Frequently asked questions

The Superactive Serum is Gleamin's most concentrated formula, with 15% vitamin C from two stable forms, 3-O-ethyl ascorbic acid and sodium ascorbyl phosphate. It pairs them with 4% niacinamide, bakuchiol (a plant-based alternative to retinol), turmeric leaf extract and hyaluronic acid. It is fragrance-free, vegan and free of essential oils, and comes in a 1 fl oz (30 mL) opaque pump bottle.

The full ingredient list is on the Superactive Serum page and its Amazon listing.

The Supernutrient Oil is a rich, deeply hydrating face oil with 3% vitamin C in its oil-soluble form, tetrahexyldecyl ascorbate. Cloudberry seed oil makes up about 42% of the formula, alongside jojoba, pumpkin seed and turmeric oils, squalene and vitamin E. It is fragrance-free, vegan and dermatologist tested (repeat insult patch test on 52 adults, 2023), in a 1 fl oz (30 mL) dropper bottle.

Read more on the Supernutrient Oil page.

Yes, the Supernutrient Oil and the Superactive Serum work well together. Apply the serum first to clean skin, then moisturizer, then press in 2 to 3 drops of oil as the last step, because oils seal in the water-based layers underneath.

Together they give you water-soluble vitamin C from the serum and oil-soluble vitamin C from the oil. Many people use the oil at night; in the morning, use it under sunscreen only if your skin is dry.

Sodium ascorbyl phosphate (SAP) is a stable, water-soluble form of vitamin C in which a phosphate group protects the part of the molecule that normally breaks down in light and air. Enzymes in the skin release active vitamin C after it's applied. SAP works at a skin-friendly pH of about 6 to 7, so it rarely stings, and it's usually used at up to 5%. It suits sensitive and breakout-prone skin.

Read the full guide to sodium ascorbyl phosphate.

Sodium ascorbyl phosphate is gentler and more stable than L-ascorbic acid, but less potent per percent. L-ascorbic acid is the active form with the most research, and it works at 10 to 20% at a pH below 3.5. SAP has to be converted by skin enzymes first, so less vitamin C becomes available, but it doesn't oxidize quickly or sting.

For sensitive or melanin-rich skin that reacts to irritation, a stable form you use every day often does more than a potent serum you can't tolerate.

3-O-ethyl ascorbic acid is a stable vitamin C derivative made by attaching an ethyl group to the third carbon of the vitamin C molecule, the spot where pure vitamin C usually breaks down. It dissolves in water and partly in oil, which helps it get into the skin, and it doesn't need a very low pH. It slows tyrosinase, the enzyme behind pigment production, and is usually used at about 0.5 to 3%.

You may also see it written as ethyl ascorbic acid or 3-0 ethyl ascorbic acid. Read the full guide to 3-O-ethyl ascorbic acid.

Tetrahexyldecyl ascorbate (THD) is an oil-soluble form of vitamin C, made by bonding vitamin C to fatty acid chains. Because it dissolves in oil, it can go into creams, balms and face oils where water-based vitamin C can't, and it's very stable and gentle, with little risk of stinging. Once in the skin, it's converted to active vitamin C. On labels it may also appear as THD ascorbate or ascorbyl tetraisopalmitate.

Read the full guide to tetrahexyldecyl ascorbate.

Tetrahexyldecyl ascorbate is effective as a gentle, stable antioxidant, but it has less research behind it than L-ascorbic acid. Lab and skin-model studies show it gets into the skin well, converts to vitamin C, and helps slow pigment production and protect against UV-related oxidative stress. Large human trials are limited.

It suits people who can't tolerate acidic serums, or who want vitamin C in a cream or oil. Use it daily for 8 to 12 weeks alongside sunscreen to judge it.

Oil-soluble vitamin C is a vitamin C derivative bonded to fatty acids so it dissolves in oil instead of water. The two main forms are tetrahexyldecyl ascorbate and ascorbyl palmitate. They blend into the skin's natural oils, stay stable in creams and face oils, and rarely sting.

They suit dry, mature and sensitive skin, and anyone who prefers a cream or face oil to a watery serum. Oily skin may prefer water-soluble forms, such as sodium ascorbyl phosphate, in a light serum.

Magnesium ascorbyl phosphate (MAP) is a stable, water-soluble vitamin C derivative, closely related to sodium ascorbyl phosphate but paired with magnesium instead of sodium. It works at a near-neutral pH, so it's mild enough for sensitive skin, and lab studies suggest it supports hydration and collagen.

It's typically used at 1 to 10%. Like other phosphate forms, it converts to vitamin C in the skin, which makes it gentler but less potent than L-ascorbic acid.

The best packaging for vitamin C serum is opaque and airtight, such as an opaque bottle with a pump or an airless pump. Light, air and heat all oxidize vitamin C, especially L-ascorbic acid, and clear dropper bottles let in the most light and air every time you open them.

Stable derivatives are less sensitive, but good packaging still helps. Keep serums closed, away from windows and steamy bathrooms, and use them within the time on the open-jar symbol (such as 6M or 12M).