Prof Chris Griffiths, a dermatologist at Manchester University, said that though sophisticated skincare products can help curb ageing, he would recommend those worried about wrinkles and dark circles to wear suncream.
He also cautioned that women could be damaging their skin by using different anti-ageing creams because the side effects of combining them had not been tested properly.
"The majority of anti-ageing skin products are actually aimed at the effects of sun exposure, not how our body naturally ages. If I had to pick just one product it would be suncream," The Telegraph quoted Prof Griffiths, as saying.
Last year, Prof Griffiths encouraged hundreds of thousands of women to buy Boots' Protect and Perfect Beauty Serum by proving that it worked.
In May, Boots stores across the country were short in supply of the face cream after his research featured on the BBC2 programme Horizon.
Now, Prof Griffiths, at a press conference in London, said that for the majority, most noticeable signs of ageing, including wrinkles and crow's feet around the eyes, are caused by sun damage.
He said that some of the most serious effects of growing older, such as deep wrinkles, would not happen until our 80s without sun damage.
He also warned that too little is known about the dangers of mixing different skin-care products because they are tested in isolation.
Combining the ingredients of popular face creams could cause allergic reactions or hazardously boost the amount of a sensitive chemical, he added.
"All the ingredients [in these creams] have been tested individually. But, of course, what they don't test is what happens when people get out in the real world they use lots of different products together. There needs to be more tests on how they are really used and what the dangers could be," he said.