You are in the state-of-the-art, PFI-funded library faced with an impossible deadline – looking desperately for copy for the Piscator column. You continue frantically masticating the chewing gum that is being used as a prophylactic stress-buster since more time-honoured remedies have been totally outlawed. You head for the heavyweight blue-tops – hoping against hope that there is something readily to hand in the shelved journals which will titillate and amuse the readership of this august journal in the dog-days of summer. And there it is – the gift of a case report – you temporarily suspend reason, good judgement and mastication… Entitled ‘When chewing gum is more than just a bad habit’ (Lancet 2009;373:1918) you just cannot believe your luck! Fascination engulfs you! So this is the story – a recalcitrant Italian youth of 13 years from the land of Mezzo giorno, in the deep south of Italy, is taken to the ER by his concerned parents because of a notable change in mood – so far so normal for adolescence you might think. He complained of abdominal discomfort, increased diuresis and prickling sensation in the legs. On examination he was restless with tachycardia and tachypnoea. Routine diagnostics were normal and in particular his toxicology screen was negative. He was discharged the following day. His mother returned to the ER with empty packets of stimulant chewing gum she had found in her son's belongings. The authors of the case report are of the opinion that the signs and symptoms the adolescent exhibited were most likely due to acute intoxication with stimulant chewing gum. Although serum caffeine was not measured, the patient met the criteria for caffeine intoxication as he admitted consuming two packets of gum containing 320 mg caffeine in a four-hour period. Caffeine is rapidly absorbed from gum and its many effects include stimulation of the endocrine and exocrine tissues, the CNS and cardiac muscle. So chewing gum now joins the myriad of items in the ever lengthening ‘bad for you’ list.

However up here among the northern lights and ‘les nuits blanches’ of midsummer, the terrain is conducive to the outdoor life and healthy living if you forgo the delights of the supermarket or confectionery shelves. While I did invest in a jacket most often worn by Everest summiteers to get me through winter, the said jacket never gets tested in the environment for which it was designed. Nor am I convinced that blood gas analysers were designed to be lugged up Everest. But there you go – what do I know? In a study undertaken by the Xtreme Everest Research Group (N Engl J Med 2009;360:140–9) and discussed in the comment section of another venerable journal (Lancet 2009;373:1589) arterial blood gases were measured in climbers on Mount Everest. Near the summit of Everest, or to give it the correct Tibetan name of Chomolungma, some exceptionally low values for PaO₂ were recorded which are probably just about compatible with human survival. Most of what was known of human physiology at extreme altitude had been obtained nearly 30 years ago and the recent expedition by the group sought to expand on this by obtaining arterial blood samples as close as possible to the summit. Some of us old enough to remember syringes for blood gas analysis being shipped on ice to the lab, can chuckle at the image of most probably Sherpa porters ‘legging it’ down Everest with samples collected from climbers at 8400 m to the gas analysers located at 6400 m. I doubt if few hospital porters could cover this distance in a time which would ensure the integrity of the measurement. And to ensure the integrity of the sample and despite the already low ambient temperature, attention to detail was followed by transporting the samples in an ice slurry in a thermos. The values recorded for PaO₂ were pretty mind-boggling, typically less than 4 kPa with PaCO₂ as low as 1.5 kPa and blood pH registering between 7.45 and 7.60. The summiteers are to be congratulated on this feat of obtaining arterial blood gases under the most extreme of conditions which so obviously illuminates human physiology under the most hypoxic of conditions. However it will be some time before thought is given to relaxing oxygenation pressures in the ITU in the light of these data – nor do I think there will be many takers keen to repeat or challenge the authenticity of the data in a hurry.

And finally back down to sea level in this very northern latitude of 57°N and with its long summer days not withstanding, there is still an appreciable risk of vitamin D deficiency – so much so that the devolved Government is considering dietary supplementation. Vitamin D is enjoying something of the Zeitgeist and one could fill this column several times over with reference to new research. However despite warnings of the recurrence of vitamin D deficiency and Government recommendations in the Sure Start programme for supplementing with vitamin D, rickets still can occur in exclusively breastfed infants (Arch Dis Child 2008;93:179). It is known that infants of Arab women are particularly at risk because of their mother's low vitamin D concentration and this is exacerbated by the lower concentration of calcium in breast milk as documented in this study.

So now that sunshine has been rehabilitated for our wellbeing should we be out there enjoying it? Never mind vitamin D supplements. How about state-funded trips to the Caribbean in mid-winter? Now that would be a very welcome health promotional activity…