Scientific review published in Advances in Nutrition finds there is no simple “yes” or “no” answer to this question
Cancer, the leading cause of death globally, accounted for nearly 10 million deaths in 2020, according to the World Health Organization (WHO). Despite extensive research, the association between dairy consumption and cancer mortality has varied among studies and therefore has remained unclear. Moreover, most studies examining the relationship between dairy consumption and cancer mortality have focused on dairy consumption in general, without examining the effects of specific types of dairy products on specific populations.
In response, nutrition scientists Shaoyue Jin and Youjin Je conducted a comprehensive scientific review to quantitatively assess the association between the consumption of total dairy products, as well as specific types of dairy products, and total cancer mortality. Furthermore, the review authors examined the effect of gender, cancer site, fat content, and geographic region on cancer mortality. The results of their research, “Dairy Consumption and Total Cancer and Cancer-Specific Mortality: A Meta-Analysis of Prospective Cohort Studies,” were published in Advances in Nutrition, the international review journal of the American Society for Nutrition.
To conduct their research, the authors performed a comprehensive search of prospective cohort studies published up to March 2021 that examined the association between dairy consumption and cancer mortality. Their search led them to 34 studies, which together included more than three million participants. On average, these studies tracked participants’ health status for about 14 years. Seventeen studies were conducted in the United States, eight in Asia, eight in Europe, and one in Oceania.
Interestingly, when the authors looked at the relationship between total dairy consumption and total cancer mortality, no significant associations were found. However, when the authors examined the relationship between specific types of dairy and cancer mortality, significant associations did emerge. For example, the authors discovered a significant association between milk consumption and total cancer mortality among females, but not among males. More specifically, for women’s cancer, high milk consumption was associated with increased mortality risk from ovarian cancer, but no significant association was detected for breast cancer.
In contrast to milk consumption, the authors discovered that high consumption of fermented milk products such as yogurt was associated with a lower total cancer mortality among females, but not among males. The authors found that “increasing fermented milk consumption by 200 grams per day was associated with a 10% decrease in total cancer mortality in females, whereas no association was found in males.” These findings may be due to the lower lactose and galactose content of fermented milk products. Studies have shown that lactose and galactose consumption are associated with an increased risk of ovarian cancer.
The effect of consuming other types of dairy products did not differ by gender. For example, high cheese consumption was associated with an increased risk of death from colorectal cancer equally for men and women.
The authors acknowledge that their scientific review has some limitations. In particular, their review was based on observational studies, rather than randomized controlled trials which tend to produce more reliable results. The authors therefore caution that “future well-designed large prospective cohort studies that investigate the association between each type of dairy product and cancer mortality in different cancer sites and populations are warranted.”