The health service, nutritionists, the government and your parents are always telling you to eat more fruit and veg. Its sound advice, it really is, but how can we actually quantify the amount of fruit and veg a person should eat? The answer is we can’t. At least not accurately enough to warrant telling people exactly how many ‘portions’ we should be eating in a day. The ‘5-a-day’ message is a reasonable one though. Even if it does seem to suggest there is a set amount of fruit and veg the average person should eat in a day, the real message is plainly eat more fruit and veg because it’s good for you.
So why then do I turn on the TV this morning to find the news barking about how a new study has shown we need to eat 7 portions of fruit and veg a day to cut the risk of dying of common diseases?
The news comes from a study carried out by researchers at University College London who analysed questionnaire data collected by the NHS on people’s diet and lifestyle. Essentially, what has been reported is that the study indicates that the more fruit and vegetables people ate, the less likely they were to die, at any given age. In other words – fruit and veg is good for you – not a particularly new message. So why, oh why, then did they have to go and quantify how much you should be eating to avoid death? It’s just not possible, and not just because it’s difficult to interpret real world quantities from a self-filled questionnaire, but because the study itself has flaws which make it impossible. This is not a criticism of the research but more a facet of this type of study which should be respected.
Snap-shot
The first thing to note about the study is that it collected data from participants from 2001-2008. Although this is better than a single measurement it still only represents a relatively short amount of time in a persons life. This isn't particularly useful when a healthy lifestyle is something you have to maintain rather than just be healthy at the exact moment you were asked. This isn't to say that this kind of study isn't useful but its definitely a limitation worth considering.
Confounding factors
The other big factor which needs to be taken into account is other lifestyle and environmental factors which affect general mortality. The participants in the study are likely to be exposed to a wide range of different factors such as smoking, drinking, exercise, where they live, what their job is etc. You can try to take these into account when analysing the data but you’ll never be able to remove them from the equation – particular when you are dealing with a large scale cross-sectional study. There’s also the issue that healthy eaters tend to live healthier lifestyles. So how do we know that the benefits of 7-a-day aren’t because those people go to the gym more often or don’t smoke?
Risk reduction paradigm
It’s also worth mentioning that lifestyle interventions that reduce risk against anything need to be assessed alongside the impact of other lifestyle factors. This is important so we can see the ‘weighting’ of each factor on risk reduction, rather than each in isolation, and as such be able to work out how much impact a certain intervention has to an individual. For example, if you eat 7-a-day but you are also a heavy smoker; does eating 7-a-day even have an impact on your risk of cancer or heart disease? The effects of eating 7-a-day, over say 5-a-day, could be so small that the increased risk from smoking makes it irrelevant. In fact, if you are a heavy smoker it might not be any benefit to eat fruit and veg at all.
Remarks
The BBC have been cautious over touting a 7-a-day message which is great to see but I haven’t yet seen the full media coverage and I expect there will be some which completely overstate the results in this study. I don’t think the study authors should have allowed a 7-a-day message to accompany their research because I think they are a long way off showing that eating 7-a-day has any benefit over 5-a-day. Whichever is the case, the important message is that a healthy diet and a healthy lifestyle are going to be your best bet at having some influence over how and when you die, but I wouldn’t get too hung up on it.
The new report is actually saying nothing new. The entire idea of N portions a day is used throughout the world, but some use 5, others use 3 and some use 10. The 5 a day message here was picked simply as a good number to build a marketing campaign around - it was not the result of a definitive study, but simply was used as a good way to encourage people to eat more fruit and veg. Any improvement was going to be a good thing, to be honest.
Really, that part of the report is neither here nor there, it is just a way of underlining that in the UK we simply do not eat enough, and actually eating more than the rather arbitrary 5 a day is a really, really good idea.
Go to France (and much of the med) and they find the idea of five a day laughable as they eat far more than that as part of their normal diet.
Also, it should be stressed that that what people really need to eat more of is veg rather than fruit. The representative from the study mentioned that on BBC News today, quite rightly.
Great post Matthew. We had a little look at the evidence behind 5 a day as part of our Ask for Evidence campaign. One of things our Voice of Young Science network did was to ask different governments around the world what their fruit and veg guidance was and why. Here's an interactive map of what they found out - there's quite a bit of variation and not to mention disagreements over how much a portion actually is!
One of the things that has been a recurring complaint to the news item over the last day has been, "I can't afford 5 a day, let alone 7."
This maybe the result of an accidental problem with the marketing, exacerbated by the media representation of the idea.
It seems to have been the case that the fruit part of the 5 a day has had more prominence than the veg side. This is partly because in the phrase "your five a day or fruit and veg" fruit is mentioned first, and partly because when the food industry promotes products that "are part of your five a day," those products are almost always fruit based.
In reality, as I mentioned earlier, the five a day (or seven, or ten) should be mostly vegetables, and a mix of vegetable types at that.
In addition, what is not made clear is that when you add several more veggies to your diet, the general idea is that they should replace other diet items not be shoved on top as an addition. So, less meat, for instance, but more veg. For the life of me, I can't think of any industry or government led campaigned which has actually pointed that out - at least not in my experience.
Once you take that into account, moving towards a more vegetable orientated diet will not just be affordable, but it may reduce costs. I listed a couple of prices here: foodloversdiary.com/good-st...
At the end of the day, this is a good report if for no other reason than it addresses the point that we really do not eat enough vegetables on a regular basis in this country.
And while we are so bad at cooking them to make them interesting, this will probably continue to be an issue. The bbc presentation on a plate yesterday of what seven a day looked like did not help - a bit of fruit, some limp salad leaves and a couple of badly peeled chunks of carrot.
Last night, I cooked for the family my reaction to the article. I chopped small cubes of swede, celeriac and carrot and gently boiled them till tender. I made up a pork stock cube based soup with some lime leaves, lemon grass, ginger, carrot, fish sauce, pepper, chilli powder and fennel, then drained it. I marinated a bit of cheap pork tenderloin in dark soy, then roasted it for 20 minutes (very slightly underdone), and then at the end, boiled up some mangetout and chopped pak choi.
In a big bowl I put a pile of the cubed veg, surrounded it with a couple of ladles of the stock, put the green veg on top then sliced and arranged the pork on top of that. I then added some very thinly sliced mooli (chinese radish) and chopped coriander.
Even the teen took a photo and ate the lot.
So, it was cheap, had a huge amount of veg and was tasty and healthy. Two lumps of fruit for pudding and that was the seven a day just in the one meal, and it was just over 300 calories for the dieters in the family.
So, why are people finding this so difficult and spending so much time criticising it all?
I agree, the message is right but telling people how much they should eat can be confusing. The 5-a-day message may not be based on any evidence either but the message is clear now that eating fruit and veg is good for you and it probably encourages people to try and eat more. Will saying 7-a-day is the right amount make any difference? I doubt it and I think that it adds more confusion to the message, which could have negative effects. The complaint about 'affordable veg' is hard to understand because everyone's personal circumstances are different. A big problem may be that people don't know how to cook or use the veg that is cheap (and tasty!) so won't buy it.
I plan my meals in advance and eat meat twice a week for dinner. Lots of veg makes its way into my diet and I spend about £20 a week on dinner. This cost obviously reduces as you make meals for more people as well. Not in any way suggesting that this can work for everyone but its an example of eating healthy on a budget.
In a lot of ways, this is the same old problem of how do you change something that is embedded in the culture?
This campaign was lifted straight from the US model (if I remember right), but had no actual basis in science - actually, that is really unfair, there was good science behind the notion of the minimum about of fruit and veg you should eat to get a good balance, but all the campaign did was to divide that up into a useful number and then work out how big a "portion" was when you did the maths.
So, for the sake of a good marketing message, the science got a little bent.
Today the problem is a bit different and this is where I agree that the selling of the new research is unhelpful. The 5 a day message has never really worked because no one knows what a portion is (without digging through the NHS paperwork) and do not have the foggiest idea about how to implement that. My partner is a great example; she is a very senior pediatric matron dealing with special needs, but she is not much of a cook. When I asked her to describe what a portion is she just said, you know, a normal portion size ... whatever that is.
In addition, the gov spends a huge amount of time talking about health v junk foods (or what they think junk foods might be). But if you look at the standard British Diet before mass junk foods, it was really low on veg and fruit - so the problem is not new, it is embedded over generations.
Like most things to do with diet in this country, we tend to tackle the wrong problem. With obesity we blame junk food as making everyone fat. But actually the problem is that we all eat too much - it is almost irrelevant whether it is a big mac or a home made pie, we are just eating too much. I am seriously obese, but I do not eat junk food at all. I eat fresh fish, meat, home made everything, (I work from home). But I eat too much.
With the five a day, the problem is not that people need to just eat more fruit and veg, they need to rebalance their diet completely. And that is a far more complicated problem.
Education is the answer, but shoving a plate full of raw, flavourless carrots in front of a kid will not reeducate them - they need to be shown how fun eating can be, even when the ingredients are mysterious or frightening. Jamie Oliver got the right idea, and look what a mix of the press, stupid MPs and reluctant schools and parents did to him?
In my opinion we have to be very careful of fruit and cereals as well as potatotes, pasta and rice. Have you seen Dr Lustig on the problems of too much fructose? He has a theory that the only time animals usually got a lot of fruit in the Northern Hemisphere was in Autumn when they had to fatten up. That it is not a good idea to eat lots of fruit. Especially if you are diabetic or have any tendency. youtu.be/ceFyF9px20Y
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