CREDIT PHOTO
RAPPEL LE LAIT EST CAUSE DE CANCER CAR LES VACHES SONT DE NOUVEAU INSEMINEES EN PERIODE DE LACTATION SANS AUCUNE PAUSE...CELA AUGMENTE LE NIVEAU D' HORMONES
Remember the backlash against the use of recombinant bovine growth hormone (rbGH)? Many commercial dairies now market their milk as free of this synthetic hormone, but that label may not tell you everything you need to know. Thanks to the way it is produced nowadays, milk from a commercial dairy is likely to contain much higher levels of natural sex hormones than you'd find in milk from a traditional (pre-industrial) dairy herd. And that could pose an rbGH-type problem. Some research suggests that elevated levels of these hormones may affect childhood development and raise a person's cancer risk.
"The milk we drink today is quite unlike the milk our ancestors were drinking," Harvard researcher Ganmaa Davaasambuu, an expert on milk-related illnesses, said during a 2006 talk at the Radcliffe Institute for Advanced Study. It "may not be nature's perfect food."
In America and Japan, commercial dairy cows are kept pregnant so they can be milked 10 months a year.
In the early 2000s, Davaasambuu began investigating why the rate of
prostate cancer in Japan, while much lower than that of the United
States, had increased 25-fold over the past 50 years. She and a
colleague, the Japanese doctor Akio Sato, examined 36 years of dietary
data in Japan and found that the incidence of, and mortality from,
prostate cancer correlated
most closely with the consumption of milk. Dairy products weren't
widely available in Japan until after WWII, when it imported American
cows and dairy techniques, and a new law, enacted in 1954, mandated that
schoolchildren drink 200 milliliters of milk at every school lunch.In a follow-up study, Davaasambu found that milk consumption strongly correlated with the rates of breast, ovarian, and uterine cancers in 40 countries. Part of the problem, she believed, was that milk contains high levels of sex hormones such as estrogen. It's well known that estrogens can induce prostate cancer in rats, and some epidemiological studies (but not others) have associated higher blood levels of estrogens in humans with prostate cancer risk. Estrogen imbalances have also been linked to breast cancer, and milk may be a delivery vehicle for the hormone. A 2004 study published in the International Journal of Cancer found that rats fed a diet of milk developed more and larger mammary tumors than those fed a diet of artificial (non-dairy) milk.
If milk does increase our risk of developing certain cancers, Davaasambuu wondered, then why aren't those cancers more common in traditional cow herding societies? Searching for answers, Sato, her Japanes colleague, took his team to Mongolia, where breast and prostate cancer rates are low. They discovered that whole milk from Japanese Holsteins contains far more estrogen and progesterone (67 percent and 650 percent, respectively) than whole milk from Mongolian cows. If Davaasambuu's theory is correct, the difference in hormone levels could help explain the difference in cancer rates between the two populations.
In one study, the researchers concluded that children's sexual maturation could be affected "by ordinary intake of cow milk."
The reason that milk produced in America and Japan has more sex
hormones than Mongolian milk is simple. The free-range cows kept by
Mongolian nomads get pregnant naturally and are milked for five or six
months after they give birth. In Japan and the United States, the
typical dairy cow is milked for 10 months a year,
which is only possible because she is impregnated by artificial
insemination while still secreting milk from her previous pregnancy.
Milk from pregnant cows contains far higher hormone levels than milk
from nonpregnant ones—five times the estrogen during the first two
months of pregnancy, according to one study, and a whopping 33 times as
much estrogen as the cow gets closer to term.As it turns out, the difference in hormone levels between Mongolian and American milk may indeed be significant enough to affect cancer rates. For example, a 2007 study published in the journal Food and Chemical Toxicology found that rats fed commercial milk developed mammary tumors more often than those fed traditional milk. Other studies suggest a possible link between milk hormones and ovarian and uterine cancers: Davasaambuu found that rats fed on commercial milk had uteruses that were significantly heavier than those of rats on a dairy-free diet. A similar study published in 2010 in the journal Environmental Health and Preventative Medicine showed that a diet of traditional milk also affected rat uteruses, but not as much as a diet of commercial milk, which resulted in uteruses about 25 percent heavier on average.
At a 2006 symposium on milk, hormones, and human health in Boston, Davasaambuu and Sato went so far as to suggest that dairy companies add a new category of premium milk to their offerings: Milk produced exclusively from non-pregnant cows.
Aucun commentaire:
Enregistrer un commentaire