Your Skin Microbiome & The Sun
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Should we soak up the sun for its health benefits, protect our skin from it at all costs? Is sunscreen the one skincare product that everyone truly needs, or is it just adding chemicals to our skin? What’s the truth in a world full of conflicting information?
We’ve tackled some of these questions before, diving into the science of the pros and cons, including:
…and:
And now, today, we’re going to be talking about some entirely new science!
An extra layer of protection
Who would win:
- a 4,600,000,000-year-old ongoing nuclear fusion event whose superheated plasma is held in place by its own immense gravity well, or
- some single-celled organisms that were born a few minutes ago?
The answer is that the latter can, in fact, help to protect us against the former.
Re “born a few minutes ago”: if you’ll pardon the rhetorical device (per “born yesterday” etc), what we mean here is that the life cycle of such microbes is very short, so while your microbiome is as old as you are (albeit in ship of Theseus sort of way), any individual living microbes will not be more than some minutes old.
We mention this not as a matter of mere interesting trivia, but rather because it has practical implications: when it comes to our microbiome (or microbiomes, depending on whether we want to count different sites on/in our body separately, as is often useful, even if technically they all do interact with each other thus they could be considered one big diverse microbiome too), it is a living community that needs to be given the right circumstances to perpetuate and favorably mutate itself constantly.
It’s not something that can be optimized and then just taken for granted. Because sure, given good conditions, an optimized microbiome will then continue to self-perpetuate, mutate as it goes, and by virtue of natural selection, continue to persist against threats. But if not given good conditions? You could wreak havoc with it and take weeks or more for it to recover. And if those bad conditions are chronic, it might never recover.
So, more on healthy microbiome curation later, but first, the exciting new science!
Teaser:
❝This pivotal study shows that microbial communities are not passive victims of environmental stress but dynamic regulators of immune responses, capable of metabolizing UV-induced skin products such as cis-urocanic acid. This newly uncovered role of microbial metabolism in modulating UV tolerance reshapes our understanding of the skin barrier — not just as a structural shield but as a metabolically active, microbially regulated interface. With increasing concerns about UV exposure, skin aging, and cancer, a deeper understanding of this axis offers promising avenues for therapy and prevention.❞
~ Dr. Anna Di Nardo (not one of the study authors, just a physician-scientist expert in the field)
In few words: researchers have discovered that certain bacteria on our skin help protect us from sun damage and also play a role in controlling our immune system.
How this works: when sunlight (especially UVB rays) hits our skin, it changes a natural chemical there (namely: trans-urocanic acid) into a dangerous form (namely: cis-urocanic acid), which also incidentally weakens the immune system. Some skin bacteria can break down this harmful chemical with an enzyme they produce (namely: urocanase). This enables the skin to better manage its skin exposure; specifically, controlling responses to UV exposure.
This is exciting, because it’s the first evidence of a direct link between UV rays, a skin molecule, and microbial activity affecting health outcomes, not just passively, but through active metabolism.
You can read the paper itself here:
Great! How can we make use of this information?
Per the researchers’ conclusions, these insights could change how we think about sun protection, immune-related skin diseases, skin cancer, and more. The note also that future sun care could include microbiome-aware treatments that adjust bacterial metabolism to improve skin health after sun exposure.
And in the meantime? Generally speaking when it comes to microbiome health (any microbiome; gut, oral, skin, etc), a good rule of thumb is “if in doubt, just leave it alone and let it do its thing”.
This might sound like passive “do-nothing” advice, and in a way it is, but a lot of people don’t do nothing, and when it comes to the skin microbiome in particular, it’s very common for people to invest a lot of time and energy into killing everything that moves, so the advice here is “stop doing that”.
Which doesn’t mean you mustn’t wash; by all means, feel free to wash, but gently.
We’ve written a bit about this before:
And if you already have sun-damaged skin…
Undo The Sun’s Damage To Your Skin
Take care!
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The Minimum Method – by Joey Thurman
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Trying to squeeze out an extra 0.5% from every effort in life can be exhausting, especially with diminishing marginal returns when it comes to linear increases in effort.
Surely there must be a sweet spot of getting the best returns on the least effort and call it a day?
That’s what this book is about. Thurman examines and explains how to get “the most for least” in various important areas of health, including diet, exercise, sleep, breathwork, recovery, and a chapter specifically on brain health, though of course all the aforementioned things do affect brain health too.
An interesting feature of the book is that at the end of each chapter, he’ll give different advice for different levels of experience/commitment, so that essentially there’s an easy/medium/hard way to proceed each time.
The style is light and personal, without much hard science. The advice given is nonetheless consistent with prevailing scientific consensus, and there are still occasional scientific references throughout, with links to appropriate studies. Mostly though, the focus is on being practical.
Bottom line: if you’ve been looking for a “most for least” way of going about health, this is a fine option.
Click here to check out The Minimum Method, and enjoy benefits disproportionate to your effort!
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Fully Present – by Dr. Susan Smalley and Diana Winston
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“The Science and the Art of…” tends to be a bit of a fuzzy obfuscation, but in this case, it’s accurate, especially in this presentation. The authors are, indeed, a scientist and an artist—and both practitioners, meeting in the middle.
As such, we get the clinical insights of a researcher and professor of psychiatry, and the grounded-yet-spiritual insights of an erstwhile Buddhist nun.
While the book is pop psychology in essence, the format is much more that of a textbook than a self-help book. Will it be useful for helping yourself anyway, though? Yes, absolutely, if you apply the information contained within.
Don’t be fooled into thinking that a textbook format makes it dry, though—the writing is very compelling, and you’ll find yourself turning pages eagerly. There’s no time like the present, after all!
Bottom line: if you find the scientific evidence-base for the usefulness of mindfulness appealing, but find a lot of guides a little fluffy, this one is perfectly balanced—and very well written, too.
Click here to check out Fully Present, bring yourself into the moment, always!
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Figs vs Passion Fruit – Which is Healthier?
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Our Verdict
When comparing figs to passion fruit, we picked the passion fruit.
Why?
Both are top-tier fruits! But the passion fruit is just that bit more passionate about delivering healthy nutrients:
In terms of macros, passion fruit has slightly more carbs, notably more protein, and a lot more fiber, giving it the win in this category.
In the category of vitamins, figs have more of vitamins B1, B5, B6, E, and K, while passion fruit has more of vitamins A, B2, B3, B9, C, and choline, making for a marginal win by the numbers for passion fruit here.
When it comes to minerals, figs have more calcium, manganese, and zinc, while passion fruit has more copper, iron, magnesium, phosphorus, potassium, and selenium. A clearer win for passion fruit this time.
Adding up the sections makes for an easy overall win for passion fruit, but again, figs are really a top-tier fruit too; passion fruit just beats them! By all means enjoy either or both; diversity is good!
Want to learn more?
You might like:
Top 8 Fruits That Prevent & Kill Cancer ← figs have antitumor effects specifically, while removing carcinogens too, and additionally sensitizing cancer cells to light therapy
Enjoy!
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Grapefruit vs Lime – Which is Healthier?
10almonds is reader-supported. We may, at no cost to you, receive a portion of sales if you purchase a product through a link in this article.
Our Verdict
When comparing grapefruit to lime, we picked the lime.
Why?
Both have their merits, but…
In terms of macros, limes have 2x the fiber, for comparable protein and carbs. Thus, the winner in the macros category.
In the category of vitamins, grapefruit has more of vitamins A, B1, and B9, while limes have more of vitamins E and K. They’re approximately equal on other vitamins they both contain (including, notably, vitamin C, of which they are both good sources, and one cup of chopped fruit will provide the RDA of vitamin C), so this is a marginal 3:2 win for grapefruit in this round.
Looking at minerals, grapefruit has more magnesium, manganese, and and potassium, while limes have more calcium, copper, iron, selenium, and zinc. So, a win for limes here.
One final consideration that’s not shown in the nutritional values, is that grapefruit contains high levels of furanocoumarin, which can inhibit cytochrome P-450 3A4 isoenzyme and P-glycoptrotein transporters in the intestine and liver—slowing down their drug metabolism capabilities, thus effectively increasing the bioavailability of many drugs manifold.
This may sound superficially like a good thing (improving bioavailability of things we want), but in practice it means that in the case of many drugs, if you take them with (or near in time to) grapefruit or grapefruit juice, then congratulations, you just took an overdose. This happens with a lot of meds for blood pressure, cholesterol (including statins), calcium channel-blockers, anti-depressants, benzo-family drugs, beta-blockers, and more. Oh, and Viagra, too. Which latter might sound funny, but remember, Viagra’s mechanism of action is blood pressure modulation, and that is not something you want to mess around with unduly. So, do check with your pharmacist to know if you’re on any meds that would be affected by grapefruit or grapefruit juice!
PS: the same substance is quite available in pummelos and sour oranges (but not meaningfully in sweet oranges); you can see a chart here showing the relative furanocoumarin contents of many citrus fruits, or lack thereof as the case may be, as it isn’t very present in lemons and most limes).
Adding up the sections gives us an overall win for limes, but by all means enjoy either or both; just watch out for that furanocoumarin content of grapefruit if you’re on any meds affected by such (again, do check with your pharmacist, as our list was far from exhaustive—and yes, this question is one that a pharmacist will answer more easily and accurately than a doctor will).
Want to learn more?
You might like:
Top 8 Fruits That Prevent & Kill Cancer ← citrus fruits in general make the list; they inhibit tumor growth and kill cancer cells; regular consumption is also associated with a lower cancer risk 🙂
Enjoy!
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Serotonin For More Than Just Happiness
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Serotonin is often known simply as the happiness hormone—which often gets it conflated with dopamine, which, like serotonin, is also a neurotransmitter strongly associated with pleasure.
For a deeper dive into the similarities and (important!) differences, see:
Serotonin vs Dopamine (Know The Differences)
And since serotonin also gets conflated with oxytocin (“the cuddle chemical”), see:
Neurotransmitter Cheatsheet ← four important neurotransmitters (the fourth being adrenaline/epinephrine), what they each do, and how to have more of them if you need more, and the downsides of having too much.
Today, we’re focusing on serotonin. Which, like 3/4 of the aforementioned neurotransmitters, is a targeted molecule in many antidepressants. In fact, selective serotonin re-uptake inhibitors (SSRIs) are perhaps the most commonly-used class of antidepressants in the world.
For more on that, see: Antidepressants: Personalization Is Key!
The lights are on…
Much like dopamine is associated with pleasure but is also critical for unrelated things such as motor skills and language faculties, serotonin does more than just make us happy.
It also makes us feel awake, and as such, is in many ways the counterpart of the closely-related hormone melatonin.
And, we now know, it’s also involved in decision-making!
Specifically, new research has shown that serotonin receptor (5-HT) neurons in the brainstem are interconnected, not acting independently as previously thought. The researchers used electrophysiology, cellular imaging, optogenetics, behavioral methods, mathematical modeling, and computer simulations, so we’ll not go into all the details (but we will link the paper in a moment).
What’s important about this is that they discovered distinct groups of serotonin neurons with specific activity patterns, each regulating serotonin release in different brain regions.
What’s important about that is that this goes against the traditional view of serotonin signaling as monolithic in a very binary sense, and supports a more dynamic, functionally competitive model among neuron groups, since high-activity serotonin ensembles can suppress the activity of lower-activity ensembles, affecting overall serotonin release.
To put it in less clinical terms: the ebb and flow of serotonin in our brain is not merely a matter of “more serotonin vs less serotonin”, but also a matter of where exactly in the brain that serotonin is more (or less) active.
For example (and with minimal use of clinical terms), the lateral habenula, a part of the brain involved in frustration and threat assessment, influences serotonin neuron activity, impacting binary decision-making (e.g. risk-taking vs safety-seeking choices).
This is big, because that was previously considered to be the sole domain of dopamine (in its role as “motivation molecule”).
For example: The Meds That Impair Decision-Making
Since this serotonin model allows for a lot more nuance, it could pave the way for new ways of treating conditions ranging from addictions to depression to anxiety and more.
You can read the paper in full here:
Nonlinear recurrent inhibition through facilitating serotonin release in the raphe
…and a pop-science article (with diagrams, taken from the paper) here:
Serotonin system’s hidden complexity may reshape understanding of day-to-day decision making
…which goes into more detail than we have room to here.
Want to learn more?
Check out:
The Gut Bacteria That Improve Your General Decision-Making In Life ← remembering that serotonin is not made in the brain like dopamine mostly is, but rather, is made in your gut, by your gut bacteria (so please look after those!)
Take care!
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The FDA Just Redefined “Healthy”—But How?
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In the ongoing war of labelling regulations (usually with advertisers on one side and regulators on the other), the FDA has updated what’s required in order to label a food as “healthy”.
Here’s what they’re now* requiring:
To bear the “healthy” claim, a food product needs to:
- Contain a certain amount of food (food group equivalent) from at least one of the food groups or subgroups (such as fruits, vegetables, fat-free and low-fat dairy etc.) recommended by the Dietary Guidelines.
- Adhere to specified limits for the following nutrients: saturated fat, sodium, and added sugars.
Source: FDA | Press Releases | FDA Finalizes Updated “Healthy” Nutrient Content Claim
*however, manufacturers have 3 years to conform, which if we’re being cynical about it, looks suspiciously like just short of a US presidential election cycle so that actual enforcement will be someone else’s problem.
Will it help?
Maybe! It’s not too dissimilar to the “traffic light system” already in use in Europe, although that currently emphasizes the absence/presence of “bad things” e.g. saturated fat, sodium, and added sugars.
It has its faults, because for example…
- not all saturated fat is bad, and a jar of coconut oil is now definitely going to get labelled as very unhealthy
- low-sodium salt is, ironically, going to to get flagged as being very high in sodium and therefore unhealthy
This latter is because on a g/100g basis, a product that’s ⅓ sodium chloride is going to have a lot of sodium, even if it’s approaching ⅔ less sodium than the product it’s (healthily!) replacing.
However, on a large scale, these kinds of problems are surely going to be small next to (hopefully) manufacturers scrambling to find ways to cut down on the saturated fats, sodium, and added sugars.
You may be wondering…
What will they replace them with?
Sometimes, companies trying to make something healthier will mess up, like when the health risks of smoking hit public consciousness, one cigarette company had the bright idea of putting asbestos in their filter tips, to market them as healthier. So, could something similar happen here?
- Saturated fat: definitely could; because the health benefits/risks of different kinds of fats and their constituent fatty acids are a lot more nuanced than just “saturated” vs “mono-/polyunsaturated”, it is definitely possible that companies may replace healthier saturated-heavy fats with less healthy unsaturated fats, depending on what is cheaper.
- See also: Can Saturated Fats Be Healthy?
- Sodium: probably not; likely go-to replacements for sodium chloride will be potassium chloride (healthier than sodium chloride) and MSG (has an unearned bad reputation in the US, but is healthier than sodium chloride).
- Added sugars: probably—things get very complicated very quickly when it comes to artificial sweeteners, and also the crux will definitely lie in what gets defined as an “added sugar”; watch out for a rise in the use of things that slide by the definition of added sugar while still being chemically (and, which is important, metabolically) the same thing.
Well that doesn’t sound great
It doesn’t, but on the flipside, the positive inclusions will probably be mostly good.
For example, the only way to get a “healthy” labelling in including fiber is to include more fiber, same with vitamins and minerals.
The low-fat dairy thing could possibly get abused (much like with the general “low-fat” trend of the 80s).
The “portion of fruit” thing will need to be carefully defined to avoid running straight back into the “this is just added sugar by another name” problem; mostly that it’ll need to still include the same amount of fiber as was in the whole fruit, gram for gram.
See also: What Matters Most For Your Heart? ← it’s about fiber, not salt or saturated fats!
Take care!
Don’t Forget…
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