Many years ago I had a discussion with a man who went on to win
multiple Mr. Olympia titles. When I asked him about drinking milk, he
told me that he always removed all dairy foods from his diet prior
to a
contest, explaining that milk was “rich in estrogens.” Estrogens are
associated with fat deposition just under the skin, which obscures
muscular definition. In addition, estrogen retains water, blunting
hard-earned muscularity. You may recall the scene in the film “Pumping
Iron” where Arnold Schwarzenegger is asked about drinking milk. He
responds by stating that “milk is for babies.”
But does milk actually contain active hormones, particularly estrogen?
Like testosterone, estrogen is a steroid hormone and is rapidly
degraded in the liver when taken orally. Unless, of course, the
structure of the hormone has been manipulated to block the first-pass
liver metabolism—as is the case with synthetic oral versions of
testosterone, a.k.a. anabolic steroids. Examples of orally active
estrogens include birth control pills for women and other forms of
estrogen that treat menopause symptoms. According to a recent study,
however, commercial milk products contain active estrogen metabolites.
Estrogen is a potent cancer agent, and some studies show that a
higher intake of milk products may be linked to ovarian and other
cancers in women and possibly prostate cancer in men. That’s highly
debatable among researchers, however, and definitive answers are not on
the record. On the other hand, milk and dairy products supply 60 to 70
percent of the total estrogen intake in food. In recent years the amount
of estrogens in milk have increased because of certain dairy-farming
practices. Most milk now comes from cows far into the late stages of
pregnancy, when estrogen concentration in the milk peaks. One study
found that milk from a cow late in pregnancy contained 33 times more
estrone sulfate than milk obtained from a nonpregnant cow.
The study analyzed the estrogen metabolite content in whole milk,
skim and 2 percent fat milk and buttermilk. Buttermilk, whole milk and 2
percent fat milk contained significant levels of biologically active
estrogen metabolites. Skim milk contained the least, buttermilk the
most. Researchers also tested soy milk and found no estrogen
metabolites. Not only was skim milk lowest in estrogen metabolites, but
98 percent of the estrogen it did contain was in the conjugated, or less
active, form. Buttermilk contained the most highly active form of
estrogen metabolites.
The authors note that while estrogen metabolites in these milk
products are much fewer than what are found in estrogen-based drugs, we
don’t yet know their long-term effect. The study also mentioned that
milk contains progesterone, another type of hormone found in higher
concentrations in women.
Other studies suggest that milk contains insulinlike growth factor 1,
considered the active anabolic component of growth hormone. Two
variants of IGF-1 are required for muscle repair and growth. Trouble is,
IGF-1 also encourages rapid cell division and prevents the
self-destruction of cells, both of which can be dangerous in regard to
cancer. The big controversy about milk is the practice of giving
recombinant IGF-1 to cows to increase their milk production. Some say
that milk from those cows contains higher than normal levels of IGF-1,
which is detectable after pasteurization and homogenization. In
addition, bovine and human IGF-1 share the same amino acid sequences,
which means that the bovine version can interact with human IGF-1 cell
receptors.
Critics contend that since IGF-1 is an amino acid–based hormone, it’s
largely degraded in the gut. On the other hand, adults who drink a lot
of milk have an average 10 to 20 percent increase in circulating IGF-1.
How can IGF-1 survive the formidable digestive barrier? The major
protein in milk, casein, contains a protease inhibitor that may shield
IGF-1 from degradation. Milk intake also increases the ratio of
free-to-bound IGF-1, which increases the activity of IGF-1 but also
speeds its breakdown.
While the link between IGF-1 and milk is hardly definitive, the one
between milk and insulin is more realistic. Although milk has a
low-glycemic-index number (about 15 to 30), milk and milk-based foods
paradoxically have a high insulin-stimulating effect, possibly because
of certain protein fractions found in milk. All dairy products, with the
exception of hard cheese, have potent insulin-boosting effects. Adding
200 milliliters of milk to a low-glycemic-index meal increases the
insulin response by 300 percent.
Ironically, many “negative” factors may aid bodybuilding. For
example, increased IGF-1 may have some anabolic impact. The increased
insulin speeds the entry of amino acids into muscle for added muscle
protein synthesis and exerts an anticatabolic effect in muscle. I
suspect that the potent insulin release is there for a reason, as milk
is the primary food for the most rapid period of human growth and amino
acid uptake is integral to it. Insulin also helps regenerate depleted
muscle glycogen. In fact, studies show that drinking milk after a
workout leads to more efficient recovery than most commercial sports
drinks do. Nor can you escape the fact that milk contains whey, the
highest-biological-value protein, as well as other active peptides that
emerging research shows may provide enormous health benefits.
If you’re still concerned about estrogen and other hormone effects of
milk, you can get most of the benefits of milk from a blend of casein
and whey milk proteins, which give you most of the health factors
contained in milk, minus the hormone activity. Whey does, however, bring
on insulin release and possibly IGF-1 activity. Also, if you believe
that drinking milk will smooth you out before a contest because of its
estrogen content, consider that the average man produces 136,000
nanograms of estrogen each day, far more than you’d get from drinking
several gallons of milk.
Farlow, D.W., et al. (2009). Quantitative measurement of endogenous
estrogen metabolites, risk factors for development of breast cancer, in
commercial milk products by LC-MS/MS. J Chromto B. 877(13):1327-1334.
©,2015 Jerry Brainum. Any reprinting in any type of media, including electronic and foreign is expressly prohibited
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