13. Diet and Cancer: a clinical research problem.

     It struck me very early on when writing this blog on nutrition and cancer that I had stepped into a virtual minefield; a field sown in the shifting sands of informed opinion that is littered with the bones of once-considered truths that have since been abandoned by dieticians in the light of new and often apparently conflicting evidence. Clinical research on nutrition and cancer prevention is regrettably sparse and is sadly lacking in trial depth in comparison to similar research and trials on drugs for a cancer cure. I wondered why this should be and invited Dr. Ian Hampson of the Institute of Cancer Sciences at the University of Manchester to discuss this anomaly.  This is his illuminating reply: 

     Diet is one of many environmental factors that combine with the genetic hand we have been dealt to promote the development of cancer. The problem with nutrition and diet, however, is that we keep getting it wrong.

     We are now beginning to appreciate that early foetal or newborn dietary programming must be taken into account, (see link to the US National Library of Medicine below).  It seems that the diet to which we are exposed in early life, and even in the womb, fixes the goalposts for what our bodies regard as normal. Our response to nutrients in early life can therefore influence how we will respond to these in later life. This in turn determines our susceptibility to many cancers and, indeed, to a whole range of diseases.  Superimpose this on the worldwide differences in youth and adult lifestyles, diet, exercise and ethnicity and you have created a complex equation, which probably explains why there are so many conflicting studies and calls for further research. It also explains why the success of clinical trials that embrace all parts of this equation would be impossible within a reasonable human timeframe, ethnic spectrum and realistic budget.

      Our newfound appreciation of the impact of early foetal and newborn nutrition and diet on our susceptibility to cancer and other diseases in later life does however open up the possibility of some disease preventive control in the future by the administration of prenatal or postnatal dietary supplements.  But that calls for yet further research!

     Meanwhile, eat a diet which is abundant in fruits, vegetables, whole grains, nuts, legumes and olive oil. Choose fish and poultry, lean sources of protein, rather than red meat, which contains more saturated fat.  This is what is known as the Mediterranean diet.  Also observe moderation in all things! Even exercise – too much is actually bad for you!

Dr Ian Hampson,

Reader in Viral Oncology,

University of Manchester

I was interested to read Dr Hampson's Mediterranean diet recommendation in his final paragraph.  The 'Mediterranean diet'  has  recently been pronounced as beneficial, not only in risk reduction of a growing number of cancers such as uterine cancer, (see my blog  12),  but is also associated with good general health, a healthy heart and weight control or obesity - itself a potential cause of some 22 different cancers according to studies published in The Lancet, including liver, colon, ovarian, breast and prostate cancers, (see my blog 3).

Further reading

US National Library of Medicine

Institute of Cancer Sciences

The Mediterranean Diet

12. Mediterranean diet cuts uterine cancer risk

     

Photo: Nazarethhealthcare.com

     A new study published in the British Journal of Cancer has shown that women who eat a Mediterranean diet could cut the risk of uterine cancer by over half.
     Pooled data from a number of case-control studies in various areas of Italy and Switzerland show that consuming food high in unsaturated fatty acids, fibre, phytochemicals and antioxidents, (as found in what we know as a 'Mediterranean diet'), dramatically reduce the odds of contracting cancer of the womb by over 50%.  
     What do researchers mean by a 'Mediterranean diet'?  They characterise it by nine dietary components: a high intake of vegetables, fruits/nuts, cereals, legumes, fish; low intake of dairy products and red meat, (see my previous blogs 11 and 1); a high monounsaturated to saturated fat ratio; and low alcohol intake.
     Study researcher Dr Cristina Bosetti, from Mario Negri Institute for Pharmaceutical Research in Milan, said, "Our study provides evidence for a beneficial role of the Mediterranean diet on endometrial [uterine] cancer risk.  It adds more weight to our understanding of how our everyday choices, like what we eat...effect our risk of cancer."
     The 'Mediterranean diet'  has  recently been pronounced as beneficial, not only in risk reduction of a growing number of cancers but is also associated with good general health, a healthy heart and weight control or obesity - itself a potential cause of some 22 different cancers according to studies published in The Lancet, including liver, colon, ovarian, breast and prostate cancers, (see my blog 3).

The Mediterranean diet Pyramid

Further Reading:
British Journal of Cancer Mediterranean Diet and Womb Cancer
Womb (uterus) Cancer All about Womb Cancer. NHS pages.
Mediterranean Diet All about the Mediterranean diet. 
How to follow a Mediterranean diet Patient Information and Support.
The Lancet Body mass and cancer risk.

11. Red Meat and Cancer - New Findings

     A new study published in the journal Nature Communications which compared high fibre/low fat diet with a high fat/high protein diet has dramatically underscored the bowel cancer risk of a Western diet typically high on red and processed meats and low on fibre, fruit and vegetables, (see my blog 1. Red Meat and Cancer).  It has also raised pointers to possible future therapies for  prevention and treatment of bowel cancer which is one of the biggest cancer killers in western countries, thanks to Western diet. Its incidence is much lower in Africa and the Far East. 
     To test the true impact of diet on bowel cancer, researchers at the Imperial College London recruited 20 African Americans from Pittsburgh, Pennsylvania and gave them a meal plan based on a ‘traditional’ African diet high in fibre and low in fat, centred on corn-based products, vegetables, fruit, and pulses. Meanwhile, 20 African volunteers living in rural South Africa were given a typical Western diet, high in red meat and low in fruit, vegetables and other sources of fibre. 
     Participants had colonoscopy examinations to look for inflammation and polyps that can indicate potential cancer risk before commencement and after completion of the study.  At the start of the study, nearly half of the Americans, and none of the South Africans, had polyps. But after only two weeks, the American group was found to have significantly reduced colon or bowel inflammation, while in the South Africans, measurements indicating cancer risk dramatically increased. 

     Professor Jeremy Nicholson from Imperial’s department of surgery and cancer commented on the findings: “What is really surprising is how quickly and dramatically the risk markers can switch in both groups following diet change.”

    The new study suggests that changing diet may affect cancer risk by altering the balance of bacteria found in the gut – known as the microbiome. At the start of the study the African group consumed between two and three times less animal protein and fat than the Americans, but consumed significantly more carbohydrate and fibre.

This led to higher levels of butyrate, a by-product made by the body when it metabolises fibre.  Butyrate is thought to have anti-cancer effects, and higher levels were seen in the Americans  after two weeks on the African diet.

     Dr James Kinross, a colorectal surgeon and clinical lecturer at Imperial, comments: "Scientists are beginning to recognise that the gut microbiome could have an important influence on human health.This research shows that gut bacteria are critically important for mediating the link between diet and colon cancer risk. This means we can look to develop therapies targeting gut bacteria as a way to prevent and treat cancer.”

   Professor Nicholson also raised the concern that  the progressive westernisation of African communities may lead to the emergence of colon cancer as a major health issue for them.

Further Reading:

Proceedings of the National Academy of Sciences USA. Study on the connection between red meat, inflammation and cancer progression. 

Nature Communications Fat, Fibre and Cancer risk