Diet and Breast Cancer: Is Dairy a Culprit?
Dear Monica, I enjoyed your post on diet and breast cancer. However, I cannot believe that you did not mention the direct relationship between the intake of casein (milk protein) and the growth of mammary tumors. T. Colin Campbell in his The China Study outlines how this protein turns on tumor growth and the lack of it in the diet turns off cancer growth. "
Before saying anything else, let me first say that I completely support anyone who does not care to consume dairy products, for whatever reason. Dairy is certainly not essential to a healthy diet. There are plenty of other ways to get calcium and vitamin D. (And those who do not consume dairy need to take care to be sure they do.) I recently did a podcast episode on the pros and cons of dairy. You can listen to it here.
Now, to Campbell's book: Lots of people commenting on this blog over the years have referenced this book as a definitive scientific rationale for various dietary practices. Obviously, Campbell's prose is compelling. But I have to be honest with you: The science behind his conclusions is less so.
You're right: There are recent (2007) studies showing that milk increases the incidence of chemically-induced breast tumors in rats. Interestingly, I also found a 2007 study showing that soy milk does the same thing. And another (2006) showing that fermented milk (yogurt) prevented tumors; and another (2001) showing that soy protein was preventive.
It appears that studies on things that cause or prevent tumors in rats injected with carcinogens might not provide a definitive answer to the question: Do dairy products cause breast cancer in humans? For that, it makes sense to turn to studies that compare what people eat to their risk of breast cancer.
Do dairy products increase breast cancer risk in humans?
The so-called "China Study" was a nutritional analysis conducted in rural China in the 1980s. This study purportedly found a link between the intake of animal protein and an increased risk of cancer and other disease. In the intervening 20 years, many researchers have tested this conclusion, specifically with regards to dairy and breast cancer. Here's a brief sampling:
2007 American Journal of Clinical Nutrition (5000 subjects in England and Scottland): Childhood dairy intake was not associated with breast cancer risk.
2007 Cancer Epidemiology (2000 subjects in U.S.): Reduced breast cancer risks were associated with increasing milk consumption from ages 10-29, probably because of the cancer-preventive effects of vitamin D.
2006 Cancer Causes and Controls (5000 subjects in Italy): Consumption of milk and diary products did not increase breast cancer risk (and, in fact, consumption of skim milk slightly reduced risk).
2005 Journal of the American College of Nutrition (meta-analysis of 52 different studies): Evidence does not support an association between diary product consumption and the risk of breast cancer.
2005 Nutrition and Cancer (study looking back 30 years and across 38 countries): No substantial effect of milk consumption on risk of breast (and other) cancers.
2004 American Journal of Clinical Nutrition (meta-analysis of 46 studies): No strong association between the consumption of milk or other dairy products and breast cancer risk.
2002 Journal of the National Cancer Institute (90,000 women followed for 16 years): "We found no association between intake of dairy products and breast cancer in postmenopausal women. Among premenopausal women, high intake of low-fat diary foods was associated with a reduced risk of breast cancer."
2002 International Journal of Epidemiology (meta-analysis of 8 prospective studies involving 350,000 subjects in N. America and W. Europe): "We found no significant associations between intake of meat or dairy products and risk of breast cancer."
Dairy is not essential to a healthy diet but it does not appear to cause breast cancer
Obviously, I would have had to have continued for quite a bit longer to work my way back to the China study. But there didn't seem to be much reason to continue. (And I wasn't cherry-picking, either...these are the studies that came up in response to my query!)
So, let me end this post the way I began: Dairy products are not essential to a healthy diet. Feel free to eliminate them. But I don't actually see evidence to suggest that doing so will reduce your risk of breast cancer. And, in fact, because dairy products are one of the only sources of vitamin D in the American diet, eliminating them might well increase your risk if you're not careful to get that nutrient from other food sources.
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Posted by: Mary | Mar 26, 2009 12:22:22 AM
The various comments here by the nonscientific community are interesting; similiar to the actions of many Americans who seek the "miracle food" as a cure-all and who will believe anything written by someone with M.D., PhD after their name instead of reading the scientific literature as Monica has nicely summarized. Of note, in their recommendations published in Fall of 2007, the American Institute of Cancer Research recommended that individuals should consume <18 ounces of red meat per week; there were no stipulations regarding chicken or fish. In fact, many populations that eat fish on a regular basis have a lower incidence of cancer and Heart disease, the number one cause of death worldwide! The panel that reviewed the literature pertaining to their recommendations not only included EXPERTS in the field of nutrition but also oncology - what a concept. So, everyone is free to eat whatever they want, however, medicine is practiced based on evidence - not opinions.
Posted by: seppi | Jan 20, 2009 6:26:27 PM
It is all about correlation and with regard to Calcium, here is one to think about...
The US consumes more cow milk per person than any other population. The US has more cases of osteoporosis than any other population.
Monica's Response: Shark attacks increase when ice cream sales go up. Does eating ice cream cause shark attacks? Correlation is the weakest evidence of causation.
Posted by: karol | Dec 28, 2008 2:19:18 PM
Can you then explain why there is ,in Western meat eating populations, way more cancer than non meat eating populations.
thank you
Posted by: lila | Dec 19, 2008 8:32:58 AM
Monica, I appreciate your mini-literature review on this topic.
This is such an interesting set of responses. I think I will show my statistics class this thread when we talk about weighing evidence and correlational data.
Posted by: David | Dec 12, 2008 11:08:43 PM
That is a long list of articles concluding that consumption of dairy products is not associated with breast cancer.
But, time after time, Dr. John McDougall has explained why the majority of epidemiological nutrition studies are flawed. These studies usually examine how two populations are affected by cancer. One population, a control group, eats a "typical" amount of dairy products. A second group eats a lesser amount of dairy products. But usually, the lesser amount is not enough to make a significant difference. If the control group gets 20% of their calories from animal proteins, and the experimental group gets 15% from animal proteins, then BOTH groups may get cancer in equal proportions.
Dr. Campbell showed that unless the experimental group reduces their intake to 5% of calorie intake, they will STILL develop cancer, if exposed to carcinogens.
The majority of these epidemiological studies are flawed in concept, or execution, or interpretation through statistics. And since we all like to hear good news about bad habits, bad science gets publicized.
Posted by: Kelly | Dec 12, 2008 10:41:49 PM
there is one problem with every single study reported here. they are all based on correlational research. this means that the researcher looks at two or more variables to see if there is a correlation.
so any results are evidence of a positive, negative or zero correlation and cannot by their very nature show a cause and effect relationship.
to show cause and effect, there must be manipulation of variables which as you will all be aware is difficult in this kind of research.
this means that we must rely on such correlation studies as reported here but they should always be responded to with caution.
in my opinion, any reduction or increase in the likelyhood of developing cancer of any kind, is probably small and any change in consumption of dairy products is not likely to have a significant impact on a person's chance of getting cancer.
anyone interested in reducing their risk of cancer is much better off taking antioxidant supplements or increasing the consumption of antioxidant rich foods.
antioxidants reduce oxidative damage which is a significant contributer to cancer.
also in regards to breast cancer specifically, there is strong evidence of a genetic component so for those who don't have a genetic predisposition to breast cancer, diet modification is likely to be of even less importance.
you may also be interested to know that there is research currently being conducted into the causes and possible treatments for breast cancer (some of my collegues are conducting such research though there are many other institutions conducting research) with evidence suggesting that certain hormone imbalances are the main cause of most kinds of breast cancer. i must stress that these hormones are not present in cows milk.
i hope this makes things a little clearer for you all.
ps. should you be wondering, i work at a university where breast cancer research is being conducted and am a research scientist myself
Posted by: Chuckles McGee | Dec 11, 2008 9:06:33 PM
Really Scott? Are there even any epidemiological studies or scientific studies finding calcium deficiencies in those who drink the most milk? If high milk consumption causes calcium deficiency, we'd expect to hoards of calcium deficient individuals. Drinking a ton of milk may not increase bone density or the like, but it's not going to create a deficiency.
Posted by: Scott | Dec 11, 2008 8:28:07 PM
I like to think about these things logically, from the perspective of nature. Nature created milk as a food for baby cows.
Why on earth would people think it is a good idea to suckle the mothers milk of a different species? I have never understood this.
We are the only animals on the planet that do this on a regular basis. Then again, we are the only people who cook our food too. Hmmm, I suppose that is why I don't eat much cooked foods.
The other debatable topic is calcium.
Drinking milk actually creates an acidic environment in the human body/blood. In turn, the body must balance this acidity by throwing minerals into the mix. One of the minerals, you guessed it, is calcium.
Thus, milk actually depletes your calcium stores, and doesn't really give you healthy bones and teeth. But in reality, calcium deficiencies.
Posted by: Daniel | Dec 5, 2008 12:06:06 PM
I have read the first few chapters of the China Study and it is very interesting. However, they seem to put a lot of emphasis on aflatoxin. I know that ruminant animals are very sensitive to aflatoxin, much more so than people. Aflatoxin is basically formed by molds like aspergillus flavus. I don't imagine that we eat much aflatoxin in the US where the action levels are 20ppb in food. We do a pretty good job here at reducing mold growth through growing, handling, distribution and preservation techniques (including using propionic acid as a mold inhibitor in breads and feed). So far it is a very convincing read though. And I do plan on making some changes to my diet now.
Daniel J. Brooker
http://www.brookerlaboratories.com
Posted by: seppi | Nov 20, 2008 4:17:37 AM
Interesting "debate" indeed.
Be sure to read it in its entirety. And pay no mind to that giant ad to purchase audio lectures.
Posted by: Monica Reinagel | Nov 19, 2008 1:00:28 PM
For anyone still following this debate, here's an interesting crtique of the China Study and its conclusions by Chris Masterjohn, including a response from Campbell:
Posted by: Monica Reinagel | Nov 19, 2008 12:50:26 PM
Many of you have made some valid points re: the China Study. The original question (as posed by the reader) was "Do milk proteins cause breast cancer?" She referenced the China Study as her source.
My review of recent literature suggests that eliminating dairy from the (Western) diet does not appear to reduce breast cancer risk.
However, as some of you have pointed out, I did not address the question of whether eliminating ALL animal protein (not just dairy) would reduce the risk of cancer.
It's a big question and one with lots of confounding variables, many of which have been touched on above. Exposure to certain chemicals also rises with animal consumption. How much of the problem is how we raise our livestock?
I think Campbell's analysis also leaves open the possibility that REDUCING consumption of animal products may greatly reduce the risk of cancer but that the further reduction of risk from ELIMINATING them is smaller. (But what's the magic amount?)
Bottom Line: I support anyone who, on the basis of reading the China Study, or because of other reasons, decides to reduce or eliminate animal products. (I actually eat very little meat myself.)
But when statements like "Dairy products cause breast cancer," start making the rounds, I like to look at the literature to see what the research shows at any given point, realizing that the research will never be complete!
Posted by: Vince | Nov 18, 2008 8:03:04 PM
Thanks Seppi.
Well put and believable. I am over seventy. I haven't had milk for many years. I limit my dairy, including meat. I eat mainly veggies fruit and whole grains. I lead fitness classes five days a week. I tell class members regularly that dairy is not neccesary for healthy nutrician. I take no medications.
I feel great, have lots of energy and no medical concerns. I am continually amazed at how little most people know about nutrician. The majority of their information comes from the dairy industry. I believe the majority of studies are also funded by the dairy industry. CTB likely still smokes.
Posted by: Monica Reinagel | Nov 18, 2008 2:11:05 PM
Just a reminder that while conflicting opinions are welcome here, let's keep the dialog civil and respectful.
Thanks.
Posted by: seppi | Nov 18, 2008 1:52:37 PM
Wow CTB...
Open you mind for a moment and read again. Why are you so defensive?
Like your beloved tobacco industry, all industry and the institutions that support it will release research results that are supportive to their cause. Look at all that wonderful research the tobacco industry release. How many smokers of the 50s and 60s went to their grave smoking knowing that cigarettes were not bad for them because they were told so?
It took time for the truth about tobacco to overcome the mass programming and to be accepted, as it will take time for truth about nutrition (not just a particular food industry) to be accepted but it will happen... though not until the "paranoia" spreads more and people start thinking.
Posted by: Emma | Nov 18, 2008 1:34:32 PM
I don't particularly think that "dairy" is the cancerous issue here. I think it's the lack of a well-balanced diet, and the overwhelming increase of obesity. Greed and Sloth are at play, and the more weight you put on, the more cells you have to go crazy and start growing uncontrollably.
We should also take a look at the chemicals that are in the environment of each of the subjects. We should also look to see how each region compares to another via diet, lifestyle (including activity levels), toxin levels, and the region as a whole (native flora and fauna).
There are always going to be many factors and what people seem to truly forget is that research only provides a Hypothesis - and educated guess. It's not TRUTH. It's a guess with evidence to back it up. Remember the red = better heart health? Look at all of those other research studies that say ANY kind of alcohol kills your heart and liver, and any anti-oxidants that "help your heart" are outweighed by the poisons that hurt it.
Who knows what the truth is? That's what we're trying to find, and until we can all agree, there is no truth. There is just generally accepted answers.
Posted by: david | Nov 18, 2008 5:19:49 AM
further to my earlier post
on re-reading yr post Monica I am dismayed at your dismissive attitude to Campbell...makes me wonder at your nutritional science foundations. Campbell's credentials are impeccable and the confusion that emerges in the posts is exactly what he is exposing in his book. But who wants to read anything but extracts these days....
Posted by: Vicky | Nov 18, 2008 3:42:36 AM
TLL - there is not "hormone free milk" breast milk - by its very nature contains hormones including human breast milk and organic cows milk. I think the wrong starting point and the wrong focus has been used here. Don't look at the China study and the issue of protiens, look at the book "Your Life in Your Hands" by Proffesor Jane Plant and the issue of the growth factor IGF1 which is in all milk - if you do that a very different picture emerges - I hope Monica and others here will take the time to look because 1 in 9 women in the west will get breast cancer but the rate is much lower in conuntries that don't consume dairy. CBT - Babies don't get breast cancer from being breast fed because babies are growing and the breast milk stimulates that growth - the problem emerges when an adult that has finished growing then comsumes a products that promotes growth - thats what cancer is - uncontrolled growth of cells.
Posted by: TLL | Nov 17, 2008 11:45:25 PM
The problems I've heard & read about in regard to milk being a possible risk factor for breast cancer, refer to the added HORMONES that are in the milk - not the protein being the cause - and the connection of early onset of menstrual periods in young girls...Does this study even address milk that is hormone-free or organic? Hormones need to be addressed in order to make a more informed assumption in regard to breast cancer risk.
Posted by: david | Nov 17, 2008 11:38:57 PM
well said Delisa
Monika needs to read the book and understand its holistic approach. Campbell deals with the problem of the Nurses Study and his exchange with Willet illustrates the complexity of things. CTB your illogical outburst is deplorable. In the 50s and 60s we had all sorts of research data that could draw no conclusive evidence linking cancer and tobacco. Where is all that data now? In the dustbin where it belongs.
Monika - citing all those studies is not all that helpful in the light of the confusion that prevails...you will need to read Campbell fully to appreciate why.
Protein and Fat <10% by calories in our diet is the compelling evidence we are faced with - interest groups will fight and dispute with it till they disappear in the heaps of scientific evidence mounting in its favour...
Posted by: Michele N. | Nov 17, 2008 10:59:58 PM
Has anyone thought about this China study and dairy products? I wonder if there results of the study have anything to do with the melamine the Chinese were putting into baby formula, milk products and chocolate products. Who knows how long they have been tainting dairy products to save money1 Melamine is a toxin and they were using it to mimic the proteins found in milk and dairy products.
Posted by: Delisa Renideo | Nov 17, 2008 7:56:48 PM
I suggest that you read the entire book, The China Study, before discounting the research and the results. Dr. Campbell DID NOT start with the notion that dairy products, or animal products in general, would promote cancer growth. Quite the opposite. So this is not a case of finding a study to support his position. Also, the point you made, Monica, that the more recent studies use people whose diets are more similar to ours, which therefore isolates the milk protein, supports Dr. Campbell's study. He never claims that it is just milk protein that causes cancer. ALL animal protein causes cancer growth, which is why his study is so good. He looked at the diets of 6000 people in China, and those eating the most animal protein had the most cancer, heart disease, diabetes, and other diseases of affluence. Those eating the least animal protein had the least of all these diseases. He never suggests that people should just eliminate dairy products while continuing to consume other animal proteins.
The fact that the study was conducted in the 1980's does not discredit the results in any way. On the contrary, the study, as it was conducted, would not be able to be done now because Chinese people have now been influenced so much by the western diet.
I appreciate your efforts to give the most up-to-date and credible research, but in this case, I think you would do well to actually read The China Study so you will understand what the research was and why he draws the conclusions that humans can prevent most of the chronic diseases of affluence by eating a whole foods, plant-based diet.
Posted by: CTB | Nov 17, 2008 7:08:01 PM
Oh, and Ish...
By your brilliant logic, babies drinking their mothers' milk would be at increased risk for breast cancer...BECAUSE THE MILK IS COMING OUT OF A BREAST.
Good one. The power of your intellect is astounding. Sheesh...
Posted by: CTB | Nov 17, 2008 7:03:08 PM
seppi,
I think you're a paranoid simpleton. To my mind, these people who categorically dismiss the weight of scientific research because of "manipulation" by the food industry are not making an intelligent argument. The dairy industry is not the only industry out there... There is also the soy industry, and of course the trial lawyer industry...
So think about it. If there were in fact any solid scientific evidence that dairy caused cancer, it would be a trial lawyer's dream. Do you have any idea how much money they could make from that? They would be all over that in a heartbeat, just like when they went after the tobacco companies. For every industry that would be damaged by the truth, there would be another that would gain.
Tobacco is a great example here... Despite the weight and power of the tobacco industry, there has been solid scientific evidence of the harm caused by tobacco going all the way back to the 50's and 60's, despite all the pseudo-science they tried to invent. So if the same were true of dairy, the dairy industry would not be able to manipulate the science any more than the tobacco industry did.
So please, just stop it with the delusional paranoia about the dairy industry.
Posted by: seppi | Nov 17, 2008 5:29:57 PM
Of course you need to look at where the so called "research" comes from.
Who funds it and for what purpose? I find it very interesting but of no surprise that all of the referenced samplings come from the main stream organizations and institutes that have been born from the mass media marketing that supports the common model of "nutrition" and "medicine" that has been based almost entirely upon industry marketing for products such as milk, eggs and meat, and not nutrition.
Of course those institutes and organizations that were founded and funded by the giant industries such as the USDA, IDFA, NIH, USNLM and so on that support the model would release such "research" to refute any negative effects of milk found in independent research.
If we all ate well and got good nutrition nearly all the diseases of affluence would disappear and along with it the medical industry as we know it and the giant "food" industries that depend upon keeping the myths alive.
Posted by: Laura | Nov 17, 2008 5:11:33 PM
Great work Monica. Did you come across anything about dairy and ovarian cancer? I remember in the past seeing things about this possible connection.
Posted by: Ish | Nov 5, 2008 12:37:42 AM
Does anyone THINK about the question posed here. Where do dairy products come from? Where is the cancer we're talking about? BREASTS! Hello!?
Posted by: Steve Parker, M.D. | Oct 27, 2008 9:25:23 PM
Very well-researched, Monica! Thank you.
-Steve
Posted by: David | Oct 27, 2008 6:48:55 PM
The fact that the conclusions are drawn from The *China* Study should set alarm bells ringing immediately. In the particular case of China there's been a massive increase in the intake of dairy products at the same time of increasingly westernised 'affluent' diets in preference of more traditional heavily vegetable based diets. Consequently more 'dairy' in this case really means 'less fruit and veg, less soy, more butter, more full fat milk, more cheese, all accompanied by more convenient/processed food than ever before.' One assumes that the health impact would be very different if one's careful choices meant 'more dairy' meant 'more low fat yogurt and skim milk.' (Anyway, whatever the downsides of dairy it's a good replacement for meat at least once in a while, the downsides of which are far less controversial).
Posted by: Dave | Oct 27, 2008 4:26:20 PM
Campbell's scientific approach is highly questionable. By his own admission it is based largely on his own "philosophy" of nutrition. One suspects that any study results are thus filtered to support his own confirmation bias. The Protein Debate (link below) between Campbell and Loren Cordain illustrates this nicely. I don't entirely agree with Cordain's conclusions, but at least he's making an attempt to behave scientifically, while Campbell's arguments largely seem to consist of "because I said so".
http://hacres.com/healthtipArticles2007/478_proteinDebate.pdf
Aren't dairy products supplemented with Vitamin D? Given that, it would seem more feasible to just take supplements or get some sunshine, rather than rely on dairy.
