Dear JULES,
The evidence behind five-a-day
Executive Summary
* Last week’s note looked at the latest epidemiological study claiming an association between intake of fruit and vegetables and mortality (there has been no reply from the authors to my adjustment query as yet). I promised in that note to share my exchange with Public Health England (PHE) when I asked for the evidence-base for five-a-day.
* For something to be evidence based, the evidence must come first.
* The UK National Health Service (NHS) five-a-day website was promoting five reasons to get five portions. The reasons were so lacking in evidence, it prompted me to email the NHS to ask for the evidence underpinning the slogan.
* PHE 5ADay replied. The reply listed a number of NHS and World Health Organization (WHO) documents.
* My reply went through all the documents referenced to show that they provided no evidence for five-a-day and most were published several years after five-a-day was first coined in 1991.
* PHE 5ADay replied back that “as you have stated the WHO reports often did not cite the data for this association” and “In the UK the 5 a day recommendation was a pragmatic recommendation” i.e. we have no evidence.
* I gave them one final chance to provide evidence – either preceding five-a-day or post-rationalising it – and none was forthcoming.
Introduction
I shared last week that my key issue with five-a-day is that it is not evidence based. For something to be evidence based, the evidence must come first. This critical fact seems to be beyond the grasp of public health officials. I promised to share the exchange I had with Public Health England, back in 2013, when I challenged them on their five-a-day advice. It forms the main part of this week’s note.
Before we get to that, I’ll share some other posts that I’ve done on five-a-day. The first thing I wrote on five-a-day was in Chapter 13 of my 2009 book The Obesity Epidemic: What caused it? How can we stop it? I posted the five-a-day section from Chapter 13 on my website in 2012 (Ref 1). That post went through the history of five-a-day; what it had become in different countries; how fruit and vegetables measure up nutritionally and the evidence for the slogan. This review ended by asking the question – even if five-a-day wasn’t evidence based, surely it’s still a good thing to do? In the context of obesity, I concluded that it is not for five key reasons:
1) There is an opportunity cost of having spent so much time and money embedding a message that has not helped obesity (to be fair it was never intended to) when the benefits of embedding an equally simple, but far more effective message, could have transformed the obesity epidemic. The single public health message, which could have made an immense difference, would have been “eat real food.”
2) If the message had been “swap five-a-day”, rather than “eat five-a-day”, this could have helped – provided that junk foods were swapped out and not meat, fish, eggs, dairy and nutritious foods. My personal experience, working in the field of obesity, is that people are trying to eat five-a-day in addition to everything else they are eating, not instead of. This can only worsen obesity and, of course, obesity has worsened dramatically since the launch of five-a-day.
3) As if it is not bad enough that people are trying to get their five-a-day on top of everything else, the means by which they are doing this is disastrous for obesity. People are adding more processed food into their diet trying to get their five-a-day. If you review internet advice sites for ‘how to get your five-a-day’, adding sweet corn to (white flour) pizza is one suggestion, eat tinned (syrupy) fruit is another, fruit juices and fructose rich drinks are frequently recommended. We are eating even more processed food trying to get our five-a-day, which is to our overall detriment.
4) Five-a-day is not helpful for the increasing number of people who are increasingly carbohydrate sensitive/insulin resistant and for whom fruit, and high-carbohydrate vegetables are best avoided.
5) Finally, for anyone who is overweight (that’s two thirds of the ‘developed’ world), non-starchy vegetables and salads should be encouraged, but fruit/fructose is best avoided.
Other posts that you may enjoy on this topic are listed in the references (Ref 2).
Below is the exchange with Public Health England – in the order of emails. It was prompted by seeing “Five reasons to get five portions” on the UK National Health Service web site – I list these in my first email to the 5ADay email address. (I’ve checked that all the links in our exchanges still work and they do unless otherwise indicated.)
The exchange – email 1 from me
From: Zoe Harcombe
Sent: 26 October 2013 11:40
To: 5ADay
Subject: Evidence behind 5-a-day
Dear NHS
I’m trying to find the evidence behind the five-a-day message and this page (http://www.nhs.uk/Livewell/5ADAY/Pages/Why5ADAY.aspx) with the following five reasons does not provide evidence.
Five reasons to get five portions&
Fruit and vegetables taste delicious and there’s so much variety to choose from.
They’re a good source of vitamins and minerals, including folate, vitamin C and potassium.
They’re an excellent source of dietary fibre, which helps maintain a healthy gut and prevent constipation and other digestion problems. A diet high in fibre can also reduce your risk of bowel cancer.
They can help reduce the risk of heart disease, stroke and some cancers.
Fruit and vegetables contribute to a healthy and balanced diet.
Please are you able to give full details for the following:
1) When did the five-a-day message start?
2) Why? What was the evidence to justify the initial message? Which condition(s) is five-a-day evidenced to benefit? Please provide the relevant clinical trial/study evidence – not just they taste delicious and there’s variety.
Many thanks
Kind regards – Zoe Harcombe
The exchange – reply 1 to me
On 28/10/2013 17:07, 5ADay wrote:
Dear Zoe,
Thank you very much for your email.
The advice to eat at least five 80g portions (400g) of a variety of fruit and vegetables per day was developed based on a recommendation from the World Health Organization (WHO). This arises from studies which show an association between the consumption of more than 400g of fruit and vegetables and lower levels of death from chronic diseases such as heart disease, stroke and some cancers by up to 20%. In the UK, the DH Committee on Medical Aspects of Food Policy and Nutrition (COMA), reviewed the evidence and endorsed the above recommendation in 1998.
This has since been endorsed by the Scientific Advisory Committee on Nutrition (SACN).
Discussions leading to the WHO conclusions on 5 A DAY and CVD are outlined in:
http://whqlibdoc.who.int/trs/WHO_TRS_916.pdf and http://www.who.int/nutrition/publications/obesity/WHO_TRS_797/en/index.html
The following paper, dietary intake of fruit and vegetables and risk of diabetes mellitus and cardiovascular disease includes a range of references that were considered by WHO. This can be found at: http://www.who.int/dietphysicalactivity/publications/f&v_cvd_diabetes.pdf
You may also be interested in the wealth of information on 5 A DAY and healthy eating at:
www.nhs.uk/livewell/5aday/pages/5adayhome.aspx
www.nhs.uk/livewell/healthy-eating/pages/healthyeating.aspx
Kind regards,
Elaine (SURNAME DELETED BY ME FOR PRIVACY)
Diet and Obesity, Health and Wellbeing
Public Health England
The exchange – email 2 from me
From: Zoe Harcombe
Sent: 29 October 2013 15:32
To: 5ADay
Subject: Re: Evidence behind 5-a-day
Dear Elaine
Many thanks for your prompt reply. I’m still struggling to see how this is an evidence based nutritional message. Please can you help with the following:
1) Five-a-day was first coined at a meeting of the National Cancer Institute (NCI) and the Produce for Better Health Foundation at a meeting in California in 1991. The Produce for Better Health Foundation is a trade body of companies that benefit from increased fruit and veg consumption (e.g. McDonalds; Nestle; Monsanto; Del Monte; Campbell Soup and Subway, to name just 6 of the over 130 current sponsors) (Ref 3). Five-a-day was created as a marketing slogan. The NCI has since trademarked the term.
Please can you confirm therefore that five-a-day was not created as an evidence based nutritional message.
2) Please can you provide the evidence that may post rationalise the five-a-day marketing slogan as presented in your opening paragraph “The advice to eat at least five 80g portions (400g) of a variety of fruit and vegetables per day was developed based on a recommendation from the World Health Organization (WHO). This arises from studies which show an association between the consumption of more than 400g of fruit and vegetables and lower levels of death from chronic diseases such as heart disease, stroke and some cancers by up to 20%”
I could not find evidence in the links that you sent through:
a) The first link (http://whqlibdoc.who.int/trs/WHO_TRS_916.pdf) is a 2003 report (12 years after the slogan was created). It has 115 references to fruit/vegetables. I have been through them all.
The only mention of the recommendation of 400g a day is in Table 6 on page 56. This says that intake of fruits and vegetables should be greater than or equal to 400g a day but does not say why. Words before Table 6 quote the following references (2-4) in support.
References 2-4 are as follows:
2. Protein and amino acid requirements in human nutrition. Report of a Joint WHO/FAO/UNU Expert Consultation. Geneva, World Health Organization, 2003 (in press).
3. Fats and oils in human nutrition. Report of a Joint FAO/WHO Expert Consultation. Rome, Food and Agriculture Organization of the United Nations, 1994 (FAO Food and Nutrition Paper, No. 57).
4. Carbohydrates in human nutrition. Report of a Joint FAO/WHO Expert Consultation. Rome, Food and Agriculture Organization of the United Nations, 1998 (FAO Food and Nutrition Paper, No. 66).
Reference 4 would thus be the one relevant to fruit and vegetables (carbohydrates). However, Reference 4 has no specific fruit and veg recommendations – no mention of 400g a day, or five-a-day, or any such recommendation. The recommendations are here in full http://www.fao.org/docrep/w8079e/w8079e0c.htm#
The only recommendation that even mentions fruit and/or veg is Recommendation 17, which merely states: “That the bulk of carbohydrate-containing foods consumed be those rich in non-starch polysaccharides and with a low glycemic index. Appropriately processed cereals, vegetables, legumes, and fruits are particularly good food choices.”
b) The second link similarly has no evidence for the claimed 400g recommendation (http://www.who.int/nutrition/publications/obesity/WHO_TRS_797/en/index.html)
P98 Clause 4.1.7 “Intakes of Vegetables, Fruits and Pulses” states:
“Vegetables and fruits are a rich source of a number of nutrients. They are relatively low in energy but high in fibre, vitamins and minerals. Thus they form a useful component, contributing to the balance of the diet. In addition, although no precise dose-response relationships between intakes and disease have been reported, there seems to be some consistency in the evidence that vegetables and fruits play some protective role in preventing the development of cancers.” (my emphasis)
Table 13 in this second link “Population nutrient goals” makes no reference to fruit and vegetable intake. There is a section following this table with the recommendation that fruit and vegetable intake should have a lower limit of 400g per day (with no evidence as to why) and that pulses, nuts and seeds should have a lower limit of 30g per day (as part of the 400g of fruit and vegetables). Again – with no evidence as to why.
c) The 2005 diabetes report (http://www.who.int/dietphysicalactivity/publications/f&v_cvd_diabetes.pdf) published 14 years after the introduction of the slogan has references to other studies reviewing associations between fruit and vegetable intake and health conditions. However, there is no evidence of causation and no claim that five-a-day or 400g a day is associated with any condition. Only two studies looked at specific servings. The Seventh Day Adventist study (bearing in mind these are vegetarians to start with) compared 2 servings of fruit with 1. The Framingham study reviewed intake of 3 servings of fruit and veg – where potatoes were included as vegetables.
d) The NHS sites are devoid of evidence. “Fruits and vegetables taste delicious and there’s so much variety to choose from” is hardly an evidence based rationale for the most widely known public health message in the field of nutrition.
e) The largest study – interestingly started in the same year as the California meeting (1991) – and investigating the condition for which five-a-day was subsequently trademarked (cancer) is the EPIC study – the European Prospective Investigation into Cancer. In April 2010 a study was published in the Journal of the National Cancer Institute written by Paolo Boffetta, as the lead of a large group of European researchers. The study sought to quantify if cancer risk were inversely associated with intake of fruit and vegetables. The article analysed data from the EPIC study, involving 142,605 men and 335,873 women for the period 1992-2000. This review of almost half a million people found that eating five portions of fruit and vegetables a day had little effect on cancer risk and the very small difference observed could be explained by other factors. The study also grouped participants into five categories from the lowest intake of fruits and vegetables (0 to 226 grams a day) to the highest intake (more than 647 grams a day). Significantly, the cancer risk did not vary between the five groups. The overall conclusion of the study was that: “A very small inverse association between intake of total fruits and vegetables and cancer risk was observed in this study. Given the small magnitude of the observed associations, caution should be applied in their interpretation.” (Paolo Boffetta et al, “Fruit and vegetable intake and overall cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC)”, Journal of the National Cancer Institute, (April 2010).)
In November 2010, the UK part of the EPIC study published their findings in the British Journal of Cancer. (http://www.nature.com/bjc/journal/vaop/ncurrent/full/6606032a.html) Professor Tim Key concluded that: “The possibility that fruit and vegetables may help to reduce the risk of cancer has been studied for over 30 years, but no protective effects have been firmly established.”
In summary, please could you
1) Confirm therefore that five-a-day was not created as an evidence based nutritional message.
2) Provide the evidence that may post rationalise the five-a-day marketing slogan.
Many thanks
Kind regards – Zoe
The exchange – reply 2 to me
From: 5ADay
Date: Mon, 2 Dec 2013 16:08:56
To: Zoe Harcombe
Subject: RE: Evidence behind 5-a-day
Dear Zoe,
The five a day message used in the UK is based upon epidemiological evidence that demonstrated an association with consumption of more than 400g of fruit and vegetables per day with reduction in ischaemic heart disease. The data supporting this association was considered by WHO but as you have stated the WHO reports often did not cite the data for this association. The easiest source of the particular studies supporting the earlier 1998 WHO discussion can be found in a later report Dietary intake of fruit and vegetables and risk of diabetes mellitus and cardiovascular diseases, Bazzaro (sic), WHO, (2005) [see table 1]; this table also includes some additional studies.
In the UK the 5 a day recommendation was a pragmatic recommendation taken following the publication of the Committee on Medical Aspects of Food Policy report on cardiovascular disease Nutritional Aspects of Cardiovascular disease Report of the Cardiovascular review group, Committee on Medical aspects of Food Policy DH , HMSO (1994). This was a pragmatic decision based upon the level of intake at the time.
As such I can confirm that the 5 a day approach to promoting fruit and vegetables was evidence based.
Kind regards,
Lucy
Lucy (SURNAME DELETED BY ME FOR PRIVACY) (Public Health)
Nutrition Advice Team
Public Health England
The exchange – email 3 from me
From: Zoe Harcombe
Sent: 04 December 2013 07:25
To: 5ADay
Subject: Re: Evidence behind 5-a-day
Dear Lucy
For a message to be evidence-based, the evidence needs to precede the message.
Five-a-day was invented in 1991 – please can you send me the evidence upon which it was based i.e. preceding 1991?
Many thanks
Kind regards – Zoe
The exchange – reply 3 to me
From: 5ADay
Date: Fri, 6 Dec 2013 16:43:15
To: Zoe Harcombe
Subject: RE: Evidence behind 5-a-day
Dear Zoe,
In the UK, the 5 A DAY programme was launched in March 2003 as part of the health promotion activity by the Department of Health to encourage people to eat more fruit and vegetables. The key population message being to ‘eat at least 5 portions of a variety of fruit and vegetables a day’. This was based on the evidence I have referred to in my previous email, in particular the Committee on Medical Aspects of Food Policy report on cardiovascular disease Nutritional Aspects of Cardiovascular disease Report of the Cardiovascular review group, Committee on Medical aspects of Food Policy DH, HMSO (1994). This has since been endorsed by the Scientific Advisory Committee on Nutrition (SACN).
The 5 A DAY message was not used as government policy in the UK before 1994.
Kind regards,
Lucy
Lucy (Public Health)
Nutrition Advice Team
Public Health England
In summary
I lost the will to reply to that last message. Our exchange boiled down to – five-a-day was invented in 1991. There was no evidence for it at the time, which means that it was not evidence-based. Unsurprisingly Public Health England could not provide any evidence base. PHE also could not provide any evidence that might post rationalise the slogan. (PHE was clearly not even familiar with the studies it was claiming provided evidence.) I managed to get PHE to admit that not even the World Health Organization cited the data and “five-a-day was a pragmatic recommendation”. But PHE didn’t start using the slogan as government policy until 1994, so that’s OK then!
Who was it who said, “You can’t have a battle of wits with an unarmed person!”?
Until the next time
All the best – Zoë
References
Ref 1: https://www.zoeharcombe.com/2012/03/five-a-day-the-truth/
Ref 2: https://www.zoeharcombe.com/2011/03/five-a-day-is-it-enough/
Ref 3: The link at the time was http://www.pbhfoundation.org/about/supporters/licensees/
The link now is https://fruitsandveggies.org/contributors/?contributor-type=members
