Ask nutritional researcher and famed diet guru Barry Sears for just one piece of advice on how to get healthy, and the creator of the best-selling "The Zone" diet books doesn't hesitate to answer:
"If you do only one thing to improve your state of health, taking fish oil is it," says Sears, author of the "Omega RX Zone: The Miracle of the New High-Dose Fish Oil" (Harper Collins, 2003). "We are seeing more and more data coming out that says if you give adequate levels of these fish oils the body responds dramatically."
While not everyone shares Sears' zeal about supplements, the general consensus among nutrition researchers and health practitioners these days is that omega-3 fatty acids (contained primarily in oily fish and certain plant oils) are indeed critical for preventing and treating heart disease.
Meanwhile, a growing array of research suggests omega-3s hold tremendous promise for: controlling the inflammation that causes chronic health problems like arthritis; fending off depression, cognitive decline, and behavioral problems; and addressing other health problems, such as macular degeneration and menstrual pain.
Yet with fish consumption in America only about 5 to 10 percent of what it was a century ago (when mothers spoon fed cod liver oil to their children daily for good health), most Americans aren't getting enough, experts say.
"The day that parents stopped giving their children fish oil was probably the largest disaster in public health care in the 20th century," says Sears, who has been studying the benefits of omega 3s for more than 25 years and recently founded a pharmaceutical-grade fish oil company.
Perhaps the best documented benefit of omega-3 fatty acids is for the promotion of heart health, a discovery that dates back to the 1970s when scientists realized that Eskimos (who ate a notoriously high-fat diet) also had an extremely low incidence of heart disease. One possible explanation: They ate a lot of fish.
Since then, numerous research papers have shown that fish oil and fish oil supplements can lower triglyceride levels and bad cholesterol levels, slow the progression of atherosclerosis, impact the electrical function and rhythm of the heart, and regulate hormone-like agents called eicosanoids, which control inflammation.
"Given how little risk there is for taking fish oil, I think it should be standard of care to prescribe it to all patients after a heart attack," says Dr. Darius Mozaffarian, a cardiologist and assistant professor of medicine and epidemiology at Harvard School of Public Health in Boston.
In the wake of reams of new research, the American Heart Association updated its dietary recommendations in 2000, urging healthy people to eat at least two servings of fish per week, and people with existing heart disease to take in as much as four times as much omega-3. In an unusual move, the AHA also suggested that some high-risk people consider taking supplements.
That same year, the U.S. Food And Drug Administration - equally notorious for being skeptical about supplement use - agreed to allow supplement makers to plainly state on their labels that omega-3s may be useful in both treating and preventing heart disease.
"That is a very difficult process," says Andrew Shao, Ph.D., vice president of scientific and regulatory affairs for the Council for Responsible Nutrition, a Washington, D.C.-based trade group for the supplement industry. "It takes a lot of data to accomplish that."
Since then, the market for fish oil supplements has exploded, with sales rising to $359 million on 2005, up from $35 million in 1995, according to the trade publication Nutrition Business Journal.
But experts stress that hearts aren't the only organs to benefit.
Because they are important components of cell membranes, allowing nerve cells to communicate with each other, omega 3s may also promote cognitive function.
One survey of 21,835 people in Norway found that those who took omega-3-rich cod-liver-oil daily were far less likely to experience depression.
Another, by researchers at Purdue University, found that out of 100 boys studied, those with ADHD had significantly lower concentrations of key fatty acids in their blood.
Other research papers have shown that people who eat more fish, or take fish oil supplements, are less likely to develop macular degeneration, have milder menstrual symptoms, and have fewer episodes of painful rheumatoid arthritis.
The big question now: Should we aim to get these miracle fatty acids from fish, or from pills?
Registered dietitian Bonnie Jortberg, a senior instructor in the department of family medicine at University of Colorado Health Sciences Center, says she almost always recommends the real thing over a supplement, because food is typically absorbed better by the body and because supplements are not subjected to the same federal scrutiny as medications or food.
"They are free to say anything that they want to," she says, so it's hard to know just what you are getting.