Detection of breastfeeding and weaning in modern human infants with carbon and nitrogen stable isotope ratios

Abstract

Carbon ((13)C/(12)C) and nitrogen ((15)N/(14)N) stable isotope ratios were longitudinally measured in fingernail and hair samples from mother-infant pairs where infants were exclusively breastfed (n = 5), breast- and formula-fed (n = 2), or exclusively formula-fed (n = 1) from birth. All exclusively breastfed infants had a dual enrichment in carbon ( approximately 1 per thousand) and nitrogen ( approximately 2-3 per thousand) when compared to maternal values. In contrast, breast- and formula-fed subjects had reduced enrichments compared to exclusively breastfed subjects, and the exclusively formula-fed infant showed no increase in delta(13)C or delta(15)N values. This finding of a carbon trophic level effect in breastfeeding infants suggests that (13)C-enrichments of approximately 1 per thousand in archaeological populations are not necessarily the result of the consumption of C(4)-based weaning foods such as maize or millet. During the weaning process, the delta(13)C results for breastfed infants declined to maternal levels more rapidly than the delta(15)N results. This suggests that delta(13)C values have the potential to track the introduction of solid foods into the diet, whereas delta(15)N values monitor the length of time of breast milk consumption. These findings can be used to refine the isotopic analysis of breastfeeding and weaning patterns in past and modern populations.

Isotope evidence for the use of marine resources in the Eastern Iberian Mesolithic

“…Two infants have more positive d 13 C values (À17.5&) but similar d 15 N ones to that of the main group. This is probably not due to breastfeeding as there is no increase in nitrogen isotope values, which we would expect with breastfeeding (Fuller et al, 2006). This isotopic pattern could be explained by a C 4 or marine resource consumption in the diet.…”

“…They also situate the humans in a higher trophic level than the herbivores (5.5& higher) and within the range of carnivore values. The isotope values for individuals do not appear to differ according to sex or age (see Table 4), not even considering the infant or perinatal individual differences that could be attributed to social practices such as breastfeeding (Fogel et al, 1989;Fuller et al, 2006) or weaning (Herring et al, 1998).…”

Isotopic anthropology of rural German medieval diet: intra- and inter-population variability

“…Higher δ 15 N col among humans consuming primarily vegetarian diets could reflect the consumption of domesticated crops grown using animal manure, which could increase plant δ 15 N by~3 to 5‰ (Bogaard et al 2007). Breastfeeding infants tend to sit at a higher trophic level relative to the parent population (Fogel et al 1989;Fuller et al, 2006) though the reasons for this pattern are still debated (Beaumont et al 2015). In the larger ecosystem, aquatic animals commonly have the highest δ 15 N col because aquatic plants typically have higher δ 15 N relative to terrestrial plants and because there are more trophic levels in marine and freshwater systems (Schoeninger et al 1983;Schoeninger and DeNiro 1984).…”

Assessing human weaning practices with calcium isotopes in tooth enamel

“…Despite possible effects of dietary transition on carbon and oxygen isotope ratios of skeletal remains (see review in ref. 14), the most widely accepted biomarker for weaning practices is the nitrogen isotope ratio measured in hair, fingernails, bone, or dentine collagen (22)(23)(24)(25). The Sr/Ca and Ba/Ca elemental ratios in tooth enamel and dentine have also proved relevant for reconstructing early-life dietary transitions (1,26,27).…”