Letters archive

Meat is the most "ultra-processed food". It is ultimately plants that have been chewed, digested, broken down, chemically altered, restructured as animal flesh, slaughtered, skinned, butchered and processed even further. Any factory processing of plant-based foods pales in comparison ( 24 February, p 21 ).

Dismissing concerns over ultra-processed food isn't so simple. We can't rely on cravings and appetite for health if we eat stuff that tells our body, by flavour and texture, that it has one nutritional profile while delivering an utterly different one. And what about the removal of essential and beneficial micronutrients when, for example, maize …

James Dinneen's review of A City On Mars was interesting. As its authors say, there has been, to our knowledge, no documented human sexual activity in space. However, given our species' predilections, I would be surprised if, with the person-hours racked up on past and present space stations, not to mention lunar and other orbital …

To find evidence to back string theory, Joseph Conlon suggests looking for certain primordial gravitational waves from very early in the universe. Presumably, these would be stretched as the universe expands, just as light waves are. Radiation we see as the cosmic microwave background was stretched many, many times from its original form . Gravitational …

Michael Paine wants to refer to extreme weather-related events as "climate disasters", rather than natural ones. Such disasters have never been natural, whether related to climate or geology ( Letters, 24 February ). That idea has been widely accepted in disasters research for at least 50 years. Disasters that emerge from a (natural) hazard event …

I sympathise with your leader concerning the reduction of meat-eating's environmental impact. If people can't be persuaded to reduce their consumption then anything we can do to improve its efficiency that isn't detrimental to animal welfare is welcome ( Leader, 2 March ). But the argument in the last paragraph, that it may be better …

You discuss manipulating animal genes to bolster meat production to allow people to keep eating what they are used to, noting that meat is a big factor in two of the greatest problems we face: global warming and biodiversity loss. We face a third major problem: our wilful failure to acknowledge the biological fact that …

Jenny Chapman makes some good points in focusing on nutrition, but why does any vegetarian food have to be ultra-processed? Caution over some margarines (those developed for profit more than for health) was warranted when the damage caused by trans fats came to light. Like most people I know, I will happily eat a veggie …

Given the burgeoning awareness of various types of barrier protection provided by the skin, and the possibilities of assisting this in many ways, has there been no study into the impact that may be caused by tattoos? Indeed, might it be that what you put on your skin isn't as important as what you (don't) …

The only use of quantum computers is to absorb vast amounts of research money and effort for no practical benefit whatsoever. Can I have my $5 million now please( 9 March, p 10 )?