What CL Found:
Among the 24 products that ConsumerLab.com selected for review, only 17 passed quality testing, meeting requirements for freshness and purity, and containing their claimed amounts omega-3 fatty acids. Seven (7) products failed to pass testing for the following reasons:
Less omega-3 than claimed:
* Natural Factors Rx Omega-3 Factors Pharmaceutical Grade contained only 83.3% of the claimed EPA
* NOW Neptune Krill Oil contained only 79.1% of claimed EPA, 76.7% of claimed DHA and 78.4% of the claimed total omega-3 fatty acids, despite showing a "GMP Quality Assured" seal (also failed for spoilage, see below).
* The Simpsons Berry Squirts contained only 88.1% of claimed EPA
Spoilage:
Three products were found to be spoiled. While spoilage does not necessarily indicate lower amounts of omega-3’s, it indicates elevated levels of spoilage compounds that may cause burping and other gastrointestinal effects. The test for spoilage results in a TOTOX value which, to be considered fresh, should not exceed a value of 26.
* Master Omega-3 (TOTOX = 54.4)
* NOW Neptune Krill Oil (TOTOX = 57.4)
* wellements PharmaOmega learn (TOTOX = 63.8)
The tests for spoilage were conducted on newly opened products, maintained out of heat and moisture. However, be aware that spoilage may occur after products are opened and exposed to air (see Keeping It Fresh for storage tips).
Enteric-coated pills:
To reduce the likelihood of a fishy aftertaste or burp, some products have enteric coatings designed to release the oil in the intestine rather than the stomach. ConsumerLab.com tested these coatings in a simulated gastric environment. While several passed the test, Spring Valley Triple Strength Enteric Coated Fish Oil did not. The capsules released oil too early. (See more information at “What to Consider When Buying – Enteric-coated Pills.”)
Contamination:
One product, 1-800-PetMeds Super Omega 3 for Cats and Dogs, exceeded the contamination limit for dioxin-like PCBs (or dl-PCBs, which are PCBs with established toxicity). It contained slightly more than the 3 picograms per 1,000 milligrams (mg) limit established by the Global Organization for EPA and DHA (GOED). The U.S. FDA has not set a limit. It is unlikely that this exposure alone would cause toxicity, but it is preferable to avoid unnecessary exposure to toxins. However, bear in mind that, in comparison to a serving of most fish, even this product contains only a small amount of PCBs.
Several products claimed to be “free of,” “void of,” or to have “no detectable” PCBs or other contaminants. Be aware that, using highly sensitive standard tests, all fish oil supplements reviewed by CL were found to contain at least trace levels of PCBs and some have trace levels of lead. However, none of these products exceeded contamination limits, other than the pet supplement noted above.
A number of products claimed to be “molecularly distilled.” This is a process in which the fish oils are first converted into an ester form and then heated, causing certain other compounds, such as contaminants, to be removed while concentrating the product. Some products make a point of the fact that they are not chemically treated and distilled, such as New Chapter WholeMega, although these products are typically less concentrated for omega-3’s. Distillation may also reduce levels of some potentially beneficial compounds (such as small amounts of vitamins) found in fish oil, but this has to be weighed against the benefit of removing contaminants. Other refinement techniques used on fish oils include “winterization” in which the oil is chilled, permitting for separation and removal of saturated fats which naturally occur in fish oil.
None of the products were found to contain detectable levels of mercury [over 10 ppb (parts per billion)]. By comparison, mercury levels in fish generally range from 10 ppb to 1,000 ppb, depending on the fish (see What to Look for When Buying – Getting EPA and DHA from Food for more information). In addition, none of the products contained unsafe levels of lead. A single product (footnoted below with a "D "in the “Purity” column) was additionally tested for dioxins, which can be found in some fish. This supplement did not contain unsafe levels of dioxins. See Testing Methods and Passing Score for more information about how products were evaluated.
There are several possible explanations for the relatively low level of contamination in the supplements: the use of species of fish that are lower on the food chain and, therefore, less likely to accumulate contaminants; the fact that most mercury is found in fish meat and not fish oil; and the use of distillation processesl that remove contaminants. It is worth noting that liver oils may contain higher amounts of contaminants than other fish oils, which are generally made from oils from whole fish. However, the one cod liver oil product tested, Carlson Norwegian Cod Liver Oil, met all quality criteria.