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Friday, April 30, 2010

Is Fructose Unhealthy?

There has recently been some concern from various sources that fructose might be unhealthy. The focus on fructose has likely been prompted by the widely increased use of high-fructose corn syrup to sweeten various foods and drinks such as sodas, iced tea, yogurt, and snacks. Yet fructose can also be found in relatively high amounts in fruits, especially apples, pears, grapes (including raisins), and pineapples, and even in vegetables such as tomatoes, cabbage and squash. Table sugar (sucrose) is a 50/50 amalgam of fructose and glucose, while high-fructose corn syrup is 55% free fructose and 45% free glucose, industrially manufactured from corn starch,

There is some fairly solid evidence supporting the negative health effects of fructose on mice, but the evidence concerning humans is much less conclusive. In human studies, fructose intake has been positively correlated with obesity (1, 2), especially fatty deposits around the waist, which is thought to be the most dangerous to health and, of course, detrimental to the 6-pack look. Fructose also increases blood triglycerides, a recognized risk factor for heart disease (3). All cells in the body can metabolize glucose, but only the liver can metabolize fructose, and high fructose consumption appears to load the liver with fatty deposits (4, 5). Also, fructose tends to suppress insulin and leptin, both of which are hormones that decrease appetite, while increasing ghrelin, which raises appetite (6, 7), thus possibly contributing to excess weight gain. However, there is little evidence that the fructose in high-fructose corn syrup is more damaging than the fructose in table sugar (typically sucrose from sugar cane).

Bottom Line
While more studies must be done to solidify the evidence on the effects of fructose on human health, it appears wise to avoid excessive intake of fructose. This can be accomplished by:
  • Completely avoiding foods and drinks containing high-fructose corn syrup
  • Limiting consumption of table sugar and any product with a high sugar content
  • Limiting fruit juice consumption, especially juice from apples and grapes
1. Lustig RH (2006). "Childhood obesity: behavioral aberration or biochemical drive? Reinterpreting the First Law of Thermodynamics". Nature clinical practice. Endocrinology & metabolism 2 (8): 447–58. doi:10.1038/ncpendmet0220. PMID 16932334.

2. Isganaitis E, Lustig RH (2005). "Fast food, central nervous system insulin resistance, and obesity". Arterioscler. Thromb. Vasc. Biol. 25 (12): 2451–62. doi:10.1161/01.ATV.0000186208.06964.91. PMID 16166564.

3. Bantle JP, Raatz SK, Thomas W, Georgopoulos A (2000). "Effects of dietary fructose on plasma lipids in healthy subjects". Am. J. Clin. Nutr. 72 (5): 1128–34. PMID 11063439.

4. Forristal, Linda (Fall 2001). "The Murky World of High-Fructose Corn Syrup". Weston A. Price Foundation.

5. Ouyang X, Cirillo P, Sautin Y, et al. (June 2008). "Fructose consumption as a risk factor for non-alcoholic fatty liver disease". J. Hepatol. 48 (6): 993–9. doi:10.1016/j.jhep.2008.02.011. PMID 18395287.

6. Teff, KL; Elliott SS, Tschöp M, Kieffer TJ, Rader D, Heiman M, Townsend RR, Keim NL, D'Alessio D, Havel PJ (June 2004). "Dietary fructose reduces circulating insulin and leptin, attenuates postprandial suppression of ghrelin, and increases triglycerides in women". J Clin Endocrinol Metab. 89 (6): 2963–72. doi:10.1210/jc.2003-031855. PMID 15181085.

7. Swan, Norman; Lustig, Robert H. "ABC Radio National, The Health Report, The Obesity Epidemic". Retrieved 2007-07-15.

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