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High fructose corn syrup and health

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The chemical structures of fructose (left) and glucose (right), the main components of HFCS

The consumption of high-fructose corn syrup (HFCS or glucose–fructose syrup) and its relationship to a healthy diet is a subject of investigation. Evidence does not indicate it is less healthy than sugar consumption in general. Concerns mainly center around excessive sugar intake and its contribution to obesity.

Background

The term high-fructose corn syrup was developed to distinguish it from all-glucose corn syrups that existed in the past, and does not accurately describe the composition of the syrup (which is composed of a mixture of 42-55% fructose, 41-45% glucose and 0-5% glucose polymers depending on the specific blend).[1] In the 1980s it replaced sucrose as the main sweetener of soft drinks in the United States. Rates of obesity subsequently rose, paralleling an increase in the consumption of soft drinks in general, but have not been linked to the usage of HFCS. Additional concerns have been raised due to laboratory research suggested a link between consuming large amounts of fructose and changes to various proxy health measures including elevated blood triglycerides, size and type of low-density lipoproteins and uric acid levels.[1]

United States guidelines regarding sugar consumption

Numerous agencies in the United States recommend reducing the consumption of all sugars, including HFCS, without singling it out as presenting extra concerns. The Mayo Clinic cites the American Heart Association's recommendation that women limit the added sugar in their diet to 100 calories a day (~6 teaspoons) and that men limit it 150 calories a day (~9 teaspoons), noting that there is not enough evidence to support HFCS having more adverse health effects than excess consumption of any other type of sugar.[2] The United States departments of Agriculture and Health and Human Services recommendations for a healthy diet state that consumption of all types of added sugars be reduced.[3]: p.27 

Obesity and metabolic syndrome

A 2004 commentary in The American Journal of Clinical Nutrition suggested that the altered metabolism of fructose when compared to glucose may be a factor in increasing obesity rates since, as compared to sucrose, fructose may be more readily converted to fat and the sugar causing less of a rise in insulin and leptin, both of which increase feelings of satiety. The authors suggested reducing intake of sugar by using sugar substitutes instead.[4] In subsequent interviews, two of the study's authors stated the article was distorted to place emphasis solely on HFCS when the actual issue was the overconsumption of any type of sugar.[5][6] While fructose absorption and modification by the intestines and liver does differ from glucose initially, the majority of the fructose molecules are converted to glucose or metabolized into byproducts identical to those produced by glucose metabolism. Consumption of moderate amounts of fructose has also been linked to positive outcomes, including reducing appetite if consumed before a meal, lower blood sugar increases compared to glucose, and (again compared to glucose) delaying exhaustion if consumed during exercise.[1]

In 2007 an expert panel assembled by the University of Maryland's Center for Food, Nutrition and Agriculture Policy reviewed the links between HFCS and obesity and concluded there was no ecological validity in the association between rising body mass indexes (a measure of obesity) and the consumption of HFCS. The panel stated that since the ratio of fructose to glucose not having changed substantially in the United States since the 1960s when HFCS was introduced the changes in obesity rates were probably not due to HFCS specifically but rather a greater consumption of calories overall, and recommended further research on the topic.[7] In 2009 the American Medical Association published a review article on HFCS and concluded that based on the science available at the time it is unlikely that HFCS contributes more to obesity or other health conditions than sucrose, and there was insufficient evidence to suggest warning about or restricting use of HFCS or other fructose-containing sweeteners in foods.[8] Other authors have disagreed, suggesting a link between HFCS and metabolic syndrome that is independent of obesity.[9]

Studies

Part of the concern over fructose arises from animal testing in which the injection of fructose directly into the brain of rats led to increased eating and subsequent research in mice seemed to confirm this effect. Re-examination of the results suggested that the results in rodents would have little meaning in humans due to the dosage given (equivalent to a 75 kg human consuming 660 grams of fructose, whereas a normal daily intake is approximately 50 grams) and the strict control over the amount of fructose that crosses the blood–brain barrier.[1] Subsequent testing with humans using both short- and long-term experiments found no important differences between the consumption of HFCS versus other sugars.[1] Most of the studies linking fructose consumption to higher blood triglycerides have been in rodents through mechanisms different from those in humans, and therefore it is unlikely that high-fructose diets would have comparable effects in humans. Tests in humans suggest that for people with insulin resistance, high fructose diets (greater than 50 grams per day, beyond the average consumption of fructose by Americans) may result in elevated triglycerides, but there is no effect with normal levels of fructose consumption.[1]

Epidemiological research has suggested that the increase in obesity is linked to increased consumption of sugars and/or calories in general, and not due to any special effect of fructose alone.[1]

Other issues

Consumption of HFCS has been associated with non-alcoholic fatty liver disease, as it is thought that fructose may cause increased fat deposits in the abdomen[10] though it has also been suggested that this association is not unique to fructose and may be due to glucose consumption as well.[11]

The presence of carbonyl compounds found in HFCS-containing beverages has been suggested as a contributor to poor health and problems for people with diabetes, though this concern is unfounded as HFCS is of no more concern than other sources and the compounds are produced endogenously by the body.[12]

High fructose consumption has been linked to high levels of uric acid in the blood, though this is only thought to be a concern for patients with gout.[1]

The possibility that significant consumption of products containing high fructose corn syrup with detectable levels of mercury could result in neurotoxicity was raised by studies in 2009.[13][14][15] The Corn Refiners Association disputes the studies conclusions and states that “no mercury or mercury-based technology is used in the production of high fructose corn syrup in North America.”[16] By then end of 2012, most chlor-alkali plants in the United States phased out older "mercury cell" technology linked to mercury contamination of HFCS, except for two chlor-alkali plants in Ohio and West Virginia run by ASHTA Chemicals and PPG Industries.[17][18][19] However mercury cell technology is still widely used outside of the United States and there are no restrictions on importing mercury-grade caustic soda for use in HFCS production.[15][20]

HFCS consumption can be problematic in those with fructose malabsorption.[21]

References

  1. ^ a b c d e f g h Attention: This template ({{cite pmid}}) is deprecated. To cite the publication identified by PMID 21050460 , please use {{cite journal}} with |pmid= 21050460 instead.
  2. ^ "High-fructose corn syrup: What are the health concerns?". Mayo Clinic. 2012-09-27. Retrieved 2012-10-17.
  3. ^ Dietary Guidelines for Americans, 2010. 7th Edition (pdf). United States Department of Agriculture and United States Department of Health and Human Services. December, 2010. Retrieved 2012-10-17. {{cite book}}: Check date values in: |date= (help)
  4. ^ Bray, GA (2004). "Consumption of high-fructose corn syrup in beverages may play a role in the epidemic of obesity". American Journal of Clinical Nutrition. 79 (4): 537–543. PMID 15051594. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  5. ^ Parker-Pope, Tara (September 20, 2010). "In Worries About Sweeteners, Think of All Sugars". The New York Times. Retrieved 2011-04-20.
  6. ^ Warner, M (2006-07-02). "A Sweetener With a Bad Rap". The New York Times. Retrieved 2012-05-02.
  7. ^ Forshee RA; Storey, ML; et al. (2007). "A critical examination of the evidence relating high-fructose corn syrup and weight gain" (pdf). Critical Reviews in Food Science and Nutrition. 47 (6): 561–82. doi:10.1080/10408390600846457. PMID 17653981. {{cite journal}}: Explicit use of et al. in: |last3= (help)
  8. ^ Attention: This template ({{cite pmid}}) is deprecated. To cite the publication identified by PMID 20516261, please use {{cite journal}} with |pmid= 20516261 instead.
  9. ^ Attention: This template ({{cite pmid}}) is deprecated. To cite the publication identified by PMID 20424937, please use {{cite journal}} with |pmid= 20424937 instead.
  10. ^ Attention: This template ({{cite pmid}}) is deprecated. To cite the publication identified by PMID 20518077 , please use {{cite journal}} with |pmid= 20518077 instead.
  11. ^ Allocca, M (2010). "Emerging nutritional treatments for nonalcoholic fatty liver disease". Nutrition, diet therapy, and the liver. CRC Press. pp. 131–146. ISBN 1-4200-8549-2. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |editors= ignored (|editor= suggested) (help)
  12. ^ Attention: This template ({{cite pmid}}) is deprecated. To cite the publication identified by PMID 19386820, please use {{cite journal}} with |pmid= 19386820 instead.
  13. ^ Dufault R, Schnoll R, Lukiw WJ, Leblanc B, Cornett C, Patrick L, Wallinga D, Gilbert SG, Crider R (2009 Oct 27). "Mercury exposure, nutritional deficiencies and metabolic disruptions may affect learning in children". Behav Brain Funct. 5: 44. doi:10.1186/1744-9081-5-44. PMC 2773803. PMID 19860886. {{cite journal}}: Check date values in: |date= (help)CS1 maint: multiple names: authors list (link) CS1 maint: unflagged free DOI (link)
  14. ^ Wallinga D, Sorensen J, Mottl P, Yablon B (January 2009). "Not So Sweet: Missing Mercury and High Fructose Corn Syrup" (PDF). Institute for Agriculture and Trade Policy. Retrieved 2012-09-20.{{cite web}}: CS1 maint: multiple names: authors list (link) (self-published)
  15. ^ a b Connie Howard (February 2010). "Mercury confusion: What's being done about mercury in our food?". VueWeekly.com. Retrieved 2013-01-08.
  16. ^ http://www.sweetsurprise.com/2011/06/08/5-reasonshighfructosecornsyrupwillkillyou
  17. ^ Rob Pavey (July 2012). "Olin prepares for mercury free future after 47 years". Augusta Chronical. Retrieved 2013-01-08.
  18. ^ Bradley J. Westfall, ASHTA Chemicals; John McIntosh, Olin Chlor Alkali Products; and Michael H. McGarry, PPG Industries Inc. (September 2009). "Letter to EC Committee". regulations.gov. Retrieved 2013-01-08.{{cite web}}: CS1 maint: multiple names: authors list (link)
  19. ^ Olin (October 2012). "Olin Announces Third Quarter Earnings". Olin. Retrieved 2013-01-08.
  20. ^ World Chlorine Council (January 2011). "Reduction of Mercury Emissions and Use from the Chlor-Alkali Sector Partnership" (PDF). EuroChlor.org. Retrieved 2013-01-08.
  21. ^ "Fructose intolerance: Which foods should I avoid?". Mayo Clinic. Retrieved 2012-09-15.
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