Paper Review: Dietary Sugars Intake and Cardiovascular Health. A Scientific Statement From the American Heart Association

High intakes of dietary sugars in conjunction with the current worldwide pandemic of obesity, hypertension, and cardiovascular disease have heightened concerns about the adverse effects of excessive consumption of sugars in humans. Between 1970 and 2005, average annual availability of sugars consumed increased by 19%, which added 76 calories to Americans’ average daily energy intake.

Excessive consumption of sugars has been linked with several metabolic abnormalities and adverse health conditions, including obesity, hypertension, and cardiovascular disease. In addition, high sugar intake may lead to the development of the metabolic syndrome, as well as increased inflammation and oxidative stress. Finally, excessive sugar intake is associated with shortfalls of essential nutrients.

In view of these considerations, the American Heart Association has published a position paper on this subject, which recommends reductions in the intake of added sugars. Click the following link to read the full paper, which was published in the journal Circulation and is available online (1). It brings home and important message that we need all heed.

My Comments:

Important Role of the Glucose-Insulin Response to Chronic Disease 
Many factors influence the body’s glucose response to foods, including the composition of the food (fat, protein, sugar, starch, and fiber content), the method of food processing and preparation, the combination of foods eaten, and physiological factors including age and body composition.

Glucose control is the net effect of metabolic processes that remove glucose from the blood for either glycogen synthesis or energy production and of gluconeogenesis and glycogenolysis, which return glucose to the blood.

The rise in blood glucose after consumption of a carbohydrate triggers the release of insulin and at the same time reduces the secretion of glucagon. Hyperinsulinemia, in turn, appears to be primarily responsible for many of the untoward metabolic problems associated with our present society, including obesity, hypertension, and cardiovascular disease.

Gary Taubes: Good Calories, Bad Calories
The recommendations found in this paper (1) are in agreement with the recommendations Gary Taubes, makes in his book, entitled Good Calories, Bad Calories: Challenging the Conventional Wisdom on Diet, Weight Control, and Disease (2) As I discussed in a recent blog post, in that book Taubes convincingly states that the problem with our diets lies in refined carbohydrates and sugars. He states that refined carbohydrates do harm via their dramatic and long-term effects on insulin, the hormone that regulates fat accumulation, and that the key to good health is the kind of calories we take in, not the number. There are good calories, and bad ones.

Robert Lustig: Sugar: The Bitter Truth
The recommendations found in this position paper are also in agreement with the recommendations Dr. Lustig makes in this lecture called “Sugar: The Bitter Truth” which was posted on YouTube. Dr. Lustig has also published extensively on this topic (3), and is also an co-author on the ADA's position paper on dietary sugar intake (1). Lustig calls fructose a "poison" and compares its metabolic effects with those of ethanol. See my previous blog post for more information.

How Do Dietary Sugars Relate to Animal Nutrition? 

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 (4-7). Like people, these sugars are not needed for our dogs or cats and are best avoided (7). 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 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 (4). 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.

Why is the sugar content so high in many 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 (8).

References:

1. Johnson RK, Appel LJ, Brands M, Howard BV, Lefevre M, Lustig RH, Sacks F, Steffen LM, Wylie-Rosett J; American Heart Association Nutrition Committee of the Council on Nutrition, Physical Activity, and Metabolism and the Council on Epidemiology and Prevention. Dietary sugars intake and cardiovascular health: a scientific statement from the American Heart Association. Circulation. 2009;120:1011-1020. http://circ.ahajournals.org/content/120/11/1011.full.pdf+html
2. Taubes G: Good Calories, Bad Calories: Challenging the Conventional Wisdom on Diet, Weight Control, and Disease 2007.
3. Lustig RH. The fructose epidemic. The Bariatrician 2009:10-18. 
4. 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. 
5. 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. 
6. Petfood Industry (www.petfoodindusty.com), December 13, 2010. Sugar in pet treats may be contributing to obesity. 
7. The Dog Food Project (www.dogfoodproject.com). Ingredients to avoid.
8. 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.