Dairy and cancer prevention
About a third of the most common cancers can be prevented through diet, weight management and physical activity. Since these are modifiable factors, change of lifestyle could help to ease the immense burden of cancer on individuals, families and health care systems. Diet (or foods) can have effects that either promote or prevent cancer. Despite many studies being conducted each year to unravel the complex link between dairy consumption and cancer, several questions remain unanswered.
Health and nutrition professionals need to be able to critically judge the wealth of published information to inform their professional decisions and viewpoints. However, a recent study among South African nutrition professionals revealed very low attitude scores in respect of dairy and the development of cancer. The finding was interpreted as being related to the novelty or complexity of the relationship.
In a meta-analysis of 11 population-based cohort studies, Lu and colleagues investigated the association between mortality due to cancer as a whole and total dairy product intake. They reported a non-association in men and women alike. The link is more often investigated with regard to a specific cancer site or dairy product, and based on incidence.
The table below summarises the findings from the authoritative second World Cancer Research Fund (WCRF) report and various subsequent continuous update project (CUP) reports.
These reports are collectively available at www.wcrf.org
- Full list of references can be found in the Nutrition Review Download below
Research into the association between cancer and nutrition, including dairy intake, is a dynamic field of investigation, with many original studies and numerous integrative knowledge synthesis studies (systematic reviews and meta-analyses) being published regularly. This umbrella review of systematic reviews and meta-analyses clearly shows that no definitive answers (convincing evidence) are available yet and that the link between a complex exposure (dairy consumption) and a complex outcome (cancer) does not have a simple answer. Consequently, none of the WCRF’s 10 recommendations for the prevention of cancer (see Box below) explicitly refer to dairy. Matters such as weight management seem to be more important in this regard.
In a holistic approach, where balance, variety, moderation and nutrition adequacy are valued, dietary recommendations cannot omit dairy. One of the South African Food-Based Dietary Guidelines include dairy as part of a balanced diet, “Have milk, maas and yoghurt every day”.
- Be a healthy weight.
- Move more.
- Avoid high-energy foods and sugary drinks.
- Enjoy more grains, vegetables, fruit and beans.
- Limit red meat and avoid processed meat.
- For cancer prevention, don’t drink alcohol.
- Eat less salt and avoid mouldy grains and cereals.
- For cancer prevention, don’t rely on supplements.
- If you can, breastfeed your baby.
- Cancer survivors should also follow these recommendations.
Evidence-based recommendations to prevent cancer
There is currently no convincing evidence that dairy, whether as a whole or in any of its forms, either increases or decreases the risk for any of the listed cancers. None of the ten nutrition-related recommendations for the prevention of cancer thus refer to dairy. When the focus is only on cancer prevention, dairy seems to offer health benefits to women by reducing the risk of the common and serious colorectal cancers. Based on current knowledge, the protective effect of dairy on colorectal cancers may outweigh a potentially increased risk of prostate cancer in men. Primary prevention should, however, not have a disease-specific focus, but rather be relevant to the whole population. There is extensive evidence that dairy intake is closely associated with the prevention of non-communicable diseases (NCDs) as a group. In addition, South Africa experiences a double burden of nutrition-related disease: not only NCDs but also under-nutrition is rife.
Full reference available in the downloads below.