The trains from London to Manchester are increasingly crowded, so a table-seat indulges my eavesdropper tendencies. Recently two women impressed me with the fact that, for some individuals, being amongst the world’s most privileged doesn’t always count for much.

Blonde turning to her companion: “Have some of my sandwich, I really can’t eat it all. It’s my homemade bread. Organic spelt; we love it, and I find this spelt makes you less hungry later.”

Brunette: “Oh thank you, but I don’t eat flour; my nutritionist says it’s the reason I feel tired and bloated.”

Blonde : “Really?”

Brunette: “Yes; it’s remarkable. Since I’ve been seeing her, she’s completely changed my life. She says it will not only increase my energy, but my life expectancy too, because it’ll reduce the amount of toxins my body is exposed to which eventually poison and kill you.

Blonde looks mournfully at her bread: “Really?”

Brunette: “You’d be amazed how much of what we eat that’s actually poisonous and slowly killing us. People don’t know that.”

Blonde: “No. Really? That’s amazing. I must be lucky; I don’t get bloating, and not with my bread.”

Brunette “It’s probably because it’s organic.”

Blonde: “Yes.” Gingerly she picks up the delicious looking sandwich and turning to her friend: “How often do you see your nutritionist?” she bites.

“When I started, I saw her everyday for a week, then I saw her every other day for a week and then I saw her once a week and now I just see her twice a month”, replied the Brunette.

Not cheap

“Gosh”, said the Blonde, “and may I ask, how much is it, a nutritionist?” to which her companion replied: “Well of course, it’s not cheap; but when you think it’s actually extending your life, well, I mean I don’t buy expensive creams; they just don’t work.”

The Blonde nodded slowly and took another large bite of the delicious looking bread. When she finished chewing she turned to her companion again and asked: “So. .. how much is it?”

Brunette: “Well it’s three thousand pounds for the initial course which is pretty intensive, then after six months you just pay two hundred pounds a session. It really isn’t bad considering it’s about the same price as my hairdresser.”

‘Not bad’, I thought. Not bad indeed, thinking I really MUST be in the wrong profession. And it struck me how the nutritionist was simply testing the market, and, rather successfully, managing to persuade somebody to part with money; just a simple sell. I didn’t agree the women needed (or indeed anyone needed) what the nutritionist was offering, but there are lots of things we buy we don’t need and there didn’t seem evidence of coercion. Still, me thinks Brunette hasn’t really thought it through... and this is why.

Cursory appraisal found Brunette to have been born sometime in the late 20th century in the northern hemisphere, probably the United Kingdom, probably England, white, middle-class; and the rings on her fingers told me she was married.

Survival of the fittest

This pretty much gave me all the information I needed to know that Brunette represents the most extreme version of survival of the fittest in relation to her gender of any of our species who has ever lived since the beginning of time. And I mean every version of every female human species that’s ever existed.

I’m not really interested either in whether or not the nutritionist had any decent evidence to back her claims about the association between the consumption of flour, white, wholemeal whatever or any other gluten-based product and Brunette’s bloating. Oh, and tiredness; nor does it really bother me that she makes claims that her intervention might increase life expectancy and Brunette believes it.

It might and it might not. The chances are, it’s near impossible to measure whether cutting out white flour, wholemeal flour, or gluten-based products would have any effect on the longevity of the white, western, married female In fact, the likelihood is that her marital status is the only blip on her otherwise life-giving demographic.

Women born in the 20th century Northern Hemisphere, White, are living longer than women have ever lived, anywhere. Indeed if you fit into that category and have reached the maturity of sixty-five, your life expectancy is approximately nineteen years. On average, you are likely to live until eighty-four. And that’s just the average for the population. It also includes women who are married and unmarried, who smoke and don’t smoke who are mothers and who aren’t. It doesn’t include women who aren’t white, aren’t middleclass, aren’t western which is the vast majority on the planet.

Fitter than ever

So I wondered whether the nutritionist was suggesting that her intervention would increase the life expectancy of Brunette by a day or a year or an hour or a minute or indeed a decade. And I thought that given her companion’s similar demographic, including the wedding band and diamond accompaniment, it seemed a good idea that she didn’t share her sandwich but enjoyed the delicious whole on her own.

And the extraordinary thing is that we are so fit, it is difficult to find an effect of anything we do on the length of our lives. Anything except consistent inhalation of hundreds of different toxins in the form of cigarette smoke over many years, enormous lack of fitness and over-eating and vast consumption of drug and alcohol; and when I say vast, I mean vast. Cutting out gluten, sugar, milk, any other diary products, eggs, acidic fruit, carbohydrate, white food, everything but brown rice is unlikely markedly to change the life expectancy in a significantly measurable way. So that although vegans may live longer than omnivorous gluttons, when compared to a group of moderately consuming omnivores, I suspect it would be unlikely we could find any difference in the life expectancy between the two (all else equal).

And I’d be loathe to bet anything on whether Blonde or Brunette will live longer.

KM Abel is Professor of Psychological Medicine and Director of the Centre for Women's Mental Health at University of Manchester and Honorary Consultant Psychiatrist at Manchester Mental Health & Social Care Trust.