Milk does contain estrogen, but whether it's considered "high" is complex and depends on several factors. While milk and dairy products contribute significantly to estrogen intake in Western diets (accounting for 60-80%), the actual amount and bioactivity vary.
Estrogen in Milk: A Detailed Look
Several factors influence the estrogen content in milk:
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Cow's Pregnancy Stage: Estrogen levels in milk are higher during the later stages of a cow's pregnancy. Modern dairy farming practices often mean cows lactate throughout pregnancy, leading to higher estrogen levels in commercially produced milk than in milk from cows not in late pregnancy.
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Milk Type: The fat content influences estrogen levels. Whole milk has higher estrogen levels than skim milk because hormones like estrogen are fat-soluble.
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Bioavailability: Not all estrogen in milk is readily absorbed by the body. While some forms, like estrogen sulfate, have relatively high oral bioactivity, others have lower bioavailability.
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Overall Dietary Intake: The amount of estrogen from milk needs to be considered in the context of total estrogen intake from all sources. Other foods and beverages, such as soy products and even red wine, also contain estrogens.
Several studies show a link between milk consumption and estrogen exposure. However, research also suggests that consuming natural estrogens in cow's milk does not necessarily affect blood estrogen levels significantly in humans. More research is needed to fully understand the long-term effects of consuming estrogen from milk.
References
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Studies show that about 60–80% of estrogens come from milk and dairy products in western diets. Although the oral bioactivity of free 17β-estradiol and oestrone may be a bit low, but oestrogen sulphate as a main conjugate in milk, has a relatively high oral bioactivity (9). (Source: Uncited study referenced in the provided text.)
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How Does Dairy Affect Your Hormone Levels? | Scientific American
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Milk, Hormones and Cancer | Office for Science and Society - McGill ...