Is thirst a good predictor of dehydration?

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Water is essential for daily functioning and health, and we can only survive a few days without it. Yet we constantly lose water through sweat, urination and even evaporation when we breathe.

This is why we have evolved a way to regulate and maintain water in our bodies. Like other animals, our survival relies on a strong biological drive that tells us to find and drink water to balance fluid loss.

This is thirst – a sensation of dryness in the mouth signalling we need to have a drink. This basic physiological mechanism is controlled mainly by part of the brain’s “control centre”, called the hypothalamus. The hypothalamus receives signals from various regions of the body and in return, releases hormones that act as a messenger to signal the thirst sensation.

KieferPix/Shutterstock

What is dehydration?

Staying hydrated (having enough water in our bodies) is important for several reasons, including:

  • regulating body temperature through sweat and respiration
  • lubricating joints and eyes
  • preventing infections
  • digesting and absorbing nutrients
  • flushing out waste (via the kidneys)
  • preventing constipation
  • brain function (including memory and concentration)
  • mood and energy levels
  • physical performance and recovery from exercise
  • skin health.

Dehydration occurs when our body doesn’t have enough water. Even slight drops in fluid levels have noticeable consequences, such as headaches, feeling dizzy, lethargy and struggling to concentrate.

Chronic dehydration can pose more serious health risks, including urinary tract infections, constipation and kidney stones.

What does the evidence say?

Despite thirst being one of the most basic biological drivers for good hydration, science suggests our feelings of thirst and subsequent fluid intake don’t always correlate with hydration levels.

For example, a recent study explored the impact of thirst on fluid intake and hydration status. Participants attended a lab in the morning and then later in the afternoon to provide markers of hydration status (such as urine, blood samples and body weight). The relationship between levels of thirst in the morning and afternoon hydration status was negligible.

Further, thirst may be driven by environmental factors, such as access to water. For example, one study looked at whether ample access to water in a lab influenced how much people drank and how hydrated they were. The link between how thirsty they felt and how hydrated they were was weak, suggesting the availability of water influenced their fluid intake more than thirst.

Exercise can also change our thirst mechanism, though studies are limited at this stage.

A man standing in a kitchen drinking a glass of water.
Being thirsty doesn’t necessarily mean we’re dehydrated. puhhha/Shutterstock

Interestingly, research shows women experience thirst more strongly than men, regardless of hydration status. To understand gender differences in thirst, researchers infused men and women with fluids and then measured their thirst and how hydrated they were. They found women generally reported thirst at a lower level of fluid loss. Women have also been found to respond more to feeling thirsty by drinking more water.

Other ways to tell if you need to drink some water

While acknowledging some people will need to drink more or less, for many people, eight cups (or two litres) a day is a good amount of water to aim for.

But beyond thirst, there are many other ways to tell whether you might need to drink more water.

1. urine colour: pale yellow urine typically indicates good hydration, while darker, concentrated urine suggests dehydration

2. frequency of going to the toilet: urinating regularly (around four to six times a day) indicates good hydration. Infrequent urination can signal dehydration

3. skin turgor test: gently pinching the skin (for example, on the back of the hand) and observing how quickly the skin returns to its normal position can help assess hydration. Slow return may indicate dehydration

A woman's index finger and thumb pinch the skin on the back of her other hand.
If skin stays elevated after pinching it may be a sign of dehydration. SusaZoom/Shutterstock

4. mouth and lips: a dry mouth or cracked lips can be early signs of dehydration

5. headaches and fatigue: frequent headaches, dizziness, or unexplained fatigue can be signs of inadequate hydration

6. sweating: in physically active people, monitoring how much they sweat during activity can help estimate fluid loss and hydration needs. Higher levels of sweat may predispose a person to dehydration if they are unable to replace the fluid lost through water intake

These indicators, used together, provide a more comprehensive picture of hydration without solely depending on the sensation of thirst.

Of course, if you do feel thirsty, it’s still a good idea to drink some water.

Lauren Ball, Professor of Community Health and Wellbeing, The University of Queensland and Kiara Too, PhD candidate, School of Human Movement and Nutrition Sciences, The University of Queensland

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

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  • Insomnia? High blood pressure? Try these!

    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.

    Your Questions, Our Answers!

    Q: Recipes for insomnia and high blood pressure and good foods to eat for these conditions?

    A: Insomnia can be caused by many things, and consequently can often require a very multi-vector approach to fixing it. But, we’ll start by answering the question you asked (and probably address the rest of dealing with insomnia in another day’s edition!):

    • First, you want food that’s easy to digest. Broadly speaking, this means plant-based. If not plant-based, fish (unless you have an allergy, obviously) is generally good and certainly better than white meat, which is better than red meat. In the category of dairy, it depends so much on what it is, that we’re not going to try to break it down here. If in doubt, skip it.
    • You also don’t want blood sugar spikes, so it’s good to lay off the added sugar and white flour (or white flour derivatives, like white pasta), especially in your last meal of the day.
    • Magnesium supports healthy sleep. A fine option would be our shchi recipe, but using collard greens rather than cabbage. Cabbage is a wonderful food, but collard greens are much higher in magnesium. Remember to add plenty of mushrooms (unless you don’t like them), as they’re typically high in magnesium too.

    As for blood pressure, last month we gave tips (and a book recommendation) for heart health. The book, Dr. Monique Tello’s “Healthy Habits for Your Heart: 100 Simple, Effective Ways to Lower Your Blood Pressure and Maintain Your Heart’s Health”, also has recipes!

    Here’s one from the “mains” section:

    Secret Ingredient Baltimore-Style Salmon Patties with Not-Oily Aioli

    ❝This is a family favorite, and no one knows that it features puréed pumpkin! Most salmon cake recipes all for eggs and bread crumbs as binders, but puréed pumpkin and grated carrot work just as well, lend a beautiful color, and add plenty of fiber and plant nutrients. Canned salmon is way cheaper than fresh and has just as much omega-3 PUFAs and calcium. Serve this alongside a salad (the Summer Corn, Tomato, Spinach, and Basil Salad would go perfectly) for a well-rounded meal.❞

    Serves 4 (1 large patty each)

    Secret Ingredient Baltimore-Style Salmon Patties:

    • 1 (15-oz) can pink salmon, no salt added
    • ½ cup puréed pumpkin
    • ½ cup grated carrot (I use a handheld box grater)
    • 2 tablespoons minced chives (Don’t have chives? Minced green onions or any onions will do)
    • 2 teaspoons Old Bay Seasoning
    • 1 tablespoon olive oil
    • ½ large lemon, sliced, for serving

    Not-Oily Aioli:

    • ½ cup plain low-fat Greek yogurt
    • Juice and zest from ½ large lemon
    • 1 clove garlic, crushed and minced fine
    • 2 tablespoons chopped fresh dill
    1. For the patties: mix all the ingredients for the salmon patties together in a medium bowl
    2. Form patties with your hands and set on a plate or tray (you should have 4 burger-sized patties)
    3. Heat oil in a large skillet over medium heat.
    4. Set patties in a skillet and brown for 4 minutes, then carefully flip.
    5. Brown the other side, then serve hot.
    6. For the Aioli: mix all the ingredients for the aioli together in a small bowl.
    7. Plop a dollop alongside or on top of each salmon patty and serve with a spice of lemon.

    Per serving: Calories: 367 | Fat: 13.6g | Saturated Fat: 4.4g | Protein: 46g | Sodium: 519mg | Carbohydrates: 13.2g | Fiber: 1.3g | Sugars: 9g | Calcium: 505mg | Iron: 1mg | Potassium 696mg

    Notes from the 10almond team:

    • If you want to make it plant-based, substitute cooked red lentils (no salt added) for the tinned salmon, and plant-based yogurt for the Greek yogurt
    • We recommend adding more garlic. Seriously, who uses 1 clove of garlic for anything, let alone divided between four portions?
    • The salads mentioned are given as recipes elsewhere in the same book. We strongly recommend getting her book, if you’re interested in heart health!

    Do you have a question you’d like to see answered here? Hit reply or use the feedback widget at the bottom; we’d love to hear from you!

    Share This Post

  • Try This At Home: ABI Test For Clogged Arteries

    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.

    Arterial plaque is a big deal, and statistically it’s more of a risk as we get older, often coming to a head around age 72 for women and 65 for men—these are the median ages at which people who are going to get heart attacks, get them. Or get it, because sometimes one is all it takes.

    The Ankle-Brachial Index Test

    Dr. Brewer recommends a home test for detecting arterial plaque called the Ankle-Brachial Index (ABI), which uses a blood pressure monitor. The test involves measuring blood pressure in both the arms and ankles, then calculating the ratio of these measurements:

    • A healthy ABI score is between 1.0 and 1.4; anything outside this range may indicate arterial problems.
    • Low ABI scores (below 0.8) suggest plaque is likely obstructing blood flow
    • High ABI scores (above 1.4) may indicate artery hardening

    Peripheral Artery Disease (PAD), associated with poor ABI results (be they high or low), can cause a whole lot of problems that are definitely better tackled sooner rather than later—remember that atherosclerosis is a self-worsening thing once it gets going, because narrower walls means it’s even easier for more stuff to get stuck in there (and thus, the new stuff that got stuck also becomes part of the walls, and the problem gets worse).

    If you need a blood pressure monitor, by the way, here’s an example product on Amazon.

    Do note also that yes, if you have plaque obstructing blood flow and hardened arteries, your scores may cancel out and give you a “healthy” score, despite your arteries being very much not healthy. For this reason, this test can be used to raise the alarm, but not to give the “all clear”.

    For more on all of the above, plus a demonstration and more in-depth explanation of the test, enjoy:

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

    Want to learn more?

    You might also like to read:

    Take care!

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  • Fluoride Toothpaste vs Non-Fluoride Toothpaste – Which is Healthier?

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    Our Verdict

    When comparing fluoride toothpaste to non-fluoride toothpaste, we picked the fluoride.

    Why?

    Fluoride is indeed toxic; that’s why it’s in toothpaste (to kill things; namely, bacteria whose waste products would harm our teeth). However, we are much bigger than those bacteria.

    Given the amount of fluoride in toothpaste (usually under 1mg per strip of toothpaste to cover a toothbrush head), the amount that people swallow unintentionally (about 1/20th of that, so about 0.1mg daily if brushing teeth twice daily), and the toxicity level of fluoride (32–64mg/kg), then even if we take the most dangerous ends of all those numbers (and an average body size), to suffer ill effects from fluoride due to brushing your teeth, would require that you brush your teeth more than 23,000 times per day.

    Alternatively, if you were to ravenously eat the toothpaste instead of spitting it out, you’d only need to brush your teeth a little over 1,000 times per day.

    All the same, please don’t eat toothpaste; that’s not the message here.

    However! In head-to-head tests, fluoride toothpaste has almost always beaten non-fluoride toothpaste.

    Almost? Yes, almost: hydroxyapatite performed equally in one study, but that’s not usually an option on as many supermarket shelves.

    We found some on Amazon, though, which is the one we used for today’s head-to-head. Here it is:

    Boka Fluoride-Free Toothpaste

    However, before you rush to buy it, do be aware that the toxicity of hydroxyapatite appears to be about twice that of fluoride:

    Scientific Committee on Consumer Safety Opinion On Hydroxyapatite (Nano)

    …which is still very safe (you’d need to brush your teeth, and eat all the toothpaste, about 500 times per day, to get to toxic levels, if we run with the same numbers we discussed before. Again, please do not do that, though).

    But, since the science so far suggests it’s about twice as toxic as fluoride, then regardless of that still being very safe, the fluoride is obviously (by the same metric) twice as safe, hence picking the fluoride.

    Want more options?

    Check out our previous main feature:

    Less Common Oral Hygiene Options

    (the above article also links back to our discussion of different toothpastes and mouthwashes, by the way)

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    Five Advance Warnings of Multiple Sclerosis

    First things first, a quick check-in with regard to how much you know about multiple sclerosis (MS):

    • Do you know what causes it?
    • Do you know how it happens?
    • Do you know how it can be fixed?

    If your answer to the above questions is “no”, then take solace in the fact that modern science doesn’t know either.

    What we do know is that it’s an autoimmune condition, and that it results in the degradation of myelin, the “insulator” of nerves, in the central nervous system.

    • How exactly this is brought about remains unclear, though there are several leading hypotheses including autoimmune attack of myelin itself, or disruption to the production of myelin.
    • Treatments look to reduce/mitigate inflammation, and/or treat other symptoms (which are many and various) on an as-needed basis.

    If you’re wondering about the prognosis after diagnosis, the scientific consensus on that is also “we don’t know”:

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    this paper, like every other one we considered putting in that spot, concludes with basically begging for research to be done to identify biomarkers in a useful fashion that could help classify many distinct forms of MS, rather than the current “you have MS, but who knows what that will mean for you personally because it’s so varied” approach.

    The Five Advance Warning Signs

    Something we do know! First, we’ll quote directly the researchers’ conclusion:

    ❝We identified 5 health conditions associated with subsequent MS diagnosis, which may be considered not only prodromal but also early-stage symptoms.

    However, these health conditions overlap with prodrome of two other autoimmune diseases, hence they lack specificity to MS.❞

    So, these things are a warning, five alarm bells, but not necessarily diagnostic criteria.

    Without further ado, the five things are:

    1. depression
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    ❝This association was sufficiently robust at the statistical level for us to state that these are early clinical warning signs, probably related to damage to the nervous system, in patients who will later be diagnosed with multiple sclerosis.

    The overrepresentation of these symptoms persisted and even increased over the five years after diagnosis.❞

    ~ Dr. Céline Louapre

    Read the paper for yourself:

    Association Between Diseases and Symptoms Diagnosed in Primary Care and the Subsequent Specific Risk of Multiple Sclerosis

    Hot off the press! Published only yesterday!

    Want to know more about MS?

    Here’s a very comprehensive guide:

    National clinical guideline for diagnosis and management of multiple sclerosis

    Take care!

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  • Planning Ahead For Better Sleep

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    Sleep: 6 Dimensions And 24 Hours!

    A woman with dark hair, planning ahead for better sleep, against a white background.

    This is Dr. Lisa Matricciani, a sleep specialist from the University of South Australia, where she teaches in the School of Health Sciences.

    What does she want us to know?

    Healthy sleep begins before breakfast

    The perfect bedtime routine is all well and good, but we need to begin much earlier in the day, Dr. Matricciani advises.

    Specifically, moderate to vigorous activity early in the day plays a big part.

    Before breakfast is best, but even midday/afternoon exercise is associated with better sleep at night.

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    Plan your time well to sleep—but watch out!

    Dr. Matricciani’s research has also found that while it’s important to plan around getting a good night’s sleep (including planning when this will happen), allocating too much time for sleep results in more restless sleep:

    ❝Allocating more time to sleep was associated with earlier sleep onsets, later sleep offsets, less efficient and more consistent sleep patterns for both children and adults.❞

    ~ Dr. Lisa Matricciani et al.

    Read more: Time use and dimensions of healthy sleep: A cross-sectional study of Australian children and adults

    (this was very large study involving 1,168 children and 1.360 adults, mostly women)

    What counts as good sleep quality? Is it just efficiency?

    It is not! Although that’s one part of it. You may remember our previous main feature:

    The 6 Dimensions Of Sleep (And Why They Matter)

    Dr. Matricciani agrees:

    ❝Everyone knows that sleep is important. But when we think about sleep, we mainly focus on how many hours of sleep we get, when we should also be looking at our sleep experience as a whole❞

    ~ Dr. Lisa Matricciani

    Read more: Trouble sleeping? You could be at risk of type 2 diabetes

    That’s not a cheery headline, but here’s her paper about it:

    Multidimensional Sleep and Cardiometabolic Risk Factors for Type 2 Diabetes: Examining Self-Report and Objective Dimensions of Sleep

    And no, we don’t get a free pass on getting less sleep / less good quality sleep as we get older (alas):

    Why You Probably Need More Sleep

    So, time to get planning for the best sleep!

    Enjoy videos?

    Here’s how 7News Australia broke the news of Dr. Matricciani’s more recent work:

    !

    Rest well!

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  • For Many Rural Women, Finding Maternity Care Outweighs Concerns About Abortion Access

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    BAKER CITY, Ore. — In what has become a routine event in rural America, a hospital maternity ward closed in 2023 in this small Oregon town about an hour from the Idaho border.

    For Shyanne McCoy, 23, that meant the closest hospital with an obstetrician on staff when she was pregnant was a 45-mile drive away over a mountain pass.

    When McCoy developed symptoms of preeclampsia last January, she felt she had the best chance of getting the care she needed at a larger hospital in Boise, Idaho, two hours away. She spent the final week of her pregnancy there, too far from home to risk leaving, before giving birth to her daughter.

    Six months later, she said it seems clear to her that the health care needs of rural young women like her are largely ignored.

    For McCoy and others, figuring out how to obtain adequate care to safely have a baby in Baker City has quickly eclipsed concerns about another medical service lacking in the area: abortion. But in Oregon and elsewhere in the country, progressive lawmakers’ attempts to expand abortion access sometimes clash with rural constituencies.

    Oregon is considered one of the most protective states in the country when it comes to abortion. There are no legal limits on when someone can receive an abortion in the state, and the service is covered by its Medicaid system. Still, efforts to expand access in the rural, largely conservative areas that cover most of the state have encountered resistance and incredulity.

    It’s a divide that has played out in elections in such states as Nevada, where voters passed a ballot measure in November that seeks to codify abortion protections in the state constitution. Residents in several rural counties opposed the measure.

    In Oregon, during the months just before the Baker City closure was announced, Democratic state lawmakers were focused on a proposed pilot program that would launch two mobile reproductive health care clinics in rural areas. The bill specified that the van-based clinics would include abortion services.

    State Rep. Christine Goodwin, a Republican from a southwestern Oregon district, called the proposal the “latest example” of urban legislators telling rural leaders what their communities need.

    The mobile health clinic pilot was eventually removed from the bill that was under discussion. That means no new abortion options in Oregon’s Baker County — and no new state-funded maternity care either.

    “I think if you expanded rural access in this community to abortions before you extended access to maternal health care, you would have an uprising on your hands,” said Paige Witham, 27, a member of the Baker County health care steering committee and the mother of two children, including an infant born in October.

    A study published in JAMA in early December that examined nearly 5,000 acute care hospitals found that by 2022, 52% of rural hospitals lacked obstetrics care after more than a decade of unit closures. The health implications of those closures for young women, the population most likely to need pregnancy care, and their babies can be significant. Research has shown that added distance between a patient and obstetric care increases the likelihood the baby will be admitted to a neonatal intensive care unit, or NICU.

    Witham said that while she does not support abortion, she believes the government should not “legislate it away completely.” She said that unless the government provides far more support for young families, like free child care and better mental health care, abortion should remain legal.

    Conversations with a liberal school board member, a moderate owner of a timber company, members of Baker City’s Republican Party chapter, a local doula, several pregnant women, and the director of the Baker County Health Department — many of whom were not rigidly opposed to abortion — all turned up the same answer: No mobile clinics offering abortions here, please.

    Kelle Osborn, a nurse supervisor for the Baker County Health Department, loved the idea of a mobile clinic that would provide education and birth control services to people in outlying areas. She was less thrilled about including abortion services in a clinic on wheels.

    “It’s not something that should just be handed out from a mobile van,” she said of abortion services. She said people in her conservative rural county would probably avoid using the clinics for anything if they were understood to provide abortion services.

    Both Osborn and Meghan Chancey, the health department’s director, said they would rank many health care priorities higher, including the need for a general surgeon, an ICU, and a dialysis clinic.

    Nationally, reproductive health care services of all types tend to be limited for people in rural areas, even within states that protect abortion access. More than two-thirds of people in “maternity care deserts” — all of which are in rural counties — must drive more than a half-hour to get obstetric care, according to a 2024 March of Dimes report. For people in the Southern states where lawmakers installed abortion bans, abortion care can be up to 700 miles away, according to a data analysis by Axios.

    Nathan Defrees grew up in Baker City and has practiced medicine here since 2017. He works for a family medicine clinic. If a patient asks about abortion, he provides information about where and how one can be obtained, but he doesn’t offer abortions himself.

    “There’s not a lot of anonymity in small towns for physicians who provide that care,” he said. “Many of us aren’t willing to sacrifice the rest of our career for that.”

    He also pointed to the small number of patients requesting the service locally. Just six people living in Baker County had an abortion in 2023, according to data from the Oregon Department of Public Health. Meanwhile, 125 residents had a baby that year.

    A doctor with obstetric training living in another rural part of the state has chosen to quietly provide early-stage abortions when asked. The doctor, concerned for their family’s safety in the small, conservative town where they live, asked not to be identified.

    The idea that better access to abortion is not needed in rural areas seems naive, the doctor said. People most in need of abortion often don’t have access to any medical service not already available in town, the doctor pointed out. The first patient the doctor provided an abortion for at the clinic was a meth user with no resources to travel or to manage an at-home medication abortion.

    “It seemed entirely inappropriate for me to turn her away for care I had the training and the tools to do,” the doctor said.

    Defrees said it has been easier for Baker County residents to get an abortion since the U.S. Supreme Court overturned Roe v. Wade.

    A new Planned Parenthood clinic in Ontario, Oregon, 70 miles away in neighboring Malheur County, was built primarily to provide services to people from the Boise metro area, but it also created an option for many living in rural eastern Oregon.

    Idaho is one of the 16 states with near-total bans on abortion. Like many states with bans, Idaho has struggled to maintain its already small fleet of fetal medicine doctors. The loss of regional expertise touches Baker City, too, Defrees said.

    For example, he said, the treatment plan for women who have a desired pregnancy but need a termination for medical reasons is now far less clear. “It used to be those folks could go to Boise,” he said. “Now they can’t. That does put us in a bind.”

    Portland is the next closest option for that type of care, and that means a 300-mile drive along a set of highways that can be treacherous in winter.

    “It’s a lot scarier to be pregnant now in Baker City than it ever has been,” Defrees said.

    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.

    Subscribe to KFF Health News’ free Morning Briefing.

    This article first appeared on KFF Health News and is republished here under a Creative Commons license.

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