In general, fish oil is considered to be a very safe product, with few known side effects or interactions. Carlson's Laboratories, a company that manufactures and distributes nutritional supplements, remains one of the most popular fish oil brands on the market. While the risks associated with fish oil are minimal compared to the many benefits, no supplement is completely without drawbacks.
Common Side Effects
The most common side effects associated with Carlson's fish oil are very mild. They may include reflux, indigestion, belching or an unusual or unpleasant aftertaste. Gastrointestinal problems, including stomach cramping and abdominal pain, are also common side effects, and some people may experience mild to moderate diarrhea. The National Institutes of Health recommend that people take fish oil with a large meal to avoid these common problems.
Effect on Fat-Soluble Vitamins
Most Carlson's fish oil products are enriched with vitamin E, since long-term use of fish oil can deplete the body's own reserves of this important vitamin. Some Carlson's fish oil supplements (specifically, cod liver oil) contain large amounts of naturally occurring vitamin A. While vitamin A is an important nutrient, it can become toxic in large amounts, especially if it is taken by pregnant women, people with kidney disease and patients with liver problems. Susceptible individuals should choose fish oil supplements that are free of vitamin A, such as salmon oil, instead of fish oil sourced from cod liver.
Blood Pressure Reduction
Several studies have demonstrated that fish oil supplements can cause a decrease in blood pressure. While this effect is generally viewed as a positive result, it may be dangerous for people with hypotension, or low blood pressure. Carlson's fish oil should only be used in recommended doses, under the guidance of a doctor, by people with moderate to severe hypotension. The National Institutes of Health also advise caution for people taking fish oil with antihypertensive drugs.
What about Heavy Metals?
The world's oceans are becoming alarmingly polluted with dioxins, mercury, PCBs, and other contaminants, and many of these toxins are appearing in the flesh of edible fish. Children and pregnant women are urged to avoid eating large amounts of high-mercury seafood, such as tuna, because of this risk. Fortunately, fish oil (as opposed to fish meat) contains almost no mercury. Carlson's Laboratories also pledges to refine, distill and test their products for contaminants, including PCB and dioxin, prior to sale.
Anticoagulant Effects
Extremely large doses of Carlson's fish oil may have anticoagulant effects in very high-risk individuals. People taking blood-thinners, including aspirin and warfarin, may be at risk of nose bleeds or bloody urine if they take megadoses of fish oil, though this effect hasn't been documented in people taking as recommended doses (500 to 3,000 mg per day). Additionally, megadoses of fish oil appear to slightly increase the risk of having a hemorrhagic stroke. People with bleeding disorders should take fish oil only under a doctor's recommendation.
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