SAN DIEGO—Individuals who consume a diet high in artificially sweetened soda or salt may be more likely to experience a decline in kidney function, new findings suggest.

At Renal Week 2009, Julie Lin, MD, MPH, FASN, Assistant Professor of Medicine at Harvard Medical School in Boston, and colleagues reported on two studies of women participating in the Nurses’ Health Study (NHS) and who had data available on dietary intake and changes in estimated glomerular filtration rate (eGFR) between 1989 and 2000. In both studies, women had a median age of 67 years and 97% were white.

In one study, researchers analyzed data on 3,256 women who had reviewable data on sugar sweetened beverages or artificially sweetened soda intake. Of these subjects, 372 (11.4%) experienced an eGFR decline of 30% or greater over 11 years of follow up.

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Compared with those who consumed one serving (an estimated 12 ounces) of artificially sweetened soda per month (reference group), subjects who consumed two or more servings per day were twice as likely to experience a 30% decline in eGFR. Artificially sweetened soda consumption of less than two per day was not associated with eGFR decline. 

The study is the first to report a link between drinking artificially sweetened soda and renal function decline, Dr. Lin said. She and her colleagues found no association between eGFR decline and consumption of sugar sweetened beverages.

The researchers concluded that the mechanisms of kidney decline associated with high intake of artificial sweeteners have not been previously studied and deserve further investigation.  Dr. Lin said the participants in this study were older Caucasian women and so the findings may not be directly applicable to men or people of other ethnicities.

The other study examined data on 3,296 women, of whom 730 were diabetic. Over the 11-year study period, 380 women (11.5%) experienced an eGFR decline of 30% or greater. The highest quartile of sodium intake was associated with a 52% increased risk of a 30% or greater decline in eGFR compared with the lowest quartile, after adjusting for age, BMI, the presence of hypertension, diabetes, and cardiovascular disease, and other potential confounders. The highest quartile of beta carotene intake was associated with a 38% decreased risk compared with the lowest quartile.

In women with well-preserved kidney function, higher sodium intake was associated with greater kidney function decline. These findings were consistent with experimental animal data that high sodium intake promotes progressive kidney decline.

“The findings with dietary sodium we were not surprised at,” Dr. Lin said. “We were a little more surprised at the association we found between artificially sweetened sodas and kidney function decline. Nothing has been reported before [about this association] and we couldn’t even find any experimental animal studies looking at this. So the findings will definitely need to be validated in another population.”

Clinicians may want to suggest to patients that they limit their intake of artificially sweetened beverages to two servings or less a day in addition to following a low sodium diet, especially if a decline in kidney function is a concern, Dr. Lin said.