Caffeine Concentrations in Human Milk Donated to a Human Milk Bank in Japan

Background: Human milk banks have been established to provide human milk to preterm infants who are unable to obtain milk from their mothers. Donor screening methods vary, and prospective donors are commonly screened for drug and recreational substance use through behavioral screening. Although the risk of illegal drug consumption in Japan is extremely low, caffeine may be consumed unknowingly and can be found in human milk. To date, only a few reports have been conducted on the concentration of caffeine in donor milk. Research Aim: This study aimed to examine the pre-pasteurization levels of caffeine in human milk donated to a milk bank in Japan. Methods: This was a cross-sectional, observational study of caffeine concentrations in human milk donated to a human milk bank in Japan. Caffeine concentration in the donor milk was measured using high-performance liquid chromatography. Results: Caffeine was detected in 70% of the donor milk samples (N = 350). The median (range) of caffeine concentration was 0.46 [< 0.10, 7.54] mg/L, and 64.0% of the samples had less than 1 mg/L of caffeine. The caffeine concentration varied widely among as well as within individuals. Conclusion: The average caffeine concentration in Japanese donor milk samples was higher than that previously reported in samples from Spain, but the range was similar. Donors should be informed that caffeine intake should be within a moderate range, to further increase the safety of donor milk.