Beauty of Joseon Glow Deep Serum: Rice + Arbutin

Your skin makes glycerin on its own (mostly from sebaceous oil breakdown) and shuttles it to your outermost layer of skin, or your epidermis, via aquaporin-3.

Aquaporin-3 is a transporter that is essential for normal skin hydration, elasticity, and repair. Interestingly, mice lacking in AQP3 have dry and less elastic skin that can be fully corrected with glycerin.

This ingredient is non-irritating, plays well with almost every ingredient, and works across all skin types. Typical use is anywhere between 3-10% but can go up to 79% in some leave-on products.

Just know very high concentrations (>40%) can feel tacky in low humidity.

Glycerin is the name for this ingredient in American English. British English uses Glycerol/Glycerine.

Though this ingredient works well with most skin types, some people with sensitive skin may experience a reaction such as allergic rashes, closed comedones, or itchiness.

Dipropylene glycol is technically an alcohol, but it belongs to the glycol family (often considered part of the ‘good’ alcohols). This means it is hydrating and gentle on skin unlike drying solvent alcohols like denatured alcohol.

As a masking agent, Dipropylene Glycol can be used to cover the smell of other ingredients. However, it does not have a scent.

Studies show Dipropylene Glycol is considered safe to use in skincare.

There are two forms of arbutin and alpha is the better one to reach for: it works at lower amounts, absorbs into skin more easily, and has a strong safety record.

The science backs this up too: lab and animal studies confirm it lowers melanin by blocking tyosinase and the more you use (up to a point), the more it works.

Human studies look good too.

A 2024 trial found a cream with 5% alpha-arbutin and 2% kojic acid worked about as well as a prescription melasma cream but with fewer side effects. Another study showed 2% alpha-arbutin paired with 10% Trihydroxybenzoic Acid Glucoside and sunscreen faded dark spots and melasma without causing irritation.

Concentration-wise, most serums land in the 1-2% range.

The EU's Scientific Committee on Consumer Safety concluded that alpha-arbutin is safe in face creams up to 2% and body lotions up to 0.5%.

Overall, this is a well-studied and low-irritation brightener that's a great pick for anyone dealing with uneven skin tone. It also pairs well with vitamin C, niacinamide, and sunscreen.

You might have heard of "niacin flush", or the reddening of skin that causes itchiness. Niacinamide has not been found to cause this.

In very rare cases, some individuals may not be able to tolerate niacinamide at all or experience an allergic reaction to it.

If you are experiencing flaking, irritation, and dryness with this ingredient, be sure to double check all your products as this ingredient can be found in all categories of skincare.

When incorporating niacinamide into your routine, look out for concentration amounts. Typically, 5% niacinamide provides benefits such as fading dark spots. However, if you have sensitive skin, it is better to begin with a smaller concentration.

When you apply niacinamide to your skin, your body converts it into nicotinamide adenine dinucleotide (NAD). NAD is an essential coenzyme that is already found in your cells as "fuel" and powers countless biological processes.

In your skin, NAD helps repair cell damage, produce new healthy cells, support collagen production, strengthen the skin barrier, and fight environmental stressors (like UV and pollution).

Our natural NAD levels start to decline with age, leading to slower skin repair, visible aging, and a weaker skin barrier. By providing your skin niacinamide, you're recharging your skin's NAD levels. This leads to stronger, healthier, and younger looking skin.

Another name for vitamin B3 is nicotinamide. This vitamin is water-soluble and our bodies don't store it. We obtain Vitamin B3 from either food or skincare. Meat, fish, wheat, yeast, and leafy greens contain vitamin B3.

The type of niacinamide used in skincare is synthetically created.

D-panthenol is also known as dexpanthenol. Most cosmetics use dexpanthenol or a mixture of D and L-panthenol.

Panthenol is famous due to its ability to go deeper into the skin's layers. Using this ingredient has numerous pros (and no cons):

Like hyaluronic acid, panthenol is a humectant. Humectants are able to bind and hold large amounts of water to keep skin hydrated.

This ingredient works well for wound healing. It works by increasing tissue in the wound and helps close open wounds.

Once oxidized, panthenol converts to pantothenic acid. Panthothenic acid is found in all living cells.

This ingredient is also referred to as pro-vitamin B5.

Having moisturized skin helps improve the skin barrier. Your skin barrier helps protect against irritants and bacteria.

Due to its antioxidant properties, trehalose may help with signs of aging. Antioxidants help fight free-radical molecules, unstable molecules that may damage your skin.

In medicine, trehalose and hyaluronic acid are used to help treat dry eyes.

Some animals, plants, and bacteria create trehalose as a source of energy to survive freeze or lack of water.

Some foods that contain glyceryl glucoside include sake, miso, and wines.

In cosmetics, HJE works mainly to soften skin, reinforce the barrier, and lock in moisture by reducing water loss. This ingredient also holds onto the skin even after rinsing which is why you'll see it in cleansers or wipes.

There's a decent clinical backing for the moisturizing claims: a small controlled study found that pairing HJE with glycerin lowered transepidermal water loss significantly than glycerin alone (and this effect lasted up to 24 hours).

Follow-up work showed HJE appear to "trap" glycerin in the film they form on skin to boost its hydrating power.

Typical use levels are low: the glycering-synergy research used around 1.25% (a common pairing is roughly 1.25% HJE and 3.75% glycerin).

This ingredient has been found safe as used in cosmetics with low irritation risk.

As for fungal acne, the fatty acids and alcohols in jojoba fall in roughly the C18-24 range. This overlaps the C11-24 window that Malassezia yeast can feed on in lab studies, so this ingredient may not be fungal acne safe.

Industry-reported use ranges from 8% in rinse-off products and 2% in leave-on formulations.

This ingredient can also be found in pill medicines to help our bodies digest other ingredients.

Xanthan gum is a pretty common and great ingredient. It is a natural, non-toxic, non-irritating ingredient that is also commonly used in food products.

It can also form a thin protective film on skin. One study found that a formula using this polymer helped slow down how quickly other ingredients (like DEET) were absorbed through skin.

A 2024 study of over 1,300 patients confirmed that sensitization to this ingredient is rare. It is also non-mutagenic and has a clean track record.

Here's an interesting thing about Arginine: your skin converts it into urea through the Krebs-Henseleit urea cycle. Urea is one of the most effective humectants your skin naturally produces.

A clinical study showed applying 2.5% arginine hydrochloride to atopic dermatitis skin showed significant urea levels in the stratum corneum and improved moisture in just four weeks.

Arginine is also a precursor to nitric oxide; nitric oxide improves microcirculation and supports wound healing and collagen synthesis.

One study found that an amino acid complex containing Arginine reduced skin irritation, improved hydration, and accelerated skin repair in clinical / in-vivo studies.

Arginine itself is an amino acid and not a fatty acid, oil, or ester. On its own, it's not a direct food source for Malassezia, or the yeast that causes fungal acne.

On top of that, this ingredient can counteract the effects of hard water by binding to the minerals in it.

One thing worth knowing is that Disodium EDTA has been shown to be a mild penetration enhancer. It can help other ingredients absorb into skin more effectively which can be a double-edged sword (great for actives, but can also make the active too strong if you have sensitive skin).

Clinical patch testing showed no significant skin irritation at typical use concentrations and minimal dermal absorption.

You'll most likely see this ingredient near the end of an ingredient list. It's typically found in concentrations less than 1%.

This makes it a promising ingredient for slimming and anti-cellulite products!

In a 24 hour occlusive patch test on 56 subjects, 10% sorbitan isostearate was completely non-irritating. Most formulas use less than 10%.

Because it's a fatty acid ester, it may not be fungal acne safe since the Malassezia yeast can utilize it as a nutrient source.

It's worth knowing sugars are already a natural component of the skin's NMF (natural moisturizing factor) so it's a molecule that your stratum corneum is well-acquainted with.

Just so you know, glucose is hydrophilic (water-loving) and the stratum corneum is a strong barrier to hydrophilic compounds. This just means penetration is slow and most of the action is happening on the surface.

Gram-to-gram, glucose is not as efficient as a humectant as glycerin. This is why you'll likely see glycose paired with stronger humectants for a bigger hydration payoff.

In skincare, glucose is typically derived from corn or other starch sources.

Job's tears is rich in nutrients, such as thiamine, riboflavin, niacin and ascorbic acid.

You can also find great antioxidants such as ferulic acid, caffeic acid.

To top if off, ceramides are also present in this grain.

Two powerful components found in the wild soybean include genistein and diadzein. These two isoflavones are potent antioxidants with anti-inflammatory properties. Genistein in particular has been found to prevent redness caused by UV exposure.

One study from South Korea found wild soybean extract to help promote hair growth at the cellular level.

The wild soybean plant is a cousin to the famous soybean that gives us tofu, soy milk, and soy sauce.

A study from 2002 found rice to help increase the rate of wound healing. The same study found an improvement of skin barrier function in the patients after taking rice baths.

Numerous in-vitro studies have found rice water to help decrease sun damage by increasing collagen production and inhibiting the process of tyrosinase.

Long story short- tyrosinase is an enzyme that controls melanin production. Our bodies start producing melanin (AKA tanning) when exposed to UV radiation to protect against damage. Rice water is found to partially block this process.

Though more research is needed on rice's ability to help with UV protection, recent studies seem promising.

Wondering why rice is hydrating? The protein in rice have emollient properties. Emollients create a barrier on the skin to trap moisture in, keeping your skin moisturized.

Some rice extract may have mildly-exfoliating properties. These are mainly limited to Oryza Sativa (Rice) Bran and Oryza Sativa (Rice) Germ Powder.

This rice was first cultivated in China over 10,000 years ago. Many cultures throughout Asia have used rice water on skin and hair for centuries.

Interestingly, it has some brightening research behind it too; the purified fraction of sprouted mung bean extract was better than arbutin at reducing melanin production in cells. Sprouted extracts also blocked tyrosinase (the enzyme that triggers pigment production) and this effect is mostly credited to a compound called vitexin.

In a separate study, researchers packaged mung been seed coat extract into tiny delivery particles called niosomes (similar idea to liposomes) and found it protected skin cells from UV damage in lab testing + boosted collagen production.

Another study tested creams with 10-25% mung bean seed coat extract and the version with the highest amount (25%) had the strongest antioxidant activity.

It's worth noting most of this evidence is in-vitro and early-stage formulation work rather than the large clinical trials on humans.

Lab research on specialized corn kernel extracts have shown increase collagen deposition in fibroblast cell models; however, human clinical data is needed to support this.