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Research suggests dairy can be deadly


Once a star food – a tasty beverage full of calcium, protein, minerals and vitamins thought essential for healthy bones – milk is now souring in controversy.
   New research shows a link between dairy products and ovarian cancer.
   The study, published today in the International Journal of Cancer, reveals a 13-per-cent increase in ovarian cancer risk with a daily increase of 10 grams of lactose – the equivalent of about one glass of milk.
   Experts in the field call it a “modest” but significant finding.
   The lead investigator, epidemiologist Susanna Larsson, said she is not recommending women stop drinking milk – until further studies are done.
   “In the future, when we know more about possible interactions between milk consumption and genetic susceptibility, it might be that some women should not drink milk because of a high risk of developing ovarian cancer,” said Larsson, of the National Institute of Environmental Medicine, in Stockholm.
   Based on animal studies, researchers suggest consuming lactose (milk sugar) is the risk factor for ovarian cancer.
   Larsson’s research, which pooled statistics from 21 studies following nearly 4,000 women, showed varied findings in cancer risks.
   Whole milk was associated with the highest increase in risk in all 21 studies.
   But three studies identified consumption of all dairy products – including low-fat milk but excluding hard cheese, which has less lactose – as increasing cancer risk.
   These studies did not identify women with a genetic susceptibility for ovarian cancer.
   “We don’t know how much milk is too much for women with genetic predisposition,” Larsson said. “Perhaps they shouldn’t drink milk at all. Perhaps lactose-free milk is safe. More research in this area is needed.”
   The latest finding comes on the heels of a Harvard University study that showed more than three glasses of milk a day could lead to obesity in children.
   An estimated 2,400 new cases of ovarian cancer will be diagnosed this year and an estimated 1,550 women will die of the disease, according to Canadian Cancer Society figures.
   “It’s a very lethal disease,” said Gerald Stanimir, a gynecological oncologist and past-president of the Society of Gynecologists of Canada.
   One in five women with the illness will survive beyond five years. “The death rate is so high because the disease, unfortunately, is diagnosed in late stages,” Stanimir said.
   But there’s no evidence in Larsson’s study to suggest eating fewer dairy products will prevent ovarian cancer, Stanimir noted.
   “The study raises an interesting finding that may require further rigid, academic study.”
   The Dairy Farmers of Canada were quick to dismiss the study.
   “It’s an observational study and it says nothing about cause and effect,” said Solange Heiss, the association’s assistant director for marketing and nutrition.
   There’s nothing conclusive that says dairy products are bad for you, she noted, but there’s a wealth of medical studies that show the benefits of dairy foods.
   Evidence suggests a diet rich in Vitamin D, which milk contains, cuts colon cancer risk and helps ward off breast cancer. Consumption of low-fat dairy foods may also lower the risk of cardiovascular disease and Type 2 diabetes.
   Barbara Vanderhyden, who holds the chair of ovarian cancer research at the University of Ottawa Centre for Cancer Therapeutics, described the 13-per-cent risk increase as “relatively modest” in absolute values.
   “But it’s important for women to be aware of the study that high intake of total dairy food, in particular milk, has been shown to increase ovarian cancer,” Vanderhyden said.
   The study raises as many questions as it answers, said Shree Mulay, director of the McGill University Centre for Research and Teaching on Women.
   “Milk is a very important source of protein in many countries and one has to be very careful before putting out a call that women should not drink milk,” Mulay said.
   Dr. Lucy Gilbert, head of gynecology oncology at the McGill University Health Centre, called for “moderation in everything,” given the health benefits of calcium and Vitamin D.
   “A 13-per-cent increase is a small risk, and against this you must balance the advantages,” she said. “The number of women dying of ovarian cancer is a fraction compared to the sheer numbers dying of breast cancer.”
   Université de Montréal nutritionist Marielle Ledoux, warned no one food product could be solely responsible for a disease.
   “We’re not talking about lung cancer and smoking, where there’s a more direct link,” she said. “It’s a lot easier to grab all your calcium through milk and milk products than through vegetables.
   “Milk is certainly one of the good foods we have, but you don’t need litres of it to satisfy your needs.”