You can train your nose – and 4 other surprising facts about your sense of smell

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Would you give up your sense of smell to keep your hair? What about your phone?

A 2022 US study compared smell to other senses (sight and hearing) and personally prized commodities (including money, a pet or hair) to see what people valued more.

The researchers found smell was viewed as much less important than sight and hearing, and valued less than many commodities. For example, half the women surveyed said they’d choose to keep their hair over sense of smell.

Smell often goes under the radar as one of the least valued senses. But it is one of the first sensory systems vertebrates developed and is linked to your mental health, memory and more.

Here are five fascinating facts about your olfactory system.

DimaBerlin/Shutterstock

1. Smell is linked to memory and emotion

Why can the waft of fresh baking trigger joyful childhood memories? And why might a certain perfume jolt you back to a painful breakup?

Smell is directly linked to both your memory and emotions. This connection was first established by American psychologist Donald Laird in 1935 (although French novelist Marcel Proust had already made it famous in his reverie about the scent of madeleines baking.)

Odours are first captured by special olfactory nerve cells inside your nose. These cells extend upwards from the roof of your nose towards the smell-processing centre of your brain, called the olfactory bulb.

Diagram showing odour particles travelling through the nose into the brain.
Smells are first detected by nerve cells in the nose. Axel_Kock/Shutterstock

From the olfactory bulb they form direct connection with the brain’s limbic system. This includes the amygdala, where emotions are generated, and the hippocampus, where memories are created.

Other senses – such as sight and hearing – aren’t directly connected to the lymbic system.

One 2004 study used functional magnetic resonance imaging to demonstrate odours trigger a much stronger emotional and memory response in the brain than a visual cue.

2. Your sense of smell constantly regenerates

You can lose your ability to smell due to injury or infection – for example during and after a COVID infection. This is known as olfactory dysfunction. In most cases it’s temporary, returning to normal within a few weeks.

This is because every few months your olfactory nerve cells die and are replaced by new cells.

We’re not entirely sure how this occurs, but it likely involves your nose’s stem cells, the olfactory bulb and other cells in the olfactory nerves.

Other areas of your nervous system – including your brain and spinal cord – cannot regenerate and repair after an injury.

Constant regeneration may be a protective mechanism, as the olfactory nerves are vulnerable to damage caused by the external environment, including toxins (such as cigarette smoke), chemicals and pathogens (such as the flu virus).

But following a COVID infection some people might continue to experience a loss of smell. Studies suggest the virus and a long-term immune response damages the cells that allow the olfactory system to regenerate.

3. Smell is linked to mental health

Around 5% of the global population suffer from anosmia – total loss of smell. An estimated 15-20% suffer partial loss, known as hyposmia.

Given smell loss is often a primary and long-term symptom of COVID, these numbers are likely to be higher since the pandemic.

Yet in Australia, the prevalence of olfactory dysfunction remains surprisingly understudied.

Losing your sense of smell is shown to impact your personal and social relationships. For example, it can mean you miss out on shared eating experiences, or cause changes in sexual desire and behaviour.

In older people, declining ability to smell is associated with a higher risk of depression and even death, although we still don’t know why.

An older woman in a hat leans towards a tomato vine to sniff it.
Losing your sense of smell can have a major impact on mental health. Halfpoint/Shutterstock

4. Loss of smell can help identify neurodegenerative diseases

Partial or full loss of smell is often an early indicator for a range of neurodegenerative diseases, including Alzheimer’s and Parkinson’s diseases.

Patients frequently report losing their sense of smell years before any symptoms show in body or brain function. However many people are not aware they are losing their sense of smell.

There are ways you can determine if you have smell loss and to what extent. You may be able to visit a formal smell testing centre or do a self-test at home, which assesses your ability to identify household items like coffee, wine or soap.

5. You can train your nose back into smelling

“Smell training” is emerging as a promising experimental treatment option for olfactory dysfunction. For people experiencing smell loss after COVID, it’s been show to improve the ability to detect and differentiate odours.

Smell training (or “olfactory training”) was first tested in 2009 in a German psychology study. It involves sniffing robust odours — such as floral, citrus, aromatic or fruity scents — at least twice a day for 10—20 seconds at a time, usually over a 3—6 month period.

Participants are asked to focus on the memory of the smell while sniffing and recall information about the odour and its intensity. This is believed to help reorganise the nerve connections in the brain, although the exact mechanism behind it is unclear.

Some studies recommend using a single set of scents, while others recommend switching to a new set of odours after a certain amount of time. However both methods show significant improvement in smelling.

This training has also been shown to alleviate depressive symptoms and improve cognitive decline both in older adults and those suffering from dementia.

Just like physiotherapy after a physical injury, olfactory training is thought to act like rehabilitation for your sense of smell. It retrains the nerves in your nose and the connections it forms within the brain, allowing you to correctly detect, process and interpret odours.

Lynn Nazareth, Research Scientist in Olfactory Biology, CSIRO

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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  • 7 Minutes, 30 Days, Honest Review: How Does The 7-Minute Workout Stack Up?

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    For those who don’t like exercising, “the 7-minute workout” (developed by exercise scientists Chris Jordan and Bret Klika) has a lot of allure. After all, it’s just 7 minutes and then you’re done! But how well does it stand up, outside of the lab?

    Down-to-Earth

    Business Insider’s Kelly Reilly is not a health guru, and here he reviews the workout for us, so that we can get a real view of what it’s really like in the real world. What does he want us to know?

    • It’s basically an optimized kind of circuit training, and can be done with no equipment aside from a floor, a wall, and a chair
    • It’s one exercise for 30 seconds, then 10 seconds rest, then onto the next exercise
    • He found it a lot easier to find the motivation to do this, than go to the gym. After all “it’s just 7 minutes” is less offputting than getting in the car, driving someplace, using public facilities, driving back, etc. Instead, it’s just him in the comfort of his home
    • The exercise did make him sweat and felt like a “real” workout in that regard
    • He didn’t like missing out on training his biceps, though, since there are no pulling movements
    • He lost a little weight over the course of the month, though that wasn’t his main goal (and indeed, he was not eating healthily)
    • He did feel better each day after working out, and at the end of the month, he enjoyed feeling self-confident in a tux that now fitted him better than it did before

    For more details, his own words, and down-to-earth visuals of what this looked like for him, enjoy:

    Click Here If The Embedded Video Doesn’t Load Automatically!

    Further reading

    Want to know more? Check out…

    Take care!

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  • How Does One Test Acupuncture Against Placebo Anyway?

    10almonds is reader-supported. We may, at no cost to you, receive a portion of sales if you purchase a product through a link in this article.

    Pinpointing The Usefulness Of Acupuncture

    We asked you for your opinions on acupuncture, and got the above-depicted, below-described, set of answers:

    • A little under half of all respondents voted for “It’s well-backed by modern science, per neurology, cardiology, immunology, etc”
    • Slightly fewer respondents voted for “We don’t understand how it works, but it works!”
    • A little under a fifth of respondents voted for “It may have some limited clinical applications beyond placebo”
    • One (1) respondent voted for for “It’s placebo at best”

    When we did a main feature about homeopathy, a couple of subscribers wrote to say that they were confused as to what homeopathy was, so this time, we’ll start with a quick definition first.

    First, what is acupuncture? For the convenience of a quick definition so that we can move on to the science, let’s borrow from Wikipedia:

    ❝Acupuncture is a form of alternative medicine and a component of traditional Chinese medicine in which thin needles are inserted into the body.

    Acupuncture is a pseudoscience; the theories and practices of TCM are not based on scientific knowledge, and it has been characterized as quackery.❞

    ~ Wikipedia

    Now, that’s not a promising start, but we will not be deterred! We will instead examine the science itself, rather than relying on tertiary sources like Wikipedia.

    It’s worth noting before we move on, however, that there is vigorous debate behind the scenes of that article. The gist of the argument is:

    • On one side: “Acupuncture is not pseudoscience/quackery! This has long been disproved and there are peer-reviewed research papers on the subject.”
    • On the other: “Yes, but only in disreputable quack journals created specifically for that purpose”

    The latter counterclaim is a) potentially a “no true Scotsman” rhetorical ploy b) potentially true regardless

    Some counterclaims exhibit specific sinophobia, per “if the source is Chinese, don’t believe it”. That’s not helpful either.

    Well, the waters sure are muddy. Where to begin? Let’s start with a relatively easy one:

    It may have some clinical applications beyond placebo: True or False?

    True! Admittedly, “may” is doing some of the heavy lifting here, but we’ll take what we can get to get us going.

    One of the least controversial uses of acupuncture is to alleviate chronic pain. Dr. Vickers et al, in a study published under the auspices of JAMA (a very respectable journal, and based in the US, not China), found:

    ❝Acupuncture is effective for the treatment of chronic pain and is therefore a reasonable referral option. Significant differences between true and sham acupuncture indicate that acupuncture is more than a placebo.

    However, these differences are relatively modest, suggesting that factors in addition to the specific effects of needling are important contributors to the therapeutic effects of acupuncture❞

    Source: Acupuncture for Chronic Pain: Individual Patient Data Meta-analysis

    If you’re feeling sharp today, you may be wondering how the differences are described as “significant” and “relatively modest” in the same text. That’s because these words have different meanings in academic literature:

    • Significant = p<0.05, where p is the probability of the achieved results occurring randomly
    • Modest = the differences between the test group and the control group were small

    In other words, “significant modest differences” means “the sample sizes were large, and the test group reliably got slightly better results than placebo”

    We don’t understand how it works, but it works: True or False

    Broadly False. When it works, we generally have an idea how.

    Placebo is, of course, the main explanation. And even in examples such as the above, how is placebo acupuncture given?

    By inserting acupuncture needles off-target rather than in accord with established meridians and points (the lines and dots that, per Traditional Chinese Medicine, indicate the flow of qi, our body’s vital energy, and welling-points of such).

    So, if a patient feels that needles are being inserted randomly, they may no longer have the same confidence that they aren’t in the control group receiving placebo, which could explain the “modest” difference, without there being anything “to” acupuncture beyond placebo. After all, placebo works less well if you believe you are only receiving placebo!

    Indeed, a (Korean, for the record) group of researchers wrote about this—and how this confounding factor cuts both ways:

    ❝Given the current research evidence that sham acupuncture can exert not only the originally expected non-specific effects but also sham acupuncture-specific effects, it would be misleading to simply regard sham acupuncture as the same as placebo.

    Therefore, researchers should be cautious when using the term sham acupuncture in clinical investigations.❞

    Source: Sham Acupuncture Is Not Just a Placebo

    It’s well-backed by modern science, per neurology, cardiology, immunology, etc: True or False?

    False, for the most part.

    While yes, the meridians and points of acupuncture charts broadly correspond to nerves and vasculature, there is no evidence that inserting needles into those points does anything for one’s qi, itself a concept that has not made it into Western science—as a unified concept, anyway…

    Note that our bodies are indeed full of energy. Electrical energy in our nerves, chemical energy in every living cell, kinetic energy in all our moving parts. Even, to stretch the point a bit, gravitational potential energy based on our mass.

    All of these things could broadly be described as qi, if we so wish. Indeed, the ki in the Japanese martial art of aikido is the latter kinds; kinetic energy and gravitational potential energy based on our mass. Same goes, therefore for the ki in kiatsu, a kind of Japanese massage, while the ki in reiki, a Japanese spiritual healing practice, is rather more mystical.

    The qi in Chinese qigong is mostly about oxygen, thus indirectly chemical energy, and the electrical energy of the nerves that are receiving oxygenated blood at higher or lower levels.

    On the other hand, the efficacy of the use of acupuncture for various kinds of pain is well-enough evidenced. Indeed, even the UK’s famously thrifty NHS (that certainly would not spend money on something it did not find to work) offers it as a complementary therapy for some kinds of pain:

    ❝Western medical acupuncture (dry needling) is the use of acupuncture following a medical diagnosis. It involves stimulating sensory nerves under the skin and in the muscles.

    This results in the body producing natural substances, such as pain-relieving endorphins. It’s likely that these naturally released substances are responsible for the beneficial effects experienced with acupuncture.❞

    Source: NHS | Acupuncture

    Meanwhile, the NIH’s National Cancer Institute recommends it… But not as a cancer treatment.

    Rather, they recommend it as a complementary therapy for pain management, and also against nausea, for which there is also evidence that it can help.

    Frustratingly, while they mention that there is lots of evidence for this, they don’t actually link the studies they’re citing, or give enough information to find them. Instead, they say things like “seven randomized clinical trials found that…” and provide links that look reassuring until one finds, upon clicking on them, that it’s just a link to the definition of “randomized clinical trial”:

    Source: NIH | Nactional Cancer Institute | Acupuncture (PDQ®)–Patient Version

    However, doing our own searches finds many studies (mostly in specialized, potentially biased, journals such as the Journal of Acupuncture and Meridian Studies) finding significant modest outperformance of [what passes for] placebo.

    Sometimes, the existence of papers with promising titles, and statements of how acupuncture might work for things other than relief of pain and nausea, hides the fact that the papers themselves do not, in fact, contain any evidence to support the hypothesis. Here’s an example:

    ❝The underlying mechanisms behind the benefits of acupuncture may be linked with the regulation of the hypothalamic-pituitary-gonadal (adrenal) axis and activation of the Wnt/β-catenin and OPG/RANKL/RANK signaling pathways.

    In summary, strong evidence may still come from prospective and well-designed clinical trials to shed light on the potential role of acupuncture in preserving bone loss❞

    Source: Acupuncture for Osteoporosis: a Review of Its Clinical and Preclinical Studies

    So, here they offered a very sciencey hypothesis, and to support that hypothesis, “strong evidence may still come”.

    “We must keep faith” is not usually considered evidence worthy of inclusion in a paper!

    PS: the above link is just to the abstract, because the “Full Text” link offered in that abstract leads to a completely unrelated article about HIV/AIDS-related cryptococcosis, in a completely different journal, nothing to do with acupuncture or osteoporosis).

    Again, this is not the kind of professionalism we expect from peer-reviewed academic journals.

    Bottom line:

    Acupuncture reliably performs slightly better than sham acupuncture for the management of pain, and may also help against nausea.

    Beyond placebo and the stimulation of endorphin release, there is no consistently reliable evidence that is has any other discernible medical effect by any mechanism known to Western science—though there are plenty of hypotheses.

    That said, absence of evidence is not evidence of absence, and the logistical difficulty of testing acupuncture against placebo makes for slow research. Maybe one day we’ll know more.

    For now:

    • If you find it helps you: great! Enjoy
    • If you think it might help you: try it! By a licensed professional with a good reputation, please.
    • If you are not inclined to having needles put in you unnecessarily: skip it! Extant science suggests that at worst, you’ll be missing out on slight relief of pain/nausea.

    Take care!

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  • Puritans Pride Resveratrol vs Life Extension Resveratrol – Which is Healthier

    10almonds is reader-supported. We may, at no cost to you, receive a portion of sales if you purchase a product through a link in this article.

    Our Verdict

    When comparing Puritan’s Pride Resveratrol to Life Extension Resveratrol, we picked the Life Extension Resveratrol.

    Why?

    It contains not only more resveratrol per serving (250mg compared to Puritan’s Pride’s 100mg), but also contains other goodies too. Specifically, each capsule also contains:

    Whereas the Puritan’s Pride softgels? The other top ingredients are soybean oil and gelatin.

    Want to check out the products for yourself? Here they are:

    Puritan’s Pride Resveratrol | Life Extension Resveratrol

    Want to know more about these supplements? Check out:
    Resveratrol & Healthy Aging
    Fight Inflammation & Protect Your Brain, With Quercetin
    Berries & Other Polyphenol-rich Foods
    Fisetin: The Anti-Aging Assassin

    Enjoy!

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  • The Breathing Cure – by Patrick McKeown

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    We’ve previously reviewed this author’s “The Oxygen Advantage”, which as you might guess from the title, was also about breathing. So, what’s different here?

    While The Oxygen Advantage was mostly about improving good health with optimized breathing, and with an emphasis on sports too, The Breathing Cure is more about the two-way relationship between ill health and disordered breathing (and how to fix it).

    Many kinds of illnesses can affect our breathing, and our breathing can affect many types of illness; McKeown covers a lot of these, including the obvious things like respiratory diseases (including COVID and Long COVID, as well as non-infectious respiratory conditions like asthma), but also things like diabetes and heart disease, as well as peri-disease things like chronic pain, and demi-disease things like periods and menopause.

    In each case (and more), he examines what things make matters better or worse, and how to improve them.

    While the style itself is just as pop-science as The Oxygen Advantage, this time it relies less on anecdote (though there are plenty of anecdotes too), and leans more heavily on a generous chapter-by-chapter scientific bibliography, with plenty of citations to back up claims.

    Bottom line: if you’d like to breathe better, this book can help in very many ways.

    Click here to check out The Breathing Cure, and breathe easy!

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  • Heart Healthy Diet Plan – by Stephen William

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    We’ve covered heart-healthy cooking books before, but variety is good, and boredom is an enemy of health, so let’s shake it up with a fresh stack of recipes!

    After a brief overview of the relevant science (which if you’re a regular 10almonds reader, probably won’t be new to you), the author takes the reader on a 28-day journey. Yes, we know the subtitle says 30 days, but unless they carefully hid the other two days somewhere we didn’t find, there are “only” 28 inside. Perhaps the publisher heard it was a month and took creative license. Or maybe there’s a different edition. Either way…

    Rather than merely giving a diet plan (though yes, he also does that), he gives a wide range of “spotlight ingredients”, such that many of the recipes, while great in and of themselves, can also be jumping-off points for those of us who like to take recipes and immediately do our own things to them.

    Each day gets a breakfast, lunch, dinner, and he also covers drinks, desserts, and such like.

    Notwithstanding the cover art being a lot of plants, the recipes are not entirely plant-based; there are a selection of fish dishes (and other seafood, e.g. shrimp) and also some dairy products (e.g. Greek yoghurt). The recipes are certainly very “plant-forward” though and many are just plants. If you’re a strict vegan though, this probably isn’t the book for you.

    Bottom line: if you’d like to cook heart-healthy but are often stuck wondering “aaah, what to cook again today?”, then this is the book to get you out of any culinary creative block!

    Click here to check out the Heart Healthy Diet Plan, and widen your heart-healthy repertoire!

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  • Managing Sibling Relationships In Adult Life

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    Managing Sibling Relationships In Adult Life

    After our previous main feature on estrangement, a subscriber wrote to say:

    ❝Parent and adult child relationships are so important to maintain as you age, but what about sibling relationships? Adult choices to accept and move on with healthier boundaries is also key for maintaining familial ties.❞

    And, this is indeed critical for many of us, if we have siblings!

    Writer’s note: I don’t have siblings, but I do happen to have one of Canada’s top psychologists on speed-dial, and she has more knowledge about sibling relationships than I do, not to mention a lifetime of experience both personally and professionally. So, I sought her advice, and she gave me a lot to work with.

    Today I bring her ideas, distilled into my writing, for 10almonds’ signature super-digestible bitesize style.

    A foundation of support

    Starting at the beginning of a sibling story… Sibling relationships are generally beneficial from the get-go.

    This is for reasons of mutual support, and an “always there” social presence.

    Of course, how positive this experience is may depend on there being a lack of parental favoritism. And certainly, sibling rivalries and conflict can occur at any age, but the stakes are usually lower, early in life.

    Growing warmer or colder

    Generally speaking, as people age, sibling relationships likely get warmer and less conflictual.

    Why? Simply put, we mature and (hopefully!) get more emotionally stable as we go.

    However, two things can throw a wrench into the works:

    1. Long-term rivalries or jealousies (e.g., “who has done better in life”)
    2. Perceptions of unequal contribution to the family

    These can take various forms, but for example if one sibling earns (or otherwise has) much more or much less than another, that can cause resentment on either or both sides:

    • Resentment from the side of the sibling with less money: “I’d look after them if our situations were reversed; they can solve my problems easily; why do they resent that and/or ignore my plight?”
    • Resentment from the side of the sibling with more money: “I shouldn’t be having to look after my sibling at this age”

    It’s ugly and unpleasant. Same goes if the general job of caring for an elderly parent (or parents) falls mostly or entirely on one sibling. This can happen because of being geographically closer or having more time (well… having had more time. Now they don’t, it’s being used for care!).

    It can also happen because of being female—daughters are more commonly expected to provide familial support than sons.

    And of course, that only gets exacerbated as end-of-life decisions become relevant with regard to parents, and tough decisions may need to be made. And, that’s before looking at conflicts around inheritance.

    So, all that seems quite bleak, but it doesn’t have to be like that.

    Practical advice

    As siblings age, working on communication about feelings is key to keeping siblings close and not devolving into conflict.

    Those problems we talked about are far from unique to any set of siblings—they’re just more visible when it’s our own family, that’s all.

    So: nothing to be ashamed of, or feel bad about. Just, something to manage—together.

    Figure out what everyone involved wants/needs, put them all on the table, and figure out how to:

    • Make sure outright needs are met first
    • Try to address wants next, where possible

    Remember, that if you feel more is being asked of you than you can give (in terms of time, energy, money, whatever), then this discussion is a time to bring that up, and ask for support, e.g.:

    “In order to be able to do that, I would need… [description of support]; can you help with that?”

    (it might even sometimes be necessary to simply say “No, I can’t do that. Let’s look to see how else we can deal with this” and look for other solutions, brainstorming together)

    Some back-and-forth open discussion and even negotiation might be necessary, but it’s so much better than seething quietly from a distance.

    The goal here is an outcome where everyone’s needs are met—thus leveraging the biggest strength of having siblings in the first place:

    Mutual support, while still being one’s own person. Or, as this writer’s psychology professor friend put it:

    ❝Circling back to your original intention, this whole discussion adds up to: siblings can be very good or very bad for your life, depending on tons of things that we talked about, especially communication skills, emotional wellness of each person, and the complexity of challenges they face interdependently.❞

    Our previous main feature about good communication can help a lot:

    Save Time With Better Communication

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