Is fluoride really linked to lower IQ, as a recent study suggested? Here’s why you shouldn’t worry
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Fluoride is a common natural element found in water, soil, rocks and food. For the past several decades, fluoride has also been a cornerstone of dentistry and public health, owing to its ability to protect against tooth decay.
Water fluoridation is a population-based program where a precise, small amount of fluoride is added to public drinking water systems. Water fluoridation began in Australia in the 1950s. Today more than 90% of Australia’s population has access to fluoridated tap water.
But a recently published review found higher fluoride exposure is linked to lower intelligence quotient (IQ) in children. So how can we interpret the results?
Much of the data analysed in this review is poor quality. Overall, the findings don’t give us reason to be concerned about the fluoride levels in our water supplies.
Not a new controversy
Tooth decay (also known as caries or cavities) can have negative effects on dental health, overall health and quality of life. Fluoride strengthens our teeth, making them more resistant to decay. There is scientific consensus water fluoridation is a safe, effective and equitable way to improve oral health.
Nonetheless, water fluoridation has historically been somewhat controversial.
A potential link between fluoride and IQ (and cognitive function more broadly) has been a contentious topic for more than a decade. This started with reports from studies in China and India.
But it’s important to note these studies were limited by poor methodology, and water in these countries had high levels of natural fluoride when the studies were conducted – many times higher than the levels recommended for water fluoridation programs. Also, the studies did not control for other contaminants in the water supply.
Recent reviews focusing on the level of fluoride used in water fluoridation have concluded fluoride is not linked to lower IQ.
Despite this, some have continued to raise concerns. The United States National Toxicology Program conducted a review of the potential link. However, this review did not pass the quality assessment by the US National Academies of Sciences, Engineering and Medicine due to significant limitations in the conduct of the review.
The authors followed through with their study and published it as an independent publication in the journal JAMA Paediatrics last week. This is the study which has been generating media attention in recent days.
What the study did
This study was a systematic review and meta-analysis, where the researchers evaluated 74 studies from different parts of the world.
A total of 52 studies were rated as having a high risk of bias, and 64 were cross-sectional studies, which often can’t provide evidence of causal relationship.
Most of the studies were conducted in developing countries, such as China (45), India (12), Iran (4), Mexico (4) and Pakistan (2). Only a few studies were conducted in developed countries with established public water systems, where regular monitoring and treatment of drinking water ensures it’s free from contaminants.
The vast majority of studies were conducted in populations with high to very high levels of natural fluoride and without water fluoridation programs, where fluoride levels are controlled within recommended levels.
The study concluded there was an inverse association between fluoride levels and IQ in children. This means those children who had a higher intake of fluoride had lower IQ scores than their counterparts.
Limitations to consider
While this review combined many studies, there are several limitations that cast serious doubt over its conclusion. Scientists immediately raised concerns about the quality of the review, including in a linked editorial published in JAMA.
The low quality of the majority of included studies is a major concern, rendering the quality of the review equally low. Importantly, most studies were not relevant to the recommended levels of fluoride in water fluoridation programs.
Several included studies from countries with controlled public water systems (Canada, New Zealand, Taiwan) showed no negative effects. Other recent studies from comparable populations (such as Spain and Denmark) also have not shown any negative effect of fluoride on IQ, but they were not included in the meta-analysis.
For context, the review found there was no significant association with IQ when fluoride was measured at less than 1.5mg per litre in water. In Australia, the recommended levels of fluoride in public water supplies range from 0.6 to 1.1 mg/L.
Also, the primary outcome, IQ score, is difficult to collect. Most included studies varied widely on the methods used to collect IQ data and did not specify their focus on ensuring reliable and consistent IQ data. Though this is a challenge in most research on this topic, the significant variations between studies in this review raise further doubts about the combined results.
No cause for alarm
Although no Australian studies were included in the review, Australia has its own studies investigating a potential link between fluoride exposure in early childhood and child development.
I’ve been involved in population-based longitudinal studies investigating a link between fluoride and child behavioural development and executive functioning and between fluoride and IQ. The IQ data in the second study were collected by qualified, trained psychologists – and calibrated against a senior psychologist – to ensure quality and consistency. Both studies have provided strong evidence fluoride exposure in Australia does not negatively impact child development.
This new review is not a reason to be concerned about fluoride levels in Australia and other developed countries with water fluoridation programs. Fluoride remains important in maintaining the public’s dental health, particularly that of more vulnerable groups.
That said, high and uncontrolled levels of fluoride in water supplies in less developed countries warrant attention. There are programs underway in a range of countries to reduce natural fluoride to the recommended level.
Loc Do, Professor of Dental Public Health, The University of Queensland
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Non-Sleep Deep Rest: A Neurobiologist’s Take
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How to get many benefits of sleep, while awake!
Today we’re talking about Dr. Andrew Huberman, a neuroscientist and professor in the department of neurobiology at Stanford School of Medicine.
He’s also a popular podcaster, and as his Wikipedia page notes:
❝In episodes lasting several hours, Huberman talks about the state of research in a specific topic, both within and outside his specialty❞
Today, we won’t be taking hours, and we will be taking notes from within his field of specialty (neurobiology). Specifically, in this case:
Non-Sleep Deep Rest (NSDR)
What is it? To quote from his own dedicated site on the topic:
❝What is NSDR (Yoga Nidra)? Non-Sleep Deep Rest, also known as NSDR, is a method of deep relaxation developed by Dr. Andrew Huberman, a neuroscientist at Stanford University School of Medicine.
It’s a process that combines controlled breathing and detailed body scanning to bring you into a state of heightened awareness and profound relaxation. The main purpose of NSDR is to reduce stress, enhance focus, and improve overall well-being.❞
While it seems a bit bold of Dr. Huberman to claim that he developed yoga nidra, it is nevertheless reassuring to get a neurobiologist’s view on this:
How it works, by science
Dr. Huberman says that by monitoring EEG readings during NSDR, we can see how the brain slows down. Measurably!
- It goes from an active beta range of 13–30 Hz (normal waking) to a conscious meditation state of an alpha range of 8–13 Hz.
- However, with practice, it can drop further, into a theta range of 4–8 Hz.
- Ultimately, sustained SSDR practice can get us to 0.5–3 Hz.
This means that the brain is functioning in the delta range, something that typically only occurs during our deepest sleep.
You may be wondering: why is delta lower than theta? That’s not how I remember the Greek alphabet being ordered!
Indeed, while the Greek alphabet goes alpha beta gamma delta epsilon zeta eta theta (and so on), the brainwave frequency bands are:
- Gamma = concentrated focus, >30 Hz
- Beta = normal waking, 13–30 Hz
- Alpha = relaxed state, 8–13 Hz
- Theta = light sleep, 4–8 Hz
- Delta = deep sleep, 1–4 Hz
Source: Sleep Foundation ← with a nice infographic there too
NSDR uses somatic cues to engage our parasympathetic nervous system, which in turn enables us to reach those states. The steps are simple:
- Pick a time and place when you won’t be disturbed
- Lie on your back and make yourself comfortable
- Close your eyes as soon as you wish, and now that you’ve closed them, imagine closing them again. And again.
- Slowly bring your attention to each part of your body in turn, from head to toe. As your attention goes to each part, allow it to relax more.
- If you wish, you can repeat this process for another wave, or even a third.
- Find yourself well-rested!
Note: this engagement of the parasympathetic nervous system and slowing down of brain activity accesses restorative states not normally available while waking, but 10 minutes of NSDR will not replace 7–9 hours of sleep; nor will it give you the vital benefits of REM sleep specifically.
So: it’s an adjunct, not a replacement
Want to try it, but not sure where/how to start?
When you’re ready, let Dr. Huberman himself guide you through it in this shortish (10:49) soundtrack:
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Want to try it, but not right now? Bookmark it for later
Take care!
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Weight Vests Against Osteoporosis: Do They Really Build Bone?
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Dr. Doug Lucas is a dual board-certified physician specializing in optimizing healthspan and bone health for women experiencing osteoporosis, perimenopause, and menopause. Here, he talks weight vests:
Worth the weight?
Dr. Lucas cites “Wolf’s Law”—bones respond to stress. A weighted vest adds stress, to help build bone density. That said, they may not be suitable for everyone (for example, in cases of severe osteoporosis or a recent vertebral fracture).
He also cites some studies:
- Erlanger Fitness Study (2004): participants with a weighted vest maintained or improved bone density compared to a control group, but there was no group with exercise alone, making it unclear if the vest itself had the biggest impact.
- Newer studies (2016, 2017): showed improved outcomes for groups wearing a weighted vest, but again lacked an exercise-only group for comparison.
- 2012 study: included three groups (control, weighted vest, exercise only). Results showed no significant bone density difference between vest and exercise-only groups, though the vest group showed better balance and motor control.
Dr. Lucas concludes that weighted vests are a useful tool while nevertheless not being a magic bullet for bone health. In other words, they can complement exercise but you will also be fine without. If you do choose to level-up your exercise by using a weight vest, then starting with 5–10% of body weight in a vest is often recommended, but it depends on individual circumstances. If in doubt, start low and build up. Wearing the vest for daily activities can be effective, but improper use (awkward positions or improper impact training) can increase injury risk, so do be careful with that.
For more on all of this, enjoy:
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Want to learn more?
You might also like to read:
- Osteoporosis & Exercises: Which To Do (And Which To Avoid)
- One More Resource Against Osteoporosis!
- The Osteoporosis Breakthrough – by Dr. Doug Lucas ← we reviewed his book a while back!
Take care!
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Marathons in Mid- and Later-Life
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It’s Q&A Day at 10almonds!
Have a question or a request? You can always hit “reply” to any of our emails, or use the feedback widget at the bottom!
In cases where we’ve already covered something, we might link to what we wrote before, but will always be happy to revisit any of our topics again in the future too—there’s always more to say!
As ever: if the question/request can be answered briefly, we’ll do it here in our Q&A Thursday edition. If not, we’ll make a main feature of it shortly afterwards!
So, no question/request too big or small
We had several requests pertaining to veganism, meatless mondays, and substitutions in recipes—so we’re going to cover those on a different day!
As for questions we’re answering today…
Q: Is there any data on immediate and long term effects of running marathons in one’s forties?
An interesting and very specific question! We didn’t find an overabundance of studies specifically for the short- and long-term effects of marathon-running in one’s 40s, but we did find a couple of relevant ones:
The first looked at marathon-runners of various ages, and found that…
- there are virtually no relevant running time differences (p<0.01) per age in marathon finishers from 20 to 55 years
- the majority of middle-aged and elderly athletes have training histories of less than seven years of running
From which they concluded:
❝The present findings strengthen the concept that considers aging as a biological process that can be considerably speeded up or slowed down by multiple lifestyle related factors.❞
See the study: Performance, training and lifestyle parameters of marathon runners aged 20–80 years: results of the PACE-study
The other looked specifically at the impact of running on cartilage, controlled for age (45 and under vs 46 and older) and activity level (marathon-runners vs sedentary people).
The study had the people, of various ages and habitual activity levels, run for 30 minutes, and measured their knee cartilage thickness (using MRI) before and after running.
They found that regardless of age or habitual activity level, running compressed the cartilage tissue to a similar extent. From this, it can be concluded that neither age nor marathon-running result in long-term changes to cartilage response to running.
Or in lay terms: there’s no reason that marathon-running at 40 should ruin your knees (unless you are doing something wrong).
That may or may not have been a concern you have, but it’s what the study looked at, so hey, it’s information.
Here’s the study: Functional cartilage MRI T2 mapping: evaluating the effect of age and training on knee cartilage response to running
Q: Information on [e-word] dysfunction for those who have negative reactions to [the most common medications]?
When it comes to that particular issue, one or more of these three factors are often involved:
- Hormones
- Circulation
- Psychology
The most common drugs (that we can’t name here) work on the circulation side of things—specifically, by increasing the localized blood pressure. The exact mechanism of this drug action is interesting, albeit beyond the scope of a quick answer here today. On the other hand, the way that they work can cause adverse blood-pressure-related side effects for some people; perhaps you’re one of them.
To take matters into your own hands, so to speak, you can address each of those three things we just mentioned:
Hormones
Ask your doctor (or a reputable phlebotomy service) for a hormone test. If your free/serum testosterone levels are low (which becomes increasingly common in men over the age of 45), they may prescribe something—such as testosterone shots—specifically for that.
This way, it treats the underlying cause, rather than offering a workaround like those common pills whose names we can’t mention here.
Circulation
Look after your heart health; eat for your heart health, and exercise regularly!
Cold showers/baths also work wonders for vascular tone—which is precisely what you need in this matter. By rapidly changing temperatures (such as by turning off the hot water for the last couple of minutes of your shower, or by plunging into a cold bath), your blood vessels will get practice at constricting and maintaining that constriction as necessary.
Psychology
[E-word] dysfunction can also have a psychological basis. Unfortunately, this can also then be self-reinforcing, if recalling previous difficulties causes you to get distracted/insecure and lose the moment. One of the best things you can do to get out of this catch-22 situation is to not worry about it in the moment. Depending on what you and your partner(s) like to do in bed, there are plenty of other equally respectable options, so just switch track!
Having a conversation about this in advance will probably be helpful, so that everyone’s on the same page of the script in that eventuality, and it becomes “no big deal”. Without that conversation, misunderstandings and insecurities could arise for your partner(s) as well as yourself (“aren’t I desirable enough?” etc).
So, to recap, we recommend:
- Have your hormones checked
- Look after your circulation
- Make the decision to have fun!
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Why scrapping the term ‘long COVID’ would be harmful for people with the condition
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The assertion from Queensland’s chief health officer John Gerrard that it’s time to stop using the term “long COVID” has made waves in Australian and international media over recent days.
Gerrard’s comments were related to new research from his team finding long-term symptoms of COVID are similar to the ongoing symptoms following other viral infections.
But there are limitations in this research, and problems with Gerrard’s argument we should drop the term “long COVID”. Here’s why.
A bit about the research
The study involved texting a survey to 5,112 Queensland adults who had experienced respiratory symptoms and had sought a PCR test in 2022. Respondents were contacted 12 months after the PCR test. Some had tested positive to COVID, while others had tested positive to influenza or had not tested positive to either disease.
Survey respondents were asked if they had experienced ongoing symptoms or any functional impairment over the previous year.
The study found people with respiratory symptoms can suffer long-term symptoms and impairment, regardless of whether they had COVID, influenza or another respiratory disease. These symptoms are often referred to as “post-viral”, as they linger after a viral infection.
Gerrard’s research will be presented in April at the European Congress of Clinical Microbiology and Infectious Diseases. It hasn’t been published in a peer-reviewed journal.
After the research was publicised last Friday, some experts highlighted flaws in the study design. For example, Steven Faux, a long COVID clinician interviewed on ABC’s television news, said the study excluded people who were hospitalised with COVID (therefore leaving out people who had the most severe symptoms). He also noted differing levels of vaccination against COVID and influenza may have influenced the findings.
In addition, Faux pointed out the survey would have excluded many older people who may not use smartphones.
The authors of the research have acknowledged some of these and other limitations in their study.
Ditching the term ‘long COVID’
Based on the research findings, Gerrard said in a press release:
We believe it is time to stop using terms like ‘long COVID’. They wrongly imply there is something unique and exceptional about longer term symptoms associated with this virus. This terminology can cause unnecessary fear, and in some cases, hypervigilance to longer symptoms that can impede recovery.
But Gerrard and his team’s findings cannot substantiate these assertions. Their survey only documented symptoms and impairment after respiratory infections. It didn’t ask people how fearful they were, or whether a term such as long COVID made them especially vigilant, for example.
Tens of thousands of Australians, and millions of people worldwide, have long COVID.
New Africa/ShutterstockIn discussing Gerrard’s conclusions about the terminology, Faux noted that even if only 3% of people develop long COVID (the survey found 3% of people had functional limitations after a year), this would equate to some 150,000 Queenslanders with the condition. He said:
To suggest that by not calling it long COVID you would be […] somehow helping those people not to focus on their symptoms is a curious conclusion from that study.
Another clinician and researcher, Philip Britton, criticised Gerrard’s conclusion about the language as “overstated and potentially unhelpful”. He noted the term “long COVID” is recognised by the World Health Organization as a valid description of the condition.
A cruel irony
An ever-growing body of research continues to show how COVID can cause harm to the body across organ systems and cells.
We know from the experiences shared by people with long COVID that the condition can be highly disabling, preventing them from engaging in study or paid work. It can also harm relationships with their friends, family members, and even their partners.
Despite all this, people with long COVID have often felt gaslit and unheard. When seeking treatment from health-care professionals, many people with long COVID report they have been dismissed or turned away.
Last Friday – the day Gerrard’s comments were made public – was actually International Long COVID Awareness Day, organised by activists to draw attention to the condition.
The response from people with long COVID was immediate. They shared their anger on social media about Gerrard’s comments, especially their timing, on a day designed to generate greater recognition for their illness.
Since the start of the COVID pandemic, patient communities have fought for recognition of the long-term symptoms many people faced.
The term “long COVID” was in fact coined by people suffering persistent symptoms after a COVID infection, who were seeking words to describe what they were going through.
The role people with long COVID have played in defining their condition and bringing medical and public attention to it demonstrates the possibilities of patient-led expertise. For decades, people with invisible or “silent” conditions such as ME/CFS (myalgic encephalomyelitis/chronic fatigue syndrome) have had to fight ignorance from health-care professionals and stigma from others in their lives. They have often been told their disabling symptoms are psychosomatic.
Gerrard’s comments, and the media’s amplification of them, repudiates the term “long COVID” that community members have chosen to give their condition an identity and support each other. This is likely to cause distress and exacerbate feelings of abandonment.
Terminology matters
The words we use to describe illnesses and conditions are incredibly powerful. Naming a new condition is a step towards better recognition of people’s suffering, and hopefully, better diagnosis, health care, treatment and acceptance by others.
The term “long COVID” provides an easily understandable label to convey patients’ experiences to others. It is well known to the public. It has been routinely used in news media reporting and and in many reputable medical journal articles.
Most importantly, scrapping the label would further marginalise a large group of people with a chronic illness who have often been left to struggle behind closed doors.
Deborah Lupton, SHARP Professor, Vitalities Lab, Centre for Social Research in Health and Social Policy Centre, and the ARC Centre of Excellence for Automated Decision-Making and Society, UNSW Sydney
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Sleep Smarter – by Shawn Stevenson
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You probably know to avoid blue light before bed, put a curfew on the caffeine, and have fresh bedding. So, what does this book offer that’s new?
As the subtitle suggests, it’s 21 tips for better sleep, so if even half of them are new, then it’ll still be adding value.
This is a book review, not a book summary, but to give an idea of the kind of thing you might not already know: there’s a section on bedroom houseplants! For example…
- Which plants filter the air best according to NASA, rather than “according to tradition”
- Which plants will thrive in what will hopefully be a cool dark environment
- Which plants produce oxygen even at night, rather than just during the day
The writing style is personable without losing clarity or objectivity:
- We read personal anecdotes, and we read science
- We get “I tried this”, and we get “this sleep study found such-and-such”
- We get not just the “what”, but also the “why” and the “how”
We get the little changes that make a big difference—sometimes the difference between something working or not!
Bottom line: if you’d like to get better sleep and a blue light filter hasn’t wowed you and changed your life, this book will bring your sleep knowledge (and practice) to the next level.
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When Bad Joints Stop You From Exercising (5 Things To Change)
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The first trick to exercising with bad joints is to have better joints.
Now, this doesn’t necessarily mean you can take a supplement and magically your joint problems will be cured, but there are adjustable lifestyle factors that can and will make things relatively better or worse.
We say “and will”, because you don’t get a choice in that part. Everything we do, every little choice in our day, makes our health a little better or a little worse in some aspect(s). But we do get a choice between “relatively better” and “relatively worse”.
With that in mind, do check out:
- Avoiding/Managing Osteoarthritis
- Avoiding/Managing Rheumatoid Arthritis
- How To Really Look After Your Joints
Ok, you have bad joints though; what next?
Let’s assume you’re doing your best with the above, and/or have simply decided not to, which is your call. You know your circumstances best. Either way, your joints are still not in sufficiently good condition to be able to exercise the way you’d like.
First, the obvious: enjoy low-impact exercises
For example:
- Swimming
- Yoga (much more appropriate here than the commonly-paired “and tai chi”)*
- Isometric exercises (i.e. exercise without movement, e.g. squeezing things, or stationary stability exercises)
*This is not to say that tai chi is bad. But if your problem is specifically your knees, there are many movements in most forms of tai chi that require putting the majority of one’s weight on one bent leg, which means the knee of that leg is going to suffer. If your knees are fine, then this won’t be an issue and it will simply continue strengthening your knees without discomfort. But they have to be fine first.
See also: Exercising With Osteoporosis
Second: support your joints through a full range of motion
If you have bad joints, you probably know that there’s an unfortunate paradox whereby you get to choose between:
- Exercise, and inflame your joints
- Rest, and your joints seize up
This is the way to get around that damaging dilemma.
Moving your joints through a full range of motion regularly is critical for their maintenance, so do that in a way that isn’t straining them:
If it’s your shoulders, for example, you can do (slow, gentle!) backstroke or front-crawl or butterfly motions while standing in the comfort of your living room.
If it’s your knees, then supported squats can do you a world of good. That means, squat in front of a table or other stable object, with your fingertips (or as much of your hands as you need) on it, to take a portion of your weight (it can be a large portion; that’s fine too!) while you go through the full range of motion of the squat. Repeat.
And so forth for other joints.
See also: The Most Underrated Hip Mobility Exercise (Not Stretching)
Third: work up slowly, and stop early
You can do exercises that involve impact, and if you live a fairly normal life, you’ll probably have to (walking is an impact exercise). You can also enjoy cycling (low-impact, but not so low-impact as we discussed in the last section) and work up to running if you want to.
However…
While building up your joints’ mobility and strength, it is generally a good idea to stop before you think you need to.
This means that it’s important to do those exercises in a way that you can stop early. For example, an exercise bike or a treadmill can be a lot of use here, so that you don’t find you need to stop for the day while miles from your house.
If you get such a device, it doesn’t even have to be fancy and/or expensive. This writer got herself an inexpensive exercise bike like this one, and it’s perfectly adequate.
Fourth: prioritize recovery, even if it doesn’t feel like you need it
Everyone should do this anyway, but if your joints are bad, it goes double:
Overdone It? How To Speed Up Recovery After Exercise (According To Actual Science)
Fifth: get professional help
Physiotherapists are great for this. Find one, and take their advice for your specific body and your specific circumstances and goals.
Take care!
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