A leading food scientist has put his hand up to say sorry for the onslaught of different surveys which seem to offer different nutritional advice every week as “5 a day” gets the knock. As soon as one piece of heavily researched evidence comes out, another seems to appear to cancel it out. Whether or not wine is good for us is one of the most striking examples, with conflicting reports coming out in a steady stream since Hippocrates said it was part of a healthy diet back in 500 BC (and he had never even heard of resveratrol).
The latest sacred tenet to fall to the wayside, is the now well-known “5 a day” World Health Organisation backed goal regarding fruit and vegetable consumption. This has become so familiar and so trusted that even small children know its advice by heart and ask “Is this one of my 5 a day?” as they tuck into a strawberry flavor ice cream. It has been in existence since 1990.
In the conclusion of a 12 year-long project conducted by University College London it was found those who ate seven portions a day were 42 percent less likely to die a premature death. It also noted that the vegetable component was much healthier, at least four times more than the fruit.
Dr Oyinlola Oyebode, the study’s lead author, said the message was loud and clear, “However much you are eating now (of fruit and vegetables) eat more.” The study was published in the Journal of Epidemiology and Community Health.
Gunter Kuhnle, a lecturer in nutritional biochemistry from the University of Reading, admits it is going to cause confusion, now that recommendation has been upgraded to “10 a day.” Apparently the old target of five is simply no where near high enough.
Despite the fact that this is based on a “truly excellent study” and that the revised ideas are based on “good scientific results” Kuhnle is first to agree that it will yet again, and inadvertently, feed “the hunger for food fads” with some of the caveats and uncertainties getting “lost in translation.” This isn’t so much the scientists fault, they are merely publishing their papers, but the transition into everyday language and the incessant amount of material, can invariably be confusing.
Kuhnle fears that “messing with the sacred cows of health advice” may do more harm than good and that scientists will lose the public’s trust. However, he is clear that this is an exceptional study and anyway it is a “no-brainer” that eating more fruit and vegetables is better for everybody.
He reminds that the targets are already significantly different in different countries. In Japan it is 17 a day, in Canada between 7 and 10 and in Denmark, 6. Whether any of these are met is another question. In the UK most people are only reaching a minimum of two pieces of fruit and just over one portion of vegetable per day. Getting that up to ten is going to be a big step-up, particularly with rising food costs. In America, the numbers were abandoned in favor of a more general “fruit and veggies – more matters” campaign, back in 2007, which now looks to be quite prescient. The USA encourages covering half the plate with vegetables as a guideline to the right proportions.
A cautionary note in this study is that tinned and frozen fruits and vegetables are far less beneficial. In practical terms, this is down to the fact that the researchers were unable to devise a methodology to discriminate between them, so they could not be accurately analysed. Kuhnle says this is the sort of anomaly that could lead to off-the-mark headlines, such as “Tinned fruit causes death.”
This may sound alarmist but the study did find that those who preferred canned and frozen fruits increased risk of dying by 17 percent, so it would actually be an accurate, if hysterical sounding, fact to report. Fruit juices were also found to have no real benefits at all. A breakfast with tinned or frozen fruit on cereal and a glass of fruit juice is therefore not contributing to the daily intake.
Dr Oyedobe commented on the findings for the canned fruit and said the amounts of sugar in the syrup probably accounted for the negative results. She also said there would have been contributory factors that could not be controlled for, such as pre-existing illnesses, or socio-economic factors, such as living in an area with little access to fresh groceries, and income levels.
In Australia, the government has taken a different tactic, pushing a “two plus five a day” message, with the five representing the vegetables. With each portion of vegetable lowering death risk by 16 percent, and fruit only four percent, the onus on eating more vegetable is the most critical. Once again, the Mediterranean Diet gets the thumbs up for its health-giving credentials.
It’s all a long way from “An apple a day keeps the doctor away” and “Ten helping of fruit and vegetables every day but more vegetable than fruit” does not trip off the tongue so easily. Keeping the advice simple and readily understandable is the trick, but that is not the food scientist’s job, they are merely doing the research and providing the data.
Naveed Sattar, a professor of metabolic medicine at the University of Glasgow, thinks getting the “5 a day” message amended to 7 or even 10, is going to require government support, and the subsidy of the costs of fruits and vegetables.
Other food scientists have agreed with Gunther Kuhlne that the UCL study is very sound and very broad (it took account of the eating habits of 65,000 people) but that any study of real people in the real world is open to suspicion. Does everyone tell the truth? How do you account for lifestyle habits, such as smoking, and what about the effects of an individual’s education? Professor Susan Jebb of the University of Oxford’s Nuffield department of primary care health science questions the reduced risk of disease and death as against these unknowns.
Catherine Collins, a dietician from St George’s Hospital also said that the results may not “necessarily be a casual relationship” given it is impossible to exclude these biases.
No doubt tomorrow and next week and ongoing there will be more and more reports which cancel or contradict previous advice. The food scientists may apologise for this circumstance but at the end of the day it is up to the individual whether they choose to consume 5 a day or up to ten fruits and vegetables.
By Kate Henderson