Long-term use of beta-carotene supplements may have a protective effect against declines in memory and other cognitive skills that often precede dementia, a new study says.

The study was published in Nov. 12 issue of the Archives of Internal Medicine and suggests that taking beta-carotene supplements for many years could have a protective effect against the decline of memory, thinking and learning skills that often precede Alzheimer's and other forms of dementia, the researchers said.

Beta-carotene is an antioxidant; these are thought to prevent health problems caused by “free radicals” circulating in the blood, including a decline in cognitive functioning. Some experts think antioxidants can lower the risk of cancer, heart disease and other conditions.

Beta-carotene can be taken in the form of supplements but is also found in its natural state in red, orange, and yellow fruits and vegetables, such as carrots, cantaloupe melons and sweet potatoes.

The researchers that conducted the study worked with nearly 6,000 men, beginning in the early 1980s; among these, some took beta-carotene for some 18 years, others took the supplement for a significantly shorter period of time.

“We found [in] the men who had been on beta-carotene long term - 18 years [on average] - their memory was significantly better than the placebo group,” study author Francine Grodstein of Brigham & Women's Hospital in Boston, told WebMD.

Grodstein added that, while the improvement was “modest,” it still led to considerable differences in a person’s eventual risk of getting dementia. Taking the supplements short term had no effect, she told WebMD.

“This is the first trial that has found any way to help your memory if you're healthy. I think it does tell us that we can change how our memory improves or worsens,” Grodstein told Reuters in a telephone interview.

The topic of beta-carotene supplements as an attempt to prevent memory problems associated with dementia ignites mixed opinions. Grodstein herself noted that there are possible risks for some people such as raising lung cancer risk in smokers.

WebMD.com notes that some experts familiar with the study do not consider that it provides reasons to begin taking beta-carotene supplements.

“It's good to be cautious,” Grodstein told Reuters.