New research presented at this year's European Congress on Obesity (held online, 10-13 May) shows that higher consumption of ultra-processed foods (UPF) in childhood is associated with an increased risk of childhood obesity and also alters the metabolome (small weight molecules / metabolites) present in the cells and involved in the body's processes at the molecular level.
The study is by Dr Evangelos Handakas, School of Public Health, Imperial College London, UK and colleagues supported by the European Commission Horizon 2020 Grant to the 'STOP Project' (Science and Technology in childhood Obesity Policy).
Diets high in ultra-processed food (UPF) have been linked with weight gain and risk of overweight, obesity, diabetes, and cardiovascular diseases. In this study, the authors aimed to investigate the associations between UPF consumption and the metabolome and their role in overweight and obesity risk, in early childhood and adolescence in a large British cohort.
The researchers used nuclear magnetic resonance spectroscopy (NMR) to analyse the metabolomic profile of plasma samples of over 4500 children from the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort.* They investigated the association between 1) UPF consumption and metabolomic profiles in mid childhood (average age:7.5 years) and 2) UPF consumption at the age of 13 years and metabolomic profile in adolescence (average age:16.8 years) using statistical modelling.
UPF intake was derived from 24-h recall using a structural diary of all food and drinks consumed by the participants. Food records were transformed into portion weights as well as energy and then expressed as a percentage of the total daily food energy intake using the NOVA food classification. The NOVA classification assigns a group to food products based on how much processing they have been through and consists of 4 groups: 1) "unprocessed or minimally processed foods" (examples: fruits, eggs), 2) "processed culinary ingredients" (such as salt, sugar, vegetable oils), and 3) "processed foods" (for example most freshly baked bread) and 4) "ultra-processed foods" that are formulations of ingredients, mostly of exclusive industrial use (such as mass produced packaged breads and cookies).
All the models were adjusted for child age, sex and BMI, maternal age, maternal education level, pre-pregnancy BMI, family income, average time spent on TV, presence of smokers at home and physical activity.
In mid-childhood, 128 of the initial 232 metabolic traits showed a statistically significant association with UPF consumption, and 98 of these associations remained after further statistical analysis. The results showed that in middle childhood, a diet with a higher proportion of UPF was negatively associated with the metabolites including docosahexaenoic acid (DHA) and omega-3 fatty acids (generally considered biomarkers of fish consumption), tyrosine and branched-chain amino acids (BCAAs) (leucine, valine and isoleucine) as well as small, medium and large high-density lipoproteins (HDL-also called 'good' cholesterol).
Additionally, in middle childhood the results showed that citrate, small, medium and large very-low-density lipoproteins (VLDL) were positively associated with UPF consumption. VLDL particles are mainly made up of triglycerides-also called 'bad' cholesterol - these are produced by the liver and are the major carrier of triglycerides in blood plasma. Alterations in VLDL levels are associated with cardiometabolic diseases and usually indicative of a lower quality diet.
In adolescence, 79 metabolic traits showed a statistically significant association with UPF consumption, and here only 19 of them were associated with UPF consumption after further statistical analysis. At adolescence, diet with a higher proportion of UPF at the age of 13 years was negatively associated with ratio of docosahexaenoic acid to total fatty acids (%), ratio of omega-3 fatty acids to total fatty acids (%), apolipoprotein A-I, glucose, sphingomyelins, and cholesterol levels in large and very large HDL. Additionally, higher UPF consumption at the age of 13 years was associated with increased triglycerides in total lipids in Intermediate-density lipoproteins (IDL) (lipoproteins similar to low-density lipoproteins (LDL) that transport a variety of triglyceride fats and cholesterol), LDL, and VLDL (%) in adolescence.
Preliminary data from the study show body mass index increased significantly by an additional 0.33 kg/m2 per 2 years in childhood for each 1% increase in the proportion of UPF in the diet.
Additionally, the mediation analysis (causal relationship analysis) showed that this effect on child body mass index is mediated by 20 metabolic traits, the most important being including docosahexaenoic acid (one of the most important omega-3 fatty acids mainly found in seafood), tyrosine (an amino acid that is essential to our diet and its intestinal levels are dependent on the gut microbiota and gut metabolism), and the free total cholesterol to total lipids ratio in very large VLDL particles. This is, say the authors, a preliminary analysis, and the findings will be updated in the coming months.
The authors conclude: "High-level consumption of UPF during childhood is associated with altered metabolomic profiles. It also increases the risk for children to become overweight/obese. The findings reveal the significant role of nutrient-poor diets and lifestyle behaviours in metabolic dysfunction in children and adolescents."