This picture represents what should constitute the majority of our diet... a variety of coloured vegetables and fruit (World Cancer Research Fund endorses this, they recommend eating mostly foods of plant origin to reduce the rist of cancer). By adopting this and a few other basic nutrition guidelines we can reduce our risk significantly of developing Type 2 Diabetes, the cardiovascular diseases (such as Choronary Heart Disease, stroke, periferal vascular disease), gut related illness (IBS, gallstones etc) and bone disease (inc osteoporosis and arthritus). For decades we have been told about a plethora of "superfoods" which preport to reduce cancer, improve our hearts, or sooth our intestines. The quesion is, which foods can be proven (through rigorous and verifiable studies) to work? I attended a course yesterday on just this topic and here is the summary:
Consistently in the UK we need to:
increase the volume of vegetable and fruit ingested,
reduce saturated & trans fat intake (e.g. pre-packaged foods, cakes and biscuits and chocolate),
reduce red meat & processed meats (including ham and sausages),
reduce salt intake (including pre-prepared foods, e.g. lasagne)
reduce alcohol intake to 1-2 units per day for women & 2-3 for men
But this isn't news, I hear you say. Tell us about the superfoods? It turns out that the question is not which ones should we eat, but how should we eat? We could reduce our risk of developing all the illnesses listed above by making (amongst others) the more all-encompasing nutiritional changes bulleted above, before we even think of gorging on individual foods, like eating large quantities of phytochemicals in the form of green tea or garlic to our diet. In fact, if we concentrate on our overall diet (using the guidelines above) we will naturally include all the individual foods which may prevent specific conditions. For example consuming cruciferous vegetables (broccolli, cauliflower, cabbage etc), which contain sulfrophane, and may reduce the risk of developing breast cancer by up to 50% (Fowke et al, 2003) and bladder cancer by 51% (Health Professionals Follow Up Study, 1999).
We do need to be cautious of overeating a particular food group in an attempt to protect from a specific condition. For example an excess of oily fish may lead to ingesting higher levels of mercury than advised, despite also increasing Omega-3 intake to help with inflamation associated with joint related illnesses. Or reading Sabate's (2006) evidence in the British Journal of Nutrition that the risk of Coronary Heart Disease is 37% reduced when eating nuts x4 per week, and then eating an excess of nuts, which will encourage weight gain.
It is also worth considering the validity of the studies we read. An example is the carotenoid studies. Interestingly carotenoids (orange & yellow foods like sweet potato, peppers, mango) have been proven in one study to reduce risk of some cancers and in other studies to be neutral or actually increase the risk of lung cancer. We can conclude that our knowlege of food is still developing and that there is lots to learn. However, the message remains that eating a variety of fruits and veg is a better cancer-prevention strategy than eating a single beta-carotenoid in volume.
So how much of each should we eat? Are we getting that right? The NHS Eatwell Plate should be our guide to proportions of food groups.
Furthermore, studies consistently show that the Cretian Mediteranian Diet (listed below) is the best for reducing the inflamation associated with osteo and rhumatoid arthritus (Sales et al 2009, Kjeldsen-Kragh J, 2003) as well as cancer prevention and dislipidaema (high blood lipid content or cholesterol). This is not new thinking, Ancel Keys, in the Seven Countries study of the 1950's noted that mortalilty rate from CHD and all other causes was significantly lower in Mediterranean regions compared with Northern Europe and the United States.
Cretian Mediterannean diet:
large quanties of fruit and veg,
olive oil as the primary source of fat,
oily fish (for the Omega-3),
only a moderate intake of wine and
(notice the lack of red meat, cakes, biscuits, etc)
Of course nutrition alone is not the solution to risk prevention for the biggest diseases. It was estimated in a recent study that overweight and obeisity accounted for 14% of all cancer deaths in men and 20% in women. Again, we can solve this by eating as per the eatwell plate, enjoying the correct volume of food (Many fall for the trap if increasing their oveall intake by adding the 5-a-day to their existing food intake), and exercising regularly.
If you must take away one small thing that you can quickly change, try these two simple steps to reduce our risk of mouth and throat cancer: avoiding drinking very hot drinks (Sieri S et al, 2004) and avoid other types of cancer by avoiding burnt food (toast, BBQ!).
If you would like to hear more about this I will be giving a talk on nutrition in November. Contact me for more details.