Diet, Nutrition, Physical Activity and Cancer: a Global Perspective was a report produced in 2018 by World Cancer Research Fund International on behalf of the World Cancer Research Fund network charities AICR, WCRF UK and WKOF.
Our Third Expert Report, Diet, Nutrition, Physical Activity and Cancer: a Global Perspective, assessed the past decade of cancer prevention research and the links between diet, nutrition, physical activity and cancer.
Go to the Resources and toolkits page to access additional downloads including the complete Summary Report PDF or to request it in print.
Our independent panel of global experts has been evaluating the evidence on cancer prevention for many years. The 2018 report was our third comprehensive analysis since 1997 of the worldwide body of research available.
This internationally acclaimed report is a collaboration between four organisations under the umbrella of the World Cancer Research Fund network:
The first and second Expert Reports, when they were published in 1997 and 2007, respectively, were landmarks in the science of cancer prevention. Since the second report, scientists at Imperial College London have been adding information to a unique and growing database of evidence relating to cancer prevention and diet, nutrition and physical activity.
This forms the basis of our flagship Global Cancer Update Programme (CUP), an ongoing analysis of evidence related to diet and cancer prevention. Evidence from the CUP Global enables World Cancer Research Fund to publish reports on individual cancer types, the most recent being our report on colorectal cancer in 2017.
Authoritative, evidence-based Cancer Prevention Recommendations
In the past ten years, the need for authoritative, evidence-based recommendations on how to reduce the global burden of cancer has grown. There is strong evidence from the CUP Global, for example, that being overweight or obese puts you at increased risk of many cancers.
We’re experiencing a global obesity epidemic, declining physical activity among both children and adults in many parts of the world, and an increase in the consumption of energy-dense foods. If these current trends continue, overweight and obesity are likely to overtake smoking as the number one risk for cancer.
A blueprint for cancer prevention
Our Third Expert Report is a vital resource for anyone involved in preventing cancer. It ensures that everyone, from researchers to policymakers to the public, can access the most up-to-date information on how to reduce the risk of developing cancer. It also identifies areas for future research into cancer prevention and survival.
You’ll find the answers to many more questions about the report, including who wrote it, how the evidence is analysed and why the world needs it, on our FAQs page. You can also browse the glossary for an explanation of many terms used throughout the report.
Changes between the Second and Third Expert Reports
There were important shifts in emphasis between the 2007 Second Expert Report and the Third Expert Report, published in 2018.
Emphasising a more holistic approach
The Cancer Prevention Recommendations in the Third Expert Report are similar to those in the 2007 Second Expert Report. However, they incorporate an important shift in emphasis in the Expert Panel’s interpretation of the evidence.
Through the years, the Continuous Update Project (CUP), and its predecessors the First and Second Expert Reports, have identified many specific foods (such as processed meat) and components of foods (such as alcohol) in the human diet that increase or decrease the risk of one or more particular cancers.
However, it appears increasingly unlikely that specific foods, nutrients or other components of foods are themselves important singular factors in causing or protecting against cancer: rather, different patterns of diet and physical activity combine to create a metabolic state that is more, or less, conducive to the acquisition of the genetic and epigenetic alterations that lead to the phenotypical structural and functional alterations in cells described by the Hallmarks of Cancer.
In humans, as with all organisms, the normal physiological and metabolic state is subject to external and endogenous challenges (stresses). Nutrition is an important component of the body’s capacity to withstand these stresses and avoid the development of diseases; in the absence of frank nutritional deficiency, this resilience is not dependent on the singular effect of specific nutrients. A more holistic focus on the determinants of resilience to external and endogenous challenge may be more fruitful than a continuing search for specific dietary factors that may cause or protect against cancer.
Furthermore, studies evaluating the impact of adherence to the Cancer Prevention Recommendations from 2007 have shown that the more people adhere to those recommendations, the greater the reductions in the risk of specific cancers, of cancer as a whole and of death from any cause.
For all these reasons, therefore, the Expert Panel emphasise the importance of recognising that, while following each individual Recommendation is expected to offer cancer protection, the most benefit is to be gained by treating them as an integrated pattern of behaviours relating to diet and physical activity, and other factors, that can be considered as a single overarching ‘package’ or way of life.
The consistency in the Recommendations since 2007 increases confidence in the evidence base and in the advice given to policymakers, the scientific community, health professionals and the public.
Fine-tuning how we assess evidence
There has been an increase in the overall amount of evidence since 2007. This has enabled the Expert Panel to fine-tune its approach to assessing and interpreting evidence:
Growth in the number of cohort studies and the number of cases in existing cohorts, as well as improvement in the quality of these studies, has enabled the Expert Panel to concentrate more on evidence from cohort studies, which are considered the best source of evidence on cancer prevention. This growth has also provided greater confidence in the accumulated evidence.
Results from pooled analyses of cohort studies have been particularly helpful in adding evidence for subgroup analyses.
Where possible when reviewing evidence on diet and nutrition, the Expert Panel has increasingly considered the effects of dietary patterns. This is important because people do not eat foods in isolation but in combination, to form an overall diet or eating pattern. In itself this is related to other health-linked behaviours, such as smoking or physical activity. While sophisticated epidemiological or statistical techniques may help to minimise the inevitable effect of the resulting confounding, confidence in the nature of the truly causal exposure must always be greater for the aggregated set of dietary factors and other behaviours than for any single food, nutrient or other behavioural marker. Therefore, even where there is no direct evidence on dietary patterns the Expert Panel has aimed to interpret evidence on specific foods in relation to dietary patterns.
There is more evidence on subtypes of cancer now, such as oesophageal cancer, and therefore more conclusions on the effect of diet, physical activity or body fatness on differential risks of these subtypes. Evidence on subtypes is still emerging. This is important because different exposures might influence the risk of different subtypes in different ways.
It has been possible to use non-linear analyses more to identify thresholds, or plateaus. For example, there may be a threshold in the level of exposure below which there is no association with the risk of cancer and above which there is. This has proved important, for example, when making Recommendations on the level of consumption of alcoholic drinks.
Stratified analyses have provided valuable insights, for example, when considering the effect of exposures stratified by smoking status.
Emerging evidence of note
Emerging evidence that is particularly noteworthy includes:
Growth in the amount of high-quality data that is available has allowed more sophisticated analyses of how effects on cancer risk change with the level of exposure – for instance on the shape of dose-response associations. For fruit and vegetables, for example, emerging evidence suggests it’s the people who consume the least, who eat very little or none of these foods, who are most at risk of developing certain cancers. It may therefore be more important for these people to increase their consumption levels than for people who already eat more than one or two portions per day.
The influence of height on cancer risk is becoming more apparent. However, height itself is unlikely to be the actual cause of cancer. It is most likely a marker for developmental factors related to growth and metabolism operating from the earliest stages of life to influence cancer susceptibility. More research is needed to build understanding of precisely how this might happen.
The importance of the life course in general is emerging more strongly. There is evidence that greater adult height predicts higher risk of several cancers; and for breast cancer specifically, that greater birthweight is associated with higher risk, while greater body fatness in young adulthood predicts lower risk. However, more research is required to help further understand the mechanisms.
Evidence on cancer survivors is accumulating, though is still at an early stage, and more is needed, particularly from well-conducted trials (some of which are under way).