madman
Super Moderator
ABSTRACT
Background: Current cow milk production practices introduce considerable levels of pregnancy hormones into the milk. Humans are exposed to these hormones when cow milk is consumed, and this may explain the observed association between cow milk consumption and several hormone-sensitive cancers.
Objectives: The aim of the study was to evaluate whether cow milk consumption is associated with an increase in urinary excretion of sex steroid hormones and their metabolites in humans.
Methods: We conducted a randomized crossover intervention feeding experiment. A total of 109 postmenopausal women consumed 1 L of semiskimmed milk (1.5% fat) per day for 4 d and 1 L of whole milk (3.5% fat) per day for 4 d, intersected by 4-d wash-out periods. Sex steroid hormone levels were measured in 24-h urine samples collected at the end of each intervention and wash-out period.
Results: Estrogens, androgens, and progesterone were detected in the examined milk samples used for our intervention. Although a very high proportion of the estrogens were conjugated, only small proportions of the androgens and progesterone were conjugated. Milk consumption resulted in a significant increase in urinary estrone (E1) excretion, whereas estradiol (E2), estriol (E3), and 16ketoE2 excretion only increased after semi skimmed milk consumption. Urinary pregnanediol glucuronide excretion was not significantly affected.
Conclusion: Cow milk consumption increases urinary excretion of E1 in humans. Ingestion of semiskimmed milk appears also to raise E2, E3, and 16ketoE2 excretion, but future studies need to confirm these associations.
In summary, in this randomized crossover intervention study we observed an increase in urinary estrogens and estrogen metabolites after ingestion of 1 L of cow milk daily for 4 d. Measurable levels of estrogens, androgens, and progesterone were identified in the cow milk selected for this study, in particular in high-fat milk. The increase in bioavailable estrogen levels—predominantly after intake of semiskimmed milk—is of concern in the context of epidemiologic studies linking regular milk consumption to hormone-sensitive cancer.
Background: Current cow milk production practices introduce considerable levels of pregnancy hormones into the milk. Humans are exposed to these hormones when cow milk is consumed, and this may explain the observed association between cow milk consumption and several hormone-sensitive cancers.
Objectives: The aim of the study was to evaluate whether cow milk consumption is associated with an increase in urinary excretion of sex steroid hormones and their metabolites in humans.
Methods: We conducted a randomized crossover intervention feeding experiment. A total of 109 postmenopausal women consumed 1 L of semiskimmed milk (1.5% fat) per day for 4 d and 1 L of whole milk (3.5% fat) per day for 4 d, intersected by 4-d wash-out periods. Sex steroid hormone levels were measured in 24-h urine samples collected at the end of each intervention and wash-out period.
Results: Estrogens, androgens, and progesterone were detected in the examined milk samples used for our intervention. Although a very high proportion of the estrogens were conjugated, only small proportions of the androgens and progesterone were conjugated. Milk consumption resulted in a significant increase in urinary estrone (E1) excretion, whereas estradiol (E2), estriol (E3), and 16ketoE2 excretion only increased after semi skimmed milk consumption. Urinary pregnanediol glucuronide excretion was not significantly affected.
Conclusion: Cow milk consumption increases urinary excretion of E1 in humans. Ingestion of semiskimmed milk appears also to raise E2, E3, and 16ketoE2 excretion, but future studies need to confirm these associations.
In summary, in this randomized crossover intervention study we observed an increase in urinary estrogens and estrogen metabolites after ingestion of 1 L of cow milk daily for 4 d. Measurable levels of estrogens, androgens, and progesterone were identified in the cow milk selected for this study, in particular in high-fat milk. The increase in bioavailable estrogen levels—predominantly after intake of semiskimmed milk—is of concern in the context of epidemiologic studies linking regular milk consumption to hormone-sensitive cancer.
