Let’s look at the evidence

Photo courtesy of Wikipedia (http://en.wikipedia.org/wiki/Fifth_Doctor)

Photo courtesy of Wikipedia (http://en.wikipedia.org/wiki/Fifth_Doctor)

A recent post on Running Buffet was looking at the ‘5 a day’ initiative and it included the statement “there is evidence that eating more fruit and vegetables can help improve your health”. Now this seems like a self-evident fact, in the same vein as “getting more exercise is good for you” and “drinking beer makes you a better person” (I may have to double-check that last one – I’ll get back to you), but it would seem sensible to ask ourselves for a little proof. A little evidence. If nothing else, it will help us feel smug and self-satisfied as we eat our greens.

Where do we turn for answers? I think I will start with Doctor Who.

*Checks the spelling*

Sorry, I meant to say I think I will start with the doctors from WHO, the World Health Organisation.

The WHO website contains the worrying statistic that “an estimated 6.7 million deaths worldwide were attributable to inadequate fruit and vegetable consumption in 2010”. In particular, they say that poor fruit and vegetable intake “is linked to poor health and increased risk of noncommunicable diseases (NCDs)”.

On the plus side, they suggest that a daily diet of fruit and vegetables may reduce your risk of some types of cancer and some NCDs, including cardiovascular diseases. They are a little sketchier on the weight benefits, and I take this to mean that it will also depend on what makes up the remainder of your diet alongside the fruit and vegetables. But crucially, they note that “fruits and vegetables are rich sources of vitamins and minerals, dietary fibre and a host of beneficial non-nutrient substances including plant sterols, flavonoids and other antioxidants and consuming a variety of fruits and vegetables helps to ensure an adequate intake of many of these essential nutrients”. Now, whilst I don’t know my flavonoids from my adenoids, I think that these all add up to A Good Thing.

Pancake layer 1

Pancake layer 1

Should you still be sceptical as to the benefits and if you wish to delve deeper, the WHO website link above will also lead you to the evidence that supports their conclusions. Let’s look at one example.

I have read the paper ‘Increased consumption of fruit and vegetables for the primary prevention of cardiovascular diseases’ (or at least the abstract for the paper, I’m not a sadist) and was very pleased to find that they included a section entitled ‘Plain language summary’. It explained that this paper details a review of other studies into the beneficial effects of eating more fruit and vegetables and concludes that, while the evidence is favourable, none of those studies ran for long enough to provide conclusive evidence as to the effect on cardiovascular disease (CVD).

The key line in the abstract for me reads as follows: “This review assessed the effectiveness of increasing fruit and vegetable consumption as a single intervention without the influence of other dietary patterns or other lifestyle modifications in healthy adults and those at high risk of CVD for the prevention of CVD”. In other words, they are looking to see if increased fruit and vegetable consumption on its own is having an impact on cardiovascular disease. And they cannot say that it definitely is; it is more likely that it’s a contributing factor alongside other lifestyle and diet choices.

This makes sense to me and I will continue to view the ‘5 a day’ regime as just one part of my armoury against the health challenges we all face.


If I were only to read one thing, then what should it be?

A subsequent page on the WHO website summarises the benefits of increasing your fruit and vegetable intake, as well as citing the evidence to support those assertions. If you are interested in finding out more, then this is a good place to start. It highlights:

  • “Current evidence indicates that fruits and vegetables consumed as part of the daily diet can help reduce the risk of:
    • Coronary heart disease
    • Stroke
    • Certain types of cancer”
  • “More limited evidence suggests that when consumed as part of a healthy diet low in fat, sugars and salt/sodium, fruits and vegetables may also help to prevent unhealthy weight gain”
  • “Very limited evidence suggests possible links between fruit and vegetable consumption and osteoporosis and type 2 diabetes”

I am a Dalek/Cyberman/ITV executive and I don’t trust this WHO fellow…

Far be it from me to criticise, but this is the World Health Organisation, which is:

The directing and coordinating authority for health within the United Nations system. It is responsible for providing leadership on global health matters, shaping the health research agenda, setting norms and standards, articulating evidence-based policy options, providing technical support to countries and monitoring and assessing health trends.

I am happy to let their team of experts pore over the many, many scientific studies to come up with these conclusions. They have done the heavy lifting so that we don’t have to.

So when I see headlines such as “Bad news for food fascists: Five fruit and veg a day doesn’t work” (the Telegraph, 2010) then my reaction is to shudder slightly. I’m pretty confident that more of the general public will be reading the Telegraph than they will be the WHO website and these articles risk undermining public belief in something that, on the balance of the evidence cited by the WHO, is A Good Thing.

Andrew BrownIt’s incredibly childish to point this out, and it in no way forms the basis of a sound counter-argument to the article, but is it telling that this article entreating us to eat “fewer carrot sticks, more crisps” was written by the Telegraph’s obituaries editor? Trying to drum up a little business perhaps?

For an alternative view on the specific links between cancer and fruit and vegetable intake, you could try this page on the Cancer UK website, whilst this New Scientist article adds a little more meat to the bones of the 2010 news story.

Whilst I will be continuing to try to get my 5 a day, I will also try to continue to be sceptical and to demand evidence to support these instructions that we are given. At the same time, I know that it is important to look at the provenance of that evidence; not everything you find on the internet (or in newspapers, on television or in books) is created equal.

Who is saying what, and how much evidence do they have to support it? That is what is important.

Running Buffet is not run by a health expert, nor a food scientist. I am like you, in that I have access to the internet and all that it contains, and I am trying to form my own opinions about what I should be eating. I genuinely believe that I have understood what the above websites and scientific papers are saying; however, any misrepresentations of that information within this post will be entirely my fault. Please do not rely solely on anything I have to say in these posts, but you may be able to use them as a start, a jumping-off point, from which to build up your own opinions on what is right and what is not.