Can a High Lysine Diet Change a Dog’s Genes and Reduce Obesity?
In our last post, we described some of the research performed by Hill’s Pet Nutrition that concluded that a diet with a high lysine to calorie ratio could change a dog’s gene expression from fat storing to fat burning. These results are certainly encouraging because they could potentially provide guidance on the types of diets that would help an overweight pet (or human, for that matter) to more quickly lose weight and keep it off. If, in fact, diets high in lysine can impact a dog’s obesity related gene expression, then we would expect that the Hill’s study used a food that contains ingredients that are naturally high in lysine, right? Not so fast.
Foods High in Lysine
The food that was used in one of the Hill’s studies was the Hill’s Prescription Diet r/d Canine. Before we look at the ingredients in this food, it is helpful to list some foods that naturally contain high amounts of lysine. Lysine is an essential amino acid, and therefore, good sources of lysine include mostly high-protein foods such as:
- Red meats (e.g. beef)
- Beans, including Soy beans
- Amaranth and Quinoa
- Milk and eggs
In comparison, the ingredients in the Hill’s Prescription Diet r/d Canine are:
Whole Grain Corn, Corn Gluten Meal, Chicken By-Product Meal, Soybean Mill Run, Powdered Cellulose, Soybean Meal, Chicken Liver Flavor, Dried Beet Pulp, Pork Flavor, Lactic Acid, Soybean Oil, Caramel color, DL-Methionine, L-Lysine, Potassium Chloride, Choline Chloride, vitamins (Vitamin E Supplement, L-Ascorbyl-2-Polyphosphate (source of vitamin C), Niacin Supplement, Thiamine Mononitrate, Vitamin A Supplement, Calcium Pantothenate, Biotin, Vitamin B12 Supplement, Pyridoxine Hydrochloride, Riboflavin Supplement, Folic Acid, Vitamin D3 Supplement), Calcium Carbonate, Iodized Salt, minerals (Manganese Sulfate, Ferrous Sulfate, Zinc Oxide, Copper Sulfate, Calcium Iodate, Sodium Selenite), Taurine, L-Carnitine, Mixed Tocopherols for freshness, Phosphoric Acid, Beta-Carotene, Natural Flavors.
Unfortunately, there is very little overlap of foods naturally high in lysine with the ingredients listed in this recipe. And where there is an overlap, the quality and appropriateness is questionable, as evidenced by the use of Chicken By-Product Meal (as the chicken source) and Soybean Mill Run and Soybean meal as a cheap protein source. (For more on the use of Soy in dog food, read our ingredient analysis of soy here.) And forget about chicken liver flavor and pork flavor. Neither of these provides much nutrition, let alone protein and lysine.
We do however, notice that L-Lysine is an ingredient in the food. No doubt, this was added to boost the lysine levels in this food as a consideration to the lower quality and cheaper sources of proteins that are present. In the animal feed industry, lysine supplementation is a strategy that allows for the use of lower-cost (e.g. plant) proteins while maintaining high growth rates in the livestock. Said another way, adding lysine is a way to ‘cover’ for the use of cheaper protein ingredients.
Further analysis of the ingredients in the r/d Canine food suggests that this food is not one that I would want to feed my pet, under most circumstances. It is not appropriate at all for the carnivore dog, contains mostly corn, and contains no fruits or vegetables (for vitamins).
I would be interested to see the results of a study using a food containing higher quality, natural sources of lysine, with real meat or fish based proteins, fruits and vegetables, and free of cheap fillers and flavorings. I would bet that the dogs would enjoy their meals more, and be healthier overall in the long run. This is the approach that I would take anyway.
Thanks to Hill’s for conducting some innovative research. Shame on Hill’s for executing the food product so poorly.
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