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The beet goes on
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THE LAST WORD
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The beet goes on
This week’s questions
Why does beetroot colour my urine? Other red foodstuffs such as tomatoes and raspberries do not. So what is in beetroot that has this effect?
■ Edible plants carry three very different types of reddish pigment: anthocyanins, betacyanins and carotenoids, which are responsible for the colour of raspberries, beetroots and tomatoes, respectively. People vary in the proportion of ingested betacyanins that they excrete, with roughly 10 per cent of us passing noticeably red urine after eating 100 grams of beetroot. Even in such individuals, most of the betacyanin is destroyed within the body, and rarely does more than 0.6 per cent of it end up in urine. Betacyanins tend to break down in the stomach; therefore, the
EGGS-TRA SHELL
All plants have carotenoids (normally masked by green chlorophyll) in their leaves. But, interestingly, plants have either betacyanins or anthocyanins, very rarely both, and this relates to their botanical classification. Betacyanins are found only
“Roughly 10 per cent of humans pass noticeably red urine after eating 100 grams of beetroot” length of time that they remain there and the acidity of your gastric juice will affect how much betacyanin enters the bloodstream to be later removed by urinating. The other two pigment classes are chemically unrelated to betacyanins, and we metabolise anthocyanins and carotenoids quite differently: only a very small proportion of these are excreted in urine.
The writers of answers published in the magazine will receive a cheque for £25 (or US$ equivalent). Answers should be concise. We reserve the right to edit items for clarity and style. Include a daytime telephone number and email address if you have one. We are pleased to acknowledge financial support from Statoil in producing The Last Word. New Scientist retains total editorial control over the content. Reed Business Information Ltd reserves all rights to reuse question
and answer material that has been submitted by readers in any medium or in any format. Send questions and answers to The Last Word, New Scientist, Lacon House, 84 Theobald’s Road, London WC1X 8NS, UK, by email to lastword@newscientist. com or visit www.newscientist.com/topic/ lastword (please include a postal address in order to receive payment for answers). Unanswered questions can also be found at this URL.
in members of the order Caryophyllales, but this encompasses surprisingly diverse plants: besides beetroot and red chard (which are both varieties of a single species, Beta vulgaris), the Caryophyllales include cacti, bougainvilleas, purslane and members of the genera Amaranthus (including love-lies-bleeding) and Mesembryanthemum (ice plants). Wherever these plants need red colours (usually in the flowers, but sometimes also in the roots or leaves), they call on betacyanins. By contrast, all plants other than the Caryophyllales – for example, raspberries, plums, roses, chrysanthemums and campions – use anthocyanins. Stephen C. Fry Professor of Plant Biochemistry Institute of Molecular Plant Sciences School of Biological Sciences, University of Edinburgh, UK
I was shopping yesterday and found these little clusters (see photo, below left) on the surface of an egg. They look like extra shell or a calcium build-up, but if they are, what causes this? If they are deposits of extra shell, why are they formed into these strange clusters, rather than spread evenly over the surface so that the whole shell is thickened? Charlene Timberlake Portsmouth, Hampshire, UK SKY LIE?
When I went on holiday from the UK to Australia, I noticed that the full moon looked different to how it appears at home. Online, I found many comments about the moon in the southern hemisphere appearing to be “upside down”. On my return home I compared photographs that were taken in Northern Ireland with those that I took in Cairns in Australia (see photos, above left), and there seemed to be only about a 70-degree difference rather than 180 degrees. So does the face of the moon have any variation locally in terms of the aspect facing Earth, and are there two places in the world that when compared would give a 180-degree difference? Graham Finney UK
THE LAST WORD ON ENERGY
Win £100 by answering our monthly question about energy issues. How can toddlers expend seemingly boundless energy when they eat so little? Answers should reach us by 2359 GMT on 5 May 2014 to answers@ newscientist.com or visit www.newscientist.com/topic/energy. Terms and conditions are also at this URL.
THE LAST WORD
sponsored byy
The beet goes on
This week’s questions
Why does beetroot colour my urine? Other red foodstuffs such as tomatoes and raspberries do not. So what is in beetroot that has this effect?
■ Edible plants carry three very different types of reddish pigment: anthocyanins, betacyanins and carotenoids, which are responsible for the colour of raspberries, beetroots and tomatoes, respectively. People vary in the proportion of ingested betacyanins that they excrete, with roughly 10 per cent of us passing noticeably red urine after eating 100 grams of beetroot. Even in such individuals, most of the betacyanin is destroyed within the body, and rarely does more than 0.6 per cent of it end up in urine. Betacyanins tend to break down in the stomach; therefore, the
EGGS-TRA SHELL
All plants have carotenoids (normally masked by green chlorophyll) in their leaves. But, interestingly, plants have either betacyanins or anthocyanins, very rarely both, and this relates to their botanical classification. Betacyanins are found only
“Roughly 10 per cent of humans pass noticeably red urine after eating 100 grams of beetroot” length of time that they remain there and the acidity of your gastric juice will affect how much betacyanin enters the bloodstream to be later removed by urinating. The other two pigment classes are chemically unrelated to betacyanins, and we metabolise anthocyanins and carotenoids quite differently: only a very small proportion of these are excreted in urine.
The writers of answers published in the magazine will receive a cheque for £25 (or US$ equivalent). Answers should be concise. We reserve the right to edit items for clarity and style. Include a daytime telephone number and email address if you have one. We are pleased to acknowledge financial support from Statoil in producing The Last Word. New Scientist retains total editorial control over the content. Reed Business Information Ltd reserves all rights to reuse question
and answer material that has been submitted by readers in any medium or in any format. Send questions and answers to The Last Word, New Scientist, Lacon House, 84 Theobald’s Road, London WC1X 8NS, UK, by email to lastword@newscientist. com or visit www.newscientist.com/topic/ lastword (please include a postal address in order to receive payment for answers). Unanswered questions can also be found at this URL.
in members of the order Caryophyllales, but this encompasses surprisingly diverse plants: besides beetroot and red chard (which are both varieties of a single species, Beta vulgaris), the Caryophyllales include cacti, bougainvilleas, purslane and members of the genera Amaranthus (including love-lies-bleeding) and Mesembryanthemum (ice plants). Wherever these plants need red colours (usually in the flowers, but sometimes also in the roots or leaves), they call on betacyanins. By contrast, all plants other than the Caryophyllales – for example, raspberries, plums, roses, chrysanthemums and campions – use anthocyanins. Stephen C. Fry Professor of Plant Biochemistry Institute of Molecular Plant Sciences School of Biological Sciences, University of Edinburgh, UK
I was shopping yesterday and found these little clusters (see photo, below left) on the surface of an egg. They look like extra shell or a calcium build-up, but if they are, what causes this? If they are deposits of extra shell, why are they formed into these strange clusters, rather than spread evenly over the surface so that the whole shell is thickened? Charlene Timberlake Portsmouth, Hampshire, UK SKY LIE?
When I went on holiday from the UK to Australia, I noticed that the full moon looked different to how it appears at home. Online, I found many comments about the moon in the southern hemisphere appearing to be “upside down”. On my return home I compared photographs that were taken in Northern Ireland with those that I took in Cairns in Australia (see photos, above left), and there seemed to be only about a 70-degree difference rather than 180 degrees. So does the face of the moon have any variation locally in terms of the aspect facing Earth, and are there two places in the world that when compared would give a 180-degree difference? Graham Finney UK
THE LAST WORD ON ENERGY
Win £100 by answering our monthly question about energy issues. How can toddlers expend seemingly boundless energy when they eat so little? Answers should reach us by 2359 GMT on 5 May 2014 to answers@ newscientist.com or visit www.newscientist.com/topic/energy. Terms and conditions are also at this URL.