To date, there is mixed evidence on whether dairy consumption is associated with cancer risk. Scientific studies in Western populations suggest that dairy products may be associated with a higher risk of prostate cancer and a lower risk of colorectal cancer, but an association with breast cancer or other cancers has not been established.
In non-Western populations, where the type and amount of dairy consumption and the metabolism of dairy products are very different, the results may not be the same.
For example, very little cheese and butter are consumed in China, and the consumption of milk and yogurt is also much lower than in Western countries. In addition, most Chinese adults cannot metabolize dairy products because they do not have lactase.
To find out whether dairy consumption is differentially associated with cancer risk in China, researchers from Oxford Population Health, the Chinese Academy of Medical Sciences and Peking University published the results of a large-scale study in BMC Medicine. This involved collecting data from more than 510,000 participants in the China Kadoories Biobank Study.
The participants, 59% of whom were female and 41% of whom were male and did not have cancer, took part in the study between 2004 and 2008 and came from 10 geographically diverse regions of the country.
At the beginning of the study, each participant, aged 30 to 79, answered a questionnaire indicating how often they consumed various foods, including dairy products. Participants were divided into three groups: monthly dairy consumers, regular dairy consumers, and people who rarely or never consume dairy products.
Follow-up of the participants lasted about 11 years, and the researchers used data from national cancer and death registries and health insurance records to identify new cancer diagnoses.