A June, 2013 study published in the Annals of Internal Medicine suggests that the use of daily sunscreen can significantly slow down the signs of skin aging in middle-aged adults.

Investigators with the University of Queensland in Australia randomly divided 903 middle-aged adults into several different study groups. Only one of the groups was assigned to be those who would consistently apply daily sunscreen.

After four and a half years, researchers assessed skin aging by changes in microtopography. They found that there was no detectable increase in skin aging observed in the group that used sun protection daily. Moreover, signs of skin aging were 24 percent less from baseline to the end of the trial in the daily sunscreen use group compared to the discretionary sunscreen use group.

The researchers also discovered that the use of beta-carotene supplements had no overall effect on skin aging. They noted, however, that further study of beta-carotene and its effects on skin aging would be required to "definitively exclude potential benefit or potential harm."