Tuesday, June 4, 2013

Carbohydrates 1 = Sugars and Starches

Next to "grains", sugars and starches are likely the biggest culprits of "anti-carb" propaganda in relation to petfoods.

Sugars are typically referred to as mono and di-saccharides and common examples  include glucose, galactose, fructose, sucrose (table sugar), lactose (milk sugar), and maltose.  They are typically included in foods to increase palatability, change viscous properties, alter texture, and/or provide color (browning reactions).  Honey is an ingredient in many of my recipes, specifically because of its balanced concentration of gluocse and fructose.  It provides a sweet taste that many dogs appreciate (or at least my Keegan thinks it's awesome).  Interestingly, I often hear performance dog handlers indicate that honey makes their dogs sluggish.  I do believe this is similar to some of the dogs that collapse during exercise (specific genetic diseases excluded).  Fructose metabolism is a bit more complicated than glucose metabolism.  It will either get used for energy or converted directly to fat (this is why high fructose corn syrup is so "fattening" for us humans if we don't use it for energy).  Therefore, in our performance dogs, if they have a high glucose demand that gluconeogenesis is not maintaining, then yes, honey may not be the best option and more rapidly available carbohydrate sources are  optimal.

Keegan (Photo by: Marsha Kingsley)
Starches are interesting ingredients as well.  Starch in its basic definition is just a lot of glucose molecules joined together in one of two patterns, linear (amylose) or branched (amylopectin).  Amylopectin is more rapidly digested and thus, higher concentrations result in higher glycemic index.  Food sources vary in the ratio of these two forms; therefore, one type of grain or carb does not equal another...hence all the confusion.  For example, low amylose and high amylopectin in rice, make it rapidly digested but also give it a very high glycemic index.  It is often used as the "go to" for many diets because of its high digestibility. I tend to not use it so much because of its very high glycemic index.  Instead I use primarily barley and oats in my formulations, or when I'm looking at petfoods. I like the fact that both have nice amylose to amylopectin ratios and they each have additional cooling (barley) or heating (oats) properties (a topic for later discussion), and viscous fibrous properties (...more on that later as well).

I would really love to see some studies related to glycemic index of grain-free petfoods.  Most of these are made with potato starch, because a good deal of starch is needed for the extrusion process in order to hold the kibble together.  I'd like to see this because I suspect that many of the grain-free foods made with potato, will actually cause a higher glycemic index (this may be a good thing for those of you with dogs that are prone to collapse at trials or during intense exercise but may be a concern for overweight cats prone to diabetes).   Interestingly, some groups in Canada are studying the increased use of peas and pea starch in petfoods.  Like barley and oats, peas have some really awesome fiber characteristics as well and the resulting glycemic index is much lower than rice or potato. I love peas (for me and the dogs!)

My dogs are fed extremely varied diets included raw, home-cooked (quite literally the only thing I cook), kibble, canned, dehyrated and combinations of all of the above.  I am fortunate they don't have issues with grains or carbs; therefore,  I can and do provide varied sources.  In my raw and cooked diets, 30% of the diet is a carbohydrate mix that includes fruits, vegetables, greens, and grains (barley, oats) in equal proportions by weight. I do not include potatoes in my blend but will on occasion include corn (especially in the summer when I can buy it fresh). I bet you wondered if I'd say the "c" word.  Absolutely, I will use corn in moderation just like the rest of my carb sources.  I try to add at least 3-5  different fruits and vegetables in every batch (typically 2 weeks worth of food).  I do buy what is seasonal (I am an Animal Scientist after all, and "least cost formulations" are important to me).

If any of my dogs seemed to have issues at trials or during exercise with hypoglycemia or collapse, I would actually utilize some of the higher protein and fat (maintaining a 2:1 protein to fat ratio) diets that have rice or potato listed in the top 5 ingredients (many many options).  I would use these throughout trial weekends, along with my raw diet and if the dogs were agreeable, I'd use them as treats (perhaps make meatballs with ground up kibble and raw meat...a little honey added if Keegan were the chef) throughout trial weekends. This might take some trial and error to see what worked best but that would be my plan A (I don't come up with Plan B until I need it)!


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