Commentary

Is fructose all to blame for obesity?


 

A recent article hypothesized that fructose causes more metabolic disease than does sucrose when overfed in the human diet. Fructose intake as high-fructose corn syrup (HFCS) has risen since its use in soft drinks in the United States and parallels the increase in the prevalence of obesity.

The newest hypothesis regarding fructose invokes a genetic survival of the fittest rationale for how fructose-enhanced fat deposition exacerbates the increased caloric consumption from the Western diet to promote metabolic disease especially in our adolescent and young adult population. This theory suggests that fructose consumption causes low adenosine triphosphate, which stimulates energy intake causing an imbalance of energy regulation.

Ongoing interest in the association between the increased use of HFCS and the prevalence of obesity in the United States continues. The use of HFCS in sugary sweetened beverages (SSBs) has reduced the cost of these beverages because of technology in preparing HFCS from corn and the substitution of the cheaper HFCS for sugar in SSBs. Although SSBs haven’t been proven to cause obesity, there has been an increase in the risk for type 2 diabetes, cardiovascular disease (CVD), nonalcoholic fatty liver disease (NAFLD), and even cancer. Research in HFCS, weight gain, and metabolic disease continues despite little definitive evidence of causation.

The relationship between SSBs consumption and obesity has been attributed to the increase in overall total caloric intake of the diet. These liquid calories do not suppress the intake of other foods to equalize the total amount of calories ingested. This knowledge has been gleaned from work performed by R. Mattes and B. Rolls in the 1990s through the early 2000s.

This research and the current work on HFCS and metabolic disease is important because there are adolescents and young adults in the United States and globally that ingest a large amount of SSBs and therefore are at risk for metabolic disease, type 2 diabetes, NAFLD, and CVD at an early age.

The concern over fructose stems from the association between the advent of increasing HFCS in SSBs and the increase in prevalence of obesity occurring at similar time periods in the United States, around 1970-1980.

Researchers noted the association and began to focus on potential reasons to pinpoint HFCS or fructose itself so we have a mechanism of action specific to fructose. Therefore, the public could be warned about the risk of drinking SSBs due to the HFCS and fructose ingested and the possibility of metabolic disease. Perhaps, there is a method to remove harmful HFCS from the food supply much like what has happened with industrially produced trans fatty acids. In 2018, the World Health Organization called for a total ban on trans fats due to causation of 500 million early deaths per year globally.

Similar to the process of making HFCS, most trans fats are formed through an industrial process that alters vegetable oil and creates a shelf stable inexpensive partially hydrogenated oil. Trans fats have been shown to increase low-density lipoprotein (LDL) cholesterol and decrease high-density lipoprotein (HDL) increasing the risk for myocardial infarction and stroke.

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