30th Apr 2011
You probably come across warnings that liver consumption may cause vitamin A toxicity. You may wonder if this is true and how safe our Liver-Hides treats are.
According to veterinarians and researchers, vitamin A toxicity really seems to occur only if one oversupplements with cod liver oil or vitamin A products (don’t forget that commercial ‘balanced’ or ‘complete’ pet foods can contain supplemental vitamin A. However, according to the manufacturers of these vitamin premixes, at least some of these vitamins degrade after 3-6 months).
It is interesting that most research cautioning about vitamin A toxicity talks about problems arising from overfeeding with ‘beef liver’ or cod liver oil and doesn’t mention livers of other livestock species (the fish oil is certainly a more concentrated form than the whole fish liver).
Dr. Messonier states that the maximum amount of vitamin A was 750,000 IU/kg food, but cats eating diets up to 2,000,000 IU/kg food for 3 to 4 years have not shown vitamin A toxicity. He goes on to say that “there have been rare reports of cats eating fresh beef liver on a daily basis who have been diagnosed with vitamin A toxicity.”
He recommends not to supplement with extra vitamin A and if in doubt have the vitamin A blood level determined (20 to 80 micro gram/dl is the normal range).
Most importantly, he then states, and here he truly speaks from my heart: “Vitamin A toxicity will not occur when using whole food sources rather than synthetic forms of vitamin A.” This does really not come as a surprise if one considers that isolated (i.e., mostly synthetic and mostly genetically engineered) supplements often have different effects than their natural counterparts do; many of these isolated/synthetic forms are ineffective while some may actually cause health problems.
Our dehydrated treats contain about 96,000 IU/50g (one bag or 1,919,000 IU/kg or 19,200 ug retinol/50g bag) and 23,500 IU/50g (one bag or 471,000 IU/kg or 4,700 ug retinol/50g bag) for the Turkey Liver-Hides and Chicken Liver-Hides, respectively.
Dehydration concentrates vitamin A just as much as it concentrates other nutrients.
And still, according to the research Dr. Messonnier summarizes, a cat could eat a kilogram (haha) of our treats for years without showing resulting in vitamin A toxicity. I think, however, that a cat eating a kilogram of liver would still get sick eventually because she doesn’t get sufficient amounts of other nutrients. And what house cat eats one kilogram (2.2 lbs) of food (and then just liver) a day?
Here are data of a few older studies (which, in my view, were often more thorough than many of today’s studies):
- Cats require 1,600-2,000 IU/day Vitamin A (more is needed during pregnancy, nursing, and growth).
- Prolonged, excessive intake of vitamin A does causes a disease which is associated with the near-exclusive feeding of raw liver and milk (these animals were pets of a slaughterhouse owner).
- The same disease symptoms can be duplicated by large supplements of vitamin A in a lean beef and milk diet. The levels of vitamin A supplied by liver, which induced skeletal lesions, ranged from 17-35ug (ug = microgram) retinol/g body weight; while 15 ug/g body weight added to the meat diet over 41 weeks had no effect. 30 ug retinol/g body weight produced lethargy after 10 weeks and spondylosis after 24 weeks.
According to these older studies, a 6kg (13.2lbs) cat could eat 90,000 ug (450,000 IU) per day in addition to a meat diet for over 41 months without ill effect. This means for our Liver-Hides treats that you could feed a 6 kg heavy cat meat and milk, and supplement with more than 4 and a half bags of Turkey Liver-Hides or 19 bags of Chicken Liver-Hides per day (!!) and they’d still not show any ill effects.
Therefore, our Liver-Hides are not only healthy but also safe (unless fed in excess to cats which eat like the poor slaughterhouse cats mentioned above). In my view, a guardian should feed a variety of foods to provide as many natural nutrients as possible.
What I like about our Liver-Hides (aside from the fact that they are raw and from pastured animals) is that the livers come from animals which haven’t been exposed to any toxins (e.g., hormones, antibiotics, toxins such as drugs and heavy metals from the sewage sludge used on most non-organic farms) which tend to accumulate in animals and their livers. Furthermore, the poultry we use are ‘processed’ in ways which prevent bacterial contamination and, in the case of our chickens, in a manner which the Humane Society considers well above ‘industry standards.’