In a recent study, researchers found that estrogens found naturally in cows’ milk are likely to be safe for human consumption in adults.
The new review brings together scientific evidence from over a dozen animal and human studies.
These studies examined the effects of ingesting estrogen-containing cows’ milk on fertility and the risk of cancer development.
The findings of the review show that the levels of estrogens found naturally in milk are too low to pose health risks to adults and that there is no need for public concern.
Estrogens are female sex hormones and naturally present in cows’ milk.
Over 160 million tons of cows’ milk is farmed in the EU in 2016 alone. It is a common constituent of the human diet.
Intensive farming practices have been shown to increase the levels of estrogens found in milk.
This has raised concerns about their potentially detrimental effects on human health.
Ingesting estrogens may have wide-reaching effects on health, including reduced fertility, altered fetal development or an increased risk of hormone-related cancers.
For example, scientists from UCLA suggest that in the interest of efficiency, cows are artificially inseminated to remain in a constant state of simultaneous pregnancy and lactation.
This means significant doses of the pregnancy hormones estrogen and progesterone make their way into milk products sold to consumers, which raises the risk for several cancers.
In the current review, the team reviewed the scientific evidence from over a dozen studies that assessed the safety of ingesting estrogen-containing milk, in both rodents and humans.
In the majority of studies where rats were fed milk or estrogens derived from milk, no differences in reproductive health or cancer risk were reported.
The studies that did report changes in reproductive function or other harmful effects examined levels of estrogens that greatly exceed the amount of milk a person might normally consume.
Some human studies have suggested that milk ingestion can affect growth hormone levels in children.
But it remains unclear whether this association is related to ingestion of estrogens, or whether there are any other adverse effects on their health.
However, the strength of the evidence from the majority of the reviewed studies would suggest that estrogen levels in milk are too low to affect the health of adults.
Nevertheless, this study only examined the possible effects of estrogens and not the other potentially harmful or beneficial health effects of cows’ milk.
The researchers suggest that the majority of studies they reviewed found that the concentrations of estrogens found naturally in milk are too low to pose a risk.
The hormones may not reproductive health or cancer development in adults.
However, studies are lacking that look at any harmful effects of hormones from cows’ milk on baby and child development and health.
Whether the estrogens found in cows’ milk could harm the children still need further research.
The review is done by Professor Gregor Majdic and Professor Tomaz Snoj from the University of Ljubljana in Slovenia.
The new study is published in the European Journal of Endocrinology.
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Source: European Journal of Endocrinology.