A new study has found that urban lifestyle behaviors such as eating out and screen time increase cardiometabolic disease risk, as assessed by measuring waist circumference to height ratio (WHtR), blood pressure (BP), levels of glycated hemoglobin (HbA1c) and C-reactive protein (CRP) in the blood.
Cardiometabolic disease, which encompasses a host of conditions including a high waist circumference to height ratio, hypertension, impaired glucose (hyperglycemia, diabetes/prediabetes) and lipid metabolism (hyperlipidemia, high LDL or low HDL cholesterol and high triglycerides), and inflammation, is a major health concern for national healthcare systems. These conditions increase the risk for cardiovascular disease or stroke. Studies indicate that a diet rich in saturated fat, sugars, and sodium, and a sedentary lifestyle contribute to an increased risk for cardiometabolic disease.
It is generally understood that in rapidly urbanizing societies the number of overweight children is increasing more and more rapidly with each generation. However, the intergenerational differences in cardiometabolic risk that accompany changes in lifestyle behaviors have not been examined.
The results of a Chinese study recently published in the American Journal of Clinical Nutrition last month attempted to do just that: identify lifestyle changes underlying increased cardiometabolic risk. The study examined the effects of eating out, snacking, screen time, and leisure time physical activity, all behaviors associated with rapid urbanization, on cardiometabolic disease risk factors in children aged 7-17 and their parents over a period of 19 years from 1991 to 2009. The cardiometabolic disease risk factors examined included WHtR, BP, and the levels of HbA1c, and CRP. Between 1991 and 2009, information related to dietary intake, blood pressure, physical activity, and other anthropometric data were collected at more or less regular intervals in 1991, 1993, 1997, 2000, 2004, 2006, and 2009. However, fasting blood samples were collected and evaluated for HbA1c and CRP only in 2009.
Dietary data included three consecutive 24-hour recalls of foods consumed and an evaluation of food inventories in individual households during this 3-day period. Snacks were divided into fruit/vegetable or other snacks to adequately delineate the effects of different types of snacking on health outcomes. Data on screen time included time spent using computers, watching TV, or playing video games. Physical activity data included participation in martial arts, dancing, gymnastics, track-and-field sports, basketball, swimming, and tennis.
To establish a temporal association between the lifestyle behaviors and cardiometabolic disease risk factors, behavioral data collected one period prior to that of the risk factor measurements was used for analysis. The study also tested whether the associations between lifestyle behaviors and risk factors differed between the child and parent generations.
Results showed that for the parental generation, eating out was negatively associated with a high WHtR, whereas for children there was a positive association between eating out and high WHtR, indicating that parents were more likely to eat healthier meals when eating out. Both parents and children snacking on fruits/vegetables were less likely to have high WHtRs or hypertension compared to nonsnackers.
Children and older parents (≥ 40 years) with ≥ 2 hours/day of screen time were more likely to have high WHtRs at follow-up. Additionally, such children were also more likely to suffer from high BP. On the other hand, children who were physically active were less likely to have high levels of CRP, but parents who engaged in high levels of physical activity showed no associations, positive or negative, with any of the risk factors. There were no significant associations between any of the lifestyle variables and elevated HbA1c levels for children or parents.
One limitation of the study was the small sample size used for CRP and HbA1c analysis, as these metabolites were only measured in 2009. Furthermore, the effect of pubertal or menopausal status of the participants was not taken into account for data analysis. Additionally, the households included in this study had generally high income and were urbanized, which could have introduced bias in the sample, making it less representative of the population.
Overall, the study found that behavior associated with an urban lifestyle increases cardiometabolic disease risk in Chinese children. High WHtRs are indicative of obesity, especially abdominal fat, which is associated with an increased risk for type 2 diabetes and heart disease. A sedentary lifestyle was found to increase the chances of obesity and hypertension, whereas high levels of physical activity were associated with lower levels of CRP, supporting established notions about exercise lowering the risk for chronic inflammation. Finally, the study underlines the importance of promoting healthier lifestyles in public healthcare programs to reduce the risk of chronic disease.
Written By: Usha B. Nair, Ph.D