BOSTON -- In Monday's medical news, NewsCenter 5's Heather Unruh reported on the benefits of fish, laser vision correction surgeries and Christmas trees.

Fish Facts

Two new studies say fish should be part of a healthy diet.

One study says despite risks from toxins, such as mercury, fish should be included in a healthy diet. Another study said a fatty acid found in fish called DHA could help brain function.

Neurologists followed elderly patients for nine years and found those who had the most DHA in their bloodstreams were the least likely to get Alzheimer's disease or dementia.

Vision Help

A new long-term study of several different laser eye surgeries shows that not only are lasers safe, but even 10 years after Lasik or similar procedures, the results were still good.

Ten years after having a laser procedure, patients in the study showed lasting improvements with vision averaging near normal or 20/20.

There are several kinds of laser eye surgery, including Lasik and photorefractive keratectomy, or PRK. Researchers said PRK was more effective for people with mild near-sightedness, while Lasik tended to be best for more severe cases.

Allergic To Christmas?

A new study said that Christmas trees could be triggering allergies in some people.

Experts said by carrying the tree into or out of the house could release mold, pollens and irritants that can cause allergies to flare up.

A small new study showed it's a problem that most allergy-sufferers need medicine to treat.

Real trees aren't the only culprits, experts said. Artificial trees that are stored during the year can also harbor just as much mold, pollen and dust.

To reduce allergy flare-ups, experts said to put the tree on the roof of the car when bringing it home, tap it off or use a leaf-blower to clean it off before taking it inside. Experts also suggested wiping down the trunk with a mild bleach solution. And once the tree is in place, change the water frequently to prevent bacteria from building up.