Summary

Production of collagen in skin slows as people age, whether or not they have been exposed to sunlight. A clinical trial shows that applying estradiol, a female hormone, to the skin of older men and women can increase collagen production. But this only happens in areas that are normally covered by clothing. Therefore collagen cannot reverse the effect of sun damage.

Introduction

There are many creams and remedies containing ingredients that claim to reverse the effects of skin aging, but the scientific evidence that they will work is not always there. Skin aging is associated with increased fragility of the skin and with fine lines and sagging. In addition, areas exposed to the sun are subject to photoaging from long-term exposure to ultraviolet light. This makes the skin look dry and accentuates the signs of natural aging. In both natural and photoaging, there is reduced production of collagen, the main structural protein of the skin.

Estrogen levels decline after the menopause, and this has been linked to skin aging in women. Some research suggests that estrogen therapy might improve the skin's condition, but the effect upon collagen production has not been clear - even though there is a widespread belief that hormone treatment can rejuvenate the skin. Researchers at the University of Michigan therefore set out to look at the effect of estradiol cream on both photoaged and normal aging skin.

What was done

The study involved a group of 70 healthy volunteers (40 postmenopausal women, 30 men) of average age 75 years. They applied an estradiol containing cream three times a day, every other day, for two weeks, to sun-protected areas near the hip and sun-exposed areas on the forearm. They also applied an estradiol containing moisturizer to the face twice a day for two weeks. Then skin biopsies were taken from the hip and forearm area 24 hours after the last treatment. Biopsies were also taken from the 'crows feet' area of the face both before the treatment began and 24 hours after the last one. These samples were analyzed for collagen production.

What was found

Estradiol treatment led to an increase in collagen production was increased in the sun-protected areas of the skin but not in the photoaged skin of the forearm or on the face. The effect on sun-protected sun was greater among women. Both sun-protected and sun-damaged skin were found to have estrogen-receptors, meaning that some interaction between estrogen and the skin was possible.

What this study means

Since estrogen receptors are found in both photoaged and sun-protected skin, collagen production in response to estradiol might not occur by direct interaction between the hormone and its receptor. This is the first study to show that topical estradiol does not increase collagen production in sun-exposed skin, including the face. Therefore, be wary of treatments and products that make this claim. It looks as if sun exposure alters the skin in some way so that it can't respond to estradiol by making more collagen. Of course, you could use a hormone cream to keep the skin on your body - normally covered by clothing - looking young. But most people are more interested in keeping wrinkles on their face at bay. For this, it looks as if sun protection is the best approach.