I am all for hammering the fake nutritionist tosh. “Doctor” Gillian McKeith “PhD (Intenet)” is an obvious charlatan. It’s very hard to see how anyone gave her any credence but – from Channel 4’s point of view – she rifled through human crap on tv, in the presence of its manufacturers even. This was always going to draw audiences. Actual nutrition qualifications would have just been icing on the poocake from the Channel 4 point of view.

I’m not a hundred per cent convinced by more official nutrition advice either. Everyone “knows” we are supposed to eat 5 pieces of fruit or vegetables a day. The government tell us so. There are posters in my doctor’s surgery. I am not disputing that we should eat fruit and vegetables (I’m a vegetarian. I would be going very hungry if I didn’t.)

I just want to know – Who said it? Where is the evidence? How big is a serving anyway?

Well, it turns out that original recommendation came from the World Health Organisation. The 5 a day is a UK version. The USA is more demanding. It wants you to eat 9.

The U.S. Department of Agriculture Food Pyramid recommends three to five servings of vegetables and two to four servings of fruits per day University of Iowa .

Are US fruit and veg weaker in their healing powers? Do American need higher standards of health than we do because of lacking an NHS?

Where does this advice come from? The UK Department of Health has some referenced links to evidence, on its site. Most of these actually turn out to be links to other DOH documents that repeat the same advice. There are however some links to research papers that report lower rates of heart disease and a couple of other reduced risks in those who eat more fruit and vegetables.

So far, fine. The researchers are scientists, so I am sure they will have adjusted the figures for other things that are correlated with living longer – apart from eating more fruit and veg – like being better off & more health conscious generally. I am perfectly capable of working out that fruit and veg are good for you, from any evidence they can produce from their research (plus a lifetime of imbibing this apparently “common sense” message.)

I would like someone to show me where the number 5 came from – was it just a think of number game? Is there any evidence?

I would also like someone to show me where the obscure rules came in – potatoes don’t count; juice only counts as one even if you drink litres of different kinds of juices. Where does the portion size of a serving come from? How can it apply to everyone from a 6’6″ tall heavy set man to a slight 5 year-old?

Unless someone shows there is a real scientific basis for this stuff, it strikes me as government promoted woo. It seems we won’t respond to messages like “It’s probably good for your health to eat a lot of fruit and vegetables.” We aren’t intelligent enough to understand that message. We need to be directed, like the good 1984-in-2007 public we are, in terms that are simple and direct and very prescriptive. It doesn’t matter if the instructions are assembled from guesswork and back of an envelope calculations. As long as we have some rules to follow. With numbers.

Rather like “Doctor” McKeith’s approach to nutrition, really. Oh hang on, she’s an obvious quack.

It seems a disturbingly short step from this nonsense to deciding that vitamins do cure AIDS. I think you’d probably find that most people in the world who have malaria don’t eat 5 to 9 portions of fruit and veg a day. (A lot of them probably are lucky to eat. )

I bet the research shows that most people in the world with HIV infections don’t have cars or travel on planes. I suggest that you drive 10 miles a day and fly 200 miles every 6 months, to lower your chances of catching it.