Robert H. Lustig, MD, Professor of Pediatrics in the Division of Endocrinology, University of California San Francisco has published and lectured extensively on the damage caused by sugary foods, especially the sugar fructose (1-8). He argues that ingestion of too much fructose and and not enough fiber appear to be cornerstones of the obesity epidemic in the US and result of the developed countries through their effects on insulin.
On May 26, 2009, Dr. Lustig gave a lecture called “Sugar: The Bitter Truth” which was posted on YouTube the following July and has become a viral success with over a million viewings. In this lecture, Lustig notably calls fructose a "poison" and compares its metabolic effects with those of ethanol. This lecture is a excellent and through review of this topic, but be warned — this is an hour and a half lecture! But I think that you will find it worth your time— it may change the way you life and eat.
Dr. Lustig's Papers on Fructose
- Lustig RH, Sen S, Soberman JE, et al. Obesity, leptin resistance, and the effects of insulin reduction. International Journal of Obesity and Related Metabolic Disorders 2004;28:1344-1348.
- Lustig RH. Which comes first? The obesity or the insulin? The behavior or the biochemistry? The Journal of Pediatrics 2008;152:601-602.
- Johnson RK, Appel LJ, Brands M, et al. Dietary sugars intake and cardiovascular health: a scientific statement from the American Heart Association. Circulation 2009;120:1011-1020.
- Lustig RH. The fructose epidemic. The Bariatrician 2009:10-18.
- Lim JS, Mietus-Snyder M, Valente A, et al. The role of fructose in the pathogenesis of NAFLD and the metabolic syndrome. Nature Reviews Gastroenterology & Hepatology 2010;7:251-264.
- Lustig RH. Fructose: metabolic, hedonic, and societal parallels with ethanol. Journal of the American Dietetic Association 2010;110:1307-1321.
- Nguyen S, Lustig RH. Just a spoonful of sugar helps the blood pressure go up. Expert Review of Cardiovascular Therapy 2010;8:1497-1499.
- Garber AK, Lustig RH. Is fast food addictive? Current Drug Abuse Reviews 2011;4:146-162.
Over the past five years, sugar has increasingly been added to some popular brands of dog and cat treats to make them more palatable and profitable (1-3). Like people, these sugars are not needed for our dogs or cats and are best avoided (4). These sugary treats are likely contributing to the rapid rise in obesity in our pets.
Sugar is also added to pet foods and treats for a variety of reasons, other than those are related to palatability. For example, corn syrup is used as a thickener and to suspend the dough for proper mixing of ingredients, and dextrose is used to evenly distribute moisture throughout a food (1). Sugar has a role in the physical and taste characteristics of many products, helping to mask bitter flavors imparted by acidifying agents, or changing the texture of specific treat types.
Dr. Lustig's work also emphasizes the importance of nutrition as part of treatment of all medical disease (see above). His work in this field has been both compelling and eye-opening, and I am now thinking more critically about the unnecessarily high sugar content in pet food treats and some pet foods. Remember that dogs, like humans, are omnivores and both species handle carbohydrates in much the same manner. Cats, on the other hand, are obligate carnivores, so sugars should never be included in their diet, if possible (5).
- Healthday, December 08, 2010. Those Sweet Pet Treats May Foster Fatness: Sugar appearing more now in dog and cat treats as veterinarian warns of the consequences.
- Press Release, Association for Pet Obesity Prevention (www.petobesityprevention.com), June 17, 2010. Kibble Crack – Vet Exposes Sugary Secret of Pet Treats. Sugar is being added to many pet treats contributing to the growing pet obesity epidemic.
- Petfood Industry (www.petfoodindusty.com), December 13, 2010. Sugar in pet treats may be contributing to obesity.
- The Dog Food Project (www.dogfoodproject.com). Ingredients to avoid.
- Kienzle, E. Blood sugar levels and renal sugar excretion after the intake of high carbohydrate diets in cats. The Journal of Nutrition 1994; 124:2563S-2567S.