Q. I keep hearing about how good fish oil is for you. Could you separate fact from fiction on this?

I, too, have seen fish oil touted so often that it's beginning to sound like a cure-all sold in little brown bottles off the back of a wagon.

[Warning: Taking high doses of fish oil can be dangerous. Always check with your doctor before changing your intake of foods or supplements.]

You get fish oil from eating fish (surprise) or by taking supplements made from oily fish. Fish loaded with beneficial oils known as omega-3 fatty acids include anchovy, bluefish, herring, mackerel, menhaden, mullet, salmon, sardines, sturgeon, trout and tuna.

Fish oil is recommended for many conditions. These include: high blood pressure, elevated triglycerides, heart disease, stroke, depression, attention deficit-hyperactivity disorder, Alzheimer's disease, glaucoma, macular degeneration, menstrual pain, diabetes, asthma, dyslexia, obesity, kidney disease, osteoporosis, psoriasis, rheumatoid arthritis, atherosclerosis, heart arrhythmia, cancer ... and more.

Holy mackerel!

How effective is fish oil? The Natural Medicines Comprehensive Database provides ratings for fish oil. Here are many of them:

Effective: High triglycerides, blood fat related to cholesterol. Researchers believe that fish oil can reduce triglyceride levels by 20 to 50 percent.

Likely Effective: Heart disease. People who already have heart disease may be able to lower their risk of dying from it by taking fish oil.

Possibly Effective:

• High blood pressure; seems to produce modest reductions of high blood pressure.

• Rheumatoid arthritis. May ease morning stiffness faster.

• Menstrual pain. Might reduce pain.

• Attention deficit-hyperactivity disorder, commonly called ADHD. May improve thinking and behavior in children.

• Stroke. Consuming fish once or twice a week seems to lower the risk of having a stroke.

• Weak bones (osteoporosis). Fish oil seems to slow bone-loss rate and increase bone density at the thigh bone and spine in older people with osteoporosis.

• Hardening of the arteries (atherosclerosis). Fish oil seems to slow or slightly reverse the progress of atherosclerosis in the coronary arteries, but not in the carotid arteries that bring blood up the neck to the head.

• Kidney problems. Long-term use (two years) of fish oil 4-8 grams daily can slow the loss of kidney function in high-risk patients with a kidney disease called IgA nephropathy.

• Bipolar disorder. Taking fish oil with the usual treatments for bipolar disorder seems to improve symptoms of depression, but doesn’t seem to improve manic symptoms.

• Psychosis. Taking a fish oil supplement might help prevent full psychotic illness from developing in some people with mild symptoms.

• Weight loss. Some evidence shows that eating fish improves weight loss and decreases blood sugar in overweight people and people with high blood pressure.

• Endometrial cancer. There is some evidence that women who regularly eat about two servings of fatty fish per week have a reduced risk of developing cancer of the endometrium, the lining of the uterus.

• Age-related macular degeneration. There is some evidence that people who eat fish more than once per week have a lower risk of developing this disease that destroys your sharp central vision.

• Blocked blood vessels. Fish oil appears to decrease the rate of reblockage after heart bypass surgery or balloon catheterization (balloon angioplasty).

• Psoriasis. There is some evidence that administering fish oil intravenously can decrease symptoms.

• Asthma. Fish oil seems to improve airflow, reduce cough, and lower the need for medications in some children with asthma.

[Our next column will cover additional ratings for fish oil uses.]