Diet and cancer in Ireland

While smoking has long been recognised as a potent risk factor for cancer,¹ prioritisation of poor diet in this area has been much neglected. Recent UK research² estimates that 9.2% of all cancers are attributable to poor diet (low fruit and vegetables, high red meat, low fibre and high salt). A further 5.5% of cases relate to overweight and obesity, with an additional 4.4% ascribed to the effects of alcohol overconsumption.  

Escalation of cancers expected in the future

The most recent statistics from the World Cancer Research Fund (WCRF) indicate that Ireland has a significantly higher cancer incidence than virtually any other country in the world.³ For instance, 356 per 100,000 of the Irish male population were diagnosed with cancer in 2008, third only behind France and Australia. 

Among women, 285 per 100,000 of the female population were diagnosed with cancer in 2008, placing Irish women third-highest in the world after Denmark and New Zealand. 

When both sexes are considered together, Ireland ranks a close second-highest in the world behind Denmark, with 317 Irish people per 100,000 of the population being diagnosed with some form of cancer in 2008. 

To put these data in context, the average yearly cancer incidence for the 50 countries with the highest rates is 182 per 100,000 of the population, 204 per 100,000 for men and 165 per 100,000 for women. 

This indicates that overall cancer rates are 75% higher among Irish men and 73% higher among Irish women than the average figures observed among even the 50 countries with highest incidence, with colorectal, breast, lung, prostate, oesophageal, liver and pancreatic cancers being particularly prevalent.³

It is also estimated that Ireland’s overall cancer burden will escalate exponentially over the coming years, with incidence rates projected to rise by 72% by the year 2030, a significantly greater increase than that anticipated for any of the other 27 EU-member states surveyed.⁴

Dietary problems

In examining the specific dietary and lifestyle issues which contribute to cancer, several factors come into sharp focus. From the diet and nutrient intake point of view, there is now very good evidence that high red meat (and especially processed red meat) intakes are associated with increased all-site cancer mortality.⁵

There is also clear evidence that high alcohol intake (more than four drinks per day) significantly increases the risk of oropharyngeal cancer (by 500%), laryngeal cancer (by 250%), colorectal cancer (by 50%), breast cancer (by 50%) and pancreatic cancer (by 30%).⁶

Low fruit and vegetable consumption has been estimated to play a role in 5-12% of preventable cancers,⁷ while high milk and dairy intakes are thought to be protective.^8,9 With regard to nutrient intakes, high saturated fat intake¹⁰ and low omega-3 (fish oil) intake¹¹ have been cited as risk factors for cancer, as have low folate intake (especially in the context of high alcohol consumption),¹² low calcium intake¹³ and especially poor vitamin D status.^14,15

From the lifestyle perspective, physical inactivity,¹⁶ overweight and obesity,¹⁷ and diabetes and metabolic syndrome¹⁸ have all been identified as potent oncogenic stimuli. 

The Irish situation

The recent National Adult Nutrition Survey (NANS),¹⁹ along with other national diet and lifestyle surveys,²⁰ suggests that such nutritional risk factors abound in the Irish population. Intakes of red and processed meats are very high, while average fruit and vegetable intakes are less than half the 400g per day recommended by the World Health Organization. Additionally, average milk and dairy intakes are estimated at less than two servings per day, with a majority of the population failing to consume fish even once per week.  

From the nutrient intake perspective, saturated fat intakes are roughly 30% higher than recommended, while only 20% of the population reach the European Food Safety Authority’s 25g/day guideline for dietary fibre. A significant minority also miss out on their daily folate and calcium requirements, while dietary vitamin D intakes are lamentably low. Indeed, there is now compelling evidence of endemic vitamin D insufficiency across the Irish population.²¹

All of these nutritional deficits are superimposed on a collage of deleterious health behaviours. One in four Irish men and one in five Irish women exceed their weekly alcohol intake guidelines, with regular binges reported in 41% of men and 21% of women.¹⁹

The Survey of Lifestyles, Attitudes and Nutrition²⁰ found that 29% of the population were current smokers, with an even higher prevalence of tobacco use observed among younger people and the lower occupational social classes. The same study revealed that 45% of Irish adults were insufficiently active, with 19% reporting no habitual physical activity at all. 

These data underscore the findings of previous research which indicated significantly poorer activity levels in Ireland than in most other European countries.²² Unsurprisingly, the prevalence of overweight and obesity is now considerably higher in Ireland than in most other EU member states,²³ while there is also emerging evidence of the devastating impact that these obesity rates are having on our prevalence of diabetes and on the overall metabolic health of the nation.²⁴

Conclusion

The above data suggest that we are standing on the precipice of a cataclysmic (but avoidable) cancer epidemic. 

By strengthening our national nutrition and health behavioural surveillance systems now, we will be able to identify and understand the spatial and socio-demographic correlates of these adverse behavioural patterns. 

It is only in this way that effective, targeted preventative strategies can be formulated to redress Ireland’s unsustainable national cancer burden.  

References 

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