Another study, however, reports no link between uric acid and intakes of fructose-sweetened beverages. Both studies add to the ongoing debate over the metabolic effects of sweetened beverages.
According to new findings published in Kidney International, a cross-sectional analysis of data from almost 16,000 people found that the risk of chronic kidney disease increased by over 150 per cent in those who more than one soda per day and had high levels of uric acid.
Researchers led by Andrew Bomback from Columbia University College of Physicians and Surgeons in New York point the finger at fructose, which is metabolised and leads to increased production of uric acid, a compound linked to kidney disease when detected in high levels.
However, analysis of the data in a longitudinal manner found no association with hyperuricemia or chronic kidney disease, said the researchers.
“This study, to the best of our knowledge, is the first to examine whether sugar-sweetened soda consumption is associated with incident forms of [renal diseases],” wrote Bomback and his co-workers.
“The results of these incidence analyses add an important note of caution to the literature on sugar-sweetened soda and HFCS. Although the cross-sectional analyses performed in this and other studies support a hypothesis that increased HFCS-sweetened soda consumption leads to higher uric acid levels that in turn induce renal damage, the longitudinal analyses do not support this theory,” they added.
ADM analysis
Another study, however, did not find a link between consumption of fructose from fructose-containing foods and beverages, and a high level of uric acid (hyperuricemia).
According to findings published in Nutrition & Metabolism, scientists from Archer Daniels Midland (ADM) report that data from almost 10,000 participants of the U.S. NHANES 1999-2004 databases did not support a link between fructose consumption and hyperuricemia. The study is said to be the first to look at the risk of hyperuricemia using multiple U.S. national nutrition survey databases associated with various dietary factors, and particularly fructose.
“These data further suggest a potential effect of fructose consumption in an ordinary diet on serum uric acid differs from results found in some short-term studies using atypical exposure and/or levels of fructose administration,” wrote the ADM scientists, led by Sam Sun.
The impact of time
So what could explain these apparent discrepancies, when one study reports a link and another does not? Bomback and his co-workers noted that the duration of exposure to sugar-sweetened soda “may be important”, an explanation which may also explain the lack of agreement between their cross-sectional and longitudinal data.
“The mean follow-up in this cohort was approximately 9 years, and a longer exposure period may be needed to produce incident disease,” they noted.
Fructose science
Studies looking at the effects of fructose and fructose-containing sweeteners have mushroomed in recent years, with attention focussing on high fructose corn syrup (HFCS). Fears about HFCS were raised in 2004, when an article was published in the American Journal of Clinical Nutrition hypothesizing that the sweetener could be linked to rising rates of obesity. One of the article’s authors Dr Barry Popkin has since said that he was wrong to pinpoint HFCS as obesity’s major cause, but consumer concern has continued nonetheless.
There are three different types of HFCS – one that is 55 per cent fructose and 42 per cent glucose (most commonly found in soft drinks), one that is 42 per cent fructose and 58 per cent glucose (usually used in food products), and one used for specialty applications that is 90 per cent fructose and 10 per cent glucose.
Industry associations such as the Corn Refiners Association (CRA) and others have repeatedly pointed out that the HFCS used in foods and beverages is not dissimilar in its makeup to sugar (sucrose), which contains 50 per cent glucose and 50 per cent fructose
Source: Kidney International
April 2010, Volume 77, Issue 7, Pages 609-616
“Sugar-sweetened soda consumption, hyperuricemia, and kidney disease”
Source: A.S. Bomback, V.K. Derebail, D.A. Shoham, C.A. Anderson, L.M. Steffen, W.D. Rosamond, A.V. Kshirsagar
Full text of the article is available here.
Source: Nutrition & Metabolism
2010, 7:16
“Lack of association between dietary fructose and hyperuricemia risk in adults”
Authors: S.Z. Sun, B.D. Flickinger, P.S. Williamson-Hughes, M.W. Empie
Full text of the article is available here.