Alternative medicine is big business in the U.S. A 2016 report found that Americans spent more than $30 billion on alternative therapies in 2012. That includes treatments such as homeopathy and acupuncture as well as supplements, yoga and meditation.

The report, released jointly by the National Center for Complementary and Integrative Health (NCCIH) and the Centers for Disease Control and Prevention, found that 59 million Americans sought out some type of alternative therapy. Most of the alternative therapies are being used by adults, not children, the researchers found. Of the $30.2 billion, about $28 billion was spent on adults, compared to $1.9 billion for children.

Researchers estimated that one out of five Americans spent money on at least one type of alternative therapy, which could include practices such as Ayurveda, biofeedback, chelation therapy, chiropractic manipulation, energy healing therapy, tai chi, hypnosis, naturopathy, progressive relaxation and massage therapy.

Overall, spending on alternative remedies amounted to just around 9 percent of out-of-pocket healthcare expenditures. But the report found that Americans with lower incomes were shelling out more of their income proportionally than their more affluent peers. Families making less than $25,000 per year spent around $314 per person on complementary medicine and $389 per person on natural supplements. Families earning more than $100,000 per year spent an average of $518 per person on alternative treatments and $377 each on supplements.

A recent NCCIH review of clinical trial evidence from 1966 through March 2016 shows that acupuncture, yoga, tai chi, massage therapy and relaxation techniques are promising treatments for pain management, especially when it comes to the back, neck, head and knees. "About 40 million American adults experience severe pain in any given year, and they spend more than $14 billion out-of-pocket on complementary approaches to manage such painful conditions as back pain, neck pain, and arthritis," according to the NCCIH.

However, other forms of complementary medicine, namely homeopathy, guided imagery, energy healing and some natural supplements have faced severe scrutiny for the lack of scientific data to support their use.

Yet despite this lack of data, the alternative medicine industry is continuing to grow in the U.S. And according to researchers, this confirms the need for more research into to ensure that the products and treatment options offered are safe.

Editor's note: This story has been updated since it was originally published in June 2016.