Are Sugary Drinks Killing Your Liver? | The Paleo Diet®
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Are Sugary Drinks Killing Your Liver?

By O. H. Okoye, MD, MBA, MSEpi
July 21, 2015
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Everyone knows that increased sugar intake increases your risk for type 2 diabetes and obesity. The consumer market competes daily on how to cater to the average individual’s sweet tooth. In a society that loves the indulgence of super-sized drinks, it becomes easy to fall prey. Given the metabolism and breakdown of sugar takes place in the liver, it is no surprise excess sugar intake can lead to major liver problems.

According to a recent study conducted at Tufts University, and published in the Journal of Hepatology, drinking sugary drinks daily puts you at risk for non-alcoholic fatty liver disease.1 This condition can eventually lead to liver cirrhosis, just like with alcohol, in some cases liver cancer, and have the individual needing a liver transplant.2

In the study, 2,634 self-reported dietary questionnaires from mostly Caucasian middle-aged men and women enrolled in the National Heart Lunch and Blood Institute (NHLBI) Framingham Heart Study’s Offspring and Third Generation cohorts were analyzed. The sugary beverages listed on the questionnaires comprised of caffeinated and caffeine-free colas, other carbonated beverages with sugar, fruit punches, lemonade or other non-carbonated fruit drinks. Afterwards, a computed tomography (CT) scan was carried out on the participants to determine the quantity of fat in the liver and the authors of the current study used a previously defined cut-point to identify NAFLD.

Among the participants who drank sugar sweetened beverages, those who drank one or more sugar-sweetened beverage per day experienced a higher prevalence rate and had a 60% greater risk of NAFLD compared to people who said they drank no sugar-sweetened beverages. This association was still evident even after controlling for possible confounders, which could affect the results, such as age, sex, body mass index, calories and other risk factors. Basically, the more sugary beverage the people drank, the greater the risk. An estimated two thirds of the participants drank at least some fruit, cola or other sugary beverage, and over 10% drank the sugary beverage daily.

Between mislabeling, misleading advertisements, and chronic sugar addiction, it’s easy to understand why Dr. Cordain advocates eating your fruit whole rather than drinking commercial juices, which may be loaded with sugar.

About 20-30% of people living in the US has nonalcoholic fatty liver disease (NAFLD)3. The primary cause behind this condition remains relatively unknown. With NAFLD, in about 25% of the cases, there are no symptoms, with the fat accumulation in the liver only found from imaging results, when the liver has pretty much lost the sugar battle. Researchers have shown obesity increases a person’s risk for NAFLD, as well as a correlation between NAFLD and heart disease and type 2 diabetes.4 In other words, keep drinking that sugary beverage daily, and not only may you need a heart transplant, but you could have also traded in your heart and received a free serving of type 2 diabetes as well. Clearly not a fair or even worthy exchange.

The problem may lie in a part of sugar used in the beverages, known as fructose, and how it is processed within the body. When taken alone, fructose is poorly absorbed from the gastrointestinal tract, and it is almost completely cleared by the liver. While regular glucose blood concentration is with 5.5 mmol/L , that of fructose is about 0.01 mmol/L in peripheral blood.5

Both fructose and glucose follow different paths for absorption in the body. While glucose results in the release of insulin from the pancreas, fructose is unable to do so. Many cells lack the type of sugar transporter that takes fructose into the cell, unlike glucose. The breakdown of fructose mainly takes place in the liver, through a process known as phosphorylation, which avoids the rate-limiting phosphofructokinase step.6 While your body uses up glucose, for example the brain for energy, hepatic metabolism of fructose leads to the free fatty acids (FFAs), VLDL (the damaging form of cholesterol), and triglycerides, which get stored as fat. So, think of drinking that sugary beverage like you are drinking fat, because essentially that is what it ends up as.

Here in the Paleo world, it is safe to understand why we stay far away from commercial products such as sugar sweetened beverages. Not only do they provide empty calories, but there is the possibility of leaving your body in worse shape than imagined. Care for a liver transplant? I’ll pass, that refreshing glass of cold water sounds even better.

References

[1] Ma, J; Fox, CS; Jacques, PF; Speliotes, EK; Hoffmann, U; Smith, CE; Saltzman, E; and McKeown, NM. (2015, June 5). Sugar-Sweetened Beverage, Diet Soda, and Fatty Liver Disease in the Framingham Study Cohorts. Journal of Hepatology.

[2] Ibid.

[3] Ma, J; Fox, CS; Jacques, PF; Speliotes, EK; Hoffmann, U; Smith, CE; Saltzman, E; and McKeown, NM. (2014, April). Sugar-sweetened beverage intake is associated with fatty liver in the Framingham Offspring Study (267.3). The FASEB Journal. 28(1).

[4] Cassidy, S., Hallsworth, K., Thoma, C., MacGowan, G., Hollingsworth, K., Day, C., . . . Trenell, M. (2015, Feb 13). Cardiac structure and function are altered in type 2 diabetes and non-alcoholic fatty liver disease and associate with glycemic control. Cardiovasc Diabetol, 14(23). doi:doi: 10.1186/s12933-015-0187-2.

[5] Bray, G. (2007). How bad is fructose?1,2. Am J Clin Nutr, 86(4), 895-896.

[6] Ibid.

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