The connection between breast cancer and dairy consumption-anecdote or science?

dairy consumptionPersonal anecdotes of triumph over disease can be very captivating. Professor Jane Plant in her book “The Plant Programme” puts forth an engaging account of her conquest of breast cancer by avoiding dairy products. But anecdote is not evidence.

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.

At one time milk fat was thought to be strongly associated with breast cancer but that association disappeared when total caloric intake was taken into account. It is excess calories that are associated with the disease, no matter where they come from. As to the estrogens, growth hormones and insulin-like growth factors in milk, they are found in minute quantities when compared to the amounts of these substances produced naturally in a woman’s body. Actually some studies have even shown that milk products may afford protection from breast cancer. Mongolia makes for an interesting case because of genetic similarities with other Asian countries but a significantly different dietary pattern. Mongolians eat mostly red meat and dairy and yet have a breast cancer rate that is about one third that seen in China. Like elsewhere breast cancer rates rae higher in urban than rural areas implying an environmental connection.

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.

It would be great if the answer to this scourge of a disease were to be found in something as simple as avoiding dairy products. Professor Plant’s good fortune, though, is more likely to be due to the chemotherapy she received than her dietary changes. Surely if dietary modifications had such marvelous results, at least some of the scientific studies would have shown the link. And while Professor Plant’s book has become a best-seller, breast cancer victims who have had less fortunate outcomes after giving up dairy don’t end up writing about their experience.


Joe Schwarcz

One response to “The connection between breast cancer and dairy consumption-anecdote or science?”

  1. Mary says:

    “This is plain nonsense. Our blood is a buffered system and its pH does not alter based upon what is eaten”. If that is the case and it is scientifically proved, I don’t understand from where originated this idea. Because I read some articles and also heard a doctor sustaining it. And it was very convincing and apparently there was a logic in his speech. I don’t understand how you can study biology, chemistry and other kinds of sciences and make such big mistakes. It is somewhat a way of subjective interpreting of facts? Because if it is so, I think it is dangerous for the part of population who rely solely on what doctors say.

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