Long-Term Consumption of Sugar-Sweetened and Artificially Sweetened Beverages and Risk of Mortality

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Sugar-sweetened beverages (SSBs) are associated with increased weight gain, diabetes, coronary heart disease, and stroke, but there is little information on how SSBs and artificially sweetened beverages (ASBs) affect mortality. Malik and colleagues have examined the effect of these drinks on mortality in the Nurses’ Health Study (NHS) and the Health Professionals Follow-Up Study (HPFS). The NHS was started in 1976 and included 121,700 women between the ages of 30 and 55 years. The HPFS was started in 1986 and included 51,529 men aged 40 to 75 years. These studies collected dietary data using food-frequency questionnaires in 1984 in the NHS and in 1986 in the HPFS and every 4 years thereafter.

Malik and colleagues demonstrate that total mortality increased with the consumption of SSBs from a reference intake of <1/month to 1–4/month (+1% mortality), 2–6/week (+6%), 1–2/day (+14%), >2/day (+21%) [P<.0001 for trend] even after adjusting for potentially confounding factors. The increased mortality was largely due to increased cardiovascular mortality, which increased 31% between the lowest and highest SSB groups (P<.0001). Cancer mortality also increased between these groups by 16% (P<.0004). Fruit juice was not considered a SSB.

ASBs were also associated with higher total and cardiovascular disease mortality but only in the highest intake group, and the increase was only 4% for total and 13% for cardiovascular mortality (P<.01 and .02, respectively). The association of ASBs with mortality was only noted in the female NHS cohort and not in the male HPFS group. Artificially sweetened beverages were not associated with cancer in either group.

Such observational studies, even when prospective, are always difficult to evaluate. Were the adjustments for confounders sufficient or were some confounders overlooked? Diet studies are especially difficult because they rely on participants accurately reporting their intake. This study has the potential for such problems. The authors note that SSB intake may simply reflect bad dietary or lifestyle habits, but adjusted for confounders appropriately. Also, the food questionnaires were validated, completed by health professionals, and appear to coincide with other physiologic data.

Consequently, this report provides the best data to date that SSBs are a potential health problem, and that their consumption should be discouraged. ASBs appear to be less of a health issue, and primarily in women, but these data require further examination to explain the different effect between the sexes.

This study is based on analyses of data from two remarkably large and long-standing investigations of diet and disease risk. The investigators looked for correlations between mortality and consumption of sugar-sweetened beverages (SSB) and found them. More than two SSB servings a day was associated with higher mortality, particularly from cardiovascular disease, and, to a lesser extent, cancer.

Thus, this study adds to the increasing body of evidence associating SSBs with poor health. SSBs provide calories, but nothing of nutritional value. Other studies correlate SSBs with obesity, type 2 diabetes, and heart disease. A further correlation with increased mortality is not surprising, but it is good to have it confirmed.

These results associate high intake of SSBs with disease risk, but cannot prove that SSBs cause disease. Epidemiological studies like these, based on self-reported dietary data, require careful interpretation. In part, this is because intake of SSBs tracks closely with other lifestyle characteristics. Heavy SSB users tend to be more sedentary, more likely to smoke, to consume more meat and calories, but to eat fewer vegetables than light users—overall, to have less healthy dietary habits in general. Still, reducing or eliminating SSB intake is harmless and could well improve health.