IGF-1, Milk and Cancer

Complete Patient
May 14, 2007

In response to an article from Harvard Magazine titled, “Modern Milk,” the following article and comments from subscribers of the Complete Patient blog who are in favor of raw milk consumption (like the blog owner), were mixed in their concern regarding the natural hormones present in all milk. The full article and comments are at Complete Patient.

Excerpt…

Part of the joy of drinking raw milk and partaking of other locally-produced and non-processed foods is being more a part of a natural system, a cyclical system that revolves around seasonal changes, old-fashioned grazing, and animal reproduction cycles.

Well, it’s this last point that may create a problem for my raw milk consumption. A friend who knows of my interest in raw milk sent me an article from the current issue of Harvard Magazine, which quotes a Mongolian physician expressing concerns about the natural hormone levels of milk (excluding BGH-fed cows). Her research indicates that much of our milk has high levels of estrogens, which have been implicated in hormone-dependent cancers like those of the prostate, breast, uterus, etc.

This physician became interested in the subject of milk when she noticed differences in dairy practices between her native Mongolia and Westernized countries. In Mongolia, pasture-fed cows are milked only through the first three months of a pregnancy, when hormone levels are still low, while in Westernized countries cows are kept pregnant and lactating 300 days a year. And, indeed, she has found evidence that hormone-based cancers in Japan, which uses Westernized dairy practices, have increased since the 1950s at about the same rate as milk consumption increased.

I wondered when I read this whether the same practices apply to farmers producing raw milk, so I called the New Hampshire farmer who supplies me with my milk. She told me that cows have the same nine-month pregnancy cycle as humans, and she milks through the first seven months of a pregnancy; the last two months the cows get “a rest,” and then after birth the cows begin being milked again. This is all standard practice, she said, whether a farmer is selling milk raw or sending it off to a processing plant for pasteurization.

The cow that has been providing my milk, she said, is currently pregnant and due in September. That means she became pregnant in January, and is currently in her fifth month of pregnancy, well into the “high-hormone” period. This farmer has a second cow, but it is currently in its rest period.

I’m uncertain what to make of this situation. As someone who has had prostate cancer, I’ve been told to avoid consuming anything that would stimulate increased testosterone production. But would estrogen do that? There is a school of thought that recommends increased consumption of soy products for men as a way to reduce prostate cancer risks, because of soy’s natural estrogen. Confusing stuff.

Yet in the case of the raw milk, I’m thinking that maybe the best thing to do is avoid drinking milk produced by cows in the fourth through seventh months of pregnancy. That means I have to start shopping around for raw milk, and inquiring of farmers about the pregnancy status of the cows producing the milk.

Obviously, other people have their own special concerns. Indeed, the Harvard Magazine article quotes the researcher as suggesting that cows in late pregnancy should not be milked or, if they are milked, their milk should be labeled to show it comes from a pregnant cow.

I guess I can’t just assume the natural cycles are always working for me. But the advantage I have as someone buying directly from a farmer I know is that at least I can find out the real situation.

Comments

The article stated that skim milk is low in hormones, so you could always use that method. With raw milk, does that mean you let it settle and take the “fat” off the top. How does one skim milk?

Of course the downside is not drinking milk whole, the way nature has made it. I’m sure the fat has many good nutrients that you would now be missing.

Decisions, decisions, decisions!

May 11, 2007 | Mary…

Very interesting…could this be one reason why goat milk is typically considered healthier? Goats have only a five month gestation and are dried off two months before due to deliver, though I usually give my dairy goats up to three months off.

Another thought to consider is that milking animals do not ~have~ to be rebred. Last fall I experimented with milking a yearling doe through the winter… she’s still milking now, some 15 months later. It was enough successful (milk production does drop during winter milking, but picks up some in the spring flush) for me to consider putting half the herd on alternate breeding years, so that each goat would be bred once every two years.

Dairy cow farmers, however, may be very reluctant to breed every other year since cow gestation is nearly twice as long, with typically only one calf to show for it, either a keeper (heifer) or future hamburger (bull), with therefore relatively few offspring per cow’s lifetime. Farmers probably won’t want to cut even further into their profits by losing the income that even a bull calf would generate.

Answer for David’s hormone milk problem: Drink goats milk!
Jenny

May 12, 2007 | Jenny…

I would slow down on reacting to that report. There are very many intertwined biological processes to consider here.

Just one which likely has a significant roll to play is that the cow’s natural cycle also begs for a spring calf. That’s when the grass is just getting tall and green, and the milk (if the cow is grass-fed!) is rich with the famous cancer-preventer, conjugated linoleic acid. A very reasonable question therefore could be this: Does following that natural cycle afford a balance between cancer causers and preventers?

I know there are a lot of assumptions in that question, but that is essentially my point–too little data leads to too many assumptions. When there is too little data, and there almost always is too little, my suggestion is to go with the natural indicators. Follow the natural cycles.

Our cow will be bred in late July, dried off in late December, and freshen in late April. I guess, according to the Mogolian physician, that puts us two months into the danger zone. But it sure seems like a very reasonable and natural cycle to me. It neither “pushes” our cow into higher than natural production, nor keeps us away from the CLA we desire, which, when milk is gone, we derive from the butter we made back in spring. (We’re making butter furiously right now.)

May 12, 2007 | Dave…

I confess to not having the background to say anything in depth about this but I have a few questions about the study. First, not all estrogens are the same. Different forms of estrogen have different effects on cancer. It is my understanding that a diet rich in dark green leafy vegetables is linked with the body creating/using more of the estrogens not linked to cancers. My guess is that grass fed cows would provide milk with a different array of hormones than commercially fed cows.

I would also guess that you’d need to look at what sort of estrogen was produced and the ratios for this to be meaningful.

Phytoestrogens (from plants) are a funny thing that I don’t think are well understood. The whole soy thing is way overdone I think - we should not be giving so much soy to young kids and the antinutrient effect of soy is of concern. Soy is also one of the most likely to be GMO foods we consume.

I see so many families who have given up dairy and where the kids are drinking gallons of soy milk every week. I’m really uneasy about this. Especially for girls.

Finally, even if the milk was high in estrogen would the effects of consumption be mitigated by a diet high in dark green leafy vegetables?

My understanding is that for humans goat’s milk is indeed superior to the cow for many reasons, but I’m not sure this is one of them.

May 12, 2007 | Linda…

I agree with Linda that there is more to know about the estrogens before making conclusions, as well as the concerns about soy, especially in the way soy is consumed in the Western countries (mostly unfermented and often in less obvious fractionated forms).

One of the things that has been a constant as I have put more thought into my family’s food is that the more I know, the more I don’t know. Initially it was dizzying, confusing, and frustrating, not to mention time-consuming (this point is where I see friends interested, making a few changes, but then giving up). But I must have reached an equilibrium point of sorts, because now new concerns don’t cause panic, they send calmly me off for more information or at least on alert, but ultimately they simplify things for me more - the more industrial it is, the less often I choose it. I don’t have to spend time reading so many labels and ingredient lists anymore because I don’t deliberate or even pick those items up anymore or they don’t have labels. *Far* less internal struggle at this point. Seems more like fine-tuning than a major overhaul.

Back to the milk. The estrogen issue is perhaps one to keep our eyes on for more developing information, but I do like the idea of matching consumption to the natural cycle of the milking animals. It’s certainly better for the animals who are managed that way and perhaps for us as well. And why should our milk be different from my pattern of buying apples or anything else in season for not out of season? I guess I just need to learn a bit more about the natural seasonality of cow milk and make adjustments accordingly (getting the child to adjust consumption is the real difficulty. Seasonality of meat is another area I would like to make adjustments in consumption as I learn more about it and find appropriate sources.

I started getting goat milk a month ago when it became available from a small farm that also provides our eggs & some meat/poultry (& they deliver to me, woo-hoo!). I mostly planned to make cheese & yogurt with the goat milk. But we ran out of cow milk one day and my son never noticed the difference so now he is drinking goat milk, too. Perhaps we’ll even time our milk buying based on the goats, as they are following a more natural cycle than the cow milk that is available to us.

May 12, 2007 | Anna…

I had a chance to talk this over this AM with a nurse midwife friend who is also a herd share member in our group. It is a lovely spring day and we were out picking stinging nettles - perfect time of year for that harvest!

She pointed out the lactation is a “low estrogen” time to begin with - supressing ovulation. So she wondered what the concentration would be - and guessed it would be pretty low.

As we think of cycles, consider that human lactation is year round, and although it is looked askance at in our western culture tandem nursing happens frequently and nursing for two years and more is perhaps somewhat rare in the US but certainly commonplace in many cultures and with many of the moms I’ve worked with. I have trouble believing this is a dangerous practice because of concentration of hormones.

There would seem to be a natural safety switch for this — if estrogen levels were high, nursing would shut off.

May 12, 2007 | Linda…

There are numerous questions that I am left with, and some of them have already been noted.

The issue of cows being milked traditionally only 3 months I beleive is erroneous for most cultures. A cow only milked for 25% of the time would not be a very efficient use of the animal.Linda made some excellent points about the first couple months typically having low estrogenic levels which suppress ovulation. In addition, the type and character of cattle was not considered. All cows are not equal. A typical commercial production cow produces much more milk, and has been bred to do so. They are also typically fed much more plant based estrogenic feed, not something that has been part of a traditional diet.Cows of 50+ years ago did not produce the volume of milk that is produced now and I question what changes have been made genetically that may affect the content in the milk..In addition, traditionally calves were dam raised.so were getting some of the milk. When the calf was weaning age, traditionally the cow was milked once a day. Many commercial dairies now milk 3x a day.The issue of A1 vs A2 proteins are also not considered in this issue. All in all, the article raises more question on the clarity of the study for me than it answers concerns,

May 12, 2007 | Kathryn…

There are always trade-offs. Dan’s article cites a very large study - nearly 15,000 subjects. The questionnaire used in the PARSIFAL study was very detailed and the study involved humans.

Retrospective studies about diet can be very deceiving. Furthermore, one of the corroborating studies was done on rats with another very small, short one on children.

I’m sticking with the raw milk.

May 13, 2007 | Kirsten…

The issue of high plant estrogen content in soy milk is compelling. I know of a ten-year old boy (child of a friend’s friend) who drank lots of soy milk - and he was growing breasts. The mom found out about the soy/estrogen issue and switched him to raw milk. Within a couple of weeks, the breasts receded to normal. Now, he could have been a chubby kid who was just maturing, but why risk it? WAPF reports truly high levels of blood estrogen in female infants on soy formula, leading to early maturation, etc. and possible deleterious effects in male infants particularly affecting early brain growth which requires that testosterone not get swamped with high estrogen levels.

May 13, 2007 | Steve….

Full article and comments at Complete Patient.