What’s the difference between physical and chemical sunscreens? And which one should you choose?
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Sun exposure can accelerate ageing, cause skin burns, erythema (a skin reaction), skin cancer, melasmas (or sun spots) and other forms of hyperpigmentation – all triggered by solar ultraviolet radiation.
Approximately 80% of skin cancer cases in people engaged in outdoor activities are preventable by decreasing sun exposure. This can be done in lots of ways including wearing protective clothing or sunscreens.
But not all sunscreens work in the same way. You might have heard of “physical” and “chemical” sunscreens. What’s the difference and which one is right for you?
How sunscreens are classified
Sunscreens are grouped by their use of active inorganic and organic ultraviolet (UV) filters. Chemical sunscreens use organic filters such as cinnamates (chemically related to cinnamon oil) and benzophenones. Physical sunscreens (sometimes called mineral sunscreens) use inorganic filters such as titanium and zinc oxide.
These filters prevent the effects of UV radiation on the skin.
Organic UV filters are known as chemical filters because the molecules in them change to stop UV radiation reaching the skin. Inorganic UV filters are known as physical filters, because they work through physical means, such as blocking, scattering and reflection of UV radiation to prevent skin damage.
Nano versus micro
The effectiveness of the filters in physical sunscreen depends on factors including the size of the particle, how it’s mixed into the cream or lotion, the amount used and the refraction index (the speed light travels through a substance) of each filter.
When the particle size in physical sunscreens is large, it causes the light to be scattered and reflected more. That means physical sunscreens can be more obvious on the skin, which can reduce their cosmetic appeal.
Nanoparticulate forms of physical sunscreens (with tiny particles smaller than 100 nanometers) can improve the cosmetic appearance of creams on the skin and UV protection, because the particles in this size range absorb more radiation than they reflect. These are sometimes labelled as “invisible” zinc or mineral formulations and are considered safe.
So how do chemical sunscreens work?
Chemical UV filters work by absorbing high-energy UV rays. This leads to the filter molecules interacting with sunlight and changing chemically.
When molecules return to their ground (or lower energy) state, they release energy as heat, distributed all over the skin. This may lead to uncomfortable reactions for people with skin sensitivity.
Generally, UV filters are meant to stay on the epidermis (the first skin layer) surface to protect it from UV radiation. When they enter into the dermis (the connective tissue layer) and bloodstream, this can lead to skin sensitivity and increase the risk of toxicity. The safety profile of chemical UV filters may depend on whether their small molecular size allows them to penetrate the skin.
Chemical sunscreens, compared to physical ones, cause more adverse reactions in the skin because of chemical changes in their molecules. In addition, some chemical filters, such as dibenzoylmethane tend to break down after UV exposure. These degraded products can no longer protect the skin against UV and, if they penetrate the skin, can cause cell damage.
Due to their stability – that is, how well they retain product integrity and effectiveness when exposed to sunlight – physical sunscreens may be more suitable for children and people with skin allergies.
Although sunscreen filter ingredients can rarely cause true allergic dermatitis, patients with photodermatoses (where the skin reacts to light) and eczema have higher risk and should take care and seek advice.
What to look for
The best way to check if you’ll have a reaction to a physical or chemical sunscreen is to patch test it on a small area of skin.
And the best sunscreen to choose is one that provides broad-spectrum protection, is water and sweat-resistant, has a high sun protection factor (SPF), is easy to apply and has a low allergy risk.
Health authorities recommend sunscreen to prevent sun damage and cancer. Chemical sunscreens have the potential to penetrate the skin and may cause irritation for some people. Physical sunscreens are considered safe and effective and nanoparticulate formulations can increase their appeal and ease of use.
Yousuf Mohammed, Dermatology researcher, The University of Queensland and Khanh Phan, Postdoctoral research associate, Frazer Institute, The University of Queensland
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Survival of the Prettiest – by Dr. Nancy Etcoff
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Beauty is in the eye of the beholder, right? And what does it matter, in this modern world, especially if we are already in a happy stable partnership?
The science of it, as it turns out, is less poetic. Not only is evolutionary psychology still the foundation of our perception of human beauty (yes, even if we have zero possibility of further procreation personally), but also, its effects are far, far wider than partner selection.
From how nice people are to you, to how much they trust you, to how easily they will forgive a (real or perceived) misdeed, to what kind of medical care you get (or don’t), your looks shape your experiences.
In this very easy-reading work that nevertheless contains very many references, Dr. Etcoff explores the science of beauty. Not just what traits are attractive and why, but also, what they will do for (or against) us—in concrete terms, with numbers.
Bottom line: if you’d like to better understand the subconscious biases held by yourself and others, this book is a top-tier primer.
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Water Fluoridation, Atheroma, & More
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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 😎
❝I watched a documentary recently on Fluoride in our drinking water & the dangers of it. Why are we poisoning our water?❞
This is a great question, and it certainly is controversial. It sounds like the documentary you watched was predominantly or entirely negative, but there’s a lot of science to back both sides of this, and it’s not even that the science is contradictory (it’s not). It’s that what differs is people’s opinions about whether benefiting one thing is worth creating a risk to another, and that means looking at:
- What is the risk associated with taking no action (error of omission)?
- What is the risk associated with taking an action (error of commission)?
The whole topic is worth a main feature, but to summarize a few key points:
- Water fluoridation is considered good for the prevention of dental cavities
- Water fluoridation aims to deliver fluoride and doses far below dangerous levels
- This requires working on consumer averages, though
- ”Where do we put the safety margins?” is to some extent a subjective question, in terms of trading off one aspect of health for another
- Too much fluoride can also be bad for the teeth (at least cosmetically, creating little white* spots)
- Detractors of fluoride tend to mostly be worried about neurological harm
- However, the doses in public water supplies are almost certainly far below the levels required to cause this harm.
- That said, again this is working on consumer averages, though.
- However, the doses in public water supplies are almost certainly far below the levels required to cause this harm.
- A good guide is: watch your teeth! Those white* spots will be “the canary in the coal mine” of more serious harm that could potentially come from higher levels due to overconsumption of fluorine.
*Teeth are not supposed to be pure white. The “Hollywood smile” is a lie. Teeth are supposed to be a slightly off-white, ivory color. Anything whiter than that is adding something else that shouldn’t be there, or stripping something off that should be there.
❝How does your diet change clean out your arteries of the bad cholesterol?❞
There’s good news and bad news here, and they can both be delivered with a one-word reply:
Slowly.
Or rather: what’s being cleaned out is mostly not the LDL (bad) cholesterol, but rather, the result of that.
When our diet is bad for cardiovascular health, our arteries get fatty deposits on their walls. Cholesterol gets stuck here too, but that’s not the main physical problem.
Our body’s natural defenses come into action and try to clean it up, but they (for example macrophages, a kind of white blood cell that consumes invaders and then dies, before being recycled by the next part of the system) often get stuck and become part of the buildup (called atheroma), which can lead to atherosclerosis and (if calcium levels are high) hardening of the arteries, which is the worst end of this.
This can then require medical attention, precisely because the body can’t remove it very well—especially if you are still maintaining a heart-unhealthy diet, thus continuing to add to the mess.
However, if it is not too bad yet, yes, a dietary change alone will reverse this process. Without new material being added to the arterial walls, the body’s continual process of rejuvenation will eventually fix it, given time (free from things making it worse) and resources.
In fact, your arteries can be one of the quickest places for your body to make something better or worse, because the blood is the means by which the body moves most things (good or bad) around the body.
All the more reason to take extra care of it, since everything else depends on it!
You might also like our previous main feature:
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Burn! How To Boost Your Metabolism
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Let’s burn! Metabolic tweaks and hacks
Our metabolism is, for as long as we live, a constantly moving thing. And it’s not a monolith either; there are parts of our metabolism that can speed up or slow down independently of others.
If we talk about metabolism without clarifying context, though, this is usually about one’s “basal metabolic rate”, that is, how many calories we burn just by being alive.
Why do we want to speed it up? Might we ever want to slow it down?
We might want to slow our metabolism down in survival circumstances, but generally speaking, a faster metabolism is a better one.
Yes, even when it comes to aging. Because although metabolism comes with metabolizing oxygen (which, ironically, tends to kill us eventually, since this is a key part of cellular aging), it is still beneficial to replace cells sooner rather than later. The later we replace a given cell (ie, the longer the cell lives), the more damaged it gets, and then the copy is damaged from the start, because the damage was copied along with it. So, best to have a fast metabolism to replace cells quickly when they are young and healthy.
A quick metabolism helps the body to do this.
Most people, of course, are interested in a fast metabolism to burn off fat, but beware: if you increase your metabolism without consideration to how and when you consume calories, you will simply end up eating more to compensate.
One final quick note before we begin:
Limitations
There’s a lot we can do to change our metabolism, but there are some things that may be outside of our control. They include:
- Age—we can influence our biological age, but we cannot (yet!) halt aging, so this will happen
- Body size—and yes we can change this a bit, but we all have our own “basic frame” to work with. Someone who is 6’6” is never going to be able to have the same lower-end-of-scale body mass of someone who is 5’0”, say.
- Sex—this is about hormones, and HRT is a thing, but for example, broadly speaking, men will have faster metabolisms than women, because of hormonal differences.
- Medical conditions—often also related to other hormones, but for example someone with Type 1 Diabetes is going to have a very different relationship with their metabolism than someone without, and someone with a hypo- or hyperactive thyroid will again have a very different metabolism in a way that that lifestyle factors can’t completely compensate for.
The tips and tricks
Intermittent fasting
Intermittent fasting has been found to, amongst other things, promote healthy apoptosis and autophagy (in other words: early programmed cell death and recycling—these are good things).
It also has anti-inflammatory benefits and decreases the risk of insulin resistance. In other words, intermittent fasting boosts the metabolism while simultaneously guarding against some of the dangers of a faster metabolism (harms you’d get if you instead increased your metabolism by doing intense exercise and then eating a mountain of convenience food to compensate)
Read the science: Intermittent Fasting: Is the Wait Worth the Weight?
Read our prior article: Fasting Without Crashing? We Sort The Science From The Hype
Enjoy plenty of protein
This one won’t speed your metabolism up, so much as help it avoid slowing down as a result of fat loss.
Because of our body’s marvelous homeostatic system trying to keep our body from changing status at any given time, often when we lose fat, our body drops our metabolism to compensate, thinking we are in an ongoing survival situation and food is scarce so we’d better conserve energy (as fat). That’s a pain for would-be weight-loss dieters!
Eating protein can let our body know that we’re perfectly safe and not starving, so it will keep the metabolism ticking over nicely, without putting on fat.
Read the science: The role of protein in weight loss and maintenance
Stay hydrated
People think of drinking water as part of a weight loss program being just about filling oneself up, and that is a thing, but it also has a role to play in our metabolism. Specifically, lipolysis (the process of removing fat).
Because, we are mostly water. Not only is it the main content of our various body tissue cells, but also, of particular note, our blood (the means by which everything is transported around our body) is mostly water, too.
It’s hard for the body to keep everything ticking over like a well-oiled machine if its means of transportation is sluggish!
Check it out: Increased Hydration Can Be Associated with Weight Loss
Take a stand
That basal metabolic rate we talked about?
- If you’re lying down at rest, that’s what your metabolism will be like.
- If you’re sitting up, it’ll be a little quicker, but not much.
- If you’re standing, suddenly half your body is doing things, and you don’t even notice them because they’re just stabilizing muscles and the like, but on a cellular level, your body gets very busy.
Read all about it: Cardiometabolic impact of changing sitting, standing, and stepping in the workplace
Time to invest in a standing desk? Or a treadmill in front of the TV?
The spice of life
Capsaicin, the compound in many kinds of pepper that give them their spicy flavor, boosts the metabolism. In the words of Tremblay et al for the International Journal of Obesity:
❝[Capsaicin] stimulates the sympathoadrenal system that mediates the thermogenic and anorexigenic effects of capsaicinoids.
Capsaicinoids have been found to accentuate the impact of caloric restriction on body weight loss.
Some studies have also shown that capsinoids increase energy expenditure.
Capsaicin supplementation attenuates or even prevents the increase in hunger and decrease in fullness as well as the decrease in energy expenditure and fat oxidation, which normally result from energy restriction❞
Read for yourself: Capsaicinoids: a spicy solution to the management of obesity?
You snooze, you lose (fat)
While exercising is generally touted as the road to weight loss, and certainly regular exercise does have a part to play, doing so without good rest will have bad results.
In fact, even if you’re not exercising, if you don’t get enough sleep your metabolism will get sluggish to try to slow you down and encourage you to sleep.
So, be proactive, and make getting enough good quality sleep a priority.
Eat for metabolic health
Aside from the chilli peppers we mentioned, there are other foods associated with good metabolic health. We don’t have room to go into the science of each of them here, but here’s a well-researched, well-sourced standalone article listing some top choices:
The 12 Best Foods to Boost Your Metabolism
Enjoy!
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Antihistamines for Runny Nose?
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It’s Q&A Day at 10almonds!
Have a question or a request? We love to hear from you!
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 😎
❝Do you have any articles about using Anti-Histamines? My nose seems to be running a lot. I don’t have a cold or any allergies that I know of. I tried a Nasal spray Astepro, but it doesn’t do much.?❞
Just for you, we wrote such an article yesterday in response to this question!
The Astepro that you tried, by the way, is a brand name of the azelastine we mentioned near the end, before we got to talking about systemic corticosteroids such as beclometasone dipropionate—this latter might help you if antihistamines haven’t, and if your doctor advises there’s no contraindication (for most people it is safe for there are exceptions, such as if you are immunocompromised and/or currently fighting some infection).
You can find more details on all this in yesterday’s article, which in case you missed it, can be found at:
Antihistamines’ Generation Gap: Are You Ready For Allergy Season?
Enjoy!
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Can We Do Fat Redistribution?
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The famous answer: no
The truthful answer: yes, and we are doing it all the time whether we want to or not, so we might as well know what things affect our fat distribution in various body parts.
There’s a kernel of truth in the “no”, though, and where that comes from is that we cannot exclusively put fat on in a certain area only, and nor can we do “spot reduction”, i.e., intentionally lose fat from only one place.
How, then, do we do fat redistribution?
Your body is a living organism, not a statue
It’s easy to think “I’ve been carrying this fat in this place for 20 years”, but during that time the fat has been replaced several times and moved often; in fact, the cells containing the fat have even been replaced. Because: fat can seem like a substance that’s alien to your body because it doesn’t respond like muscles, isn’t controllable like muscles, doesn’t have the same sensibility as muscles, etc. But, every bit of fat stored in your body is stored inside a fat cell; it’s not one big unit of fat; it’s lots of tiny ones.
In reality, any given bit of fat on your body has probably been there for 18–24 months at most:
Fat turnover in obese slower than average
…and there are assorted factors that can modify the rate at which our body deals with fat storage:
Human white adipose tissue: A highly dynamic metabolic organ
So, how do I get rid of this tummy?
There are plenty of stories of people who try to lose weight from one part of their body, and lose it from somewhere else instead. Say, a person wants to lose weight from her hips, and with careful diet and exercise, she loses weight—by dropping a couple of bra cup sizes while keeping the hips.
So, we must figure out: why is fat stored in certain places? And the main driving factors are:
- hormones
- metabolic health
- stress
Hormones affect fat distribution insofar as estrogen and progesterone will favor the hips, thighs, butt, breasts, and testosterone will favor a more central (but still subcutaneous, not visceral) distribution. Additionally, estrogen and progesterone will favor a higher body fat percentage, while testosterone will favor a lower one.
This is particularly relevant later in life, when suddenly the hormone(s) you’ve been relying on to keep your shape, are now declining, meaning your shape does too. This goes for everyone regardless of sex.
See:
- What You Should Have Been Told About The Menopause Beforehand
- The BAT-pause! ← this is about the conversion of white adipose tissue to brown adipose tissue, and how estrogen helps this happen
- Topping Up Testosterone?
Metabolic health affects fat distribution insofar as poor metabolic health will result in more fat being stored in the viscera, rather than in the usual subcutaneous places. This is a serious health risk.
See: Visceral Belly Fat & How To Lose It
Stress affects fat distribution insofar as chronically elevated cortisol levels see more fat sent to the stomach, face, and neck. This fat redistribution isn’t dangerous itself, but it can be indicative of the chronic stress, which does pose more of a general threat to health.
See: Lower Your Cortisol! (Here’s Why & How)
What this means in practical terms
Assuming that you would like the fat distribution that says “this is a healthy woman” or “this is a healthy man”, respectively, then you might want to:
- Check your sex hormone levels and get them adjusted if appropriate
- Improve your overall metabolic health—without necessarily trying to lose weight, just, take care of your blood sugars for example, and they will take care of you in terms of fat storage.
- Manage your stress (which includes any stress you are experiencing about your body not being how you’d like it to be).
If you are doing these things, and you don’t have any major untreated medical abnormalities that affect these things, then your fat will go to the places generally considered healthiest.
Can we speed it up?
Yes, we can! Firstly, we can speed up our overall metabolism:
Let’s Burn! Metabolic Tweaks And Hacks
Secondly, we can encourage our body to “move” fat by intentionally “yo-yoing”, something usually considered bad in dieting when people just want to lose weight and instead are going up and down, but: if you lose weight healthily, it comes off everywhere evenly, and if you gain weight healthily, it goes mostly to the places where it should be.
So, a sequence of lose-gain-lose-gain might look like “lose a bit from everywhere, put it back in the good place, lose a bit more from everywhere, put it back in the good place”, etc.
So, you might want to gently cycle these a few months apart, for example:
How To Lose Fat (Healthily!) | How To Gain Fat (Healthily!)
You can also cheat a little, if it suits your purpose! By this we mean: if you’d like a little extra where you already have a little fat, then you can put muscle on underneath it, it will pad it up, and (because of the layer of actual fat on top) nobody will know the difference unless you flex it with their hand on it.
Let’s put it this way: people doing squats for a bubble-butt aren’t doing it to put on fat; they’re putting muscle on under the fat they have.
So, check out: How To Gain Muscle (Healthily!)
And finally, for all your body-sculpting needs, we present these excellent books:
Women’s Strength Training Anatomy Workouts – by Frédéric Delavier
Strength Training Anatomy (For Men) – by Frédéric Delavier
Enjoy!
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How To Avoid Self-Hatred & Learn To Love Oneself More
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Alain de Botton gives a compassionate, but realistic, explanation in this video:
The enemy within
Or rather, the collaborator within. Because there’s usually first an enemy without—those who are critical of us, who consider that we are bad people in some fashion, and may indeed get quite colorful in their expressions of this.
Sometimes, their words will bounce straight off us; sometimes, their words will stick. So what’s the difference, and can we do anything about it?
The difference is: when their words stick, it’s usually because on some level we believe their words may be true. That doesn’t mean they necessarily are true!
They could be (and it would be a special kind of hubris to assume no detractor could ever find a valid criticism of us), but very often the reason we have that belief, or at least that fear/insecurity, is simply because it was taught to us at an early age, often by harsh words/actions of those around us; perhaps our parents, perhaps our schoolteachers, perhaps our classmates, and so forth.
The problem—and solution—is that we learn emotions much the same way that we learn language; only in part by reasoned thought, and rather for the most part, by immersion and repetition.
It can take a lot of conscious self-talk to undo the harm of decades of unconscious self-talk based on what was probably a few years of external criticisms when we were small and very impressionable… But, having missed the opportunity to start fixing this sooner, the next best time to do it is now.
We cannot, of course, simply do what a kind friend might do and expect any better results; if a kind friend tells us something nice that we do not believe is true, then however much they mean it, we’re not going to internalize it. So instead, we must simply chip away at those unhelpful longstanding counterproductive beliefs, and simply build up the habit of viewing ourselves in a kinder light.
For more on all this, enjoy:
Click Here If The Embedded Video Doesn’t Load Automatically!
Want to learn more?
You might also like to read:
- Escape From The Clutches Of Shame
- To Err Is Human; To Forgive, Healthy
- How To Get Your Brain On A More Positive Track (Without Toxic Positivity)
Take care!
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