Washington (CNN) Democratic presidential candidate and author Marianne Williamson once gave a platform to the unfounded theory that vaccines are linked to autism and called on her audience to "be awake" and "do your due diligence" before making the decision to vaccinate their children.

In a January 2012 episode of her radio show , "Living Miracuously," reviewed by CNN's KFile, Williamson said she "agonized" as a mother over the decision to vaccinate her children and that she could see "both sides" of the issue. Her guest, author Gwen Olsen, said on the program that she knew a number of people who were vaccinated and were later diagnosed with autism, to which Williamson responded, "Yes, absolutely."

A spokesman for Williamson told CNN she was neutral on the program, saying, "As with any radio show host, Williamson spoke with a variety of guests from all walks of life and some were provocative. This guest had a specific point of view on the issue, but it's clear from Williamson's comments that she was neutral. For example, when someone like Kellyanne Conway is interviewed on CNN, we don't assume the host agrees with everything she says."

Williamson's comments on vaccines shed new light on positions she has downplayed since running for president. Williamson issued an apology earlier this year after calling mandatory vaccines "Orwellian" and "draconian," writing in a tweet that she understood "many vaccines are important and save lives." Williamson described herself in an interview with MSNBC as "pro-vaccination, pro-medicine, pro-science."

But her comments on her radio program in 2012 show that she was willing to entertain and give credence to claims about vaccines that have been roundly criticized as unfounded and dangerous by scientists and medical professionals.

In the episode, Williamson interviewed Olsen, the author of "Confessions of an RX Drug Pusher." The book details Olsen's 15-year career in the pharmaceutical industry, along with her family's own mental health medical history, until she turned on pharmaceuticals, particularly antidepressants.

Williamson said she had "never been more enthusiastic about a show," calling it "one of the most important programs you could ever hear" for anyone who had taken prescription drugs or anti-depressants.

Williamson invited on a prescreened caller with a question on vaccines. The caller, a pregnant woman who identified as Kristin from San Jose, California, said she had avoided vaccinating her 3-year-old daughter by not taking her to the doctor. The caller acknowledged the problem of viruses like smallpox and polio, that have been mostly eradicated by vaccines, but wondered what she should do about vaccinating her kids.

"Let's have Gwen answer," Williamson said. "I'm curious myself, Gwen, I know I agonized as a mother on this topic."

In the discussion, Olsen said she knew people whose children were diagnosed with autism after receiving vaccinations.

"I don't have the medical authority to make those kinds of recommendations, but I do know a number of people that have had children that have become diagnosed with autism," Olsen added.

Williamson responded affirmatively to the remark.

"Yeah, I know," Williamson said. "Yes, absolutely. And I know that one, too. And I have a friend who had the same experience. So I know it's huge and I think all I'm calling for in this program is for everybody to be awake and really do your due diligence and do your research."

Earlier in the discussion, Olsen told the caller she had vaccinated all her children, but wished she had not.

"If I had to do it over again, I would not," Olsen said, adding that she disputed the scientific consensus that herd immunity -- the idea that many people getting vaccinated leads to fewer people getting sick and thus fewer germs to spread -- protects people from getting infected.

"So I guess without getting too controversial, I would say I would do my own due diligence if I were you," Olsen said. "I know lots and lots of chiropractors. I have over 4,000 chiropractors in my network and I know that they do not vaccinate their children. And I know lots of chiropractors with healthy children that are in fact have higher IQs than many of the children that are vaccinated and they don't suffer from all of the ear infections and all of the chronic problems that a lot of the children that are vaccinated do."

"And the expert on the vaccines that I would send you to would be Dr. Sherri Tenpenny and she is -- you can visit her website," Olsen said. "But Dr. Sherri and I worked together occasionally and we are colleagues and she is the vaccine expert and that is the person that I would be the go-to person for if I were you."

Williamson added, "I want to reiterate about each of us doing our own due diligence."

"I personally, and I'm not an expert, but just as another mother who was another parent who has dealt with this and had to really agonize over that decision, I sort of see both -- you know, not coming from any kind of a medical or professional perspective, but just as a person -- I see both sides on that one," she said. "I wouldn't presume to make anyone else's decision for them, but I think everybody needs to do your own due diligence on that one."