Type of Sugar, Not Just Amount, Influences Metabolic Effects

MedicalResearch.com Interview with:
Dr. Marta Alegret

Department of Pharmacology, Toxicology and Therapeutic Chemistry
Pharmacology Section
School of Pharmacy and Food Sciences
University of Barcelona

MedicalResearch.com: What is the background for this study?

Response: In humans, an excessive intake of sugars has been linked to the development of metabolic disturbances, and therefore to an increase in the risk for cardiovascular diseases. Specifically, increased consumption of simple sugars in liquid form, as beverages sweetened with high fructose corn syrup or sucrose, has been linked to obesity, insulin resistance and type 2 diabetes. However, two questions remain unresolved: what is/are the underlying molecular mechanism(s) linking these metabolic alterations to cardiovascular diseases? Are the adverse cardiovascular and metabolic effects of sugar-sweetened beverages merely the consequence of the increase in caloric intake caused by their consumption?

To answer to these questions, we performed a study in female rats, which were randomly assigned to three groups: a control group, without any supplementary sugar; a fructose-supplemented group, which received a supplement of 20% weight/volume fructose in drinking water; and a glucose-supplemented group, supplemented with 20% weight/volume glucose in drinking water.

MedicalResearch.com: What are the main findings?

Response: Our main findings were that both the metabolic and cardiovascular responses were worse in the fructose-supplemented rats, although the total caloric consumption was higher in glucose-supplemented rats.

For example, only fructose-supplemented rats display significant hypertriglyceridemia and increases in body and liver weight. We also showed that fructose supplementation attenuates the aortic relaxation response to a nitric oxide (NO) donor, whereas glucose potentiates it. On the other hand, both sugars impair insulin signaling in the liver and aortic tissue, but the effect is far more intense in fructose- than in glucose-supplemented rats. The fact that we observed insulin resistance not only in the liver but also in aortic tissues of the fructose-supplemented animals, suggests a common origin for both metabolic and vascular dysfunction. Clearly, further studies are needed to elucidate the direction and magnitude of these interactions in sugar-supplemented rats.

MedicalResearch.com: What should readers take away from your report?

Response: The main message is that fructose exerts specific cardiovascular and metabolic effects, which are independent from the calories ingested, because the animals that received the glucose supplement consumed even a higher amount of calories but some of these deleterious effects were absent.

MedicalResearch.com: What recommendations do you have for future research as a result of this study?

Response: In our opinions it is important to be able to delineate if the sugar effects are simply related to increased caloric intake or the type of sugar or are specific, due to the particular metabolism of fructose. Therefore, we would recommend that in studies investigating the effects of fructose, an experimental group supplemented with another sugar providing the same amount of calories as fructose should be included.

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Gemma Sangüesa, Sonali Shaligram, Farjana Akther, Núria Roglans, Juan C Laguna, Roshanak Rahimian, Marta Alegret
American Journal of Physiology – Heart and Circulatory Physiology Published 6 December 2016 Vol. no. , DOI: 10.1152/ajpheart.00339.2016

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