CLA (Conjugated linoleic acid) refers to a group of chemicals found in the fatty acid linoleic acid. Dairy products and beef are the major dietary sources. Conjugated linoleic acid is used for cancer, "hardening of the arteries" (atherosclerosis), obesity, weight loss caused by chronic disease, bodybuilding, and limiting food allergy reactions. I have taken CLA over the years to aid in fat loss.
EPA (eicosapentaenoic acid) is a fatty acid found in the flesh of cold water fish, including mackerel, herring, tuna, halibut, salmon, cod liver, whale blubber, or seal blubber. EPA is used for high blood pressure in high-risk pregnancies (eclampsia), age-related macular degeneration (AMD), heart disease, schizophrenia, personality disorder, cystic fibrosis, Alzheimer's disease, depression, and diabetes.
DHA (Docosahexaenoic Acid) is also found in the same stuff that EPA is found in but don't get them confused. DHA is used for treating type 2 diabetes, coronary artery disease (CAD), dementia, and attention deficit-hyperactivity disorder (ADHD).
GLA (Gamma linoleic acid) is a fatty substance found in various plant seed oils such as borage oil and evening primrose oil. People use it as medicine. Gamma linoleic acid is an omega-6 fatty acid, which the body can convert to substances that reduce inflammation and cell growth.