Our blood-brain barrier stops bugs and toxins getting to our brain. Here’s how it works
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Our brain is an extremely complex and delicate organ. Our body fiercely protects it by holding onto things that help it and keeping harmful things out, such as bugs that can cause infection and toxins.
It does that though a protective layer called the blood-brain barrier. Here’s how it works, and what it means for drug design.
First, let’s look at the circulatory system
Adults have roughly 30 trillion cells in their body. Every cell needs a variety of nutrients and oxygen, and they produce waste, which needs to be taken away.
Our circulatory system provides this service, delivering nutrients and removing waste.
Where the circulatory system meets your cells, it branches down to tiny tubes called capillaries. These tiny tubes, about one-tenth the width of a human hair, are also made of cells.
But in most capillaries, there are some special features (known as fenestrations) that allow relatively free exchange of nutrients and waste between the blood and the cells of your tissues.
It’s kind of like pizza delivery
One way to think about the way the circulation works is like a pizza delivery person in a big city. On the really big roads (vessels) there are walls and you can’t walk up to the door of the house and pass someone the pizza.
But once you get down to the little suburban streets (capillaries), the design of the streets means you can stop, get off your scooter and walk up to the door to deliver the pizza (nutrients).
We often think of the brain as a spongy mass without much blood in it. In reality, the average brain has about 600 kilometres of blood vessels.
The difference between the capillaries in most of the brain and those elsewhere is that these capillaries are made of specialised cells that are very tightly joined together and limit the free exchange of anything dissolved in your blood. These are sometimes called continuous capillaries.
This is the blood brain barrier. It’s not so much a bag around your brain stopping things from getting in and out but more like walls on all the streets, even the very small ones.
The only way pizza can get in is through special slots and these are just the right shape for the pizza box.
The blood brain barrier is set up so there are specialised transporters (like pizza box slots) for all the required nutrients. So mostly, the only things that can get in are things that there are transporters for or things that look very similar (on a molecular scale).
The analogy does fall down a little bit because the pizza box slot applies to nutrients that dissolve in water. Things that are highly soluble in fat can often bypass the slots in the wall.
Why do we have a blood-brain barrier?
The blood brain barrier is thought to exist for a few reasons.
First, it protects the brain from toxins you might eat (think chemicals that plants make) and viruses that often can infect the rest of your body but usually don’t make it to your brain.
It also provides protection by tightly regulating the movement of nutrients and waste in and out, providing a more stable environment than in the rest of the body.
Lastly, it serves to regulate passage of immune cells, preventing unnecessary inflammation which could damage cells in the brain.
What it means for medicines
One consequence of this tight regulation across the blood brain barrier is that if you want a medicine that gets to the brain, you need to consider how it will get in.
There are a few approaches. Highly fat-soluble molecules can often pass into the brain, so you might design your drug so it is a bit greasy.
Another option is to link your medicine to another molecule that is normally taken up into the brain so it can hitch a ride, or a “pro-drug”, which looks like a molecule that is normally transported.
Using it to our advantage
You can also take advantage of the blood brain barrier.
Opioids used for pain relief often cause constipation. They do this because their target (opioid receptors) are also present in the nervous system of the intestines, where they act to slow movement of the intestinal contents.
Imodium (Loperamide), which is used to treat diarrhoea, is actually an opioid, but it has been specifically designed so it can’t cross the blood brain barrier.
This design means it can act on opioid receptors in the gastrointestinal tract, slowing down the movement of contents, but does not act on brain opioid receptors.
In contrast to Imodium, Ozempic and Victoza (originally designed for type 2 diabetes, but now popular for weight-loss) both have a long fat attached, to improve the length of time they stay in the body.
A consequence of having this long fat attached is that they can cross the blood-brain barrier, where they act to suppress appetite. This is part of the reason they are so effective as weight-loss drugs.
So while the blood brain barrier is important for protecting the brain it presents both a challenge and an opportunity for development of new medicines.
Sebastian Furness, ARC Future Fellow, School of Biomedical 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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Farmed Fish vs Wild Caught
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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 😎
❝Is it good to eat farm raised fish?❞
We’ll answer this as a purely health-related question (and thus not considering economy, ecology, ethics, or taste).
It’s certainly not as good as wild-caught fish, for several reasons, some more serious than others:
Farmed fish can have quite a different nutritional profile to wild-caught fish, and also contain more contaminants, including heavy metals.
For example, farmed fish tend to have much higher fat content for the same amount of protein, but lower levels of minerals and other nutrients. Here are two side-by-side:
Wild-caught salmon | Farmed salmon
See also:
Quantitative analysis of the benefits and risks of consuming farmed and wild salmon
Additionally, because fish in fish farms tend to be very susceptible to diseases (because of the artificially cramped and overcrowded environment), fish farms tend to make heavy use of antibiotics, which can cause all sorts of problems down the line:
So definitely, “let the buyer beware”!
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This Week In Brain News
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While reading this week’s health news, we’ve singled out three brain-related articles to feature here:
Bad breath now, bad brain later?
Researchers found links between oral microbiome populations, and changes in brain function with aging. The short version is indeed “bad breath now = bad brain later”, but more specifically:
- People who had large numbers of the bacteria groups Neisseria and Haemophilus had better memory, attention and ability to do complex tasks
- People who had higher levels of Porphyromonas had more memory problems later
- People with a lot of Prevotella tended to predict poorer brain health and was more common in people who carry the Alzheimer’s Disease risk gene, APOE4.
If you’ve never heard of half of those, don’t worry: mostly your oral microbiome can take care of itself, provide you consistently do the things that create a “good” oral microbiome. So, see our “related” link below:
Read in full: Mouth bacteria may hold insight into your future brain function
Related: Improve Your Oral Microbiome
Weeding out a major cause of cognitive decline
Cannabis may be great for relaxation, but regular use is not great for mental sharpness, and recent use (even if not regular, and even if currently sober) shows a similar dip in cognitive abilities, especially working memory. In other words, cannabis use for relaxation should be at most an occasional thing, rather than an everyday thing.
While the results of the study are probably not shocking, something that we found interesting was their classification system:
❝Heavy users are considered young adults who’ve used cannabis more than 1000 times over their lifetime. Whereas, using 10 to 999 times was considered a moderate user, and fewer than 10 times was considered a non-user.❞
Which—while being descriptive rather than prescriptive in nature—suggests that, to be on the healthy end of the bell curve, an occasional cannabis-user might want to consider “if you have 999 uses before you hit the “heavy user” category, project those 999 uses against your life expectancy, and moderate your use accordingly”. In other words, a person just now starting use, who expects to live another 40 years, would calculate: 999/40 = 24.9 uses per year, so call it 2 per month. A person who only expects to live another 20 years, would do the same math and arrive at 4 per month.
Disclaimer: the above is intended as an interesting reframe, and a way of looking at long-term cannabis use while being mindful of the risks. It is not intended as advice. This health-conscious writer personally has no intention of using at all, unless perhaps in some bad future scenario in which I have bad chronic pain, I might consider that pain relief effects may be worth the downsides. Or I might not; I hope not to be in the situation to find out!
Read in full: Largest study ever done on cannabis and brain function finds impact on working memory
Related: Cannabis Myths vs Reality
Mind-reading technology improves again
We’ve come quite a way from simple 1/0 reads, and basic cursor control! Now, researchers have created a brain decode that can translate a person’s thoughts into continuous text, without requiring the person to focus on words—in other words, it verbalizes the ideas directly. Most recently, the latest upgrade means that while previously, the device had to be trained on an individual brain for many hours, now the training/calibration process takes only an hour:
Read in full: Improved brain decoder holds promise for communication in people with aphasia
Related: Are Brain Chips Safe?
Take care!
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Heart Health vs Systemic Stress
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At The Heart Of Good Health
This is Dr. Michelle Albert. She’s a cardiologist with a decades-long impressive career, recently including a term as the president of the American Heart Association. She’s the current Admissions Dean at UCSF Medical School. She’s accumulated enough awards and honors that if we list them, this email will not fit in your inbox without getting clipped.
What does she want us to know?
First, lifestyle
Although Dr. Albert is also known for her work with statins (which found that pravastatin may have anti-inflammatory effects in addition to lipid-lowering effects, which is especially good news for women, for whom the lipid-lowering effects may be less useful than for men), she is keen to emphasize that they should not be anyone’s first port-of-call unless “first” here means “didn’t see the risk until it was too late and now LDL levels are already ≥190 mg/dL”.
Instead, she recommends taking seriously the guidelines on:
- getting plenty of fruit, vegetables, whole grains, lean protein
- avoiding red meat, processed meats, refined carbohydrates, and sweetened beverages
- getting your 150 minutes per week of moderate exercise
- avoiding alcohol, and definitely abstaining from smoking
See also: These Top Five Things Make The Biggest Difference To Health
Next, get your house in order
No, not your home gym—though sure, that too!
But rather: after the “Top Five Things” we linked just above, the sixth on the list would be “reduce stress”. Indeed, as Dr. Albert says:
❝Heart health is not just about the physical heart but also about emotional well-being. Stress management is crucial for a healthy heart❞
~ Dr. Michelle Albert
This is where a lot of people would advise mindfulness meditation, CBT, somatic therapies, and the like. And these things are useful! See for example:
No-Frills, Evidence-Based Mindfulness
…and:
However, Dr. Albert also advocates for awareness of what some professionals have called “Shit Life Syndrome”.
This is more about socioeconomic factors. There are many of those that can’t be controlled by the individual, for example:
❝Adverse maternal experiences such as depression, economic issues and low social status can lead to poor cognitive outcomes as well as cardiovascular disease.
Many jarring statistics illuminate a marked wealth gap by race and ethnicity… You might be thinking education could help bridge that gap. But it is not that simple.
While education does increase wealth, the returns are not the same for everyone. Black persons need a post-graduate degree just to attain similar wealth as white individuals with a high school degree.❞
~ Dr. Michelle Albert
Read in full: AHA president: The connection between economic adversity and cardiovascular health
What this means in practical terms (besides advocating for structural change to tackle the things such as the racism that has been baked into a lot of systems for generations) is:
Be aware not just of your obvious health risk factors, but also your socioeconomic risk factors, if you want to have good general health outcomes.
So for example, let’s say that you, dear reader, are wealthy and white, in which case you have some very big things in your favor, but are you also a woman? Because if so…
Women and Minorities Bear the Brunt of Medical Misdiagnosis
See also, relevant for some: Obesity Discrimination In Healthcare Settings ← you’ll need to scroll to the penultimate section for this one.
In other words… If you are one of the majority of people who is a woman and/or some kind of minority, things are already stacked against you, and not only will this have its own direct harmful effect, but also, it’s going to make your life harder and that stress increases CVD risk more than salt.
In short…
This means: tackle not just your stress, but also the things that cause that. Look after your finances, gather social support, know your rights and be prepared to self-advocate / have someone advocate for you, and go into medical appointments with calm well-prepared confidence.
Take care!
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Burned Out By Tuesday?
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Avoiding Burnout, The Active Way
This is Dr. Claudine Holt. She’s double board-certified, in Occupational & Environmental Medicine, and Lifestyle Medicine.
In short: preventative medicine in all parts of our life.
Hopefully, you are reading this bright-eyed and bushy-tailed and ready to take on another exciting day in this wonderful, beautiful world!
On the other hand, it’s possible that you’re reading this semi-focussed, looking for a crumb of dopamine as much as you are looking for information.
If you’ve ever had the “What a week!” / “It’s only Tuesday” moment, this one’s for you.
What does Dr. Holt want us to know?
You can recover from burnout without guilt
Sometimes, we overreach ourselves. Sometimes, life overreaches us! Sometimes it’s not that we overcommitted—it’s just that we were taking each day as it comes, but sometimes several days gang up on us at once.
Sometimes, even, we can feel exhausted when it seems like we haven’t done anything.
Note: if you feel exhausted and it seems like you haven’t done anything, then be aware: you are exhausted for a reason!
What that reason might be may vary, but contrary to popular belief, energy does not just vanish. It went somewhere.
This goes double if you have any chronic illness(es), even if you’re not aware of having had a flare-up, chances are you were just exceptionally busy (on a cellular level).
And it’s easy to think that “mere” cellular activity shouldn’t be exhausting, but that is 100% of where our energy transactions happen—whether or not we are consciously aware of them!
See also: Eat To Beat Chronic Fatigue ← yes, this also covers when you are too exhausted to shop and cook like a TV chef
Dr. Holt specializes in working with burned out medical professionals (and also specifically specializes in working with women), but there are lessons for everyone in her advice. For example:
Fiction: ”Medicine is my calling–it’s who I am.”
Fact: You are more than medicine! Remember that your career is just one aspect of your life. Don’t forget to create your big-picture vision and tend the garden of the other areas of your life too.
Read more: Dr. Claudine Holt | Burnout: Fact vs Fiction
This same thing can go for whatever part of your identity frequently follows “I’m a…”, and is somewhere that you put a lot of your energy; it could equally be a non-professional job like “homemaker”, or a relational status like “husband”, or a cultural identifier like “Christian”, or a hobby like “gardener” (assuming that is not also your profession, in which case, same item, different category).
Indeed, a lot of women especially get hit by “the triple burden” of professional work, housework, and childcare. And it’s not even necessarily that we resent any of those things or feel like they’re a burden; we (hopefully) love our professions, homes, children. But, here’s the thing:
No amount of love will add extra hours to the day.
So what does she recommend doing about it, when sometimes we’re juggling things that can’t be dropped?
Start simple, but start!
Dr. Holt recommends to start with a smile (yes even if, and sometimes especially when, the circumstances do not feel like they merit it), and deploy some CBT tools:
Two Hacks to Quickly Rise Above Burnout (Or Any Circumstance)
We’ve expanded on this topic here:
With a more level head on, it becomes easier to take on the next step, which creating healthy boundaries—and that doesn’t just mean with other people!
It also means slaying our own perfectionism and imposter syndrome—both things that will have us chasing our tails 36 hours per day if we let them.
See also:
- Perfectionism, And How To Make Yours Work For You
- Imposter Syndrome (And Why Almost Everyone Has It)
❝Burnout is the culture of our times. A culture that expects us to do more and think our way out of everything. A culture that asks for more than the body can bear. Unfortunately, even though the situation might not be of our creation, burnout culture is our inheritance.
An inheritance we can either perpetuate—or change—depending on what we embody.❞
Source: The Embodied MD on Burnout with Dr Claudine Holt
That “embodiment” is partly our choices and actions that we bring and own just as we bring and own our body—and it’s partly our relationship with our body itself, and learning to love it, and work with it to achieve wonderful things, instead of just getting through the day.
Which yes, does also mean making space for good diet, exercise, sleep and so forth, per:
These Top Five Things Make The Biggest Difference To Health
Want to know more?
You might like to check out Dr. Holt’s website:
The Embodied M.D. | Burnout Coach
…where she also offers resources such as a blog and a podcast.
Enjoy!
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A drug that can extend your life by 25%? Don’t hold your breath
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Every few weeks or months, the media reports on a new study that tantalisingly dangles the possibility of a new drug to give us longer, healthier lives.
The latest study centres around a drug involved in targeting interleukin-11, a protein involved in inflammation. Blocking this protein appeared to help mice stave off disease and extend their life by more than 20%.
If only defying the ravages of time could be achieved through such a simple and effort-free way – by taking a pill. But as is so often the case, the real-world significance of these findings falls a fair way short of the hype.
Halfpoint/Shutterstock The role of inflammation in disease and ageing
Chronic inflammation in the body plays a role in causing disease and accelerating ageing. In fact, a relatively new label has been coined to represent this: “inflammaging”.
While acute inflammation is an important response to infection or injury, if inflammation persists in the body, it can be very damaging.
A number of lifestyle, environmental and societal drivers contribute to chronic inflammation in the modern world. These are largely the factors we already know are associated with disease and ageing, including poor diet, lack of exercise, obesity, stress, lack of sleep, lack of social connection and pollution.
While addressing these issues directly is one of the keys to addressing chronic inflammation, disease and ageing, there are a number of research groups also exploring how to treat chronic inflammation with pharmaceuticals. Their goal is to target and modify the molecular and chemical pathways involved in the inflammatory process itself.
What the latest research shows
This new interleukin-11 research was conducted in mice and involved a number of separate components.
In one component of this research, interleukin-11 was genetically knocked out in mice. This means the gene for this chemical mediator was removed from these mice, resulting in the mice no longer being able to produce this mediator at all.
In this part of the study, the mice’s lives were extended by over 20%, on average.
Another component of this research involved treating older mice with a drug that blocks interleukin-11.
Injecting this drug into 75-week old mice (equivalent to 55-year-old humans) was found to extend the life of mice by 22-25%.
These treated mice were less likely to get cancer and had lower cholesterol levels, lower body weight and improved muscle strength and metabolism.
From these combined results, the authors concluded, quite reasonably, that blocking interleukin-11 may potentially be a key to mitigating age-related health effects and improving lifespan in both mice and humans.
Why you shouldn’t be getting excited just yet
There are several reasons to be cautious of these findings.
First and most importantly, this was a study in mice. It may be stating the obvious, but mice are very different to humans. As such, this finding in a mouse model is a long way down the evidence hierarchy in terms of its weight.
Research shows only about 5% of promising findings in animals carry over to humans. Put another way, approximately 95% of promising findings in animals may not be translated to specific therapies for humans.
Second, this is only one study. Ideally, we would be looking to have these findings confirmed by other researchers before even considering moving on to the next stage in the knowledge discovery process and examining whether these findings may be true for humans.
We generally require a larger body of evidence before we get too excited about any new research findings and even consider the possibility of human trials.
Third, even if everything remains positive and follow-up studies support the findings of this current study, it can take decades for a new finding like this to be translated to successful therapies in humans.
Until then, we can focus on doing the things we already know make a huge difference to health and longevity: eating well, exercising, maintaining a healthy weight, reducing stress and nurturing social relationships.
Hassan Vally, Associate Professor, Epidemiology, Deakin University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Why Psyllium Is Healthy Through-And-Through
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Psyllium is the powder of the husk of the seed of the plant Plantago ovata.
It can be taken as a supplement, and/or used in cooking.
What’s special about it?
It is fibrous, and the fiber is largely soluble fiber. It’s a “bulk-forming laxative”, which means that (dosed correctly) it is good against both constipation (because it’s a laxative) and diarrhea (because it’s bulk-forming).
See also, because this is Research Review Monday and we provide papers for everything:
In other words, it will tend things towards being a 3 or 4 on the Bristol Stool Scale ← this is not pretty, but it is informative.
Before the bowels
Because of how it increases the viscosity of substances it finds itself in, psyllium slows stomach-emptying, and thus improves feelings of satiety.
Here’s a study in which taking psyllium before breakfast and lunch resulted in increased satiety between meals, and reduction in food-related cravings:
Satiety effects of psyllium in healthy volunteers
Prebiotic benefits
We can’t digest psyllium, but our gut bacteria can—somewhat! Because they can only digest some of the psyllium fibers, that means the rest will have the stool-softening effect, while we also get the usual in-gut benefits from prebiotic fiber first too:
The Effect of Psyllium Husk on Intestinal Microbiota in Constipated Patients and Healthy Controls
Cholesterol-binding
Psyllium can bind to cholesterol during the digestive process. Why only “can”? Well, if you don’t consume cholesterol (for example, if you are vegan), then there won’t be cholesterol in the digestive tract to bind to (yes, we do need some cholesterol to live, but like most animals, we can synthesize it ourselves).
What this cholesterol-binding action means is that the dietary cholesterol thus bound cannot enter the bloodstream, and is simply excreted instead:
Heart health beyond cholesterol
Psyllium supplementation can also help lower high blood pressure but does not significantly lower already-healthy blood pressure, so it can be particularly good for keeping things in safe ranges:
❝Given the overarching benefits and lack of reported side effects, particularly for hypertensive patients, health care providers and clinicians should consider the use of psyllium supplementation for the treatment or abatement of hypertension, or hypertensive symptoms.❞
Read in full: The effect of psyllium supplementation on blood pressure: a systematic review and meta-analysis of randomized controlled trials ← you can see the concrete numbers here
Is it safe?
Psyllium is first and foremost a foodstuff, and is considered very safe unless you have an allergy (which is rare, but possible).
However, it is still recommended to start at a low dose and work up, because anything that changes your gut microbiota, even if it changes it for the better, will be easiest if done slowly (or else, you will hear about it from your gut).
Want to try some?
We don’t sell it, but here for your convenience is an example product on Amazon
Enjoy!
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