By Clare Murphy
Health reporter, BBC News
Broccoli - it's still good for you
As the decade draws to a close, hopes that just eating a bit more broccoli will help banish disease appear to be waning - and some are urging a rethink of how we approach the many messages about diet and disease.
The five-a-day campaign - with its roots in the US - hit England in 2003 with the aim of increasing fruit and vegetable consumption as a "national priority".
But the role these play in protecting us from cardiovascular disease and cancer above and beyond acting as substitutes for more calorific fare now seems murkier than it did then.
A major piece of recent research found that while vegetarians did seem to develop fewer cancers than meat-eaters they were not protected against bowel cancer - one of the most common forms of the disease and one which had been thought to be particularly influenced by the consumption of red and processed meat.
"We're clear on obesity - and also alcohol - as disease risk factors," says Tom Sanders, Professor of Nutrition & Dietetics at King's College, London.
"But the suggestion of a reduced risk with increased fruit and vegetable intake once you take out all the other factors is much harder to prove. We are pretty much drawing a blank.
"One of the myths is that fruit is bursting with minerals - it's not. It's essentially vitamin C and potassium - and most of us really have enough of these without five-a-day."
Green and leafy
Even nutrient-rich vegetables such as broccoli, spinach and cabbage do not appear to confer the protective benefits against serious disease once hoped for - at least at the levels consumed by the general population.
"It's driven a huge amount of research in recent years, and we have seen that biological activities - of which there are thousands in plant foods - can prevent cancer in certain models," says Professor Ian Johnson of the Institute of Food Research.
"But confidence has waned that what we were seeing in the lab was actually operating in the population. We aren't where we thought we would be ten years ago."
But there remains hope that if the active chemicals in these products were artificially harnessed and optimised, they could prove a key weapon in preventing cancer from developing in the first place in certain individuals.
The chemicals in broccoli for instance have been shown to have an effect on levels of the GSTP gene, which has been shown in mice to protect against tumours of the bowel, lung and skin.
"I think the next ten years will be about further understanding the human genome and genetic variations - working out why people with similar lifestyles have such different vulnerabilities to disease," says Professor Johnson.
"Once we can do this we can - in principle at least - start to target groups, and provide personalised diet information - nutritional genomics, we call it - rather than the blanket advice we issue at the moment."
While waiting for this tailored treatment, it appears that apart from giving up smoking, striving to attain a Body Mass Index within the healthy range is a good step towards guarding against disease.
"Weight is important - so portion sizes and calories are important, however healthy the food may seem," says Professor Sanders. "You can have a virtuous middle-class lunch of a vegetarian wrap and a banana, washed down with a smoothie - but that may well be a lot more calories than you think."
Rachel Cooke of the British Dietetic Association says the healthy eating message does indeed need tweaking.
"Many people see all healthy foods as 'free calories' - they don't understand that other things have to be taken out of the diet, and that you can't just eat as much yogurt or cereal as you want just because they are low-fat options.
"Our portion sizes have increased dramatically - and that's what we should be looking at in the years ahead. The whole notion of getting value for money means people expect more food on their plate."
But it has been suggested that this may just be the inevitable human response to a specific historical epoch - to stock up on food during a time when it is plentiful and cheap.
Obesity and its accompanying diseases, it is argued, may be the cost of a period of prosperity which has seen the elimination of conditions which crippled or killed our poorer, hungrier ancestors - whose life-expectancy was considerably lower than our own.
Indeed for one doctor at least, it is the constant parade of government health exhortations which may be making us ill.
"Health messages have taken over - it seems to be an area where politicians feel they can stamp their authority," says Dr Mike Fitzpatrick, a London GP and author of the Tyranny of Health.
"But people know about the dangers of smoking and being overweight - they don't need all these initiatives, many of which are incredibly patronising and paternalistic.
"This mounting preoccupation with health issues is making many people anxious and incredibly inward looking - and that doesn't seem to me a particularly healthy basis for a society as it enters a new decade."