Taken directly from a letter my vet gave out (I bolded the important points just in case you didn't want to read the entire thing):
New Diet Recommendations for Cats
Timothy J Govers, D.V.M.
Diplomate, American Board of Veterinary Practitioners, Avian Specialty
"Good nutrition is the single most important step you can take to improve your cat's health. Yet, most cats are not on a healthy diet, and the veterinary community needs to shoulder a large part of the blame. For years, with the emphasis on dental health, we have been recommending dry foods for cats, thinking "crunching" the dry food is healthier for the teeth and gums. Now, West Valley Pet Clinic is taking a 180 degree turn in recommending canned food over dry food for cats.
Why the dramatic change? The credit goes to Dr. Elizabeth Hodgkins, a veterinarian who has been working on a protocol for the prevention and treatment of feline diabetes, with an emphasis on the role of diet. Here's her reasoning:
During its evolution, the cat became very dependent on meat, high in protein and fat, for energy. The pathway for metabolizing protein for energy production became primary. The cat will even begin to consume its own structural proteins (muscle) for energy during starvation or protein restricted diets. The pathways for metabolizing carbohydrates for energy became less important, and eventually less functional. The bottom line: the cat has a huge protein requirement and a very low carbohydrate need (in fact, cannot handle carbohydrates well at all).
The Problem: all dry cat foods are very high in carbohydrates, and relatively low in protein. This is a requirement in the extrusion process (the process where the food is subjected to high heat and high pressure) that "pops" the food into a pellet. This won't happen unless there is a certain level of carbohydrates. Low quality meat meal is then sprayed on the surface to increase palatability. As a result of this process, the carbohydrates are predigested and easily enter the cat's blood stream as sugar. Corn is the cereal most commonly used in dry cat foods which has a high glycemic index. That is, corn raises the cat's blood sugar levels to high values shortly after eating.
Another Problem: in the same evolutionary process, the signal to the cat that it ate enough (satiety signal) was related to the amount of protein and fat consumed. Consumption of carbohydrates has minimal effect on the satiety signal. As a result, cats over eat dry food since the carbohydrates in the kibble don't satiate them, and constantly overload on sugars. The end result is fat cats, and worse, because the excess sugar causes repeated surges of insulin from pancreatic reserves, diabetic cats.
Compare the types of food. Canned cat foods are relatively high in protein (40-55% on a dry matter basis), moderate fat (25-35% on a dry matter basis), and low carbohydrates (2-8% on a dry matter basis). A dry food will typically have 20-33% protein, 10-25% fat, and 20-50% carbohydrates. And the only reason for these differences is that this dry food ratio is necessary to make a kibble (with no regard to the cat's nutrient requirements).
Of course, not all cats that eat dry food exclusively become obese, or develop diabetes. But an alarming percent do, and it is impossible to predict which individual will. Inherited factors make some animals more resistant to environmental and nutritional maladies than others. Not all people who smoke a pack of cigarettes daily for 60 years will develop emphysema or lung cancer. Yet we don't question the harm of cigarette smoking. For the same reason, we can't ignore the harmful effect of carbohydrate laden dry foods, and we should consider all cats at risk for obesity and diabetes if fed a commercial dry cat food.
ADDITIONALLY, THERE ARE NO SCIENTIFIC STUDIES THAT PROVE DRY FOODS PROVIDE BETTER DENTAL HEALTH THROUGHOUT A CAT'S LIFE THAN WET FOODS DO."
New Diet Recommendations for Cats
Timothy J Govers, D.V.M.
Diplomate, American Board of Veterinary Practitioners, Avian Specialty
"Good nutrition is the single most important step you can take to improve your cat's health. Yet, most cats are not on a healthy diet, and the veterinary community needs to shoulder a large part of the blame. For years, with the emphasis on dental health, we have been recommending dry foods for cats, thinking "crunching" the dry food is healthier for the teeth and gums. Now, West Valley Pet Clinic is taking a 180 degree turn in recommending canned food over dry food for cats.
Why the dramatic change? The credit goes to Dr. Elizabeth Hodgkins, a veterinarian who has been working on a protocol for the prevention and treatment of feline diabetes, with an emphasis on the role of diet. Here's her reasoning:
During its evolution, the cat became very dependent on meat, high in protein and fat, for energy. The pathway for metabolizing protein for energy production became primary. The cat will even begin to consume its own structural proteins (muscle) for energy during starvation or protein restricted diets. The pathways for metabolizing carbohydrates for energy became less important, and eventually less functional. The bottom line: the cat has a huge protein requirement and a very low carbohydrate need (in fact, cannot handle carbohydrates well at all).
The Problem: all dry cat foods are very high in carbohydrates, and relatively low in protein. This is a requirement in the extrusion process (the process where the food is subjected to high heat and high pressure) that "pops" the food into a pellet. This won't happen unless there is a certain level of carbohydrates. Low quality meat meal is then sprayed on the surface to increase palatability. As a result of this process, the carbohydrates are predigested and easily enter the cat's blood stream as sugar. Corn is the cereal most commonly used in dry cat foods which has a high glycemic index. That is, corn raises the cat's blood sugar levels to high values shortly after eating.
Another Problem: in the same evolutionary process, the signal to the cat that it ate enough (satiety signal) was related to the amount of protein and fat consumed. Consumption of carbohydrates has minimal effect on the satiety signal. As a result, cats over eat dry food since the carbohydrates in the kibble don't satiate them, and constantly overload on sugars. The end result is fat cats, and worse, because the excess sugar causes repeated surges of insulin from pancreatic reserves, diabetic cats.
Compare the types of food. Canned cat foods are relatively high in protein (40-55% on a dry matter basis), moderate fat (25-35% on a dry matter basis), and low carbohydrates (2-8% on a dry matter basis). A dry food will typically have 20-33% protein, 10-25% fat, and 20-50% carbohydrates. And the only reason for these differences is that this dry food ratio is necessary to make a kibble (with no regard to the cat's nutrient requirements).
Of course, not all cats that eat dry food exclusively become obese, or develop diabetes. But an alarming percent do, and it is impossible to predict which individual will. Inherited factors make some animals more resistant to environmental and nutritional maladies than others. Not all people who smoke a pack of cigarettes daily for 60 years will develop emphysema or lung cancer. Yet we don't question the harm of cigarette smoking. For the same reason, we can't ignore the harmful effect of carbohydrate laden dry foods, and we should consider all cats at risk for obesity and diabetes if fed a commercial dry cat food.
ADDITIONALLY, THERE ARE NO SCIENTIFIC STUDIES THAT PROVE DRY FOODS PROVIDE BETTER DENTAL HEALTH THROUGHOUT A CAT'S LIFE THAN WET FOODS DO."
