Craig Baumrucker’s Blog

Ms. Davassambuu has some publish aspects of cows’ milk hormones  that provide some background for her Harvard presentation.  The introduction (Fertility & Sterility 2004. 82:1106) states that “cows’ milk, which contains a considerable quantity of estrogen”.  Current analysis shows that commercial cows’ milk contains <2.5 pg/ml (J.Dairy Sci. Suppl 1 2006 pg 81).  Furthermore, the next sentence in the introduction states “Modern milk has high estrogen content because most is produced during pregnancy when estrogen levels are markedly elevated”. While this statement is generally correct in that ~7/10 of milk production from cows occurs while they are pregnant, the increase in the cow’s blood is not markedly elevated.  There is a minor increase in blood estrogens at the initial stages of pregnancy and the greatest increase occurs during the final stages of pregnancy. However, the pregnant dairy cow is not milked during the final 2 months of pregnancy when the highest estrogens are present in the blood.  In still anther publication, the author states “milk that we are now consuming is quite different from that consumed 100 years ago” and “modern dairy cows are usually pregnant and continue to lactate during the latter half of pregnancy” (Medical Hypotheses. 2005. 65:1028).  First, there is no evidence to suggest that today’s milk (2007) is any different than milk consumed 100 years ago.  In addition, milk estrogen is typically 1/10 that of blood estrogen concentrations.  The statement that “Milk from a cow in the late stage of pregnancy contains up to 33 times as much of a signature estrogen compound (estrone sulfate) than milk from a non-pregnant cow” (Harvard Gazette, Dec 7, 2006) does not consider that estrone sulfate is a degradation product of estrogen and has low bio-activity. Surprisingly, Ms Davaasambuu attended the October 2006 Harvard meeting on Milk, Hormones, and Human Health where these incorrect concepts were addressed.  In addition, what one consumes in their diet does not reflect what will appear in their blood.  Specific enzymes exist in the gastrointestinal tract and liver to specifically degrade dietary steroids prior to their entrance into the systemic circulation.  This is why oral doses of steroid have been clearly shown to require high doses in order to detect an alteration in animal (rodent) physiology.

The statement that Mongolian milk has 10x less progesterone is based on only a few milk samples that was not pasteurized and obtained from non-pregnant cows.  However, the appearance of progesterone in milk is highly variable due to ovarian cycles, and the authors had no reference to these occurrences.  “The statement that “milk we drink today may not be nature’s perfect food” is conjecture.

The pilot study in Mongolia states that “hormone levels jumped among the children fed commercial US milk”, but what is not stated is what hormones jump and what is a jump?  It is expected that this jump is the children’s human growth hormone and human insulin-like growth factors that are most likely the result of the excellent nutritional value of milk when compared with nutritional sources available to Mongolian children.  Mongolian children do not have milk as a staple in their diets.

Finally, her statement “the hormonal effects of milk are very new” is far from reality since hormones in milk and their potential effects on animals have been researched and published for many years – a PubMed search on milk and hormones revealed 6246 published manuscripts.

First, most dietary milk and dairy product links to disease (cancer, etc) are derived from correlations studies utilizing rating scales (see below).  These studies rely on survey data obtain from individuals who list their diets (mostly from memory).  Most current surveys are enhanced by the fact that they are obtained from “professional nurses” who are better at recording or remembering their diets, but recent information suggests that such information is around ~60% reliable.  However, the accumulation of thousands of survey results from numerous countries provides statistical power to diet and correlations.

Statistical Correlations:  This is a statistical technique which can indicate whether and how strongly pairs of variables are related.  Several different correlation techniques may be utilized, but like all statistical techniques, correlation is only appropriate for certain kinds of data.  Correlation works for data in which numbers are quantities of some type and cannot be utilized for categorical data.  Another problem that arises with correlations is the analysis with rating scales (0 to 1; 2 to 4; 5 to 7, etc.).  While these scales represent quantity, their meaning in not precise.  Most statisticians avoid correlations with rating scales because the technique assumes the differences between numbers are exactly equal.

The summation of all of the available diet/survey data from nurses studies indicates a wide variety of slight positive (more incidence) and negative (protective) correlations with selective diseases without providing any possible mechanism of such contradictory action (positive and negative).  Furthermore, the studies do not take into account the highly nutritious nature of milk and dairy products when compared to other foods.  Thus, the correlation data is only a gross indicator that suggests that milk and other dairy products have something different than other foods.  It is logical to suspect nutritional quality.