You would think that cat food manufacturers would make sure that the ingredients they use are safe for cats. Unfortunately, this is not always the case.
Rice bran is what makes brown rice brown. It is the fibrous outer portion of the rice grain. Many cat foods incorporate brown rice and/or rice bran; these are allowed ingredient in pet foods. Unfortunately, a study done about 10 years ago found that rice bran depletes taurine when fed to cats…and because brown rice includes the bran, researchers speculated that it may also cause problems.
Taurine is an essential amino acid in cats. It is found in meat, although some meats (particularly red meats like beef and bison, as well as rabbit) are on the low end of the scale. Taurine can also be produced synthetically, although it is not made in the U.S. (most of the taurine used in pet food comes from China).
Pet food manufacturers universally add synthetic taurine to cat foods, because taurine deficiency can cause blindness as well as congestive heart failure. Pet food companies have, over time, substituted ever more corn and other grains, as well as animal by-products, in place of real meat. In the late 1980s, alert veterinarians at UC Davis realized that the same diet was being fed to cats who had developed these unusual conditions. They looked into it, and found that taurine deficiency was the culprit.
The fact that rice bran specifically depletes taurine in cats is less widely known than it should be. Here is what the rice bran study concluded:
Although rice bran or whole rice products are included in commercial cat foods at levels between 5 and 20% diet (DM), this study shows that feline diets containing these materials may need a higher content of taurine than that in similar products without them.
There are several brands of cat food that use rice bran as an ingredient. Some of these are “weight management” foods, and most of them are dry foods. Of course, dry food itself is very bad for cats, but the rice bran issue is worth noting as well. The research indicates that foods containing rice bran or brown rice need extra taurine, but it is impossible to tell from the limited information on the label if this caution is being followed. In at least one case, rice bran is the third ingredient, while taurine is far down on the list, after Vitamin D; this suggests that the taurine may be inadequate.
If you are feeding your cat dry food, please consider switching to canned or homemade…but in any case, make sure that your cat food does not contain rice bran or excessive amounts of brown rice.