Table 3 Biospecimen sample collection at visit 2 (Day 7 following intervention)

Maternal blood

• 30 mL blood (Serum tube 10 mL, K2 EDTA 10 mL and 5 mL, and Trace Elements 5 mL)

• Cryopreservation of plasma trace element, serum, plasma, buffy coat, red blood cells aliquots

• Collected between 10 am and 12pm

Breast milk

• Expressed milk (3–8 mL) from a single breast expression episode

• Cryopreserved aliquots of whole milk

Maternal urine

• 25 mL urine

• Cryopreserved aliquots

Maternal stool

• 1x Collection pot (Norgen Biotek)

• Cryopreserved sample pot

Maternal buccal swab

• FloqSwab (Copan Diagnostics)

• Air-dried swab cryopreserved

• Researcher collected