Cats and Carbs

Cats and Carbohydrates – Separating Fact from Fiction

 

Photo credit: Robert Couse-Baker/http://Flickr.com

Cats have adapted evolutionarily to a high-protein, low-carbohydrate diet. According to most sources, the makeup of the natural prey (i.e. rodents, etc.) is roughly 55% protein, 45% fat and 1-2% carbohydrate (on a dry matter basis.)

That does not, however, mean that cats are unable to successfully metabolize digestible forms of carbohydrates, though they do metabolize them in a way that is different from dogs and people. It has been repeatedly demonstrated that cats can efficiently use carbohydrates to meet their energy needs, though it is not a requirement unless the cat is pregnant or feeding kittens. Normal healthy cats do quite well on a diet of 40% carbohydrates or more.

You don’t need to take my word for this, or that of Eukanuba or Iams. Here are several references that look at carbohydrate metabolism in cats and conclude that cats can utilize carbohydrates pretty well, particularly finely ground or cooked grains. (In case you’re wondering, these sources were not provided by Iams or Eukanuba.)

Kienzle E. Carbohydrate metabolism of the cat – 2. Digestion of starch. J Anim Physiol Anim Nutr 1993;69:102-114.

Morris JG, Trudell J, Pencovic T. Carbohydrate digestion by the domestic cat (Felis catus). . Brit J Nutr 1977;37:365-373.

de-Oliveira LD, Carciofi AC, Oliveira MC, et al. Effects of six carbohydrate sources on cat diet digestibility and postprandial glucose and insulin response J Anim Sci 2008;86:2237-2246.

Now, that being said, I don’t think you should purposely look for a food that has a high carbohydrate content to feed your cat. However, I also don’t think you need to look for a food that has 1-2% carbohydrates (on a dry matter basis) either. Foods that have a moderate amount of carbohydrates, say 20-45%, can be a good choice for a normal healthy cat.

One of the most important things you can do for your cat though, regardless of the type of food you are feeding, is to keep your cat lean. Cats that are overweight or obese have a much higher incidence of disease and live shorter lives with a lower quality of life. In many cases, that will mean that feeding your cat free choice is a bad decision.

There is no evidence to support the theory that carbohydrate levels have any bearing on obesity. Cats that overeat will gain weight, regardless of the amount of carbohydrates in their diet. However, because dry foods are more palatable to some cats and dry foods typically contain at least moderate carbohydrate levels, there may an indirect relationship simply because, if allowed, many cats will eat more of these diets than necessary to support their maintenance requirements.

Carbohydrates and Feline Diabetes

Photo credit: Dag Endresen/http://Flickr.com

It has been well established that high-protein low-carbohydrate diets can be effective for controlling the glycemic response in diabetic cats. (A glycemic response measures the changes in the blood glucose or sugar level in the blood stream over time in response to eating a particular food.) Knowing that begs the question “Will feeding a high-protein low-carbohydrate diet prevent diabetes in cats?”

This has been the topic of conversation in many veterinary circles. This is what Claudia A. Kirk, DVM, PhD, DACVN, DACVIM presented in a session at the World Small Animal Veterinary Association World Congress in 2011 entitled Cats and Carbohydrates – What is the Impact?

Several studies have evaluated the potential role of carbohydrates in the pathogenesis of DM (diabetes mellitus) in cats.

Summarizing key findings:

An epidemiological study of cats from the Netherlands found indoor confinement and low physical activity and not amount of dry food were associated with DM. High carbohydrate intake was not considered a risk factor for feline DM. But recent reports from these investigators have suggested an association of high carbohydrate foods with calcium oxalate urolithiasis. (Reference: Slingerland LI, Fazilova VV, Plantinga EA, et al. Indoor confinement and physical inactivity rather than the proportion of dry food are risk factors in the development of feline type 2 diabetes mellitus. Vet J 2009 Feb; 179(2) :247-53.)

In cats fed a high carbohydrate/low fat (HC/LF) versus low carbohydrate/high fat (LC/HF) food, cats eating the LC/HF demonstrated reduced insulin responsiveness during glucose tolerance testing compared with cats eating the HC/LF food. Dietary fat appeared to be related to insulin resistance and weight gain more so than carbohydrate intake. (Reference: Thiess S, Becskei C, Tomsa K, et al.  Effects of high carbohydrate and high fat diet on plasma metabolite levels and on i.v. glucose tolerance test in intact and neutered male cats. J Feline Med Surg 2004;6:207-218.)

A study comparing the effect of a HC/low-protein food vs. a LC/high-protein food on glucose and fat metabolism in lean and obese cats before and after weight loss. Obesity, but not dietary protein or carbohydrate content, led to severe insulin resistance in cats. (Reference: Hoenig M, Thomaseth K, Waldron M, et al. Insulin sensitivity, fat distribution, and adipocytokine response to different diets in lean and obese cats before and after weight loss. Am J Physiol Regul Integr Comp Physiol 2007;292:R227-234.)

Effects feeding different amounts of carbohydrate and fat were evaluated in 24 cats before and after gonadectomy. Cats were fed either 4%, 27%, 45%, or 56% carbohydrate (DMB) by free choice. 1) High concentrations of dietary carbohydrate did not induce weight gain or increased plasma glucose and insulin concentrations prior to gonadectomy, 2) gonadectomy resulted in increased food intake and weight gain, in which high dietary fat appeared more important. (Reference: Backus RC, Cave NJ, Keisler DH. Gonadectomy and high dietary fat but not high dietary carbohydrate induce gains in body weight and fat of domestic cats. Brit J Nutr 2007;98:641–650.)

Another study comparing a traditional high carbohydrate fiber enhanced weight control food with a low carbohydrate diet found similar weight loss when caloric intake was restricted to the same level. (Reference: Michel KE, Bader A, Shofer FS, et al. Impact of time-limited feeding and dietary carbohydrate content on weight loss in group-housed cats. J Feline Med Surg 2005;7:349–355.)

Current published evidence does not support a direct cause-and-effect relationship between increased carbohydrate consumption and DM or obesity in cats. (Reference: Buffington C. Dry foods and risk of disease in cats. Can Vet J 2008;49:561-563.)

Further, she goes on to conclude:

Although some clinicians strongly recommend that diabetic cats be fed less than 7% carbohydrates (DMB), the evidence supports that amounts ranging from 5 to 26% of calories as carbohydrates are associated with diabetic remission and improved glycemic control. In fact, the highest reported remission rate has been associated with feeding 12% of calories as carbohydrates. There currently are no published studies to show that feeding less than 12% of calories as carbohydrates is more beneficial in managing DM in cats. (References: 1. Bennett N, Greco DS, Peterson ME, et al. Comparison of a low carbohydrate-low fiber diet and a moderate carbohydrate-high fiber diet in the management of feline diabetes mellitus. J Feline Med Surg 2006;8:73-84. 2. Frank G, Anderson W, Pazak H, et al. Use of a high-protein diet in the management of feline diabetes mellitus. Vet Ther 2001;2:238-246. 3. Mazzaferro EM, Greco DS, Turner AS, et al. Treatment of feline diabetes mellitus using an alpha-glucosidase inhibitor and a low-carbohydrate diet. J Feline Med Surg 2003;5:183-189.)

The known risk factors for diabetes in cats are these: increasing age, male gender, Burmese breed, being neutered, decreased physical activity and obesity. Feeding a high carbohydrate diet is not a recognized risk factor for the development of diabetes and there is no reason to believe that feeding a low carbohydrate diet can prevent the development of diabetes. However, feeding a low carbohydrate diet can be useful in regulating/treating a diabetic cat. Many of these cats can achieve adequate glycemic control by ingesting a low carbohydrate diet and may not need to continue insulin administration.

Another subject worth mentioning here is that not all diabetic cats are candidates for a high-protein low-carbohydrate diet. Cats with concurrent illnesses may not be able to handle the increased protein load, necessitating an increase in either fat and/or carbohydrates to compensate.

I know there is much contradictory information scattered throughout the internet and a lot of people will disagree with these thoughts. However, as a veterinarian and a scientist, I need to rely on scientific evidence to make decisions regarding treatment of the patients under my care, not the latest trends. These are the latest facts relating to cats and carbohydrate metabolism as I know them.

You’re free to disagree and I don’t necessarily see anything wrong with choosing a low carbohydrate diet for your healthy cat if that is your preference. In fact, I think that most healthy cats do well on a high-protein low-carbohydrate diet. On the other hand, I recognize that the dietary requirements of a healthy cat can be met in more than one way and I’ve seen many cats, my own included, that do well with a diet that is not truly a low carbohydrate diet.

I’ve also met a number of people who are feeding a grain-free diet believing that the lack of grain in the diet equates to a low-carbohydrate diet. It does not, at least not in all cases. But that’s a subject for another post.

Carbohydrates in Iams and Eukanuba Cat Diets

You may be wondering about the carbohydrate content and makeup of the Iams and Eukanuba diets. This is the information that they provided to us:

Iams® and Eukanuba® dry cat foods contain moderate amounts of digestible carbohydrates (with moderate defined as between 20-45% of calories from carbohydrates.)

Select dry Iams® and Eukanuba® formulas for cats contain a patented carbohydrate blend of grain sorghum and corn. This carbohydrate blend optimizes the rate of carbohydrate digestion and assimilation and helps maintain stable blood sugar and energy levels.  Based upon the amount and type of digestible carbohydrate, the overall glycemic load of dry Iams® and Eukanuba® cat foods is in the moderate range.

The bottom line is how well or how poorly your cat responds to any diet. There is no one perfect diet for every cat any more than there is one perfect diet for every dog or for every person.

This article is through the courtesy of the Pet Health Care Gazette