Hi, I’m Dr. John Cannell, a board certified psychiatrist with over 35 years clinical experience.

Five years ago I discovered a connection between vitamin D and autism, and I want to help you put vitamin D into practice. I can help your family manage and treat some of your child’s autistic symptoms through a number of nutritional means, including vitamin D.

Through remote education, I will educate you about the importance of vitamin D in autism spectrum disorder (ASD). I will send you specific directions on the basic supplement regimen to follow that has helped so many children with ASD. To be clear, I do not sell supplements; I am offering coaching and education, to help you and your child.

Call for a free consultation


Before you call, consider reading some of the letters parents wrote to me after I published my first autism and vitamin D paper in Medical Hypotheses, a paper that is the most cited paper in the history of that journal.

Please keep in mind that the letters below represent a biased population; the parents who found no benefit of vitamin D in their child were unlikely to write to me. However, with my clinical experience, I believe vitamin D and other nutritional measures can help your child with ASD.


  • Dear Dr Cannell

    My name is Dr. David Smith. I am an MD, Board Certified in Pediatrics. I began a private pediatric practice in 2006. Since day 1 of my practice, I have gone against the grain, and I have recommended to the mothers in my practice to take their newborns out for regular walks outside and to make sure they soak up some sun. In the winter, I strongly recommend Vit D supplementation.

    Interestingly enough, out of all of the babies that were born into my practice, none of them have developed Autism. I do have a handful of autistic patients, but these kids transferred to my practice from other places after infancy.

    I am not a researcher, but I do understand scientific principles and rules of statistics. Having said that, according to national data, I should have had at least four kids who were born into my practice that are now autistic. I have had ZERO.

    My numbers are small, but I would love to talk if possible and share thoughts and present my ongoing experiences and personal testimony.

  • Dear Dr Cannell

    I started supplementing with Vitamin D, 2000 IU a day, on April 15 and have increased his dose to 6000 IU a day just last week. It seemed that he was having a bit more language on just the 2000 IU but it was hard to tell. Last week, after he had been on 6,000 IU for several weeks, it seemed as if everyone began to notice. Just yesterday I received a call from his staff that was so excited to report that “Jake cannot stop talking”.

    We are seeing the same improvement at home. Not only talk but singing as well. The complex language is amazing, he asked me “why would you limit that” and when he told me he had a bad dream he said, “I’m crying because I had a bad dream that I got sick and died.” Prior to this I would have just assumed that he woke crying because his stomach was bothering him. He would have never been able to explain his problem in fact I didn’t even realize he knew the concept of a dream. Today I increased his dose to 10,000 IU per day. I’ll keep him on this dose for several weeks before running another level. His first level was 17 ng/ml.

    Thanks again, Dr. Cannell, I’ll keep you updated on his progress.

  • Dear Dr Cannell

    Larry is now sleeping through the night which has a tremendous positive impact on functioning throughout the day. (as well as the functioning of the rest of the family). He does take a sleeping medication as well. I do think the D has had a positive effect on the length and quality of his sleep. He no longer wakes several times throughout the night and sleeps the proper amount of time. He wakes up with a smile.

    He definitely has more eye contact. He is mostly “present” and aware of his environment. He seems to pay more attention to what is going on around him.

    He has started a picture program to help him communicate. He was having slow progress with this at school. He started additional home therapy a little after he started the vitamin D. He now communicates very well with a variety of picture cards including cookie, outside and music. When he can’t find his card, he attempts to communicate in an alternative way.

  • Dear Dr Cannell

    My son has been on Vitamin D for a month now and I wanted to report back to you that we have seen repeated bursts of spontaneous language. He has also started asking questions, and is initiating conversation with us. It has been truly remarkable; the teachers at school cannot believe it.

    Additionally he is pedaling on his tricycle, just like a regular kid, whereas before, he was struggling just trying to pedal. We are very impressed with his progress and I do not know how to thank you so much for all of your help.

Further reading

Get a better idea of what autism is, the treatments we use, and Dr. Cannell’s vitamin D hypothesis:

Autism spectrum disorders are disorders of brain development and function characterized by difficult and decreased social interaction, difficulty with communication, and by restricted or repetitive actions. The diagnostic criteria used to require that symptoms usually become apparent before a child is three years old but may not become manifest until social demands exceed the individual’s capacity. ASD affects information processing in the brain by changing how nerve cells connect and organize.

Read more…

Dr Cannell theorized in 2008 that vitamin D deficiency during pregnancy and infancy could increase the risk of developing autism. He has published peer-reviewd papers on the topic. He has since theorized that vitamin D may help in autism by means of anti-inflammatory actions, autoimmune actions, neurotrophins and increasing antioxidants like glutiathione.

Read more…

About San Luis Obispo Integrative Medicine

San Luis Obispo Integrative Medicine is a practice led by John Cannell, MD.

Dr. Cannell has over 35 years of clinical experience. He is board certified by the American Academy of Psychiatry and Neurology. He obtained his MD degree from the University of North Carolina School of Medicine. Dr. Cannell has published 17 scientific papers in the peer-reviewed medical literature; three of his papers are the most cited papers in the history of their respective journals.

He has written and spoken widely on integrative medicine, including speaking about vitamin D supplementation before the 92nd annual meeting of the Pacific Division of the American Association for the Advancement of Science (AAAS) in 2011. In the spring of 2013, he served as a visiting professor at Marshall University School of Medicine.

Our office
1411 Marsh St. Suite #203
San Luis Obispo, CA 93401
Fax: 1-805-439-1073

Office hours
Monday – Friday : 10:00 am – 5:00 pm
Saturday, Sunday : Closed

What you can expect from therapy
Professional service

Professional service

John Cannell MD is an experienced physician, having served the medical field for over 35 years. You can expect to be treated professionally.

Supplement and diet regimen

Supplement and diet regimen

We will place you on a supplement regimen, tailored to helping autism. As need be, we will continually alter your regimen.

Lab work

Lab work

We will regularly send you in for lab work to see what your vitamin D blood levels are. This will ensure safe and effective treatment.

Tracking of your condition

Tracking of your condition

We will track clinical markers to see if the add-on treatment is improving your condition.

Financial information
  • Our rate is $300/hr. Initial sessions are about 1-1.5 hours. Follow up sessions are approximately 20-30 minutes.
  • At the moment, we only accept self pay fee for service.
  • This means at this moment, we do not accept insurance of any kind.
  • For those patients who are seen in our San Luis Obispo office, if you want to be reimbursed by your insurance company, we will help you send in a superbill. It is your responsibility to see if your insurance will cover our care, lab work or x-rays.
  • For tele-educational sessions, you do not have the option to send in a superbill.
  • We do not accept Medicare or MediCal.
Session cancellation
  • It is your responsibility as a patient to make your session in a timely fashion.
  • If you need to cancel a session, you need to cancel 24 hours prior to the session.
  • If you fail to keep to a session and cancel in time, your account will be charged $300.00.