega-6 fatty acids: linoleic
acid (LA) (60 to 80 percent) and gamma-linolenic acid (GLA)
(8 to 14 percent) (Schulz, Hänsel, and Tyler, 2001). These acids are
considered essential fatty acids (EFAs) because they are required for
health and are not synthesized by the body. Linolenic acid deficiency
produces visible signs in the skin, including eczema, impetigo, and
erythema. Evening primrose oil is used in the formulation of cosmetic
products and also as a dietary supplement (Chen, 1999).

Essential fatty acids, including linoleic acid found in evening
primrose oil, cannot be manufactured in the human body, and their
supply is dependent on adequate dietary intake. Inadequate intake or
compromised conversion to active metabolites can result in symptoms
such as hair loss, eczema, disorders in connective tissue, poor
wound healing, poor immune and reproductive function, and degeneration
of organs, including the liver and kidney (Chen, 1999).
Trials using evening primrose oil preparations have been conducted
on subjects with eczema, arthritis, attention-deficit hyperactivity
disorder (ADHD, in children), diabetic neuropathy, premenstrual
syndrome (PMS), benign fibroadenomas in the breast, and
obesity. The majority of trials have focused upon atopic eczema, in
which there appears to be a trend toward efficacy. EPO may also help
ameliorate the uremic skin symptoms of those undergoing dialysis. In
addition, EPO may improve mild diabetic neuropathy. No evidence
indicates that it has any effect on ADHD in children, improves symptoms
of arthritis or PMS, reduces benign fibroadenomas in the breasts,
or helps obese women lose weight.

Atopic eczema or atopic dermatitis is a type of dermatitis in which
an inflammation of the skin develops in persons subject to allergic reactions.
It is associated with itching, redness, swelling, and blisters
that may be weeping and progress to crusted, scaly, and thickened
skin. The skin rash can be widespread or limited to a few areas. In
teens and young adults, the patches typically occur on the hands and
feet (American Academy of Dermatology, 1995).