- J Public Health (Oxf). 2020 Aug 18;42(3):639. doi: 10.1093/pubmed/fdz048.
We have read the interesting study by Kennedy et al.1 that examined the association between nutrient intake during early pregnancy and offspring adiposity at birth. The study concluded that the intake of polyunsaturated fat was positively associated with neonatal adiposity.1
We would like to share our concerns on how to interpret this association. In the report,1 the polyunsaturated fats have not been differentiated into their n-3 and n-6 families, or into their active metabolites, the long-chain polyunsaturated fatty acids (LCPUFA), which may trigger a variety of biological responses, particularly in adipose tissue.2,3 This discrimination might be available through the program WISP4.0 (Tinuviel Software, UK) used in the study. Although there is insufficient scientific evidence regarding the individual effects of n-3 and n-6 PUFA on fetal body composition in humans,4 studies in vitro, in animal models, and in humans have reported that n-6 fatty acids exert an adipogenic effect whereas n-3 fatty acids exert an antiadipogenic effect.2–4 One mechanism implicated is the enhancement of preadipocyte differentiation into functional adipocytes promoted by the n-6 LCPUFA arachidonic acid through the action of its metabolite, prostacyclin; in contrast, both n-3 LCPUFA eicosapentaenoic acid and docosahexaenoic acid, seem to counteract this process.2–4 We are very interested on knowing if the associations observed by Kennedy et al.1 are consistent to those found in our similar, recently published study.5 Pereira-da-Silva et al.5 assessed the association between the intake of LCPUFA during pregnancy and offspring adiposity at birth in 100 mother-infant dyads. Similar to the study by Kennedy et al.,1 the gestational age was confirmed by early ultrasound measurements, air displacement plethysmography was used to measure neonatal body composition, and maternal height and weight were measured rather than self-reported.5 In addition to the pre-pregnancy body mass index, the energy and macronutrient intake and gestational weight gain have been considered in a multivariable analysis.5 An adjusted positive association was found between maternal n-6:n-3 LCPUFA ratio intake and adiposity in female offspring,5 a finding that suggests that the n-6:n-3 fatty acid ratio is at least as important as the individual effect of each fatty acid family.2,6 We suggest that studies exploring the relationship between nutrient intake during pregnancy and offspring adiposity should specifically analyze n-6- and n-3 fatty acid intake and their ratio. Moreover, factors other than pre-pregnancy body mass index that may affect offspring adiposity should be controlled, such as macronutrient intake7 and excessive weight gain during pregnancy.