Is there any part of human life that hasn’t been turned into a medical condition?

When Greg, my old uni pal, came to stay from NYC he brought with him an extra bag for his pills: vitamins A, B, C, D, zinc, magnesium, selenium, ginseng. They decamped to the kitchen, the pills, and stood in rows beside the kettle awaiting their morning ritual. They were bigger than British versions, I noticed, and more violently coloured.

Come breakfast, Greg requested pomegranate juice, not for taste but for antioxidants, and orange juice for electrolytes. Then there was lunch. We’d be nearing the end of a trek round some royal palace when suddenly Greg’s voice would flatten: ‘You know, I think my blood sugar’s getting low?’ Then, in a dangerous monotone: ‘I need to eat.’

At first I didn’t take much notice. Greg isn’t diabetic or thin. This turned out to be a mistake. The lower his ‘blood sugar levels’ dropped, the worse Greg’s mood became, and because it was medical he saw no need to buck up. On we’d plod, past evening dresses once worn by Diana, Princess of Wales, locked in a murderous silence: the very definition of a lose-lose situation.

As Greg’s visit progressed, I learnt to be quicker off the mark. Blood sugar? I’d race us to a restaurant. For anyone expecting an American guest, I recommend an American franchise for lunch. Just as branded ‘Nurofen’ works better (for placebo reasons) than cheapo supermarket replicas, so McDonald’s and Starbucks were most helpful to Greg’s blood sugar. We’d sit in silence as he self-medicated with brownies.

I like Greg, I really do, but over the week I realised that most of the ordinary fluctuations in his everyday life had been redefined as medical issues. A bad night’s sleep? Light sensitivity. Headache? Sugar intolerance. (So why all the brownies, Greg?) Hunger was invariably this joyless ‘need to eat’.