|In the fashion business, "light or not light" (light=diet as in "Diet Coke" US vs Coke Light Germany) is not really a question to ask.|
I mean, who would not want to know whether moderate amounts of various sugars (including fructose, sucrose, and glucose) in sugar-sweetened beverages (SSBs) will have differential effects on fatty acid synthesis and degradation in healthy young men?
Now that I'd probably even have Dr. Lustig attention, let's first take a look at what exactly Michel Hochuli and his colleagues from the University Hospital Zurich did to answer this question.
The study we are dealing with is a randomized controlled crossover trial with a total of four different dietary interventions. During each of these, subjects were supplied with SSBs containing various sugars in different concentrations in random order during 3 weeks:
- 40 g fructose per day [medium fructose (MF)]
- 80 g fructose per day [high fructose (HF)]
- 80 g glucose per day [high glucose (HG)]
- 80 g sucrose per day [high sucrose (HS)]
|Figure 1: Relative levels of palmitate to linoleic acid ratio (left) and palmitoylcarnitine (right) after the ingestion of the four test-SSBs; values expressed rel. to baseline (Hochuli. 2014)|
These changes went hand in hand with increases in fasting palmitoylcarnitine (=palmitic acid that's "carried" by carnitine to the mitochondria for oxidation) that signifies impaired or at least insufficient fatty acid oxidation and, last but not least, a decreased inhibition of lipolysis by insulin in the clamp condition.
Now, this is what happens next...
In a lab setting and after the consumption of an isolated test beverage this obviously isn't much of a problem, but if you think of a real-life SSB-consumption scenario, you will have to agree that people tend to use their fructose sweetened beverage to wash down a greasy piece of pizza ... and, believe it or not, this is where the whole fructose problem begins.
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Now even that wouldn't be a problem. People could, after all, burn the fat off by fasting. Unfortunately, the combination of insulin resistance and impaired fatty acid oxidation leaves them starving in abundance. What nutrients are their cells supposed to use? Glucose? Doesn't work, because of the insulin resistance. Fats? Can't be oxidized because of the elevated insulin levels. The consequence? Well, if we are talking about the average overweight inhabitant of the Western obesity belt, he will find himself sneaking through the kitchen, opening the fridge and annihilating a family packet of ice-cream only 30 minutes after his 1,500kcal+ "all American" version of the Italian way of making use of leftovers... eventually al this takes us - you won't believe it - back to the simple but undeniable truth that eating processed foods promotes overeating and overeating promotes obesity, hyperlipidemia and diabetes. My gosh! Who would have thought that?
- Hochuli, et al. "Sugar-Sweetened Beverages With Moderate Amounts of Fructose, but Not Sucrose, Induce Fatty Acid Synthesis in Healthy Young Men: A Randomized Crossover Study." J Clin Endocrinol Metab (2014). Early Release.
- Priore, Paola, et al. "Extra virgin olive oil phenols down-regulate lipid synthesis in primary-cultured rat- hepatocytes." The Journal of Nutritional Biochemistry (2014). Accepted Manuscript.
- Roden, Michael, et al. "Mechanism of free fatty acid-induced insulin resistance in humans." Journal of Clinical Investigation 97.12 (1996): 2859.