The Vagus Nerve’s Power for Weight Loss

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Dr. Arun Dhir is a university lecturer, a gastrointestinal surgeon, an author, and a yoga and meditation instructor, and he has this to say:

Gut feelings

The vagus nerve is the 10th cranial nerve, also known as “vagus” (“the wanderer”), because it travels from the brain to many other body parts, including the ears, throat, heart, respiratory system, gut, pancreas, liver, and reproductive system. It’s no surprise then, that it plays a key role in brain-gut communication and metabolism regulation.

The vagus nerve is part of the parasympathetic nervous system, responsible for rest, digestion, and counteracting the stress response. Most signals through the vagus nerve travel from the gut to the brain, though there is communication in both directions.

You may be beginning to see how this works and its implications for weight management: the vagus nerve senses metabolites from the liver, pancreas, and small intestine, and regulates insulin production by stimulating beta cells in the pancreas, which is important for avoiding/managing insulin resistance and metabolic syndrome in general.

Dr. Dhir cites a study in which vagus nerve stimulation (originally used for treating epilepsy and depression) was shown to cause unintentional weight loss (6-11%) in patients, revealing a link to weight management. Of course, that is quite a specific sample, so more research is needed to say for sure, but because the principle is very sound and the mechanism of action is clear, it’s not being viewed as a controversial conclusion.

As for how get these benefits, here are seven ways:

  1. Cold water on the face: submerge your face in cold water in the morning while holding water in your mouth, or cover your face with a cold wet washcloth (while holding your breath please; no need to waterboard yourself!), which activates the “mammalian dive response” in which your body activates the parasympathetic nervous system in order to remain calm and thus survive for longer underwater
  2. Alternate hot and cold showers: switch between hot and cold water during showers for 10-second intervals; this creates eustress and activates the process of hormesis, improving your overall stress management and reducing any chronic stress response you may otherwise have going on
  3. Humming and gargling: the vibrations in the throat stimulate the nearby vagus nerve
  4. Deep breathing (pranayama): yoga breathing exercises, especially combined with somatic exercises such as the sun salutation, can stimulate the vagus nerve
  5. Intermittent fasting: helps recalibrate the metabolism and indirectly improves vagus nerve function
  6. Massage and acupressure: stimulates lymphatic channels and the vagus nerve
  7. Long walks in nature (“forest bathing”): helps trigger relaxation in general

For more on all of this, enjoy:

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You might also like to read:

The Vagus Nerve (And How You Can Make Use Of It)

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  • The Powerful Constraints on Medical Care in Catholic Hospitals Across America

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    Nurse midwife Beverly Maldonado recalls a pregnant woman arriving at Ascension Saint Agnes Hospital in Maryland after her water broke. It was weeks before the baby would have any chance of survival, and the patient’s wishes were clear, she recalled: “Why am I staying pregnant then? What’s the point?” the patient pleaded.

    But the doctors couldn’t intervene, she said. The fetus still had a heartbeat and it was a Catholic hospital, subject to the “Ethical and Religious Directives for Catholic Health Care Services” that prohibit or limit procedures like abortion that the church deems “immoral” or “intrinsically evil,” according to its interpretation of the Bible.

    “I remember asking the doctors. And they were like, ‘Well, the baby still has a heartbeat. We can’t do anything,’” said Maldonado, now working as a nurse midwife in California, who asked them: “What do you mean we can’t do anything? This baby’s not going to survive.”

    The woman was hospitalized for days before going into labor, Maldonado said, and the baby died.

    Ascension declined to comment for this article.

    The Catholic Church’s directives are often at odds with accepted medical standards, especially in areas of reproductive health, according to physicians and other medical practitioners.

    The American College of Obstetricians and Gynecologists’ clinical guidelines for managing pre-labor rupture of membranes, in which a patient’s water breaks before labor begins, state that women should be offered options, including ending the pregnancy.

    Maldonado felt her patient made her wishes clear.

    “Under the ideal medical practice, that patient should be helped to obtain an appropriate method of terminating the pregnancy,” said Christian Pettker, a professor of obstetrics, gynecology, and reproductive sciences at the Yale School of Medicine, who helped author the guidelines.

    He said, “It would be perfectly medically appropriate to do a termination of pregnancy before the cessation of cardiac activity, to avoid the health risks to the pregnant person.”

    “Patients are being turned away from necessary care,” said Jennifer Chin, an OB-GYN at UW Medicine in Seattle, because of the “emphasis on these ethical and religious directives.”

    They can be a powerful constraint on the care that patients receive at Catholic hospitals, whether emergency treatment when a woman’s health is at risk, or access to birth control and abortions.

    More and more women are running into barriers to obtaining care as Catholic health systems have aggressively acquired secular hospitals in much of the country. Four of the 10 largest U.S. hospital chains by number of beds are Catholic, according to federal data from the Agency for Healthcare Research and Quality. There are just over 600 Catholic general hospitals nationally and roughly 100 more managed by Catholic chains that place some religious limits on care, a KFF Health News investigation reveals.

    Maldonado’s experience in Maryland came just months before the Supreme Court’s ruling in 2022 to overturn Roe v. Wade, a decision that compounded the impact of Catholic health care restrictions. In its wake, roughly a third of states have banned or severely limited access to abortion, creating a one-two punch for women seeking to prevent pregnancy or to end one. Ironically, some states where Catholic hospitals dominate — such as Washington, Oregon, and Colorado — are now considered medical havens for women in nearby states that have banned abortion.

    KFF Health News analyzed state-level birth data to discover that more than half a million babies are born each year in the U.S. in Catholic-run hospitals, including those owned by CommonSpirit Health, Ascension, Trinity Health, and Providence St. Joseph Health. That’s 16% of all hospital births each year, with rates in 10 states exceeding 30%. In Washington, half of all babies are born at such hospitals, the highest share in the country.

    “We had many instances where people would have to get in their car to drive to us while they were bleeding, or patients who had had their water bags broken for up to five days or even up to a week,” said Chin, who has treated patients turned away by Catholic hospitals.

    Physicians who turned away patients like that “were going against evidence-based care and going against what they had been taught in medical school and residency,” she said, “but felt that they had to provide a certain type of care — or lack of care — just because of the strength of the ethical and religious directives.”

    Following religious mandates can be dangerous, Chin and other clinicians said.

    When a patient has chosen to end a pregnancy after the amniotic sac — or water — has broken, Pettker said, “any delay that might be added to a procedure that is inevitably going to happen places that person at risk of serious, life-threatening complications,” including sepsis and organ infection.

    Reporters analyzed American Hospital Association data as of August and used Catholic Health Association directories, news reports, government documents, and hospital websites and other materials to determine which hospitals are Catholic or part of Catholic systems, and gathered birth data from state health departments and hospital associations. They interviewed patients, medical providers, academic experts, advocacy organizations, and attorneys, and reviewed hundreds of pages of court and government records and guidance from Catholic health institutions and authorities to understand how the directives affect patient care.

    Nationally, nearly 800,000 people have only Catholic or Catholic-affiliated birth hospitals within an hour’s drive, according to KFF Health News’ analysis. For example, that’s true of 1 in 10 North Dakotans. In South Dakota, it’s 1 in 20. When care is more than an hour away, academic researchers often define the area as a hospital desert. Pregnant women who must drive farther to a delivery facility are at higher risk of harm to themselves or their fetus, research shows.

    Many Americans don’t have a choice — non-Catholic hospitals are too far to reach in an emergency or aren’t in their insurance networks. Ambulances may take patients to a Catholic facility without giving them a say. Women often don’t know that hospitals are affiliated with the Catholic Church or that they restrict reproductive care, academic research suggests.

    And, in most of the country, state laws shield at least some hospitals from lawsuits for not performing procedures they object to on religious grounds, leaving little recourse for patients who were harmed because care was withheld. Thirty-five states prevent patients from suing hospitals for not providing abortions, including 25 states where abortion remains broadly legal. About half of those laws don’t include exceptions for emergencies, ectopic pregnancies, or miscarriages. Sixteen states prohibit lawsuits against hospitals for refusing to perform sterilization procedures.

    “It’s hard for the ordinary citizen to understand, ‘Well, what difference does it make if my hospital is bought by this other big health system, as long as it stays open? That’s all I care about,’” said Erin Fuse Brown, who is the director of the Center for Law, Health & Society at Georgia State University and an expert in health care consolidation. Catholic directives also ban medical aid in dying for terminally ill patients.

    People “may not realize that they’re losing access to important services, like reproductive health [and] end-of-life care,” she said.

    ‘Our Faith-Based Health Care Ministry’

    After the Supreme Court ended the constitutional right to abortion in June 2022, Michigan resident Kalaina Sullivan wanted surgery to permanently prevent pregnancy.

    Michigan voters in November that year enshrined the right to abortion under the state constitution, but the state’s concentration of Catholic hospitals means people like Sullivan sometimes still struggle to obtain reproductive health care.

    Because her doctor worked for the Catholic chain Trinity Health, the nation’s fourth-largest hospital system, she had the surgery with a different doctor at North Ottawa Community Health System, an independent hospital near the shores of Lake Michigan.

    Less than two months later, that, too, became a Catholic hospital, newly acquired by Trinity.

    To mark the transition, Cory Mitchell, who at the time was the mission leader of Trinity Health Muskegon, stood before his new colleagues and offered a blessing.

    “The work of your hands is what makes our faith-based health care ministry possible,” he said, according to a video of the ceremony Trinity Health provided to KFF Health News. “May these hands continue to bring compassion, compassion and healing, to all those they touch.”

    Trinity Health declined to answer detailed questions about its merger with North Ottawa Community Health System and the ethical and religious directives. “Our commitment to high-quality, compassionate care means informing our patients of all appropriate care options, and trusting and supporting our physicians to make difficult and medically necessary decisions in the best interest of their patients’ health and safety,” spokesperson Jennifer Amundson said in an emailed statement. “High-quality, safe care is critical for the women in our communities and in cases where a non-critical service is not available at our facility, the physician will transfer care as appropriate.”

    Leaders in Catholic-based health systems have hammered home the importance of the church’s directives, which are issued by the U.S. Conference of Catholic Bishops, all men, and were first drafted in 1948. The essential view on abortion is as it was in 1948. The last revision, in 2018, added several directives addressing Catholic health institution acquisitions or mergers with non-Catholic ones, including that “whatever comes under control of the Catholic institution — whether by acquisition, governance, or management — must be operated in full accord with the moral teaching of the Catholic Church.”

    “While many of the faithful in the local church may not be aware of these requirements for Catholic health care, the local bishop certainly is,” wrote Sister Doris Gottemoeller, a former board member of the Bon Secours Mercy Health system, in a 2023 Catholic Health Association journal article. “In fact, the bishop should be briefed on a regular basis about the hospital’s activities and strategies.”

    Now, for care at a non-Catholic hospital, Sullivan would need to travel nearly 30 miles.

    “I don’t see why there’s any reason for me to have to follow the rules of their religion and have that be a part of what’s going on with my body,” she said.

    Risks Come With Religion

    Nathaniel Hibner, senior director of ethics at the Catholic Health Association, said the ethical and religious directives allow clinicians to provide medically necessary treatments in emergencies. In a pregnancy crisis when a person’s life is at risk, “I do not believe that the ERDs should restrict the physician in acting in the way that they see medically indicated.”

    “Catholic health care is committed to the health of all women and mothers who enter into our facilities,” Hibner said.

    The directives permit care to cure “a proportionately serious pathological condition of a pregnant woman” even if it would “result in the death of the unborn child.” Hibner demurred when asked who defines what that means and when such care is provided, saying, “for the most part, the physician and the patients are the ones that are having a conversation and dialogue with what is supposed to be medically appropriate.”

    It is common for practitioners at any hospital to consult an ethics board about difficult cases — such as whether a teenager with cancer can decline treatment. At Catholic hospitals, providers must ask a board for permission to perform procedures restricted by the religious directives, clinicians and researchers say. For example, could an abortion be performed if a pregnancy threatened the mother’s life?

    How and when an ethics consultation occurs depends on the hospital, Hibner said. “That ethics consultation can be initiated by anyone involved in the direct care of that situation — the patient, the surrogate of that patient, the physician, the nurse, the social worker all have the ability to request a consultation,” he said. When asked whether a consultation with an ethics board can occur without a request, he said “sometimes it could.”

    How strictly directives are followed can depend on the hospital and the views of the local bishop.

    “If the hospital has made a difficult decision about a critical pregnancy or an end-of-life care situation, the bishop should be the first to know about it,” Gottemoeller wrote.

    In an interview, Gottemoeller said that even when pregnancy termination decisions are made on sound ethical grounds, not informing the bishop puts him in a bad position and hurts the church. “If there’s a possibility of it being misunderstood, or misinterpreted, or criticized,” Gottemoeller said, the bishop should understand what happened and why “before the newspapers call him and ask him for an opinion.”

    “And if he has to say, ‘Well, I think you made a mistake,’ well, all right,” she said. “But don’t let him be blindsided. I mean, we’re one church and the bishop has pastoral concern over everything in his diocese.”

    Katherine Parker Bryden, a nurse midwife in Iowa who works for MercyOne, said she regularly tells pregnant patients that the hospital cannot perform tubal sterilization surgery, to prevent future pregnancies, or refer patients to other hospitals that do. MercyOne is one of the largest health systems in Iowa. Nearly half of general hospitals in the state are Catholic or Catholic-affiliated — the highest share among all states.

    The National Catholic Bioethics Center, an ethics authority for Catholic health institutions, has said that referrals for care that go against church teaching would be “immoral.”

    “As providers, you’re put in this kind of moral dilemma,” Parker Bryden said. “Am I serving my patients or am I serving the archbishop and the pope?”

    In response to questions, MercyOne spokesperson Eve Lederhouse said in an email that its providers “offer care and services that are consistent with the guidelines of a Catholic health system.”

    Maria Rodriguez, an OB-GYN professor at Oregon Health & Science University, said that as a resident in the early 2000s at a Catholic hospital she was able to secure permission — what she calls a “pope note” — to sterilize some patients with conditions such as gestational diabetes.

    Annie Iriye, a retired OB-GYN in Washington state, said that more than a decade ago she sought permission to administer medication to hasten labor for a patient experiencing a second-trimester miscarriage at a Catholic hospital. She said she was told no because the fetus had a heartbeat. The patient took 10 hours to deliver — time that would have been cut by half, Iriye said, had she been able to follow her own medical training and expertise. During that time, she said, the patient developed an infection.

    Iriye and Chin were part of an effort by reproductive rights groups and medical organizations that pushed for a state law to protect physicians if they act against Catholic hospital restrictions. The bill, which Washington enacted in 2021, was opposed by the Washington State Hospital Association, whose membership includes multiple large Catholic health systems.

    State lawmakers in Oregon in 2021 enacted legislation that beefed up powers to reject health care mergers if they would reduce access to the types of care constrained by Catholic directives. The hospital lobby has sued to block the statute. Washington state lawmakers introduced similar legislation last year, which the hospital association opposes.

    Hibner said Catholic hospitals are committed to instituting systemic changes that improve maternal and child health, including access to primary, prenatal, and postpartum care. “Those are the things that I think rural communities really need support and advocacy for,” he said.

    Maldonado, the nurse midwife, still thinks of her patient who was forced to stay pregnant with a baby who could not survive. “To feel like she was going to have to fight to have an abortion of a baby that she wanted?” Maldonado said. “It was just horrible.”

    KFF Health News data editor Holly K. Hacker contributed to this report.

    Click to open the methodology Methodology

    By Hannah Recht

    KFF Health News identified areas of the country where patients have only Catholic hospital options nearby. The “Ethical and Religious Directives for Catholic Health Care Services” — which are issued by the U.S. Conference of Catholic Bishops, all men — dictate how patients receive reproductive care at Catholic health facilities. In our analysis, we focused on hospitals where babies are born.

    We constructed a national database of hospital locations, identified which ones are Catholic or Catholic-affiliated, found how many babies are born at each, and calculated how many people live near those hospitals.

    Hospital Universe

    We identified hospitals in the 50 states and the District of Columbia using the American Hospital Association database from August 2023. We removed hospitals that had closed or were listed more than once, added hospitals that were not included, and corrected inaccurate or out-of-date information about ownership, primary service type, and location. We excluded federal hospitals, such as military and Indian Health Service facilities, because they are not open to everyone.

    Catholic Affiliation

    To identify Catholic hospitals, we used the Catholic Health Association’s member directory. We also counted as Catholic a handful of hospitals that are not part of this voluntary membership group but explicitly follow the Ethical and Religious Directives, according to their mission statements, websites, or promotional materials.

    We also tracked Catholic-affiliated hospitals: those that are owned or managed by a Catholic health system, such as CommonSpirit Health or Trinity Health, and are influenced by the religious directives but do not necessarily adhere to them in full. To identify Catholic-affiliated hospitals, we consulted health system and hospital websites, government documents, and news reports.

    We combined both Catholic and Catholic-affiliated hospitals for analysis, in line with previous research about the influence of Catholic directives on health care.

    Births

    To determine the share of births that occur at Catholic or Catholic-affiliated hospitals, we gathered the latest annual number of births by hospital from state health departments. Where recent data was not publicly available, we submitted records requests for the most recent complete year available.

    The resulting data covered births in 2022 for nine states and D.C., births in 2021 for 23 states, births in 2020 for nine states, and births in 2019 for one state. We used data from the 2021 American Hospital Association survey, the latest available at the time of analysis, for the eight remaining states that did not provide birth data in response to our requests. A small number of hospitals have recently opened or closed labor and delivery units. The vast majority of the rest record about the same number of births each year. This means that the results would not be substantially different if data from 2023 were available.

    We used this data to calculate the number of babies born in Catholic and Catholic-affiliated hospitals, as well as non-Catholic hospitals by state and nationally.

    We used hospitals’ Catholic status as of August 2023 in this analysis. In 10 cases where the hospital had already closed, we used Catholic status at the time of the closure.

    Because our analysis focuses on hospital care, we excluded births that occurred in non-hospital settings, such as homes and stand-alone birth centers, as well as federal hospitals.

    Several states suppressed data from hospitals with fewer than 10 births due to privacy restrictions. Because those numbers were so low, this suppression had a negligible effect on state-level totals.

    Drive-Time Analysis

    We obtained hospitals’ geographic coordinates based on addresses in the AHA dataset using HERE’s geocoder. For addresses that could not be automatically geocoded with a high degree of certainty, we verified coordinates manually using hospital websites and Google Maps.

    We calculated the areas within 30, 60, and 90 minutes of travel time from each birth hospital that was open in August 2023 using tools from HERE. We included only hospitals that had 10 or more births as a proxy for hospitals that have labor and delivery units, or where births regularly occur.

    The analysis focused on the areas with hospitals within an hour’s drive. Researchers often define hospital deserts as places where one would have to drive an hour or more for hospital care. (For example: [1] “Disparities in Access to Trauma Care in the United States: A Population-Based Analysis,” [2] “Injury-Based Geographic Access to Trauma Centers,” [3] “Trends in the Geospatial Distribution of Inpatient Adult Surgical Services Across the United States,” [4] “Access to Trauma Centers in the United States.”)

    We combined the drive-time areas to see which areas of the United States have only Catholic or Catholic-affiliated birth hospitals nearby, both Catholic and non-Catholic, non-Catholic only, or none. We then joined these areas to the 2021 census block group shapefile from IPUMS NHGIS and removed water bodies using the U.S. Geological Survey’s National Hydrography Dataset to calculate the percentage of each census block group that falls within each hospital access category. We calculated the number of people in each area using the 2021 “American Community Survey” block group population totals. For example, if half of a block group’s land area had access to only Catholic or Catholic-affiliated hospitals, then half of the population was counted in that category.

    KFF Health News is a national newsroom that produces in-depth journalism about health issues and is one of the core operating programs at KFF—an independent source of health policy research, polling, and journalism. Learn more about KFF.

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  • The Intelligence Trap – by David Robson

    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.

    We’re including this one under the umbrella of “general wellness”, because it happens that a lot of very intelligent people make stunningly unfortunate choices sometimes, for reasons that may baffle others.

    The author outlines for us the various reasons that this happens, and how. From the famous trope of “specialized intelligence in one area”, to the tendency of people who are better at acquiring knowledge and understanding to also be better at acquiring biases along the way, to the hubris of “I am intelligent and therefore right as a matter of principle” thinking, and many other reasons.

    Perhaps the greatest value of the book is the focus on how we can avoid these traps, narrow our bias blind spots, and play to our strengths while paying full attention to our weaknesses.

    The style is very readable, despite having a lot of complex ideas discussed along the way. This is entirely to be expected of this author, an award-winning science writer.

    Bottom line: if you’d like to better understand the array of traps that disproportionately catch out the most intelligent people (and how to spot such), then this is a great book for you.

    Click here to check out The Intelligence Trap, and be more wary!

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  • It Didn’t Start with You – by Mark Wolynn

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    There is a trend in psychology to “blame the parents” for “childhood trauma” that can result in problems later in life. Sometimes fairly, sometimes not. This book’s mostly not about that.

    It does touch on our own childhood trauma, if applicable. But mostly, it’s about epigenetic trauma inheritance. In other words, not just trauma that’s passed on in terms of “the cycle of abuse”, but trauma that’s passed on in terms of “this generation experienced trauma x, developed trauma response y, encoded it epigenetically, and passed it on to their offspring”.

    So, how does one heal from a trauma one never directly experienced, and just inherited the response to it? That’s what most of this book is about, after establishing how epigenetic trauma inheritance works.

    The author, a therapist, provides practical advice for how to do the things that can be done to rewrite the epigenetic code we inherited. Better late than never!

    Bottom line: it is well-established that trauma is inheritable. But unlike one’s eye color or the ability to smell asparagus metabolites in urine, we can rewrite epigenetic things, to a degree. This book explains how.

    Click here to check out It Didn’t Start With You, and put things to rest!

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  • It’s Not Hysteria – by Dr. Karen Tan

    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.

    Firstly, who this book is aimed at: in case it wasn’t clear, this book assumes you have, or at least have had, a uterus. If that’s not you, then well, it’ll still be an interesting read but it won’t be about your reproductive health.

    Secondly, about that “reproductive health”: it’s mostly not actually about reproductive health literally, but rather, the health of one’s reproductive organs and the things that they affect—which is a lot more than the ability to reproduce!

    Dr. Tang takes us on a (respectably in-depth) tour of the relevant anatomy, before moving on to physiology, before continuing to pathology (i.e. things that can go wrong, and often do), and finally various treatment options, including elective procedures, and the pros and cons thereof.

    She also talks the reader through talking about things with gynecologists and other healthcare providers, and making sure concerns are not dismissed out-of-hand (something that happens a lot, of course).

    The style throughout is quite detailed prose, but without being difficult at all to read, and (assuming one is interested in the topic) it’s very engaging.

    Bottom line: if you would like to know more about uteri and everything that is (or commonly/unfortunately) can be attached to them, the effects they have on the rest of the body and health, and what can be done about things not being quite right, then this is a good book for that.

    Click here to check out It’s Not Hysteria, and understand more of what’s going on down there!

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  • Microplastics are in our brains. How worried should I be?

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    Plastic is in our clothes, cars, mobile phones, water bottles and food containers. But recent research adds to growing concerns about the impact of tiny plastic fragments on our health.

    A study from the United States has, for the first time, found microplastics in human brains. The study, which has yet to be independently verified by other scientists, has been described in the media as scary, shocking and alarming.

    But what exactly are microplastics? What do they mean for our health? Should we be concerned?

    Daniel Megias/Shutterstock

    What are microplastics? Can you see them?

    We often consider plastic items to be indestructible. But plastic breaks down into smaller particles. Definitions vary but generally microplastics are smaller than five millimetres.

    This makes some too small to be seen with the naked eye. So, many of the images the media uses to illustrate articles about microplastics are misleading, as some show much larger, clearly visible pieces.

    Microplastics have been reported in many sources of drinking water and everyday food items. This means we are constantly exposed to them in our diet.

    Such widespread, chronic (long-term) exposure makes this a serious concern for human health. While research investigating the potential risk microplastics pose to our health is limited, it is growing.

    How about this latest study?

    The study looked at concentrations of microplastics in 51 samples from men and women set aside from routine autopsies in Albuquerque, New Mexico. Samples were from the liver, kidney and brain.

    These tiny particles are difficult to study due to their size, even with a high-powered microscope. So rather than trying to see them, researchers are beginning to use complex instruments that identify the chemical composition of microplastics in a sample. This is the technique used in this study.

    The researchers were surprised to find up to 30 times more microplastics in brain samples than in the liver and kidney.

    They hypothesised this could be due to high blood flow to the brain (carrying plastic particles with it). Alternatively, the liver and kidneys might be better suited to dealing with external toxins and particles. We also know the brain does not undergo the same amount of cellular renewal as other organs in the body, which could make the plastics linger here.

    The researchers also found the amount of plastics in brain samples increased by about 50% between 2016 and 2024. This may reflect the rise in environmental plastic pollution and increased human exposure.

    The microplastics found in this study were mostly composed of polyethylene. This is the most commonly produced plastic in the world and is used for many everyday products, such as bottle caps and plastic bags.

    This is the first time microplastics have been found in human brains, which is important. However, this study is a “pre-print”, so other independent microplastics researchers haven’t yet reviewed or validated the study.

    Plastic bag and plastic bottle left on beach
    The most common plastic found was polyethylene, which is used to make plastic bags and bottle caps. Maciej Bledowski/Shutterstock

    How do microplastics end up in the brain?

    Microplastics typically enter the body through contaminated food and water. This can disrupt the gut microbiome (the community of microbes in your gut) and cause inflammation. This leads to effects in the whole body via the immune system and the complex, two-way communication system between the gut and the brain. This so-called gut-brain axis is implicated in many aspects of health and disease.

    We can also breathe in airborne microplastics. Once these particles are in the gut or lungs, they can move into the bloodstream and then travel around the body into various organs.

    Studies have found microplastics in human faeces, joints, livers, reproductive organs, blood, vessels and hearts.

    Microplastics also migrate to the brains of wild fish. In mouse studies, ingested microplastics are absorbed from the gut into the blood and can enter the brain, becoming lodged in other organs along the way.

    To get into brain tissue, microplastics must cross the blood-brain-barrier, an intricate layer of cells that is supposed to keep things in the blood from entering the brain.

    Although concerning, this is not surprising, as microplastics must cross similar cell barriers to enter the urine, testes and placenta, where they have already been found in humans.

    Is this a health concern?

    We don’t yet know the effects of microplastics in the human brain. Some laboratory experiments suggest microplastics increase brain inflammation and cell damage, alter gene expression and change brain structure.

    Aside from the effects of the microplastic particles themselves, microplastics might also pose risks if they carry environmental toxins or bacteria into and around the body.

    Various plastic chemicals could also leach out of the microplastics into the body. These include the famous hormone-disrupting chemicals known as BPAs.

    But microplastics and their effects are difficult to study. In addition to their small size, there are so many different types of plastics in the environment. More than 13,000 different chemicals have been identified in plastic products, with more being developed every year.

    Microplastics are also weathered by the environment and digestive processes, and this is hard to reproduce in the lab.

    A goal of our research is to understand how these factors change the way microplastics behave in the body. We plan to investigate if improving the integrity of the gut barrier through diet or probiotics can prevent the uptake of microplastics from the gut into the bloodstream. This may effectively stop the particles from circulating around the body and lodging into organs.

    How do I minimise my exposure?

    Microplastics are widespread in the environment, and it’s difficult to avoid exposure. We are just beginning to understand how microplastics can affect our health.

    Until we have more scientific evidence, the best thing we can do is reduce our exposure to plastics where we can and produce less plastic waste, so less ends up in the environment.

    An easy place to start is to avoid foods and drinks packaged in single-use plastic or reheated in plastic containers. We can also minimise exposure to synthetic fibres in our home and clothing.

    Sarah Hellewell, Senior Research Fellow, The Perron Institute for Neurological and Translational Science, and Research Fellow, Faculty of Health Sciences, Curtin University; Anastazja Gorecki, Teaching & Research Scholar, School of Health Sciences, University of Notre Dame Australia, and Charlotte Sofield, PhD Candidate, studying microplastics and gut/brain health, University of Notre Dame Australia

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

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  • Does intermittent fasting have benefits for our brain?

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    Intermittent fasting has become a popular dietary approach to help people lose or manage their weight. It has also been promoted as a way to reset metabolism, control chronic disease, slow ageing and improve overall health.

    Meanwhile, some research suggests intermittent fasting may offer a different way for the brain to access energy and provide protection against neurodegenerative diseases like Alzheimer’s disease.

    This is not a new idea – the ancient Greeks believed fasting enhanced thinking. But what does the modern-day evidence say?

    First, what is intermittent fasting?

    Our diets – including calories consumed, macronutrient composition (the ratios of fats, protein and carbohydrates we eat) and when meals are consumed – are factors in our lifestyle we can change. People do this for cultural reasons, desired weight loss or potential health gains.

    Intermittent fasting consists of short periods of calorie (energy) restriction where food intake is limited for 12 to 48 hours (usually 12 to 16 hours per day), followed by periods of normal food intake. The intermittent component means a re-occurrence of the pattern rather than a “one off” fast.

    Food deprivation beyond 24 hours typically constitutes starvation. This is distinct from fasting due to its specific and potentially harmful biochemical alterations and nutrient deficiencies if continued for long periods.

    4 ways fasting works and how it might affect the brain

    The brain accounts for about 20% of the body’s energy consumption.

    Here are four ways intermittent fasting can act on the body which could help explain its potential effects on the brain.

    1. Ketosis

    The goal of many intermittent fasting routines is to flip a “metabolic switch” to go from burning predominately carbohydrates to burning fat. This is called ketosis and typically occurs after 12–16 hours of fasting, when liver and glycogen stores are depleted. Ketones – chemicals produced by this metabolic process – become the preferred energy source for the brain.

    Due to this being a slower metabolic process to produce energy and potential for lowering blood sugar levels, ketosis can cause symptoms of hunger, fatigue, nausea, low mood, irritability, constipation, headaches, and brain “fog”.

    At the same time, as glucose metabolism in the brain declines with ageing, studies have shown ketones could provide an alternative energy source to preserve brain function and prevent age-related neurodegeneration disorders and cognitive decline.

    Consistent with this, increasing ketones through supplementation or diet has been shown to improve cognition in adults with mild cognitive decline and those at risk of Alzheimer’s disease respectively.

    2. Circadian syncing

    Eating at times that don’t match our body’s natural daily rhythms can disrupt how our organs work. Studies in shift workers have suggested this might also make us more prone to chronic disease.

    Time-restricted eating is when you eat your meals within a six to ten-hour window during the day when you’re most active. Time-restricted eating causes changes in expression of genes in tissue and helps the body during rest and activity.

    A 2021 study of 883 adults in Italy indicated those who restricted their food intake to ten hours a day were less likely to have cognitive impairment compared to those eating without time restrictions.

    older man playing chess
    Matching your eating to the active parts of your day may have brain benefits.
    Shutterstock

    3. Mitochondria

    Intermittent fasting may provide brain protection through improving mitochondrial function, metabolism and reducing oxidants.

    Mitochondria’s main role is to produce energy and they are crucial to brain health. Many age-related diseases are closely related to an energy supply and demand imbalance, likely attributed to mitochondrial dysfunction during ageing.

    Rodent studies suggest alternate day fasting or reducing calories by up to 40% might protect or improve brain mitochondrial function. But not all studies support this theory.

    4. The gut-brain axis

    The gut and the brain communicate with each other via the body’s nervous systems. The brain can influence how the gut feels (think about how you get “butterflies” in your tummy when nervous) and the gut can affect mood, cognition and mental health.

    In mice, intermittent fasting has shown promise for improving brain health by increasing survival and formation of neurons (nerve cells) in the hippocampus brain region, which is involved in memory, learning and emotion.

    medical clinician shows woman a sheet of brain scans
    What we eat can affect our brain, and vice versa.
    Shutterstock

    There’s no clear evidence on the effects of intermittent fasting on cognition in healthy adults. However one 2022 study interviewed 411 older adults and found lower meal frequency (less than three meals a day) was associated with reduced evidence of Alzheimer’s disease on brain imaging.

    Some research has suggested calorie restriction may have a protective effect against Alzheimer’s disease by reducing oxidative stress and inflammation and promoting vascular health.

    When we look at the effects of overall energy restriction (rather than intermittent fasting specifically) the evidence is mixed. Among people with mild cognitive impairment, one study showed cognitive improvement when participants followed a calorie restricted diet for 12 months.

    Another study found a 25% calorie restriction was associated with slightly improved working memory in healthy adults. But a recent study, which looked at the impact of calorie restriction on spatial working memory, found no significant effect.

    Bottom line

    Studies in mice support a role for intermittent fasting in improving brain health and ageing, but few studies in humans exist, and the evidence we have is mixed.

    Rapid weight loss associated with calorie restriction and intermittent fasting can lead to nutrient deficiencies, muscle loss, and decreased immune function, particularly in older adults whose nutritional needs may be higher.

    Further, prolonged fasting or severe calorie restriction may pose risks such as fatigue, dizziness, and electrolyte imbalances, which could exacerbate existing health conditions.

    If you’re considering intermittent fasting, it’s best to seek advice from a health professional such as a dietitian who can provide guidance on structuring fasting periods, meal timing, and nutrient intake. This ensures intermittent fasting is approached in a safe, sustainable way, tailored to individual needs and goals.The Conversation

    Hayley O’Neill, Assistant Professor, Faculty of Health Sciences and Medicine, Bond University

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

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