KAWASAKI, Japan, July 23 (UPI) -- Japanese researchers have confirmed what many aroma therapists have long advocated -- the scent of plants like lemon, mango, lavender reduce stress.

The study, published in the Journal of Agricultural and Food Chemistry, found certain fragrances alter gene activity and blood chemistry in ways that can reduce stress levels.

Akio Nakamura of the Technical Research Center at the T. Hasegawa Co. in Kawasaki, Japan, and colleagues note that people have inhaled the scent of certain plants since ancient times to help reduce stress, fight inflammation and depression and induce sleep.

Aromatherapy, the use of fragrant plant oils to improve mood and health, has become a popular form of alternative medicine today, Nakamura said. Linalool is one of the most widely used substances used to soothe away emotional stress.

The scientists exposed lab rats to stressful conditions while inhaling and not inhaling linalool. Linalool returned stress-elevated levels of neutrophils and lymphocytes -- key parts of the immune system -- to near-normal levels. Inhaling linalool also reduced the activity of more than 100 genes that go into overdrive in stressful situations, the researchers said.