Salmon is a popular food. Classified as an oily fish,[83] salmon is considered to be healthy due to the fish's high protein, high omega-3 fatty acids, and high vitamin D[84] content. Salmon is also a source of cholesterol, with a range of 23–214 mg/100 g depending on the species.[85] According to reports in the journal Science, however, farmed salmon may contain high levels of dioxins. PCB (polychlorinated biphenyl) levels may be up to eight times higher in farmed salmon than in wild salmon,[86] but still well below levels considered dangerous.[87][88] Nonetheless, according to a 2006 study published in the Journal of the American Medical Association, the benefits of eating even farmed salmon still outweigh any risks imposed by contaminants.[89] Farmed salmon is shown to have a high omega 3 fatty acid content comparable to wild salmon.[90] The type of omega-3 present may not be a factor for other important health functions.