Combining a prescription cholesterol-lowering medication with omega-3 supplements may not be the best approach, a new review suggests.

Statins are medications that prevent the liver from producing cholesterol, which can help reduce the risk of heart attacks. Every year, Canadian doctors write more than 12 million prescriptions for statins, making them the most-prescribed drugs in the country. Omega-3's are heart-healthy oils that some evidence suggests help reduce the risk of coronary disease.

In the Nov. 3 issue of the Annals of Internal Medicine, Dr. Mukul Sharma, medical director of the Regional Stroke Centre at the Ottawa Hospital, and his team reviewed five different cholesterol-lowering medications that can be combined as well as omega-3 supplements sold over the counter. They concluded there is little evidence to support mixing them.

Bad cholesterol increase

In one case, the researchers found taking prescription medication with omega-3 had the opposite effect.

"Your bad cholesterol, the LDL, actually goes up," Sharma said. "There isn't a benefit in terms of heart disease, stroke or mortality."

Most cholesterol patients may be better off taking higher doses of one drug instead of multiple medications, since there may be less chance of side-effects and long-term problems developing, he said. People are also less likely to take their medications the more that are prescribed.

The combinations are marketed in the U.S. to consumers and physicians, but studies haven't compared combinations to simply raising the dose of statins.

About 10 years ago, John Meissner, a psychologist in Ottawa, needed a medical procedure to clear blocked arteries, and has been taking two types of cholesterol-lowering medications since then.

"A father and uncle didn't survive beyond their 40s, and an aunt didn't survive beyond her 50s," Meissner said. "So with that kind of family history, to be nearly 60 in another couple of months is a victory of sorts."

Meissner said he won't change his medication routine based on the study because he suspects future research could easily come to different conclusions.

Sharma agreed people should not suddenly stop taking medication because of this study, and should talk to their doctor first.

For people who wish to avoid the supplements, eating fish rich in omega-3 such as salmon, mackerel, herring, anchovies and sardines is advised. The Canada Food Guide recommends eating at least 150 grams of cooked fish each week.

(Health Canada advises against eating more than 300 grams of cooked canned albacore or white tuna a month because of the potential for mercury contamination.)