The global prevalence of obesity and its associated chronic diseases demands that strategies be identified to halt this public health problem. Although growing evidence shows that increased intake of sugar-sweetened beverages (SSBs) is linked with increased energy intake, weight gain, and cardiometabolic risks, few randomized clinical trials have been conducted in adults.
[Photo: Dr. Barry Popkin in the Carolina News Studio]
According to recent data from the Mexican National Survey, more than seven out of every 10 Mexican women are overweight or obese and almost four of 10 are obese. According to the World Health Organization, by 2012, the leading causes of death in the country were coronary heart disease and diabetes. In 2006, the prevalence of metabolic syndrome among Mexican women older than 20 years was 52.2 percent, and 26.9 percent of women in that group were found to have hypertriglyceridemia, i.e., elevated concentrations of triglycerides, or fatty acids, in the blood.
A study published early this year by the National Institute of Public Health in Mexico (INSP) and the University of North Carolina at Chapel Hill (UNC) reported that by 2012, people in Mexico were among the highest consumers of SSBs in the world, with those beverages representing 19 percent of Mexicans’ energy intake.
The high level of SSB intake in Mexico led researchers at UNC and the INSP to develop a randomized controlled trial to study whether replacing sugar-sweetened beverages with water would affect plasma triglycerides, weight, and other cardiometabolic risk factors. The study showed that providing water and nutritional counseling was effective in increasing water intake and in partially decreasing intake of SSBs. Even though the researchers found no overall effect on plasma triglycerides, weight, and other cardiometabolic risks in women participating in the study, the intervention (providing water and nutritional counseling) lowered plasma triglycerides and the metabolic syndrome prevalence among obese participants (representing almost four of every 10 Mexican women).
Study co-authors included Dr. Barry Popkin, senior author and Kenan Distinguished Professor of nutrition at UNC’s Gillings School of Global Public Health; and from INSP, Dr. Sonia Hernández Cordero, study principal investigator and assistant professor; Dr. Juan Rivera Dommarco, senior study author and founding director of INSP’s Center for Research in Nutrition and Health (CINyS, for its acronym in Spanish); Dr. Simón Barquera, area director of policy research and nutrition programs at CINyS, and Dr. Sonia Rodríguez-Ramírez, Dr. Teresa González de Cossío, and Ms. María Angeles Villanueva, all CINyS researchers.
To study the effect of substituting water for SSBs, researchers at the INSP and UNC designed a randomized controlled trial, in which overweight and obese Mexican women, ages 18 to 45 years, were invited through an advertising campaign to participate in a nine-month study. Half of the participants, the intervention group, received water and nutrition counseling every two weeks during the study. The counseling included individualized and group meetings targeted to the rationale and strategies to increase water intake, reduce SSB intake, and substitute water for those beverages. The other half, the control group, received nutrition counseling that targeted general nutrition topics not related to weight loss or water intake and SSBs.
A considerable percentage of women in the control group increased their water consumption and decreased the SSB intake. This phenomenon was unexpected, given that none of the women in the control group received guidance about healthy beverage consumption. This unanticipated change among women in the control group resulted in both groups drinking more water and fewer SSBs.
“The effect of water substitution for SSBs among obese women possibly is explained by a greater physiological response to a modification intervention in subjects with greater risk (i.e., heavier initial weight),” Dr. Barquera said. “These results have been suggested by others in studies conducted with children.”
“The results are very relevant in a population like Mexico’s, where the prevalence of obesity in women reaches almost 40 percent,” added Dr. Rivera Dommarco.
Dr. Hernández Cordero said that even though more research is needed, the study results are very encouraging. ”It is important to find that a simple intervention such as substituting water for sweetened beverages could have a positive impact on public health,” she said.
“These results are particularly relevant,” Dr. Popkin said, “given that Mexico is one of the first Latin American countries to tax SSBs with the hope that the tax will reduce SSB intake and increase water consumption.”