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The No-Dairy "Breast Cancer Prevention" Program

Dr. Jane Plant has caused quite a stir with her book, “The No-Dairy Breast Cancer Prevention Program” in which she proposes a causal link between the consumption of dairy products and breast cancer.

Dr. Jane Plant has caused quite a stir with her book, “The No-Dairy Breast Cancer Prevention Program” in which she proposes a causal link between the consumption of dairy products and breast cancer. Plant is an eminent scientist, but her expertise is in geochemistry and nutritional knowledge is suspect. I am astounded by how an "eminent scientist" can make an argument based on one case history, which happens to be her own. 

Plant, a respected British geochemist was struck by the disease at age 42, and while undergoing standard treatment, began a search for other options. She knew that breast cancer rates in China were much lower than in the west, and wondered why.  The rates are indeed lower, but not buy as much as Plant states.  She claims that only one in 100,000 Chinese women are affected by the disease, compared with one in twelve in the West. This is utter nonsense! The breast cancer incidence in China is indeed less than in the West but not by the factor that Plant claims. The age adjusted breast cancer rate in developed countries is about 110 cases per 100,000 women per year, and the rate in China is about half that, but the likelihood of diagnosis in China is not the same as in the western world.

Genetics are not the explanation for the lower rate in China because Asians who migrate to North America eventually take on our cancer patterns. So some lifestyle factor must be involved. Plant explains that while she was musing over this, she experienced an epiphany. She came to the realization that the Chinese consume no dairy products! So she decided to eliminate milk, cheese, yoghurt, and in fact any food that had even a trace of dairy. As she describes it, within days, a lump on her neck, a recurrence of the cancer that had started in the breast, began to shrivel up and eventually disappeared.

A great story, to be sure, but still, an anecdote is an anecdote. I wish I could say that Professor Plant made a great discovery and found the secret, as she in fact implies, for the difference in cancer rates between Asians and westerners. In fact, she seems oblivious of the fact that she was not the first one to formulate such a hypothesis. Not by a long shot. The medical literature is loaded with studies exploring possible dietary connections to breast cancer, including that to dairy products. This is a reasonable assumption to follow up because milk contains saturated fat, estrogens, growth hormones and a protein called insulin like growth factor, all of which potentially may be linked to breast cancer. There have been over fifty excellent studies exploring the breast cancer dairy link and the overall conclusion is that there is no link.

Plant of course has an emotional connection. She had breast cancer and now appears to be cured. She had radiation and chemotherapy, but somehow she gives the credit to a dairy free diet. She makes one of the most fundamental errors in science, coming to the conclusion "after it, therefore because of it." Her breast cancer resolved, she ate a dairy free diet, and concluded cause and effect. Because Plant has convinced herself of this, she looks to buttress her arguments with data. But some of her numbers are ridiculous. Suggesting that only 1 in 10,000 women die of breast cancer in China is just nonsense. Of course, government conspiracies, nutritional remedies and Chinese secrets make for good press, but they do not make for good science.

Much of Plant’s discussion revolves around insulin-like growth factors which are indeed found in milk, and which she targets as a causative agent in breast cancer. There is a great deal of research on IGF and it does seem to play a role in breast cancer. But the culprit, if it can be so-called, is IGF that is made within the body, not IGF that is ingested in the diet. IGF is a protein and is unlikely to survive digestion in any significant way. So while milk does contain IGF, this is not absorbed intact into the bloodstream. Plant also argues that cows treated with bovine growth hormone (BGH) produce more IGF. Maybe so, but since IGF is minimally absorbed, this is hardly an issue. In any case, there is no evidence that breast cancer rates in the US, where BGH is widely used, are any higher than in Canada or Europe, where they are not used. Contrary to what people may think, BGH is not banned in Canada or Europe, it’s just that producers have not asked for approval. This is not because of any safety issue, but rather is a reflection of different systems of milk production. In Canada there is a milk quota system and farmers already produce as much milk as they can sell. Plant also is high on soy milk as protective against breast cancer. While there is evidence that consuming soy products around the age of puberty is protective, the jury is out on the benefits or risks of soy consumption by estrogen sensitive breast cancer patients. The current view is that soy consumption should not be increased. 

Shockingly, given Plant’s scientific background, she buys into the theory that an “acidic” diet favours the development of cancer. She explains that if we consume too much acid-generating food, our bodies become acidic — an environment in which cancer cells can flourish. The foods highest in generating acid (not, as might be assumed, citrus fruit) include eggs, meat, fish and dairy — with cheese the most acid generating-food of all. This is plain nonsense. Our blood is a buffered system and its pH does not alter based upon what is eaten

If you examine the peer-reviewed scientific literature on breast cancer, it most certainly does not support Plant's allegations. In fact there is evidence that conjugated linoleic acids in dairy may actually offer protection. I really do find it hard to understand that someone trained in science could be so unscientific. But I guess when it comes down to personal concerns emotions can displace science.
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