The Dermatology Blog

Vitamin C, also called ascorbic acid, is a popular natural ingredient used in skin care cosmetics. There are two mechanisms by which it can affect your skin.

First, vitamin C is an essential component for collagen synthesis. Without adequate vitamin C, the collagen in your skin would be malformed and your skin and gums would not heal properly. This is obvious in patients who are clinically deficient of vitamin C, a condition called scurvy. Among other problems, scurvy patients have bleeding from their gums and poorly healing wounds.

Secondly, vitamin C is a potent antioxidant. Like other antioxidants, it helps to prevent skin damage and wrinkles by soaking up harmful free radicals.

The problem is how to get the vitamin C into your skin. Your skin is designed to keep things out (on the whole, a good idea), but this makes getting medications and creams below the surface, where they exert their effects, rather difficult.

In order for vitamin C to penetrate the skin, it needs to be in an acidic environment, and it needs to be in a high concentration in the product. Unfortunately products that contain 5-10% ascorbic acid are expensive and it’s unlikely that products with low amounts of ascorbic acid have any measurable impact on your skin.

In addition, topical vitamin C is highly degradable. When exposed to air it oxidizes and its free radical soaking capabilities are muted — it becomes an inert, yet nicely citrus fragranced, cream. This is obvious if you have a vitamin C cream at home; you will see that the cream around the cap turns brown (like an apple slice) indicating that the vitamin C in it has oxidized.

If your are going to purchase a topical vitamin C cream, this is one place where more expensive might be worth the cost. La Roche-Posay makes Active C, a nightly eye cream with 5% vitamin C.

If you are trying to save a few dollars this year, I recommend just eating a citrus fruit everyday. You need only 90 mg of vitamin C daily which can be found in a couple of orange slices. Eating a whole orange or other citrus fruit will easily give you many times the amount of vitamin C you need.

There is no evidence that taking vitamin C supplements or consuming huge amounts of vitamin C will have any impact on your skin. Once you have an adequate supply of vitamin C to make collagen, having a huge oversupply is not likely to lead to more collagen production. But it certainly will lead to lots more vitamin C in your urine — it’s simply eliminated by your kidneys.

Other foods high in vitamin C can be found here.

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Should I use different moisturizers for different body parts?

Yes. You wouldn’t use shampoo to wash your hands, so don’t use the same moisturizer on your face that you use on your feet.

• For your face, which is more delicate and often less tolerant to heavy moisturizers, try Oil of Olay Regenerist Daily Regenerating Serum for women and L’Oreal Men’s Expert Hydra-Power Invigorating Moisturizer for men.

• For your hands, which take the brunt of harsh, cold weather and excessive hand washing to prevent catching the flu, use a cream that contains dimethicone (silicone). Eucerin Plus Intensive Repair Hand Creme moisturizes well and isn’t greasy, so your keyboard won’t get sticky when you blog. Have multiple tubes (for your purse, office, and home) so you won’t forget to reapply every time you wash your hands. Don’t forget to massage the cream into your nails which also get dry and brittle.

• For the body, my patients have had success with Aveeno Skin Relief Moisturizing Cream, made with colloidal oatmeal, an ingredient that helps hold in moisture.

• For dry, cracked feet, use a moisturizer that contains a mild acid, such as lactic acid which softens thick, scaly skin. My patients like AmLactin Cream.

What is the best way to moisturize?

• Shower or bathe in comfortably warm, not hot water.
• Use a mild cleanser such as Dove instead of soap. I can’t tell you how often patients’ dry skin is caused by some “natural” or “organic” soap. Unless these soaps are specifically designated as moisturizing, they are often too drying for your skin in the winter.
• Pat dry with a towel, leaving your skin damp.
• Apply cream to your damp skin, locking in moisture. Doing this everyday will significantly relieve your dry, itchy skin in just a week’s time.

What is the best way to moisturize during an economic recession?

OK. So maybe we aren’t in a recession just yet, but skin care products can be prohibitively expensive. If you are moisturizing properly, then you could easily use 5 ounces each week. That means you could use up one Aveeno Skin Relief Moisturizing Cream every two weeks!

Simple petroleum jelly (Vaseline Ointment) — it might be old-school, but it works.

Use a thin coat right after the shower. You can blot excess with your towel. Some patients like to use it only at bedtime since it can mark your clothing.

Cooler, dry air has hit San Diego, and it is making my patients’ skin dry. Many tell me that their skin remains scaly and itchy despite moisturizing daily. The best advice I can give is to teach them to moisturize properly.

The first question I ask is: Are you using a lotion or a cream?

The difference between the two comes down to the water content. Creams and lotions are mixtures of oil and water. It is the oil component that is most important for your dry skin.

Lotions are droplets of oil mixed in water. They have a high water and low oil content. As such they are easy to spread on dry skin. However, the water is not well absorbed and quickly evaporates, which actually dries your skin further.

In contrast, creams are droplets of water mixed in oil. They have a high oil and low water content. They are more difficult to smear on dry skin but apply easily to moist skin. Therefore, they are best used immediately after your shower or bath when your skin has soaked up the water like a sponge. Applying cream then creates a layer of oil that locks the moisture in your skin. The water does not evaporate, and your skin stays hydrated.

This is why in the wintertime I advise patients to use only creams. In the warm, humid summer, lotions are actually better.

Products I recommend include:

Olay Body Creme Serum

Eucerin Body Creme (don’t let the feminine model deter you guys, this one’s unisex)

Or, if your budget is a bit tight this winter, even old-school, plain Vaseline Petroleum Jelly works quite well. Rub some onto your hands then apply a thin coat all over your body.

A patient asked me this morning, “What is a good acne concealer?”

This comes up often. In fact, it was a recent post at The Makeup Minute blog. I often recommend Neutrogena’s SkinClearing® oil-free concealer. Concealers are commonly oil based and can further clog your pores, worsening your acne. This Neutrogena product is oil free. It also contains salicylic acid which helps the skin to exfoliate, unblocking the hair follicle and allowing for the trapped sebum to come to the surface. This helps speed-up the healing.

They come in different shades to match your skin color and even have a concealer with a green tint — the green color helps to offset the underlying red color of the spot, making it look more like your natural skin tone.

Soybeans contain a whole host of molecules that act on the skin; the key ones are isoflavones (or phytoestrogens) which are potent antioxidants. They also contain protease inhibitors, which are much less known than the antioxidants but no less potent.

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