In a recent review, researchers in Germany examined the associations between various dietary factors and biomarkers of childhood and adolescent obesity.
Childhood and adolescent obesity is on the rise worldwide, although it is not clear why. Diet has consistently been shown to be an important factor in obesity, but most studies have not been able to specify the foods or nutrients associated with the disease. Biomarkers are specific molecules or substances that health care providers can measure to give an indication of health. For instance, in adults, doctors often measure C-reactive protein as a biomarker for inflammation, and triglycerides as a biomarker for obesity. The specific biomarkers to use in children and adolescents, however, may not be the same as in adults.
In an article recently published in Nutrition Journal, researchers reviewed existing studies to clarify the associations between diet and biomarkers of obesity in children and adolescents 3 to 18 years old.
To select studies for analysis, the researchers searched PubMed and the Web of Science Core Collection for articles pertaining to childhood and adolescent obesity. With thousands of studies, the researchers reviewed the abstracts individually and compiled 81 potentially relevant articles to use, which included 52,764 participants in total. They rated each study for quality from 0-11, with 11 being high quality, based on factors such as sample size and study design. Only 3.7% of studies were high quality and over half (58%) were low quality. Additionally, 79% of studies were cross-sectional and to collect data on food intake 38.3% of studies used questionnaires, and 37% used food recall surveys.
Which Dietary Factors are Linked to Biomarkers of Obesity?
In the 81 articles used for the review, there were 1,111 instances where diet was associated with a biomarker of obesity. The biomarkers of systolic blood pressure, total cholesterol, diastolic blood pressure, and Homeostasis Model Assessment insulin resistance were most frequently linked to dietary factors.
Systolic blood pressure had the most instances of being linked to dietary factors and 16% of these instances were significant. However, the findings varied from study to study, with some stating a dietary factor was linked to systolic blood pressure, while others reported the same dietary factor had no association with the biomarker. This inability to conclude on an association between biomarkers and dietary factors was found with other biomarkers as well.
Weak Associations Between Dietary Factors and Biomarkers of Obesity
The researchers also looked at the data by the significance of the association between dietary factors and a specific biomarker. The three biomarkers with the highest significance were C-reactive protein (35.5%), fasting triglycerides (31.1%) and fasting insulin (25%). The researchers found that for most studies there were only one or two instances where a single dietary factor was associated with C-reactive protein.
Although some associations between dietary factors and biomarkers of obesity have been found, the researchers were unable to make conclusions about these associations. In many of the studies, the participants’ self-reported food intake, or the parents reported for their children. There is a tendency to underreport unhealthy foods eaten, and parents cannot be completely sure of what their child consumed while not in their care (i.e., while the children are at school), which may have led to inaccuracies in the dietary data. Furthermore, the biomarkers chosen may not have been optimal as there are hormonal changes during adolescence that could influence the biomarkers found.
To better understand childhood and adolescent obesity and their related dietary factors, research on this subject should find the most appropriate biomarkers for this age group, use suitable methods of dietary data collection, and conduct longer-term studies.
Written by Monica Naatey-Ahumah, BSc
Reference: Bosle, C., Motoc, I., and Hoffmann, K. (2017). Associations between dietary factors and obesity-related biomarkers in healthy children and adolescents – a systematic review. Nutrition Journal, 16(85). https://doi.org/10.1186/s12937-017-0300-3