Writing in January issue of the Journal of the Academy of Nutrition and Dietetics, Esther Lopez-Garcia and colleagues from the Universidad Autónoma de Madrid outlined their prospective study with 4,445 individuals aged 18 or older (65% of whom were yogurt eaters) recruited from 2010 to 2012 and followed up in 2012.
The team collected data on HRQL at baseline from groups with different yogurt consumption habits: no consumption, 1-3 servings per month to six servings per week, and greater than or equal to 1 serving (125g was taken as the average serving size across all groups) per day.
“To our knowledge, the effect of yogurt has not yet been studied in epidemiological investigations in the general population,” Lopez-Garcia et al. write.
“The objective of this article was to examine the prospective association between habitual yogurt consumption and the physical and mental components of HRQL among the general adult population,” they add.
HRQL covers physical, mental, social aspects of life
Contextualising their study, Lopez-Garcia et al. said health-related quality of life (HRQL) was a global indicator of perceived health status covering physical and mental factors.
Poor HRQL has been associated with greater use of healthcare systems and higher mortality rates, particularly among older adults; this study used a healthy survey (SF-12 Version 2) to gauge individual perception of the impact of a disease or a risk factor (e.g. yogurt eating) on the physical, mental and social aspects of life.
“Because most studies have focused on the effect of total dairy, it is interesting to assess the independent association between each type of dairy and global indicators of health, such as HRQL,” Lopez-Garcia et al. write.
“Several biological mechanisms suggest that there is a pathway by which yogurt consumption might influence, directly or indirectly, HRQL.
“Specifically, yogurt consumption has been associated with lower weight gain…In addition, consumption of dairy products has been linked to lower blood pressure, and hypertension awareness and treatment are related to impaired HRQL,” the academics add.
They note, moreover, that yogurt is high in calcium – which protects bones, where osteomuscular diseases is one of the health disorders with the greatest HRQL impact.
In addition, the team writes, it has been suggested that probiotics in yogurt can improve gastrointestinal disorders and affect activity in brain regions that control central processing of emotion and sensation.
Consistent results for whole-milk and reduced-fat yogurt
But the reported results did not support these benefits. “We found no association between yogurt consumption and the physical and mental components of HRQL after 3.5 years of follow-up of a population-based cohort. The results also held for whole-milk and reduced-fat yogurt,” Lopez-Garcia et al. write.
They note the role of the European Food Safety Authority health claims regulation (No. 1924/2006), while the US Food and Drug Administration (FDA) regulates structure/function and health claims – where the latter characterizes the relationship between a substance and a disease or health-related condition.
“Our results add a new piece of information to evaluate health claims from the dairy industry,” the academics write.
“Future population-based research should use disease-specific instruments to assess HRQL, in addition to generic instruments, because it can increase the likelihood of finding a potential benefit of yogurt on HRQL,” Lopez-Garcia et al. add, noting the limitations of the SF-12 questionnaire they used to asses HRQL, in terms of capturing data on domains such as digestive or bone health.
Other study limitations they flag up include relatively low yogurt consumption even among the highest-consuming group, a relatively short follow-up period and the fact that HRQL information was self-reported.
Title: 'Habitual Yogurt Consumption and Health-Related Quality of Life: A Prospective Cohort Study'
Authors: Lopez-Garcia, E., Leon-Munoz, L., Guallar-Castillon, P., Rodriguez-Artalejo, F.
Source: Journal of the Academy of Nutrition and Dietetics, Vol. 115, Issue 1, January 2015. Available online, July 19 2014. doi:10.1016/j.jand.2014.05.013