Plant seed oils are popular supplements that provide omega-3 and omega-6 fatty acids, but which products offer the best value and quality? Recent analyses by ConsumerLab.com found that only 14 of 16 products selected for testing contained what was stated on the labels. One supplement was found to completely lack the omega-6 fatty acid GLA (gamma-linolenic acid), indicating that it didn't contain a plant oil it promised. Another product mislabeled its amount of oleic acid, an omega-9 fatty acid.

Flaxseed oil is rich in the omega-3 fatty acid ALA (alpha-linoleic acid).  Black currant, borage, and evening primrose oils are good sources of the omega-6 fatty acid GLA (gamma-linolenic acid). Supplements containing these oils are used in treating a variety of inflammatory diseases and other conditions.

In addition to testing each product for omega-3 and -6 fatty acids, ConsumerLab.com tested for freshness and potential heavy metal contamination (lead, arsenic, and cadmium). ConsumerLab.com found that, among top-quality products, a consumer could obtain 200 mg of GLA for as little as 11 cents and 500 mg of ALA for just 2 cents.

Test results and comparisons of the 16 products selected by ConsumerLab.com for testing, as well as for 10 supplements which passed the same testing through ConsumerLab.com's voluntary Quality Certification Program, are provided in a new report online. The report, which includes information about the uses, dosage, and potential side-effects of these seed oil supplements, covers the following products, including two products for pets and two products similar to one which passed testing: