Your Sense of Smell May Be the Key To a Balanced Diet (phys.org) 38
Scientists at Northwestern University found that people became less sensitive to food odors based on the meal they had eaten just before. These findings show that just as smell regulates what we eat, what we eat -- in turn -- regulates our sense of smell. Phys.Org reports: The study found that participants who had just eaten a meal of either cinnamon buns or pizza were less likely to perceive "meal-matched" odors, but not non-matched odors. The findings were then corroborated with brain scans that showed brain activity in parts of the brain that process odors was altered in a similar way.
Feedback between food intake and the olfactory system may have an evolutionary benefit, said senior and corresponding study author Thorsten Kahnt, an assistant professor of neurology and psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine. "If you think about our ancestors roaming the forest trying to find food, they find and eat berries and then aren't as sensitive to the smell of berries anymore," Kahnt said. "But maybe they're still sensitive to the smell of mushrooms, so it could theoretically help facilitate diversity in food and nutrient intake."
Kahnt said while we don't see the hunter-gatherer adaptation come out in day-to-day decision-making, the connection between our nose, what we seek out and what we can detect with our nose may still be very important. If the nose isn't working right, for example, the feedback loop may be disrupted, leading to problems with disordered eating and obesity. There may even be links to disrupted sleep, another tie to the olfactory system the Kahnt lab is researching. Kahnt said with a better understanding of the feedback loop between smell and food intake, he's hoping to take the project full circle back to sleep deprivation to see if lack of sleep may impair the loop in some way. He added that with brain imaging, there are more questions about how the adaptation may impact sensory and decision-making circuits in the brain. The study has been published in the journal PLOS Biology.
Feedback between food intake and the olfactory system may have an evolutionary benefit, said senior and corresponding study author Thorsten Kahnt, an assistant professor of neurology and psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine. "If you think about our ancestors roaming the forest trying to find food, they find and eat berries and then aren't as sensitive to the smell of berries anymore," Kahnt said. "But maybe they're still sensitive to the smell of mushrooms, so it could theoretically help facilitate diversity in food and nutrient intake."
Kahnt said while we don't see the hunter-gatherer adaptation come out in day-to-day decision-making, the connection between our nose, what we seek out and what we can detect with our nose may still be very important. If the nose isn't working right, for example, the feedback loop may be disrupted, leading to problems with disordered eating and obesity. There may even be links to disrupted sleep, another tie to the olfactory system the Kahnt lab is researching. Kahnt said with a better understanding of the feedback loop between smell and food intake, he's hoping to take the project full circle back to sleep deprivation to see if lack of sleep may impair the loop in some way. He added that with brain imaging, there are more questions about how the adaptation may impact sensory and decision-making circuits in the brain. The study has been published in the journal PLOS Biology.
Desensitized? (Score:5, Interesting)
Being constantly surrounding by those smells I become desensitized and hardly notice it any more. But when I've been in urban environments, being exposed to different kinds of smells for a while, and then return back to agricultural areas, I notice the local smells again until I get used to them.
From a technical standpoint it makes sense to me that the brain dampens out sensory input as it becomes to 'normal'. At that point it turns into background noise that's better filtered out so the brain can focus on things that change more dynamically.
So what's the big difference with eating food here? Olfactory sense and taste are closely tied together.
I'm asking, because this is not my field.
Re:Desensitized? (Score:4, Informative)
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Which makes sense, really. Hunter/gatherers, which we were until yesterday, evolutionarily, snack as they're harvesting. If you're picking berries and munching on them you obviously know where the berries are, but you don't necessarily know that there are apples nearby. Berries get de-prioritized so there's more processing available. Also, if you're picking berries you don't want the smell of berries to overwhelm the stink of bear shit that might warn you that you're not the only one eating these.
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It's interesting that becoming "used to" a smell can also possibly be caused by the brain, but I'm a bit surprised. In the case of hearing, when the sensor is damaged, the brain increases gain and causes tinnitus (ringi
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I had always thought that becoming "used to" a smell was about the receptors being clogged with the molecule that is in abundance
I assumed it was not a chemical thing in the receptor, but either in the sensory nervous system, or in the brain itself. Because the same phenomenon happens with other senses; if you hear a noise constantly for a long time, you'll eventually stop noticing it (and if it stops, you'll either keep hearing it, or you'll experience a sudden "something is missing but I don't quite know what it is" feeling). And this isn't simply certain frequencies getting tired in your ear, because it can happen with white noise
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From being tested for tinnitus I'm not sure if the brain increases 'gain', or at least not in the way I would define 'gain' like from an opamp. Hearing tests show what the 'gain' is effectively reduced in the affected frequency ranges, equaling a hearing loss, because it requires a higher amplitude in the signal for you becoming consciously aware of the sound over the constant false
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Our sense of smell is actually used a lot, we culturally just don't use it too much because it is often difficult to quantify and qualify. So it never translates much in normal communication. I think that may mostly be from a hole in our vocabulary that doesn't have us really explaining smell well. Much like how only historically recently did we start seeing the color blue, While we have been seeing the color that we call blue, it never had a name for it, so we saw it has just a hue of gray, until someon
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the smell of cow manure doesn't equate to food in my mind
That's because you're not walking around with a spear looking for an aurochs for dinner.
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Animal poop is indeed a way that even modern hunters use to identify animal types in the vicinity. Well, at least in my case I had to learn some stuff there and pass a test before I was legally allowed to obtain a hunting license. Yes, that's what it takes in Germany.
And as far as bovine manure goes... well people have learned to be flexible with that 'shit'.
Dry cow dung serves as decent enough fuel for a wooden stove, especially when local firewood sources aren't plentiful.
Because of how in
Counter-example (Score:3)
I eat healthy (and I enjoy it too) yet my sense of smell has been clobbered by 25 years of smoking. I quit 10 years ago, but I still can't smell a fart in an elevator - let alone delicious veggies.
Re: Counter-example (Score:2)
I eat healthy too, and I enjoy it (mostly healthy meat), but I can smell pretty well. Smoked for 10-ish years, quit for 10-ish, recently started again because why not?... Buy my sense of smell is as good as ever.
I don't think smoking is the cause. Maybe you had an infection, or just your body isnt "into" smelling much...
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Probably inflammation desensitizing the smell receptors due to years of eating toxic vegetables.
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I offered one counter-example. I never claimed it was statistically relevant :)
On the other hand ... (Score:5, Funny)
If you consider cinnamon buns a "meal", you may have other problems -- like understanding "balanced diet".
[ Not saying pizza is a great balanced diet either, though... ]
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What about cinnamon pizza?
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And therein makes it all suspect.
Your digestive system has a feedback loop for carbohydrates that rewards you with serotonin when you eat them. This also creates the "crave" cycle that is rewarded when you eat most carbs.
Worse, some sugars like fructose can specificallyexpand the uptake of fats. This was great when carbs became available to store fat because, darn it, Winter was coming and food scarcity would become a problem, but supply chains through Winter obviate the need. So we get fat.
It's for this re
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Since they are usually something outrageous, calorie wise - 1000-1400+, and sometimes way more, hadn't they better be taking the place of (at least) one of your meals?
No, the cat does not "got my tongue." (Score:2)
They've long known your sense of taste drops, e.g. saltiness, the more you eat it.
Same for smell. This is why your stinking 4 day unbathed self-quarantined body doesn't make you gag, but any visitor will smell your stinking house when they walk in.
So the observation is not new for either smell or taste. That only leaves the rationalized evolutionary cause.
Have they ruled out simple temporary clogging of the receptors? Anyone who's seen a dog knows when they go to sniff something, they then do a blowout o
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I strongly disagree. (Score:1)
Got an ex girlfriend with the most amazing sense of smell. ;)
She makes the best perfumes and can't even go through a city street without holding her breath when passing perfume shops or perfumed people.
But the only balance in her life was the scale her fat ass broke from being so fat.
Explain THAT, dear Northern University scientists!
(I can: She lives in a place with a diet extremely based on things made from flour. And that's mostly white flour. Usually with butter. So of course, her digestive microbiome is
Avoid Processed Foods (Score:2)
I read it a while ago, I think it was a fitness program when I was in my 20's. I tried it and never looked back, I walk into a super market and it's like being on autopilot. I don't even think about it and the fridge gets filled with healthy yummy stuff.
I've never really known how it works, only that it does. Having seen this makes me wonder if processed foods interfere with a sense of smelling what is good to eat because they overpower everything else.
I'm concerned about the control group (Score:1)
The linked article only mentions one control group: The group that hadn't eaten in awhile.
It would be interesting to see this study replicated but with additional control groups which had eaten foods that didn't share the same smell and/or the same nutritional value as the food whose odor was being tested.
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The linked article only mentions one control group: The group that hadn't eaten in awhile.
So, Ethiopians?
True For Dogs? (Score:2)
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I've heard cops say they don't feed K-9 officers before duty, because it weakens their sense of smell.
Like cops have a clue about science.
It's been pretty well established, by researchers, not cops, that K-9s "find" contraband because they know they'll get a treat for performing certain actions. If they've chowed down they may be less interested in subsequent treats would seem to be a more likely explanation.
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Then they're morons (they're cops so I guess that's to be expected). You don't feed a working dog before they go do their job because they'll get sick. Their physiology is different. That's why you feed working dogs at the end of the day, so they can digest it comfortably.
Covid-19 Infected People (Score:2)
If the nose isn't working right, for example, the feedback loop may be disrupted, leading to problems with disordered eating and obesity. There may even be links to disrupted sleep, another tie to the olfactory system the Kahnt lab is researching. Kahnt said with a better understanding of the feedback loop between smell and food intake, he's hoping to take the project full circle back to sleep deprivation to see if lack of sleep may impair the loop in some way.
Maybe Kahnt lab should study people who were infected with Covid-19 and that are still having problems with olfactory disorders [jamanetwork.com] and taste to see if there's a feedback loop between smell and food intake and sleep deprivation and overall health [thelancet.com]
Dining vs. refueling (Score:1)
IMHO, there is a big difference between dining (really enjoying what you eat) and simply consuming for the purpose of caloric intake or nutrition. In my experience, people who browbeat the loudest about eating healthy tend to see eating as merely a way of refueling their body. I'll bet that these people don't have a developed sense of smell nor are they super-tasters.
Obesity? (Score:2)
If the nose isn't working right, for example, the feedback loop may be disrupted, leading to problems with disordered eating and obesity.
That feedback loop is based on quality not quantity. Obesity is a quantity issue. If you eat more kcal per day than you need, the excess is stored as fat.