Yuzo Tamari

Longitudinal study on selenium content in human milk particularly during early lactation compared to that in infant formulas and cow's milk in Japan

239 samples of human breast milk were collected from 36 healthy Japanese women. Selenium content of the samples was determined mainly by highly sensitive fluorometric analysis with 2,3-diaminonaphthalene. The highest selenium content, 247 micrograms/kg, was found on the first day postpartum. The arithmetic mean of selenium content was higher in colostrum (< 4 days) 47 micrograms/kg (SD 42, n = 116) than in transitional milk 24 micrograms/kg (SD 13, n = 87) or in mature milk (> 10 days) 10 micrograms/kg (SD 4, n = 36). Selenium content was also determined for six brands of commercial infant formula powder (32-58 micrograms/kg) based on cows milk, seventeen brands of cows milk (10-25 micrograms/kg) and eight brands of powered cream for cofee (9-162 micrograms/kg). The average selenium content was significant lower in the liquid formula prepared for infant lactation, 6.0 micrograms/L, than in the human colostrum and transitional milk. The dietary selenium intake of newborns fed on colostrum is estimated to be in the range of 2-12 micrograms per day.

Neutron activation analysis of biologically essential trace elements in environmental specimens using pyrrolidinedithiocarbamate extraction

A new radiochemical group separation method using APDC reagent in the extraction procedure has been developed. The method has been applied to the radiochemical separation for activated biological samples and also to the preconcentration technique for sea water samples. The transition elements are extracted into chloroform phase from the pH 3.0 aqueous phase and only manganese is subsequently extracted from the pH 7.0 aqueous phase. The validity of the method is demonstrated by analyzing the NBS standard reference materials. In the specimens preconcentrated from the sea water samples adjusted pH to 5.5, vanadium, manganese, copper and zinc can be determined.

Quantitation of Taurine and Selenium Levels in Human Milk and Estimated Intake of Taurine by Breast-Fed Infants during the early Periods of Lactation

With these results we report the following: Taurine levels in human milk decreased slightly during the early lactation period. The concentration of taurine (406 +/- 174 nmol/ml) in colostrum was significantly higher than that (335 +/- 115 nmol/ml) in mature milk. Selenium content of human milk also decreased slightly during the early lactation period. The content of selenium (28.6 +/- 19.6 ng/ml) in colostrum was significantly higher than that (1 5.1 +/- 5.9 ng/ml) in mature milk. A correlation was not found between the taurine and selenium content of human milk. The intake of taurine and selenium by breast-fed infants progressively increased with days postpartum. These results were due to the significant increase in milk intake by infants. It is suggested that the taurine and selenium levels in colostrum are more concentrated than those in mature milk. However, the absolute intake of taurine and selenium by infants are higher in mature milk.

Longitudinal Study of the Dietary Selenium Intake of Exclusively Breast-fed Infants During Early Lactation in Korea and Japan

213 samples of human breast milk were collected from 51 healthy Korean women. Selenium content of the samples was determined by atomic absorption spectrometry with hydride generation. The selenium content of Korean milk decreased with increase of days after birth: The arithmetic mean of selenium content was higher in colostrum (< 4 days) 34 micrograms/kg (SD +/- 11, n = 44) than in transitional milk 21 micrograms/kg (SD +/- 8, n = 78) or in mature milk (> 10 days) 13 micrograms/kg (SD +/- 6, n = 91). The daily dietary selenium intake of 0-1 month aged Korean infants fed on breast milk is estimated to be around 10 micrograms per day (3 micrograms/kg body weight) regardless of days postpartum, resulting from the calculation of our selenium data and daily milk intake during early lactation. The same result on selenium intake for Japanese newborns, as well as Korean infants, is also estimated to be around 10 micrograms per day (3 micrograms/kg body weight) regardless of days postpartum.

Selenium Intake for Infants Immediately After Delivery

Abstract Selenium content of colostral milk and mature milk in 5 months after birth was determined by fluorometry with 2,3- diaminonaphthalene. In the first milk after birth selenium was contained to be the highest amounts of 29.4 ng/g but selenium concentration decreased to about 9 ng/g after the birth of 1 week. In the lactation period of 10 to 171 days, the concentration was almost constant to be 9.0 ± 1.2 ng/g. The content of infant formulas (milk powder for young infants) based on cows milk was 42.9 ± 8.4 ng/g corresponding to 6.0 ± 1.2 ng/ml in the liquid milk prepared for lactation. Therefore selenium intake was calculated to be about 17 μg/d in the colostral milk-feeding infants after delivery and about 8 μ g/d in mature milk-feeding infants at the age of more than 1 month after birth, whereas it was 3 -6 μ g/d in formula-feeding infants.