By Martin S. Lipsky, MD
Adjunct Professor,
Institute on Aging,
School of Community Health,
Portland State University;
Dean Emeritus,
University of Illinois College of Medicine,
Rockford
Dr. Lipsky is a retained consultant for Health Solutions & Strategies.
SYNOPSIS: Increasing diet soda intake was associated with increasing abdominal obesity in an aging population.
SOURCE: Fowler PG, et al. Diet soda intake is associated with long-term increases in waist circumference in a bi-enthic cohort of older adults: The San Antonio Longitudinal Study of Aging. J Am Geriatr Soc 2015; DOI: 10.1111/jgs.13376.
Over the past several decades, concerns about increased sugar consumption has led some experts to recommend the use of non-nutritive sweeteners (NNSs).1 However, while it may seem counterintuitive, the impact of NNSs and diet soda intake (DSI) on health outcomes appears to be negative.2,3 To date, most studies exploring DSI focused primarily on middle-aged or younger adults rather than on older individuals. Since older adults are at high risk for cardiovascular disease, evaluating the impact of DSI on this group is important. To determine the relationship of DSI and health outcomes on older adults, Fowler and colleagues3 studied a bi-ethnic cohort of older Mexican-American and European individuals as part of the San Antonio Longitudinal Study of Aging (SALSA). They assessed DSI and followed waist circumference (WC), an indirect measure of total and abdominal adiposity associated with greater cardiometabolic risk.4
SALSA gathered data on the health status of 749 Mexican-American and European-American elders, aged 65 and older, and tracked their health outcomes for more than 9 years. Interviewers recorded the number of sodas consumed and whether they were diet or regular at the beginning of the study and at each of three follow-up visits. The investigators also measured WC, DSI, height, weight at onset and at each of the three intervals.
The study tracked 466 survivors for more than 9 years. After adjusting for initial WC, demographic characteristics, physical activity, diabetes mellitus, and smoking, the mean interval WC change of DSI users was 2.11 cm, almost triple the WC change 0.77 cm for those who did not consume diet sodas. In a subanalysis stratified for covariates, WC changes were consistently higher among DSI users.
The authors concluded that DSI was associated with escalating abdominal obesity and is a potential cardiometabolic risk factor in an aging population.
COMMENTARY
Personally, I like diets soda and used to recommend that individuals who drank soda to switch to diet soda to avoid the sugar and calories found in soft drinks. Intuitively it made sense that substituting 140 calories of sugar for a diet drink without calories would be beneficial. Unfortunately, this study adds to a growing literature associating the frequent use of DSI and NNSs with obesity and metabolic dysregulation. Therefore, for clinicians who advise older adults to drink diet soda as a strategy to help maintain their waistlines, these findings are sobering. Instead of helping, DSI may instead be a “belly” promotor. Among participants who reported occasional DSI — drinking less than one diet soda a day — waist circumference increased almost 2 inches, and among those who consumed diet sodas daily, their waist circumference increased more than 3 inches, or more than triple those with no DSI.4
The findings of an increase in waist size — the proverbial spare tire — correlates with a disproportionate increase in visceral fat, which is associated with a greater risk of metabolic disease, diabetes, heart attack, stroke, cancer, and mortality. A recent study5 also linked drinking diet soda to an increased risk of heart disease in younger women.
A key question is whether the association between diet soda and adverse health outcomes is actually caused by DSI. The authors note that they are not establishing causation but reporting an association. However, they also note that their results are consistent with other studies linking DSI to an increased risk of diabetes, heart attack, stroke, and other major medical problems. However, if DSI is causal, the reasons why remain unclear.
So what are some possible reasons?6,7 One is that there is no causal relationship and DSI is a marker of those with weight issues who are already on an increased waist circumference trajectory. Another common speculation is that DSI may trigger cravings to overeat, or because consumers overestimate their calorie savings, believe they have earned the right to eat more. The actual biological effect of DSI is still being explored, and it may be that DSI slows metabolic rate. Of interest, a recent study in Nature8 found that artificial sweeteners changed the colonies of gut bacteria in mice in ways that adversely affected their glucose tolerance, suggesting a direct biological effect.
So at this time, what should one do with older patients? Perhaps counseling about the risks of DSI and stressing other alternatives, such as plain water, as a prudent strategy.
REFERENCES
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Malik VS, et al. Intake of sugar-sweetened beverages and weight gain: A systematic review. Am J Clin Nutr 2006;84:274-288.
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Swithers SE. Artificial sweeteners produce the counter intuitive effect of inducing metabolic derangements. Trends Endocrinol Metab 2013;24;431-441.
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Fowler PG, et al. Diet soda intake is associated with long-term increases in waist circumference in a bi-enthic cohort of older adults: The San Antonio longitudinal study of aging. 2015 J Am Geriatr Soc DOI: 10.1111/jgs.13376.
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Chang SH, Beason TS et. al. A systematic review of body fat distribution and mortality in older people. Maturitas 2012;72:175-191.
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Vyas A, et. al. Diet drink consumption and the risk of cardiovascular events: A report from the women’s health initiative. J Gen Intern Med 2015;:462-468.
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Fowler SP, et al. Fueling the obesity epidemic. Intake of sugar-sweetened beverages and weight gain: A systematic review. Obesity 2008;16::1894-1900.
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Malik VS, et al. Intake of sugar-sweetened beverages and weight gain: A systematic review. Am J Clin Nutr 2006;84:274-288.
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Suez J, et al. Artificial sweeteners induce glucose intolerance by altering the gut microbiota. Nature 2014 ;514:181-186.
