Think Like a Nutritionist: Carbohydrates Part One
April 8, 2011 at 6:40 pm
Let’s face it; people are really bothered by carbs these days. And with good reason, in many cases; excessive carb, especially simple sugars and those that contain gluten, contribute to not only our own, but our dogs’ tendency to gain excess weight, plus a whole host of other conditions we used to blame on “fat”. Too much carb can be a factor in Type II diabetes, in heart disease, all kinds of inflammation and possibly even cancer. And that’s for us – the fact that dogs are preferential carnivores and need LESS carb than we do, makes them all the more susceptible to carb-related dietary problems.
Add to that, the simple fact that dog food companies have consistently used grains to provide the bulk of energy and even protein in kibbles, a cheap and *technically* adequate means of feeding – and that a grain heavy diet does indeed lead to a myriad of canine health issues – well, things are not looking good for carbohydrates these days. In fact, the single most popular comment I hear from dog lovers who want to impress me with their knowledge and good care is “I feed grainfree”.
And, for many dogs, that’s extremely good news. But, there are a number of deeper issues here. All grains are not created equal. Carbs, while not a requirement technically speaking, like vitamin A, for example – DO offer health benefits beyond the important but basic “adequacy” paradigm. “Grainfree” doesn’t mean “carbfree”. And diets that have replaced too much carb with none at all, are simply replacing one potential series of health issues with a different one. Perhaps subtler and likely taking longer to manifest, a diet based entirely on protein and fat can be very problematic for dogs. Let’s take a peek and see what we can learn from the science. I warn you, this is looking like a three part entry…
First off, there’s a lot of confusion between carbs and grains. In my practise I hear a wide variety of understandings; some people equate carbs entirely with grains, and are a little taken aback when I say those healthy vegetables and fruits they’re feeding are carbs, too; some believe that CARB is ok as long as there’s no grain involved; some feel a little fiber is good but not too much; some think dogs can’t digest carb at all; and so on. Many believe grains are terrible but that veggies are ok ; when I point out that the chronic diarrhea and malabsorption of nutrient they’re worried about may be related to the veggies, and that a little well cooked brown rice may resolve the whole issue, they’re aghast. But seeing is believing! Dogs DO digest carbs, and can even convert nutrients from them (such as beta carotene into Vitamin A) and ferment fiber (according to the type, at a good or not so good rate); they do benefit from fiber, within reason, and veggies offer good stuff on the one hand and create potential issues on the other (think; nightshades, oxalates, phytic acid).
So; basically, is there a role in the canine diet for carbohydrate? Emphatically, yes there is.
I feed about 30% of the diet- for a healthy individual -using carbohydrate; never simple forms, and only gluten-grains when a health condition such as diabetes, mandates I do. Never nightshade vegetables and not a lot of green anything. I use brown rice (soaked), quinoa, sweet potato and squashes, and a little legume. I’ve fed dogs with pancreatitis diets as high as 70% carb (and they do very well!) and some with cancer as low as 20% (but super high fiber, as much as I can get in that small level;). I am here to tell you; fiber, used correctly, is GOOD. Carbs are digestible, they are not a *requirement* but they are helpful, and your dog can benefit from the right ones. As with all aspects of dietary choice, we will use the science we trust, and then work with the dog in front of us. Carbs are not the enemy; overfeeding of the wrong kind, is. So let’s break this down a bit and get the facts straight. Knowledge is power!
Before entering into a discussion of the merits of a nutrient, it’s important to be clear what we’re talking about.
Definitions range from very dry and technical to simple and straightforward. There’s an audience for both of those, so let’s offer up a version of each.
Technically(from the 2006 NRC Guidelines):”Dietary carbohydrates include low and high molecular weight sugars, starches, and various cell wall and storage non-starch polysaccharides (NSPs) or dietary fibers (DFs) produced by plants during photosynthesis.”
Canine and Feline Nutrition;A Resource for Companion Animal Professionals” is more succinct, at least initially: “carbohydrates are the major energy-containing constituents of plants”.
OK! That works. The energy from plants that is not protein/amino acids, fat/fatty acids is carbohydrate. This means energy from grains, but also vegetables, fruits, and legumes. Dairy, too, has carbohydrate. And, there are several different types; we have almost all heard of “simple and complex” carbohydrates with regard to our own diet; sugar, for example is a “simple” carb and whole wheat, a complex one . In technical terms, we have mono, di-, oligo and polysaccharides . Monosaccharides are the simplest form, and include glucose, fructose and galactose. Disaccharides, which are made up of two monosaccharides linked together, include lactose, sucrose and maltose. (If you want to read a great long winded tome about all the chemistry, take my course, lol). We really don’t want to feed any of these to dogs. Now, POLYsaccharides get interesting; Starch, glycogen, dextrin and fiber are all polysaccharides. Grains such as wheat, corn, barley and rice are very high in starch, and this more energy dense (glycogen is the storage form of carbohydrate, in the body(. Fiber, is made up of (again the fast and easy version here) of cellulose and hemi- cellulose, pectin, plant gums and mucilages- and always, fiber resists digestion. When people say “dogs can’t digest carbs” a lot of the time they’re referring specifically to fiber; fiber is not digested. What happens to fiber is, microbial agents in the large intestine ferment it and produce some really good healthy things in there, such as “SCFAs” or short chain fatty acids. I’ll go into the healthful actions of fiber in Carbs Part Two; for now, I just want to clarify what it is.
Most importantly – and this is the “Think like a nutritionist” part; Carbohydrate is one of three nutrients that provide significant energy to the body. You get energy – calories – from just three nutrients; protein, fat and carbohydrate. So if you feed a 40 pound dog 1000 calories a day, and 25% is carb, that means 250 calories is fom rice, sweet potato, or quinoa.That could mean about a half cup each of cooked brown rice and cooked, mashed sweet potato. And leave room for 750 calories from, you guessed it – MEAT (protein and fat). That small amount of carb, offers some whopping health advantages (again – next post.) It is world’s away from the soy, corn gluten meal, wheat and brewer’s rice glop with a little chicken by product thrown in, that cheap dog foods (and some expensive ones!) contain.
And WHY should we add the carb? Well, several reasons. To remove it means 100% of the calories come from protein and fat. While dogs can tolerate a LOT of both, too much protein (and specifically, the byproducts the body makes when breaking it down) can stress the liver. Too much fat, eve the good stuff, can trigger pancreatitis. Too much phosphorus, can contribute to renal disease. Never mind that all glucose must now be derived from fat and protein – something a carnivore can do, but is it optimal? I for one do not believe it is. Very briefly, the right kind of carb/fiber contributes greatly to intestinal health; some forms have proven anti-cancer properties.Carbs provide immediately accessible energy, sparing protein for other uses and reducing the stress an all protein and fat diet places on the system, over time. Carbs also perform a number of metabolic functions such as combining with fat and proteins to form specific structural components of tissue. Foods that we call “carbs” also contain myriad nutrients, from essential vitamins and minerals to non-essential but health-supportive phytochemicals.
There are more health benefits and further classifications – soluble/insoluble, as well as absorbable/digestible/fermentable; further to THAT, the fermentability RATE is critical when choosing a carb type and amount for an individual dog, and I’m going to tell you all about this stuff ( but you knew that…right?) . And once we have this out of the way, we can talk about the problems associated with too MUCH plant matter, with green veggies, and how to know what YOUR dog needs most…and we’ll still have fat and protein to explore – some eye openers there as well, I promise.
In summary; carbs are not all created equal; they have pros and cons like other food groups do; adding some is easy and beneficial; adding none can place undue stress on the system; green veggies don’t really count; your dog is an individual (I think I mentioned that) and next; which foods to select and what benefits they offer.
On our road to truly optimal – personalized – nutrition for your dog.