Is There a Link Between Fish Oil and Hyperthyroidism in Cats?

A rumor about a possible link between iodine toxicity,Purdue University found an association between
fish oils, and and feline hyperthyroidism is flyingcertain flavors and types of cat food and
around on the Internet. So what's the real deal? Thehyperthyroidism pointed out that pop-top cans (most
short answer is--excellent quality, purified fish oils areof which contain BPA in their linings), giblets
not a problem--but many commercial products could(by-products), and fish had the highest associations.
be implicated. Read on for more inAgain, the fish going into these products are whole
Iodine, a basic chemical element and a necessaryfeeder fish, damaged or spoiled fish, or fish parts
nutrient, is stored in animals' bodies in the thyroid(heads, tails, internal organs) not wanted for human
gland. Pet foods or products that use fish, fish meal,consumption. Iodine levels in fish meal made from
or fish oils that are derived from processing orthese products is likely to be quite high. Fish meal is a
pressing the whole fish (including the thyroid) willcommon ingredient in cat food and on many labels is
contain that iodine. Cod liver oil is pressed from fishcredited as the source of Omega-3 fatty acids. In
livers after they are removed from the fish, and isreality, it is a very minor source of Omega 3's and is
not a significant source of iodine. The best fish andused in cat food mainly for flavoring. Fish oil derived
cod liver oils are also molecularly distilled, whichfrom similar sources could be similarly contaminated,
further removes virtually all solids and other impurities.which is why we stress choosing a distilled,
The purest Omega-3 fish oils contain, at most, a tinypharmaceutical grade fish oil for your cat (I personally
trace of iodine. Good quality, fresh Omega-3 fish anduse and recommend Nordic Naturals).
cod liver oils are not the problem when it comes toFurther studies have also suggested a link between
iodine.fire-retardant chemicals and feline hyperthyroidism. It
Most of the iodine consumed by our pet cats comesturns out that cheap pet food ingredients--particularly
from commercial cat foods, primarily from the mineralfish and by-products--are the most likely to be
pre-mixes used in these foods. Minerals, includingcontaminated with these chemicals. This could not
iodine, are often included in great excess. Iodine isonly account for the Purdue findings, but it could also
difficult and expensive to test for, so it's cheaper andbe creating a "double-whammy" for our cats in terms
easier for pet food makers and suppliers to add wayof exposure to these toxins.
more than necessary to make sure the food is notPure, properly processed fish and cod liver oils contain
deficient. They don't care if too much gets into cat(at most) trace levels or zero iodine, and certainly are
food. One study of adult and growth dog and catnot implicated in any situation of iodine overdose. The
foods found 10-100 times the recommended amountfact remains that Omega-3's are seriously deficient in
for many minerals. There are few maximum limits setvirtually every pet food, raw food, and even
(12 for dog food, 4 for cat food). Iodine has ahomemade food for pets, because livestock and
maximum limit for dog food, but no similar maximumpoultry raised in North America are fed on grains,
in cat food. This approach makes the food cheap,which shifts the natural fatty acids to mostly
but it can cause a host of physical problems for ourOmega-6s. Omega-3 fatty acids are an essential
cats.component of your cat's diet, and must be
In addition, you may recall that a study out ofsupplemented for optimal levels to be reached.