Colorectal cancer cases are rising in low milk-consuming regions—this major global study reveals who’s most at risk and why the right amount of milk might matter more than you think.
The ASR of deaths and DALYs attributable to diet low in milk for prostate cancer and colon and rectum cancer among countries and territories in 2021. A. ASMR of colon and rectum cancer; B. ASDR of colon and rectum cancer; C. ASMR of prostate cancer; D. ASDR of prostate cancer. ASMR, age-standardized mortality rate; ASDR, age-standardized DALY rate; DALYs, disability-adjusted life year rates. Study: Global, regional, and national burden of disease attributable to diet low in milk, 1990-2021: an updated analysis of the Global Burden of Disease study 2021.
In a recent study published in the Journal of Dairy Science, researchers investigated the impact of a diet low in milk. Milk, rich in calcium, vitamin D, protein, and phosphorus, plays a vital role in maintaining bone health, supporting immunity, and promoting overall well-being. Adequate milk intake has been linked to a lower risk of several chronic diseases, including some cancers, cardiovascular diseases (CVDs), and osteoporosis. Nevertheless, excessive milk consumption may have undesirable effects, such as inflammation and oxidative stress.
About the study
In the present study, researchers evaluated the disease burden attributable to a diet low in milk. They used data from the Global Burden of Diseases (GBD) 2021 study, which assessed the burden of 371 diseases, impairments, injuries, and 88 risk factors in 204 countries and territories. Specifically, the team accessed estimates of deaths and disability-adjusted life years (DALYs) attributable to low-milk diets from 1990 to 2021.
Additionally, data on age-standardized rates (ASRs) of mortality (ASMRs) and DALYs (ASDRs) were obtained. The optimal range of milk consumption was 280–340 g/day for males and 500–610 g/day for females, based on a mean intake with a 20% variation. Consumption below the midpoint of these ranges was considered low milk intake. This definition only included low-, non-, and full-fat dairy milk, excluding plant-based alternatives, cheese, and fermented milk products.
The primary outcomes were prostate cancer and colorectal cancer (CRC) burden attributable to low milk intake. Joinpoint regression was applied to estimate annual percent changes in CRC ASRs, and a linear age-time cohort model was used to project CRC trends through 2050. The estimated annual percentage change (EAPC) was used to quantify long-term trends in ASMRs and ASDRs.
ASMR and ASDR of prostate cancer and colon and rectum cancer attributable to diet low in milk in different regions and global average levels in 1990 and 2021. A. Prostate cancer and colon and rectum cancer age-standardised mortality rate (ASMR) in 1990 and 2021; B. Prostate cancer and colon and rectum cancer age-standardised DALY rate (ASDR) in 1990 and 2021.
Findings
The ASMRs and ASDRs attributed to a low-milk diet were negative for prostate cancer and positive for CRC between 1990 and 2021. The global CRC-associated ASMR per 100,000 decreased from 2.22 in 1990 to 1.87 in 2021, with an EAPC of -0.62. Likewise, the global CRC-associated ASDR decreased from 51.52 in 1990 to 42.9 in 2021, with an EAPC of -0.66.
Prostate cancer ASMRs and ASDRs showed smaller changes. The ASMR was -0.12 in 1990 and -0.13 in 2021, while the ASDR was -2.22 in 1990 and -2.49 in 2021. However, the study notes that these negative rates may reflect modeling limitations and should not be interpreted as definitive evidence of a protective effect.
Global CRC deaths attributable to a low-milk diet rose from 81,405 to 157,563 between 1990 and 2021. DALYs also increased, from 2.07 million to 3.7 million.
The CRC burden was higher among females and increased with age. Although females experienced a greater burden overall, their ASMRs and ASDRs declined more rapidly than those of males. Most CRC deaths occurred in the 70–74 age group.
Regionally, Southern Latin America had the highest CRC ASMR and ASDR in 2021, followed by the Caribbean. Central Asia had the lowest ASMR, and Australasia had the lowest ASDR. For prostate cancer, Western Sub-Saharan Africa and Central Sub-Saharan Africa had the highest ASMRs and ASDRs. Most cancer deaths and DALYs were concentrated in East Asia in 2021.
At the country level, China had the highest CRC deaths and DALYs, followed by Japan (deaths) and India (DALYs). Barbados recorded the highest CRC ASMR and ASDR, while Germany showed the greatest reduction from 1990 to 2021. Lesotho had the largest increase. Prostate cancer deaths and DALYs saw the greatest change in China, Nigeria, and India.
Projections suggest a continued decline in CRC burden by 2050, especially among women. Males, however, are expected to maintain higher age-standardized rates than females, reinforcing sex-based disparities.
Socioeconomic and cultural context
The study found that cancer burden trends varied by development level. Countries with higher Human Development Index (HDI) scores generally experienced sharper declines in CRC burden. CRC showed an S-shaped relationship with national development, while prostate cancer showed a U-shaped trend—indicating that the burden was highest in countries with both low and high levels of development. The study used the Socio-demographic Index (SDI), a composite metric incorporating income, education, and fertility, to categorize development levels.
Cultural dietary patterns also influence milk intake. For instance, lower milk consumption in East Asia may be linked to lactose intolerance and a preference for soy-based beverages.
Conclusions
The findings suggest that the global CRC burden attributable to a diet low in milk has slightly declined over the past three decades. Conversely, the ASMRs and ASDRs for prostate cancer were negative, but this may reflect model uncertainty rather than a true protective effect.
Together, the study provides crucial insights into how milk consumption relates to cancer risk. It highlights the need for public health guidance tailored by age, sex, and region, including strategies to improve milk intake in older adults and populations with traditionally low consumption.