Wikipedia:Reference desk/Archives/Science/2023 December 6

= December 6 =

Mixing foods into poison
A fairly common folk belief is that certain combinations of foods are unhealthy - even poisonous - to eat in close sequence to each other. For example, a Newfoundlander friend of mine once warned me not to eat ice cream after eating shellfish as it would give me a stomach ache. And a Turkish friend commented today that eating yogurt and unfresh fish (such as canned fish or smoked fish) would "make poison" in your stomach if eaten together. Curiously, both of these are not too far from the Jewish food laws. I've always assumed these are nothing more than superstitions, but I thought I'd ask the overarching question: is there any combination of foods that, although perfectly healthful on their own, have harmful effects if eaten together? Just to be clear, I'm not talking about eating too much of something or of combinations that might taste gross eaten together, but straightforward: A is fine and B is fine but eating A+B in the same meal could be dangerous. I guess technically the opposite might be true: not including the sodium in your table salt is unlikely to have health benefits. Matt Deres (talk) 02:49, 6 December 2023 (UTC)
 * I googled "foods unsafe to eat together", and several entries arose that are merely about getting too fat from them or whatever (such as burgers and fries), but some possible answers came up, including this one from Hindustantimes.com: "'Banana should not be eaten with milk, curds, or buttermilk because the combination can diminish digestion and produce toxins in the body. Eating this combination can lead to cold, cough, and allergies,' says the Ayurveda expert. Curds can cause swelling and aggravate blood (rakta), pitta, and kapha." I can't vouch for the accuracy of this claim, but it looks like there are at least some possibilities of things not to eat together. ←Baseball Bugs What's up, Doc? carrots→ 06:44, 6 December 2023 (UTC)
 * Banana milkshake is almost a staple of the American diet, but we have seen few reports of a resulting vāta–pitta–kapha imbalance. --Lambiam 08:57, 6 December 2023 (UTC)
 * Even more common in the American diet (or at least it was when I was a child) is sliced bananas in a bowl of breakfast cereal (Cheerios, Corn Flakes, etc) and milk.--User:Khajidha (talk) (contributions) 13:56, 6 December 2023 (UTC)
 * And on this side of the Atlantic, there's banana custard. Alansplodge (talk) 18:00, 6 December 2023 (UTC)
 * What side is that? Wikipedia doesn't reside on any particular side of the Atlantic. Are we supposed to go to your userpage to figure out that you meant the British side? Dhrm77 (talk) 18:20, 6 December 2023 (UTC)
 * "a staple of the American diet", followed by "common in the American diet" sort of sets the scene for "And on this side of the Atlantic". Think of an Anglophone country on the opposite side of the Atlantic to the USA, there aren't that many to choose from. Martin of Sheffield (talk) 20:59, 6 December 2023 (UTC)
 * While rhubarb leaves are already poisonous, cooking them with baking soda can make them more poisonous. --Lambiam 09:13, 6 December 2023 (UTC)
 * I guess it all comes down to chemical reactions. Which happens all the time with food, such as in cooking or digesting. For instance, citric acid in lemon juice will react with some components of tea, possibly the tanins, to form something else, equally harmless. To find 2 foods that shouldn't mix, you need to find 2 naturally occurring chemicals in foods that can react with each other to form a form of poison, or strong toxin. Lots of food already have mild toxins, such as some uncooked beans, rhubarb leaves, potatoes growing above ground (green), some nuts. It might just be a matter of somehow increasing their potency, or decreasing the ability of the human body to deal with them. Dhrm77 (talk) 14:02, 6 December 2023 (UTC)
 * One classic example is not strictly a "food" but a well-known traditional medicine: St John's wort. Our article covers the issues quite well. Some of the components may have health benefits but others can, in combination with other foods or medicines, have unwanted and sometimes serious side-effects. Grapefruit can have similar problems. Mike Turnbull (talk) 14:24, 6 December 2023 (UTC)
 * Yes, I was curious if grapefruit would come into this as it has many well-known impacts with drugs (our article is not exactly short...). It doesn't seem to have any significant interactions with other foods, though. Matt Deres (talk) 15:35, 6 December 2023 (UTC)
 * I noticed years ago that pizza plus ice cream bother my gut more than over-indulging on one or the other alone. Something about the combination of fats, I guess. —Tamfang (talk) 18:27, 6 December 2023 (UTC)


 * Eating ink-cap fungi in combination with alcohol makes one ill. This has been utilised to help alcoholics desist in their addiction. See Coprinopsis atramentaria. JMCHutchinson (talk) 14:06, 7 December 2023 (UTC)


 * In past years I have gorged on hot cross buns.  These usually appear in the shops at the beginning of January, irrespective of the date of Easter (31 March this year, although a table at Reference desk/Archives/Humanities/2023 November 28 indicates 5 May).   I'm not referring to the table that's there now, but to a second table which has disappeared.   Recently I've not bought them because they started to make me very ill.   Could the culprit be cinnamon, which is made from tree bark?   Camphor is also made from trees, and it's extremely dangerous. 92.12.76.4 (talk) 14:10, 7 December 2023 (UTC)
 * What a bizarre non sequitur! Do you avoid forks because they're made of steel and so are bazookas? Matt Deres (talk) 18:56, 7 December 2023 (UTC)
 * If there were a food combination that worked in the way the OP suggests, then Agatha Christie would be the one who would have used it! Mike Turnbull (talk) 14:33, 7 December 2023 (UTC)
 * Not quite "makes poison", but but an interesting related topic is antinutrient. DMacks (talk) 15:11, 7 December 2023 (UTC)


 * Wow, this sounds like a question I would ask. And yes, medications can contraindicate other medicines, and some foods like grapefruit does contraindicate. In any event, so far no 1 said antacids, which can react with acidic foods, but likely not in any bad ways. 170.76.231.162 (talk) 19:13, 8 December 2023 (UTC).

Bird head movements
My bird feeder is usually swinging a little in the wind or from the momentum of birds landing and taking off. Some birds, such as robins, when perched on the feeder (or on a branch) make their heads remain still while their body is rocking along with the perch. Other birds, such as tits, won't bother with this and just allow their whole body to rock. Why do some birds do this and does this behaviour have a name? I am not talking about the back and forth head movements exhibited by walking fowl, nor the side to side movements by raptors to enhance their depth perception. All my Googling only brings up those types of movement. Shantavira|feed me 12:23, 6 December 2023 (UTC)


 * My take on this is that the european robin is principally a groundfeeding bird, so, unlike the great and blue tits, which are both woodland birds, they will not be adapted to a moving target. Unfortunately, I've not yet found a source to back up my OR. Mikenorton (talk) 12:42, 6 December 2023 (UTC)
 * It's possible that the stabilizing behavior is a necessity in some hovering birds that isn't learned in ground feeding species, per your conjecture and an article I found with less than 20 citations. Reconrabbit (talk) 23:04, 6 December 2023 (UTC)
 * Might it be that the tits are just too small to bother trying to compensate? NadVolum (talk) 12:45, 6 December 2023 (UTC)
 * The great tit is, however, almost exactly the same size and weight as the robin. Mikenorton (talk) 13:28, 6 December 2023 (UTC)
 * Probably not the first exchange we've had here about tit size. —Tamfang (talk) 18:53, 10 December 2023 (UTC)
 * Head-bobbing in birds, easily observed in walking chickens and pigeons, has the same function as the phenomenon of saccades in human vision, namely to fix the image seen by the eye between movements. When a head-bobber is not walking but swaying, so does its head but in contrary motion so as to fix the image. "The best examples are seen in ground feeding birds, which need a clear field of view to the side while foraging, in order to recognize small items of food." This provides a source to back up Mikenorton's hypothesis that the difference lays in one species being a ground feeder while the other is not. --Lambiam 08:35, 7 December 2023 (UTC)
 * "Head stabilization" would be the phrase to look for. Shyamal (talk) 08:49, 7 December 2023 (UTC)
 * Thanks, I've tried that specifically for the great tit and blue tit, but found very few results and nothing useful. What would appear to be unusual in these birds is not having noticeable head stabilization during feeding, which seems to be the norm in birds. I'll have to look more carefully at the birds in my garden - I get all three species on a daily basis. Mikenorton (talk) 21:05, 7 December 2023 (UTC)

Glacier models
Has anyone developed formulas or models that describe the behaviour of a radial ice cap with a given insolation, wind, temperature profile, precipitation and bedrock slope? Jo-Jo Eumerus (talk) 16:11, 6 December 2023 (UTC)
 * @Jo-Jo Eumerus, I found a paper on continental ice sheet simulation. Here's a link to it - https://arxiv.org/pdf/1711.09947.pdf Leoneix (talk) 17:22, 6 December 2023 (UTC)
 * This is a model of the Vestfonna ice cap. Mikenorton (talk) 17:28, 6 December 2023 (UTC)
 * The summary of this paper tells us that knowledge of basal conditions such as friction is important and that these conditions can be variable. A realistic model is sensitive to such variation in the basal conditions. --Lambiam 08:08, 7 December 2023 (UTC)
 * Is there a model or formula for a given friction law? Jo-Jo Eumerus (talk) 17:14, 7 December 2023 (UTC)
 * That paper says that it assumes no basal melting and uses a linear friction law, which it describes as a Weertman type sliding law with a Robin type boundary condition, citing Greve and Blatter (2009), which I'm unable to look at the relevant parts of on Google Books. It does say that values for the basal friction parameter are inferred from surface velocity observations, for what it's worth. Mikenorton (talk) 21:56, 7 December 2023 (UTC)