Holford Watch: Patrick Holford, nutritionism and bad science

Prof Patrick Holford the international bowel-whisperer and supplement entrepreneur is familiar to us. We’ve even been dazzled by Patrick Holford the tap-dancer as he delivers a very partial account both of the training of nutritionists and the status of his own nutritional qualifications in a bravura performance on RTE’s The Late Late Show. But now, we have Patrick Holford the…well, judge for yourself.

A little bird tells us that Holford has just sent round his 100%health Newsletter, No 41, September 2007. In it, we share Holford’s delight in recounting his recent holiday “kayacking in the Arctic Circle” and having “close encounters with seals” while avoiding polar bears and admiring beluga whales. Just to show us what an all round, green conservationist sort of guy he is, the readers are given this little homily:

We also had a school of beluga whales pass us gracefully. Whales were mercilessly hunted to almost extinction in the first ‘oil’ wars, primarily as a source of fuel. Fortunately, their numbers are starting to increase.

Very touching. I shall refrain from the obvious comments.

More interestingly, Holford has a little Research Round-Up on pg 6. One of the sections announces, Wi-Fi Concerns Aren’t Scaremongering. So, you might expect some research, yes? Well, no. The reader is treated to the following:

Back in June, Panorama reported on the dangers of electromagnetic radiation (EMR) and wi-fi systems. ‘Bad Science’ Guardian columnist Ben Goldacre attacked the programme, and the programme’s expert Alasdair Phillips, in his usual vitriolic and inaccurate way. [Edited to include link to Goldacre's piece but also look at the follow-ups. Holford refers you to Alasdair Phillips response to Goldacre's response as "the truth about EMR dangers". Emphasis added.]

That is just so entertaining, especially when one considers Holford’s own pronouncements on others and his own track record for accuracy and rigour. Why, only recently, he labelled some children as “stupid” and referred to some as “thicker”. Some readers might recall Holford’s ill-founded comments about Prof Colquhoun’s research funding.

As for inaccuracy, Holford Watch has documented a number of particularly egregious inaccuracies in Holford’s writing: e.g., statins or premature mortality statistics among too many others. More recently, we have been dwelling on the errors and inaccuracies in Holford’s CV, as submitted as part of his application for a post as Visiting Professor at the University of Teesside. By way of a change, we thought we would take a light 5 minute browse through the contents of the latest Patrick Holford mail-out.

In no time at all, we had an embarrassment of riches. Just to choose one in an area in which Holford claims particular expertise, we looked at Is Taking Vitamin C For A Cold A Waste Of Time? (pp 4-5). Holford gives an overview of the recent Cochrane Review on the topic of vitamin C and colds (unlike Holford, we’ve decided to include the links because it would be helpful if you were to read the actual text: pdf for whole report; plain-language summary).

The review, headed by Dr Harri Hemila from the Univeristy of Helsinki in Finland, reported: “consistent benefit in the duration of colds, but the effect was greatest in children”. The average reduction in duration was 13.6% for children and 8% for adults across all doses. This equates to up to a month less ‘cold’ days per year for the average child. [Emphasis added.]

Wow, that would have been an amazing headline and one that we should be shocked that the newspapers and other mainstream media somehow missed. Just think of the potential productivity increases at work and in schools if children could experience “up to a month” of fewer ‘cold’ days per year. Except, the authors didn’t write any such thing. Those figures do not “equate to up to a month less ‘cold’ days per year”. Holford’s ability to interpret and communicate numbers has long ceased to be amusing and become irritating. It is long past time that somebody started to proof-read Holford’s material to assure the reader of some degree of numerical accuracy.

Take a moment to think about it. If the reduction of “up to a month” is truly a reduction of 13.6% then think of how many days a year those children would have to have a cold to make that reduction true. What does your instinct tell you on this point without even engaging your mental arithmetic skills? Do you have a vague feeling that this would imply that these unfortunate children would have to experience more than 200 days of cold symptoms a year in order to experience a 13.6% reduction that amounts to “up to a month”.

The National Library for Health looked at this report and the news coverage: they summed up this point as follows:

For cold duration, there was a modest benefit of vitamin C with an estimated reduction from 12 to 11 days for the annual number of days with a cold for adults and from 28 days to 24 days for children. [Emphasis added.]

You will notice that this is a reduction of 4 days in a year, not “up to a month” unless there is some separate Holford calendar in play here that he has not mentioned. What does the primary source, the actual Cochrane Review (pdf) say?

Our pooled estimate suggests that long term supplementation might result in an upper estimate average reduction of annual common cold morbidity from about 12 days (Douglas 1979) to about 11 days per year for adults. For children under 12, who experience colds more frequently (on average for this age, the upper estimate could be as high as 28 days of cold morbidity annually), our pooled estimate of benefit suggests that long term prophylaxis might be associated with an average reduction in four symptom days from about 28 days to 24 days per year per child. [Emphasis added.] [pg 10]

So, that’s a pooled estimate that is extrapolated from the relevant trials; the authors refer to 28 days as the upper estimate of cold morbidity in children under the age of 12 rather than the general range, and the reduction might be 4 days from that upper estimate. Just to belabour the point, 4 days is nothing like “up to a month”.

Yet, Holford believes in his own ability to detect and publicise the “inaccurate way[s]” of others in commentary and reporting. Marvellous. Perhaps he is relying upon dowsing and the finely-tuned implement is being lead awry by the dLan that he has fitted to his home to prevent EMR exposure from wireless broadband (except, you’ve got it, it probably doesn’t).

There are many other mistakes and joys in this mail-out; we may share some of the choicer ones with you over the next few days.

Update: 19:00 We can’t resist telling you that within the last 10 minutes we have seen a letter from Holford in which he is lecturing a very knowledgeable person about accuracy and Vitamin C in particular…We wish that we could share it with you because what the world needs is more laughter, particularly on a Friday evening.

Update 2: 19:10 A little birdy tells us that you might set aside some time to visit the Adjudications Section of the ASA website on Wednesday 19 September where you might learn of something to your advantage or at least entertainment.

Update 3: 23:30 Holford Watch has been fortunate enough to see a copy of Holford’s latest letter to Prof Colquhoun: we wish that we were in a position to share some of the contents with you.
However, you may be interested to read an overview of the Justin Kruger and David Dunning paper that discusses how difficulties in understanding one’s own incompetence can lead to inflated self-assessments.

What’s even more amazing is that when they then shared the performance of other participants with the people who performed poorly (hoping that they would then adjust their self-perception downward) people who scored poorly failed to adjust their self-perception of their performance. In other words, they are completely unaware of their own [in]competence, and can’t detect competence in others.

It really it a very helpful paper that explains many otherwise inexplicable actions.

Update Jan 15 2008: A Photon in the Darkness offers a helpful discussion of this paper: The Arrogance of Ignorance