I know you usually review supplements and dicey holistic treatments, but I'm wondering if you would comment on this. I recently visited the dermatologist for my annual check-up following removal of a couple of pre-cancerous moles a few years ago. I was asking him to look at some roughened, itchy areas of skin on my legs that never quite clear up, despite twice-daily application of lotion. He advised me that I should always use a cream, never a lotion, because lotion contains water and actually dries the skin. Assuming this is true, why is this not common knowledge, and why do I have to pay a doctor to find this stuff out?
I'd be more than happy to take a break from supplement-bashing to take a swing at moisturizers, if only because their ads are better. Even so, skin cream commercials are no less prone to misleading innuendo than, say, the fat-burner Stacker II—though they have significantly higher production values. The slow pan of a softly focused model, bare to her perfect skin, holding a tiny bottle of magic serum is much more appealing than watching a body builder, pushing the outer limits of spandex, with muscles so swollen he appears to have been stung by bees. But what do I know? I hardly ever watch Judge Judy, so I'm not really the target audience for either.
Although the moisturizer commercials imply that their products can repair the effects of aging or injury, these results are minimal at best. The real purpose of moisturizers, and nearly their only effect, is to increase water retention in the outer layers of skin and increase flexibility of the tissue. The outermost skin layer is called the stratum corneum and consists of a couple of dozen sheets of essentially dead cells. Once young and vibrant in the deep skin layers, as they age—much like that softly focused model—they get pushed out, dried up and eventually sloughed off. Toward the end of this death march, they fill with keratin, a hard fibrous protein that serves to block evaporation. Application of moisturizer assists the keratin by acting as an additional barrier to water loss.
The barrier in most formulas is oil, like cocoa butter or white petrolatum, or an oily animal product like lanolin. Lanolin is a waxy, fatty substance that is secreted by the pores of sheep and is meant to repel water from their wool. Without it, after a heavy rain, a sheep would look less like a grazing animal and more like a giant, immobile pasture sponge. As a blockade against water loss, lanolin is second only to petrolatum (aka Vaseline), but the sheep squeezins are a better skin softener, or emollient. Other ingredients in creams and lotions—called humectants—absorb and hold water themselves (label examples include lactic acid and urea). Although humectants can actually be absorbed into cells, their plumping effect is only temporary. Most surprisingly, except for Vitamin A-related retinoids (which encourage more sloughing of the stratum corneum, leaving smoother skin layers visible), added vitamins, antioxidants and botanicals have never been definitively proven to have actual healing effects and must be classified as a waste of money. I guess I can say goodbye to my L'Oreal endorsement deal.
Lotions and creams differ, generally, by the amount of water they contain. There are exceptions, but lotions are water solutions containing an emulsion of oils, and creams are just the opposite: tiny water droplets suspended in a primarily oil base. As your doctor noted, the creams with their higher oil content are better barriers, though they usually feel greasier. On the other hand, lotions are easier to apply, but don't protect as well. Nonetheless, for best results, use a cream and apply immediately following a short bath or shower. This helps trap moisture in the now-hydrated outer skin layers. Additionally, a bedroom humidifier can reduce nighttime shrivel and—along with drinking plenty of fluids—help flesh out your flesh.
One final heads-up: Television and print ads for moisturizers often use the very dramatic before-and-after photos. Amazingly, those little lines and wrinkles disappear completely moments after applying the formula. This sleight-of-hand is accomplished by simply withholding all products (except soap) for the few days before the photo shoot. Starved for moisture, the withered skin immediately sucks in the humectants and plumps up, ready for the close-up. If, at home, you expect to instantly become Victoria (or David) Beckham, be ready for disappointment. Though you might find some sympathy from me, I'd advise against claiming fraud; your naivete will surely provoke a trademarked tongue-lashing from Judge Judy.