Hello and welcome to more or less on the BBC World Service. I'm Tim Halford.

In this week's programme, we'll be dipping our toes into the UK's election. But first...

In last week's edition of that long-running BBC radio show, Desert Island Disks,

author Isabella Trey made a claim about the versatile and delicious red berry

of the plant, so larnum like a persicum. You have to eat 10 tomatoes to get the nutrition

out of one tomato in the 1950s. Some loyal listeners wrote in to Morales at bbc.co.uk to ask us about this.

Is this correct? Is it comparing like with like? Which nutrients does it cover and does it matter?

To help us find out if this is true, we turn to Paul Thingluss from the Quadrum Institute,

a British research centre devoted to food and health. Back in 1950, there would have been a very

different type of tomato that was available to the consumer. And was it 10 times better?

No, not at all. Not at all. It's very hard to compare a tomato in 1950 with one in 2019.

For every nutrient that has gone down, there's probably a nutrient that's gone the other way.

Do you have any idea where Isabella Trey might have got that idea from?

I really don't. I went back and looked at the 2017 publication in the Journal of Food

Conversation Analysis and they were talking now about our big reduction in copper values.

It said that copper had gone from 0.1 down to 0.01 today. Whereas if you look at some of the data

that we have now, we see that folic acid has gone from 5 to 22 and vitamin C, which is quite

sensitive, has gone from 20 to 22. So in terms of changes, these numbers might look quite big,

but nutritionally wise, they don't make much difference to what you're consuming from the diet.

Paul says the reason why tomatoes seem to have had so much more copper in the past

might be down to the variety, but it might also be a measurement error.

The types of methods that were used in 1950 were quite crude in terms of how the copper was measured.

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