Tiny bottles hold droplets some say have ancient healing powers.

Essential oils, the concentrated liquid extracted from aromatic plants such as flowers, citruses and herbs, are used for skin care, household cleaning and mood enhancement, and to treat medical concerns such as headaches, congestion, digestive issues and more.

They are said to be antibacterial, antiviral and/or antifungal. Some are even said to inhibit the growth of tumors.

Essential oils have been a staple product at Simple Abundance in Red Wing since the store opened in 2000, owner Kiki Gheen said. Customer demand for the oils has been growing ever since.

Simple Abundance sells a line of products by Bloomington, Minn., based Veriditas Botanicals, the only company in the U.S. selling 100 percent organic essential oils.

Veriditas' oils are derived from plants grown by small, family owned farms from around the world, and are certified by both the U.S. Department of Agriculture's National Organic Program and French certification organization ECOCERT.

Organic growing and extraction "ensures that oils are free of pesticides, synthetics and adulterants," according to the Veriditas website.

Gheen said organic methods are important to maximize the potency of essential oils.

"Essential oils are part of a plant's immune system to ward off pests and viruses," Gheen said. "If they're not organic and sprayed with pesticides, those antimicrobial properties are reduced."

Additionally, the organic certification means many Veriditas oils can be ingested by humans.

"Because of that, you can get a pretty comprehensive use out of them," Gheen said.

Although certain oils can be eaten, they more commonly are used in aromatherapy. The idea is that the scent of oils can affect mood, Gheen said.

For example, orange and tangerine oils can be uplifting, while the scent of lavender can be very soothing, she said.

Simple Abundance also sells a number of essential oil blends, including Veriditas' Mental Clarity.

The product is used by placing a few drops on the palms of the hands, rubbing them together and inhaling the scent.

"It can clear the mind and help wake a person up from that 3 p.m. sluggishness," Gheen said.

Simple Abundance regularly offers samples of essential oils -- including Mental Clarity -- in the store, as well as recipe cards for people to make their own blends.

One of the most popular recipes is for an mosquito repellent that Gheen said she personally has found to be quite effective.

Prices for the oils vary from $2 up to $40 per vial depending on how difficult it is to extract, Gheen said. Plants like lemons and oranges are relatively abundant with oil, whereas roses are not.

It takes 5.5 million freshly picked roses to create a liter of essential rose oil, Gheen said.

Scientific support, dissent

Monoterpenes -- compounds produced by plants -- are the basis for essential oils, says Esther McGinnis, North Dakota State University Extension horticulturist.

These compounds aid in self-defense of the plant, for example, repelling insects or attracting pollinators.

"Plants produce compounds for their purposes, to enhance their chances of survival," McGinnis says. "Sometimes the chemicals plants produce are beneficial to us."

Skeptics on the healing power of essential oils abound.

Quackwatch.org lambasted D. Gary Young, the founder of leading essential oils manufacturer Young Living, in an article by Dr. Stephen Barrett. Published evidence on their effectiveness is "sparse to nonexistent," according to an article on sciencebasedmedicine.org.

A recent article on the University of Minnesota website says more scientific studies are being conducted worldwide, but doing such research is challenging as essential oils are not standardized (they vary depending on geography, weather, harvesting and processing practices), blind studies are difficult with aromatic substances, and funding is limited.

The site listed reference information for 75 published studies.

"Research studies on essential oils show positive effects for a variety of health concerns, including infections, pain, anxiety, depression, tumors, premenstrual syndrome, nausea and many others," the University of Minnesota article says.