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How much can skin really absorb?

It’s often expounded that our skin is our largest organ and that our body absorbs 60 to 70 per cent of what we put on it, but is that really true?

After all, skin also has a barrier function and if it were as easy as that, we’d just have to shower rather than drinking the recommended eight glasses of water a day for starters.

It turns out this widely held belief is false, though of course there are some exceptions.

“The skin is the largest organ, but it is also our first line of defence. Whilst it performs many functions, it is foremost a barrier, to protect us from the outside world,” says Snowberry’s skin scientist, Dr Travis Badenhorst.

What the skin absorbs is also affected by age, what is being absorbed, skin composition, climate and skin condition, explains Badenhorst. “It can vary from absolutely nothing, as is the case for larger zinc oxide particles, to 100 per cent for certain lipophilic chemicals.”

It is very dependent on formulation, pH and the size of the molecules in a product, agrees House of Camille business developer manager and trainer Brooke Taylor. Examples of easily absorbed ingredients are nano-sized fragments of less than 100nm in diameter.

“Nanoparticles in sunscreens are often a controversial topic – there is some evidence that they may penetrate the bloodstream and can sometimes influence our endocrine system. There is fierce debate among scientists. Our view at medik8 is to avoid them until there is overwhelming clarity of opinion,” says Taylor.

The use of sunscreen filter oxybenzone is now restricted for this reason and banned in Hawaii due to its impact on coral reefs. “Oxybenzone is so easily absorbed that in a recent study it was determined in the blood of 97 per cent of the population,” says Badenhorst. “It can cause allergic reactions, disrupt hormone function and trigger cell damage that may lead to cancer. We’re starting to see a move away from it, but because it is cheap it still exists in as much as 56 per cent of beach and sport sunscreens available.”

Absorption versus penetration

Penetration is when a chemical makes it into the deeper layers of the skin, while absorption is when the chemical makes it into the bloodstream. However, anything that penetrates your skin has the chance of getting into the bloodstream, says Badenhorst, and that’s why choosing skincare products is so important.

“Technically entering the bloodstream is still penetration and transport. Once it is at the final destination, and is stored or used, it becomes absorbed. Sugar is a great example of this. We eat it, it travels through our bodies, is stored as glycogen, and is used by cells when required,” he says. “Normally compounds, once used, become metabolites as waste. These are harmlessly excreted by the kidneys and liver.”

Skin elimination system

We excrete toxins through our sebum and sweat glands in our skin, says Taylor. The lymphatic system also removes excess fluid, and waste products from the interstitial spaces between the cells.

However, human cells store oil-soluble toxins as we are unable to remove them from our body readily. “If we absorbed too many water-soluble compounds we can excrete them out of our body quite easily through our sweat glands or bladder,” says formulation chemist and Biologi founder Ross Macdougald.

“This is the reason why we can overdose on vitamin A but not vitamin C as A is oil-soluble and C is water-soluble. Most skin allergies and sensitivity are caused by a build-up of oil-soluble toxins in cells. This build-up can be slow and may take several years but it will happen if the toxins are continually applied to the skin or consumed.”

Hope in a bottle?

Most skincare products, such as cleansers, and toners, work on the surface of the skin and are not actively trying to penetrate it.

Cosmetic products are really just for hydration and superficial penetration, and leave the top layers of the skin feeling hydrated, says Taylor, while cosmeceutical skincare is formulated to penetrate deeper into the skin.

Human cells (including skin cells) require an activator to allow the penetration of nutrients into the cell. If the activator is not present then the nutrients and also toxins penetrate through osmosis – hence why most skin care products don’t work or take a long time to show any type of benefit, says MacDougald. “This is also the reason why sensitivity and the allergic reaction takes time to build,” he says. “When a cell gets to a point it can no longer operate for its intended purposes (due to toxin build-up) it will dysfunction causing signs of sensitivity and allergenicity and then cell death.”

Getting ingredients to ‘get in’ and help with anti-ageing is not easily achieved and something scientists are continually working on. Some have success, such as Snowberry, which has developed a special delivery technology, backed by gold standard clinical evidence, to reach the dermis and target different areas of the skin.

“For actives, like peptides or vitamins, they need to penetrate and be absorbed by cells to work,” explains Badenhorst. “One of the cool ways to do this is to activate the cells’ clathrin-mediated endocytosis mechanism. This tells the cell to grab the molecule and use it.”

So, does our body absorb what we put on our skin? The answer is yes and no, which is why it’s smart to know what’s in the products you use.

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