We applied the BQI to assess overall beverage intake quality in a large cohort of Mexican women. There was suggestive evidence for a lower diabetes incidence among women in the upper category of BQI (indicating higher beverage quality), but findings were not statistically significant, and could not be confirmed in continuous analysis.
Research on overall beverage quality assessed with a priori developed beverage scores and cardiometabolic outcomes is limited. Two previous studies showed that higher scores on the HBI and the HBS were associated to lower cardiometabolic risk factors, less kidney function decline, and a lower risk of mortality in US populations [13, 14]. However, two other studies that used the HBI in European population-based cohorts did not find associations with cardiometabolic outcomes, including diabetes [30, 31]. In a previous study, we found that a higher BQI (T3 vs. T1), was associated with lower risk of recurrent cardiovascular disease (CVD), lower risk of CVD mortality and with a potential decrease of diabetes incidence in Dutch patients with history of myocardial infraction from the Alpha Omega Cohort [15]. Similarly, in our population of Mexican women with different beverage patterns, a potential decrease in diabetes incidence was observed.
The BQI was developed based on the current Dutch dietary guidelines [19, 32]. Based on our findings, we conclude that the BQI may not optimally reflect guidelines or intake patterns in Mexico. Previously, Rivera et.al, adapted beverage guidelines developed for the US population to the Mexican context [33]. These guidelines prioritize water, skimmed and semi-skimmed milk consumption, and in third place, unsweetened coffee and tea, and promote the limitation of full-fat milk intake. Unlike the Dutch dietary guidelines, which do not provide recommendations for milk with varying fat content due to insufficient evidence yet to make distinctions between high- and low-fat dairy (milk) [19], the Mexican context, characterized by a relatively high proportion of the population with overweight or obesity, may warrant differentiated scoring based on milk fat content.
Existing literature lends support to health effects of the individual BQI components. The unhealthy beverage components of the BQI, like SSBs, have been consistently associated with higher risk of diabetes [6]. A previous study within the MTC showed that soda consumption is associated with a higher rate of diabetes in a magnitude similar to that reported in other populations (40), and with a higher risk of other cardiometabolic diseases, such as hypertension [34]. On the other hand, coffee and tea, and possibly dairy beverages (yogurt) have been shown to be largely protective for cardiometabolic health [7, 8, 35]. However, in Mexico, healthy beverages such as coffee, tea and dairy beverages tend to be drivers of added sugar intake. Most participants (83%) added sugar to their coffee and tea, and the Mexican beverage pattern is also characterized by added sugar in other popular beverages such as aguas frescas and atoles on top of high SSBs intake. Besides, the most consumed type of coffee in Mexico is instant coffee, rather than the filtered coffee consumed in the Netherlands, for which associations with cardiometabolic outcomes are not fully clear [36, 37]. Teas in Mexico tend to be (sweetened) herbal teas, in contrast to (mostly unsweetened) black tea which is popular in the Netherlands. These factors may counteract a potential beneficial effect of dairy beverages, tea, and coffee intake. And therefore, make this score less suitable to estimate beverage quality in this population.
Moreover, the unhealthy beverage pattern of the participants from the MTC, characterized by high consumption of beverages with added sugar and thus a considerable proportion of energy coming from beverages (20%), was relatively homogeneous. Almost all participants consumed SSBs (99.5%), including those in the highest BQI category. This relative homogeneity in beverage intake patterns affected the scoring, placing most participants in the central categories of the BQI, which hampered comparisons.
Results from sensitivity analyses were in line with main findings, showing a potential lower risk of developing diabetes at higher BQI scores. Also, excluding individual components from the BQI did not greatly change the estimates. However, when excluding the component energy from beverages, the HR decreased the most, although the uncertainty around the estimate was high. We scored calories from beverages separately from other beverage components in the BQI. This approach was taken because cohort studies often adjust for total energy intake, not allowing for ad libitum intake (and overconsumption) of caloric beverages. Therefore, the role of (excessive) energy intake from beverages on chronic disease risk may be underestimated. Healthy, non-caloric alternatives (e.g. water, unsweetened coffee and tea) are available for sweetened beverages, and there is no need to quench thirst with caloric beverages, providing additional rationale for this penalty.
Upon further subgroup analysis, among participants with overweight and obesity, those with the healthiest beverage intake patterns exhibited lower diabetes incidence, with a significant interaction observed between BQI and BMI. BMI could act as a confounder, mediator or effect modifier in the BQI-diabetes association. Therefore, these findings need to be interpreted with caution because BMI could also be a collider (Supplemental Fig. 1), and conditioning on a collider could result in overadjustment bias [38].
Strengths of this study include its large sample size and prospective design with long-term follow-up, access to clinical data for diabetes case identification, detailed information on risk factors for diabetes enabling extensive control for confounding, and the conducted sensitivity analyses. Some limitations of this study should be acknowledged. Self-reported dietary intakes are prone to non-differential misclassification. Aguas frescas and atoles together with sweetened probiotic fermented milk drinks were categorized as SSBs due to their added sugar content, however, their role in cardiometabolic risk is unknow. These beverages may have potential beneficial effects (probiotics, fruits) that could counterbalance the negative effects of added sugar, which may have introduced misclassification biasing the HRs towards the null. Future studies need to clarify the role of these popular beverages on cardiometabolic health. In the FFQ, participants were asked about their added sugar intake in foods and beverages. While we could not differentiate the specific amounts for each, we attributed all reported added sugar intake to beverages such as coffee, tea, aguas frescas, and atoles. This assumption is based on the common practice in Mexico of sweetening these beverages, whereas sugar is generally not added to foods. Approximately 11% of participants did not respond to follow-up questionnaires and were considered lost to follow-up, potentially resulting in selection bias. Those lost to follow-up were slightly older and less likely to have access to internet (proxy for socioeconomic status) at baseline compared to participants included in the study. However, no other significant differences were observed. Finally, the BQI was not specifically created for the Mexican population, thus it may not be the most suitable scoring system to evaluate beverage quality in populations that consume significant amounts of beverages with added sugar.
In conclusion, in a cohort of Mexican women, the BQI for overall beverage quality showed no consistent association with T2D. Future studies should explore and develop composite beverage scores that better reflect population-specific beverage intake patterns and identify optimal beverage intake patterns for cardiometabolic health.