Plain language summary
Ultra-processed foods (UPFs) are foods of little or no nutritional quality and often contain high amounts of saturated fat, trans fats, salt, additives, preservatives, colourings, and flavourings. These foods have become increasingly present in the diet of individuals who live in lower-middle, upper-middle, and high-income countries and may be part of the reason why several non-communicable diseases, such as obesity, type 2 diabetes, heart disease and cancer, are increasing. These foods may impact health at many stages in an individual’s lifecycle and in those who are pregnant increased consumption of UPFs may negatively affect both mother and child. This systematic review and meta-analysis aimed to determine the health impacts of UPFs on the health of mother and child. The results showed that higher dietary intake of UPFs was associated with gestational weight gain, early weaning, lower diet quality, alterations to metabolism in the baby and increased weight in the baby. It was concluded that UPF negatively affected nutrition and disease in the mother and child. There was a limited amount of research, however the quality was deemed quite high. This study could be used by healthcare professionals to recommend a high quality nutrient rich diet with limited UPFs during pregnancy.
Background and Aims: Changes in eating patterns have been leading to an increase in the consumption of ultra-processed foods (UPF), negatively impacting the quality of the diet and generating risk of harm to the health of the adult population, however, there is no systematized evidence of the impact of UPF in maternal-child health. Thus, in this study we aimed to evaluated the association between UPF consumption and health outcomes in the maternal-child population. Methods: Systematic review registered on the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42021236633), conducted according to the PRISMA diagram in the following databases: PubMed, Medline, Scopus, Web of Science, Scielo, and CAPES thesis and dissertation directory. We included original cross-sectional, case-control and cohort studies in any language. Eligibility criteria were (a) food consumption assessment by the NOVA classification, (b) health outcome (nutritional or diseases), and (c) maternal-child population (pregnant, lactating women and infants/children). All data were analyzed and extracted to a spreadsheet structured by two independent reviewers. We evaluated the methodological quality of the studies included using the Newcastle-Otawa Scale and RoB 2. Results: Searches retrieved 7,801 studies and 15 contemplated the eligibility criteria. Most studies included were cohort studies (n = 8, 53%), had children as their population (n = 9, 60%) and only one study evaluated UPF consumption in infants and lactating women. Panoramically, we observed that a higher participation of UPF in children's diet has been associated with different maternal-child outcomes, such as increase of weight gain, adiposity measures, overweight, early weaning, lower diet quality, metabolic alterations, diseases, and consumption of plastic originated from packaging. Only one of the studies included did not present high methodological quality. Conclusion: Despite the limited literature on UPF consumption and health outcomes in the maternal-child population, the highest UPF consumption negatively impacted nutrition and disease development indicators in pregnant, lactating women and children. Considering the expressive participation of these foods in the diet, other studies should be conducted to further investigate the impact of UPF consumption on different health indicators, especially in the lactation phase for this was the one to present the most important knowledge gap. Systematic Review Registration: [https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021236633], identifier [CRD42021236633].
Conflicts of interest:
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
B: Systematic reviews including RCTs of limited number
C: Non-randomized trials, observational studies, narrative reviews
D: Case-reports, evidence-based clinical findings
E: Opinion piece, other
This systematic review aimed to summarise the consumption of Ultra-Processed Food (UPF) in pregnant and lactating women, and infants or children, and identify any associations with relevant health outcomes.
In informing their research question, the authors reference a marked increase in consumption of UPF in recent years, stating that consumption is estimated to count for >50% of energy intake in high-income countries such as the UK. They describe the literature associating UPF with non-communicable disease (NCD) risk, depression, and other morbidities in adulthood, as well as increasing evidence indicating negative associations during key developmental life stages such as the first 1,000 days, childhood, and adolescence.
Methodology followed standard robust systematic review procedures, including an assessment of quality. Of note; percentage of total energy from dietary UPF was defined by NOVA classification*.
From 7,801 hits, 15 studies (eight cohort and seven cross-sectional) were included in the final review; nine conducted in children <10 yr, five in pregnant women and one in lactating women. Fourteen of 15 studies were of high methodological quality.
UPF dietary contribution ranged from 15% to 76% with higher consumption rates reported in English children >1.5 yr, in whom 75% had an excessive free sugar intake. Overall, 12/15 studies found an association between UPF and negative health outcomes.
Pregnancy and lactation: positive associations or trends with: gestational weight gain, indicators of glucose metabolism, feelings of depression/sadness, neonatal adiposity, increased ADHD symptoms and reduced vitamin E status in lactation.
Childhood: positive associations or trends with: weight gain/BMI, waist circumference, fat mass, sugar intake, dental caries, wheezing and respiratory diseases, and urinary biomarkers of plastic compounds (phthalates and bisphenols). Dietary intake revealed increases in dietary energy, saturated fat, carbohydrates, total sugars and vitamin D, and a negative association with protein, polyunsaturated fats, sodium, zinc, vitamin A, folate and fibre.
Authors main conclusion: UPF consumption negatively affects dietary nutritional quality and health outcomes in pregnant and lactating women and their infants, and children. However, literature in this area is limited.
- Robust systematic review methodology.
- Registered protocol on PROSPERO (CRD42021236633).
- Assessment of quality of included studies.
- Subgroup analyses between the highest and lowest UPF consumption groups.
- Limited number of studies included.
- Exclusion of studies that did not assess dietary patterns using the NOVA classification, which may have missed other relevant articles.
- Only includes cross-sectional and cohort studies, which are prone to confounding and bias (Murad et al, 2016).
- Meta-analyses not attempted or not possible.
- No randomized controlled trials (e.g., assessing changes in response to reductions in UPF) included, and unclear from the review if such studies exist.
- Lacking a discussion on possible fortification of UPFs with vitamins and minerals that may be helpful to some population groups e.g., non-meat substitutes fortified with vitamin B12.
Funding: CAPES Foundation (Coordination for the Improvement of Higher Education Personnel in Brazil.
Conflicts of Interest: none declared
*The NOVA classification system was developed by researchers at the University of Sao Paulo, Brazil, and published in 2010. At that time, the term “ultra-processed foods” was a concept (FAO, 2019) that is now considered mainstream. NOVA classifies all foods into four groups according to the nature, extent and purposes of the industrial processes they undergo. The four groups are 1. Unprocessed and minimally processed foods; 2. Processed culinary ingredients; 3. Processed foods; 4. Ultra-processed foods.
FAO 2019. Ultra-processed foods, diet quality, and health using the NOVA classification system. Available at https://www.fao.org/3/ca5644en/ca5644en.pdf, accessed 22.07.2022
Murad MH, Asi N, Alsawas M, et al. New evidence pyramid. BMJ Evidence-Based Medicine 2016;21:125-127.
Clinical practice applications:
- UPF are ubiquitous in the food system, though many people may not be aware of the negative implications of their consumption.
- Education about UPF consumption and the risks associated should be provided, alongside recommendations and advice on how to adopt and maintain a more whole-foods dietary pattern. Education should refer to UPF available in the patient/client’s locality and include help with reading and interpreting food labels.
- In the cases of childhood overweight or obesity, ADHD or respiratory disorders, or during peri-conception, pregnancy and lactation, and especially where there is risk of excessive gestational weight gain, diabetes mellitus, hypertension, depression or risk of depression, UPF should be limited or avoided.
Considerations for future research:
- Evidence in this area is sparse.
- Robust, high quality clinical trials to assess the response on health outcomes to UPF reduction or avoidance, particularly at critical life stages, are warranted.
- In particular, research during the lactation period is lacking. No study was identified investigating the effect of UPF consumption on production and composition of breastmilk and development of specific nutritional deficiencies in infants.