Elias and Williams: The Inside-Out of Skin by dermatologists and skin researchers Peter M. Elias, M.D. and Mary L. Williams, M.D.

The Inside-Out of Skin

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Q&A

While we strive to reply to queries posted to us, we may not be able to answer all individually. Many of the questions you pose may be of general interest to our readers and will be addressed here.

Q& A: Preventing Dry Skin From COVID-19 Hand Washing And Toxic Hand Sanitizers

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Q: I have developed dry skin from COVID-19 because I have to wash my hands so often. Hand sanitizers are even worse in drying out my skin and, anyway, I’m afraid to use them because I’ve heard they’re toxic.  What should I do?

A: Unquestionably, both soap and skin cleansers, as well as alcohol-based hand sanitizers are drying, because, in the process of washing away dirt and killing microorganisms, they also extract some of the natural oils from our skin that hold in our moisture. They inevitably remove some of lipids that are responsible for the skin’s permeability barrier. 

People endowed with sensitive skin are more susceptible to the drying effects of soaps and sanitizers, because their skin barrier is weaker.  I’m guessing that you may be one of the many among us who have “sensitive” skin. 

Dry skin from COVID-19 is becoming a common problem.

Sensitive skin or not, we all must protect ourselves from the virus that causes COVID-19.  So what can we do?

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Q: Will Bathing Dry Out My Skin?

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If you have patches of dry skin to begin with, how often you bathe and how you do it can make a big difference. Too frequent bathing, particularly if using hot water and a strong soap, can aggravate dry skin.

Bathing two or three times weekly in tepid water, using a mild soap or cleanser, and preferably followed by the application of a moisturizing cream or ointment soon afterwards – but not a lotion – may not pose a problem for your skin.

Normal skin is somewhat like a well-greased frying pan.  Skin generates fat (lipids) for its outermost layer, the stratum corneum, in order to waterproof us – that is, to produce our skin’s permeability barrier. We all know that if you want to clean a frying pan of all of its grease, you need to plunge it into hot water, and scrub it using a generous amount of dish soap or detergent.

Unfortunately, many of us treat our skin just as if it were a greasy frying pan.

We take showers or baths using water as hot as we can tolerate, and then we scrub our skin vigorously with a soapy cloth. While this is an effective means to remove dirt and other accumulated debris, it also extracts some of the  protective lipids from our stratum corneum. As our stratum corneum becomes deficient in these natural oils or ‘lipids’, it gets even dryer. And as a result, if our skin tends to be dry in the first place, bathing like this can make it worse.

A gentle skin care routine – cooler water, milder cleanser, and the use of a moisturizer afterwards – is especially important for people with skin conditions like eczema or atopic dermatitis, and for seniors, all of whom are particularly prone to problematic dry skin.  Most lotions are mostly water and continue too little lipid or other moisturizing contents to be effective. For this reason, in most cases a cream or ointment is a better choice for a moisturizer.

For more information on skin care practices, sign up to receive our free booklet: “Taking Good Care of Your Skin”.

Q & A: Oxidative stress

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Q: You mentioned that air pollution can produce ‘oxidative stress’ in the skin. What is oxidative stress and why is it a problem?

A: Oxidative stress is implicated in the cause of many common diseases, such as heart disease from atheroscleosis and high blood pressure, diabetes, cancer, and even Alzheimer’s disease. It is also linked to skin aging, skin cancer and common skin diseases like atopic dermatitis (or eczema). Oxidative stress occurs when the body’s own defenses against oxidative injuries are overwhelmed.

Oxygen is both good and bad at the same time.

Oxygen, of course, provides the key to animal life. We breathe in oxygen from the atmosphere and use it to access the energy stored within the foods we eat. But oxygen has its dark side. As our cells use oxygen to capture energy in glucose and other fuels, they also generate on the side a number of highly reactive compounds, called ‘reactive oxygen species’ or ROS for short. These include: superoxide, hydrogen peroxide, hydroxyl radicals and singlet oxygen. These undesired ROS can cause damage to membranes of the cell, as well as its proteins and DNA. This damage can lead to inflammation, cell death or cell proliferation – processes that underlie many of these chronic diseases associated with aging.

This type of oxidative stress, produced as a byproduct of normal metabolism, represents the vulnerable, underbelly of life.

Oxygen is essential for our very existence, but, in using its magic, we also risk its unwanted other effects. To prevent or minimize these undesirable and even lethal injuries to our cells, we have evolved an abundant array of defenses. These include a host of antioxidant molecules and detoxifying enzymes. When this system is in balance – when the generation of ROS is counteracted by these antioxidant defenses – the injury from our dependence on oxygen is minimized.

But when out of balance – when our antioxidant defenses are weakened or overwhelmed – ‘oxidative stress’ ensues, and cellular injury and disease can result.

In addition to the internal oxidative stress that can result from our own body’s metabolism, oxidative stress can also be engendered from the outside. Ultraviolet rays from the sun act directly on components of the skin to generate ROS. Sunlight also interacts with certain air pollutants, to produce ozone, nitrous oxide and other free radicals – all ROS that can damage the skin.

Skin, not surprisingly, has a robust antioxidant defense system, because it is continually exposed to outside. But even the most robust defenses can become overwhelmed when there is a sustained ROS attack, leading to oxidative stress, and with sufficient stress, leading to injury and disease.

Bottomline:

The best way to protect yourself from the oxidative stress generated by ultraviolet light is to practice good sun-protection. On days with a high air-pollution index, you should protect your lungs and your skin by staying indoors. If you must be out and about, you could protect your skin by wearing long-sleeves and long pants, and laundering them when you return home.

Q: I’ve heard that anything you put on your skin can get absorbed. Is that true? Should I be worried about this?

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Urushiol the antigen found in poison oak imparts an oily sheen to the leaves of poison oak. This antigen readily crosses the skin barrier and provokes an allergic reaction.
Leaves of poison oak in spring, glistening with urushiol. Skin absorption of this antigen causes an allergic contact dermatitis in people who have been sensitized. Photo by Mary L. Williams.

A: No – not everything you put on your skin will make its way inside. Skin absorption is selective about what is allowed in and what is kept out.

To understand how the absorption of chemicals through the skin is determined, we need to go back to the beginning of life on land.

Eons past, when plants and animals left the watery confines of the sea to inhabit the dry land, they had to devise a means to hold onto the water in their cells – for all living cells are a water-based system. They had to prevent its evaporation into the drier atmosphere that now surrounded them. The near-universal solution to this dilemma was to develop a covering or ‘integument’ that could prevent the loss of precious internal water.

It is our skin’s permeability barrier that allows us to be ‘grapes’, and not ‘raisins’. It also prevents us from ballooning into ‘watermelons’ when we bathe or swim.

Thus, our skin was designed by evolution to hold our body’s water inside, to prevent it from evaporating away, like water from a shallow bowl. And all of these integumental barriers – whether on plants or animals – use a coating of water-unfriendly materials (or ‘lipids’) to seal off their watery interiors from a desiccating environment outside. The differences between the barrier systems of a leaf or an insect or of humans lie only in the details of their lipid-based barrier systems.

The Basic Principles of Skin Absoption

Because our skin’s barrier was designed to prevent water-movement, it follows that small, water-friendly molecules – ones that readily dissolve in water (like sugar or salts) – are also prevented from moving in or out of the skin. Thus, for example, we don’t become salt-intoxicated when we swim in the ocean.

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Q: What is the best sunscreen to use?

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How to Choose the Best Sunscreen | Elias and Williams
Shelf of sunscreens at the local pharmacy. Photo by Mary L. Williams

A: The best sunscreen is the one that will best protect you from the harmful rays of sunlight. That may be obvious, but when faced with the vast array of choices on your pharmacy’s shelves, the right answer is not so easily discerned. So, let’s reduce this to a few general principles.

These general principles are: choose the right product (SWAB); and use it effectively (RESWAB)

In making that choice at the pharmacy, look for a sunscreen that is “SWAB”, where:
• S = Strong. Get one with enough protective power.
This means choose one with a big SPF number – at least 30 or more!
• W = water-resistant or water-proof. This is important even if you don’t plan on going swimming. You don’t want your protection to wash away when you sweat.
• AB = protects against both UV-A and UV-B. This is critical because both wavelengths of sunlight are toxic to your skin. As a general rule, only the sunscreens with an SPF of 30 or more protect from UVA.

When using your sunscreen don’t forget to RESWAB, where
• R = Reapply every 2-3 hours and after swimming.
• E = Enough. Apply enough product to achieve effective sun protection. Don’t be stingy – slather it on. Most people apply too little sunscreen and don’t reapply as often as they should.

As a general rule, an adult would need to use about 1 oz (30 g) of a lotion or cream to effectively cover and protect their entire body.

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