2018 SIBO Symposium Speakers


Steven Sandberg-Lewis, N.D., has been a practicing naturopathic physician since his graduation from National College of Naturopathic Medicine (now NUNM) in 1978. He has been a professor at NUNM since 1985, teaching a variety of courses but primarily focusing on gastroenterology and GI physical medicine. His clinic rotations are particularly popular among NUNM doctoral students. In addition to supervising clinical rotations, he also maintains a part-time practice at 8 Hearts Health & Wellness in Portland. He is a popular international lecturer at functional medicine seminars; presents webinars; writes articles for NDNR and the Townsend Letter; and is frequently interviewed on issues of digestive health and disease. Dr. Sandberg-Lewis is the author of the medical textbook Functional Gastroenterology: Assessing and Addressing the Causes of Functional Digestive Disorders, Second Edition, 2017. In 2010 he co-founded the SIBO Center at NUNM, which is one of only four centers in the U.S. for small intestine bacterial overgrowth diagnosis, treatment, education and research. In 2014 he was named one of the “Top Docs” in Portland Monthly magazine’s yearly healthcare issue, and in 2015 was inducted into the OANP/NUNM Hall of Fame. Within gastroenterology, he has special interest and expertise in inflammatory bowel disease (including microscopic colitis), irritable bowel syndrome (including post-infectious IBS), small intestine bacterial overgrowth (SIBO), hiatal hernia, gastroesophageal and bile reflux (GERD), biliary dyskinesia, and chronic states of nausea and vomiting. Many of the patients referred to Dr. Sandberg-Lewis have digestive conditions that have defied diagnosis and effective resolution. Often these patients desire naturopathic treatment options in lieu of the courses of treatments they have previously undergone. He understands diseases of the gastrointestinal tract, but also can assess function and often find successful treatments to regain a balance in the digestive system.


Mark Pimentel, M.D., is Professor of Medicine at Cedars-Sinai Medical Center in Los Angeles, California. Dr. Pimentel completed 3 years of an undergraduate degree in honors microbiology and biochemistry at the University of Manitoba, Canada. This was followed by his medical degree, and his BSc (Med) from the University of Manitoba Health Sciences Center in Winnipeg, Manitoba, Canada, where he also completed a residency in internal medicine. His medical training includes a fellowship in gastroenterology at the UCLA Affiliated Training Program. Active in research, Dr. Pimentel has served as a principal investigator or co-investigator for numerous basic science, translational and clinical studies in such areas as IBS, and the relationship between gut flora composition and human disease. His work has been published in the New England Journal of Medicine, Annals of Internal Medicine, American Journal of Physiology, American Journal of Medicine, American Journal of Gastroenterology and Digestive Diseases and Sciences, among others. Dr. Pimentel has been invited to present his work at meetings, grand rounds, and advisory boards in the United States and Internationally. He is diplomate of the American Board of Internal Medicine (Gastroenterology) and a fellow of the Royal College of Physicians and Surgeons of Canada. Dr. Pimentel is also a member of several medical associations including the American Gastroenterological Association, the American College of Gastroenterology, and the American Neurogastroenterology and Motility Society.

A few of Dr. Pimentel’s most significant accomplishments include:

  1. The discovery of rifaximin as a treatment for irritable bowel syndrome (IBS)
  2. He developed the first blood test for IBS on the basis of IBS being derived from acute gastroenteritis
  3. Described the association between IBS and bacterial overgrowth which forms the basis for microbiome therapies in this condition
  4. Uncovered the methanogen ( smithii) as an agent for causing constipation in humans.
  5. Discovered the use of lovastatin as a microbiome treatment for constipation on the basis of inhibiting methane production by methanogens


Alena Guggenheim, N.D., is a Naturopathic Physician with a passion for helping patients that don’t fit neatly in the medical box. Medicine is in her genes as a 4th generation physician, but she brings a new approach in which seemingly unrelated symptoms are approached within the context of the whole person. In 2015 she started working for a technology driven health care system working with a collaborative multidisciplinary team. Dr. Guggenheim became the go to provider when patients had complex symptoms in many systems and started to notice that many patients had undiagnosed hypermobile connective tissue diseases. Helping to understand and treat these diseases has become her passion. Starting in Spring of 2018 she will start seeing patients at the Oregon Health Sciences University Comprehensive Pain Clinic with an emphasis on the diagnosis and treatment of Ehlers-Danlos Syndrome and related syndromes.


Megan Taylor, N.D., practices integrative primary care and naturopathic gastroenterology for adults and children with digestive complaints, allergies, and autoimmune disease in Seattle, WA. Dr. Taylor earned her doctorate in naturopathic medicine from National University of Natural Medicine in Portland, OR, graduating with honors. She completed two years of post-graduate residency training in primary care and naturopathic gastroenterology under the mentorship of Steven Sandberg-Lewis, ND and Allison Siebecker, ND, LAc. She has advanced training in the diagnosis and treatment of specific conditions such as GERD, Gastritis, Inflammatory Bowel Disease, including microscopic colitis, gallbladder and liver disorders, Functional abdominal pain, Functional dyspepsia, Visceral Hypersensitivity, Irritable Bowel Syndrome, and Small Intestinal Bacterial Overgrowth (SIBO), among others. For more information about Dr. Taylor and her practice, visit her website at megantaylornd.com.


Sara Hopkins, ND, LAc, is a Naturopathic Physician and Licensed Acupuncturist in Portland, Oregon. She is co-owner of The Ren Clinic, an integrative medicine clinic that emphasizes trauma informed care, patient empowerment, and respect for size diversity. She provides primary and complementary care to her patients from a Health At Every Size model and has a specialization in the treatment of eating disorders and disordered eating.



Leonard B. Weinstock, M.D., is Board Certified in Gastroenterology and Internal Medicine. He is president of Specialists in Gastroenterology and the Advanced Endoscopy Center. He teaches at Barnes-Jewish Hospital and is an Associate Professor of Clinical Medicine and Surgery at Washington University School of Medicine. He is a primary investigator at the Sundance Research Center. Dr. Weinstock received a BA Magna Cum Laude from University of Vermont and the medical degree from University of Rochester School of Medicine. He completed his postgraduate trainingand was chief resident in Internal Medicine at Rochester General Hospital. His Gastroenterology Fellowship was performed at Washington University School of Medicine. Dr. Weinstock is an active lecturer and has published more than 85 articles, abstracts, editorials and book chapters. He is currently researching the role and treatment of small intestinal bacterial overgrowth in restless legs syndrome, irritable bowel syndrome, and rosacea. Dr. Weinstock has expertise with low dose naltrexone (LDN) in multiple inflammatory and autoimmune conditions. He is very interested in colon cancer prevention and has expertise in colon cancer screening. Further information is available at www.gidoctor.net.


Lara Williams, MD is an obstetrician-gynecologist in Portland, Oregon and is affiliated with multiple hospitals in the area, including Legacy Emanuel Hospital and Health Center and Providence Portland Medical Center. She received her medical degree from Texas A&M Health Science Center College of Medicine and has been in practice between 11-20 years.  She specializes in Obstetrics & Gynecology at Legacy Emanuel Hospital and Health Center, and Providence Portland Medical Center. She also speaks multiple languages, including Spanish.


Stefani Hayes, N.D., LAc, is a Naturopathic Doctor and Licensed Acupuncturist in Portland, Oregon.  She practices at Kwan Yin Healing Arts Center, West – a large integrative natural medicine clinic.  Dr. Stefani Hayes loves offering a collaborative model of care to her patients.  Her practice focuses on women’s health through all ages – from fertility concerns through peri- and post-menopausal management.  She thinks about women’s health concerns, such as endometriosis, unexplained infertility, and PCOS, from a holistic perspective that involves treatment of any sources of inflammation, including SIBO.  Actively co-treating with her SIBO specialist wife, Dr. Whitney Hayes, they have been successful in assisting many patients in achieving optimal wellness.  She is specially trained in the Arvigo Techniques of Maya Abdominal Therapy, for fertility, pregnancy and postpartum, as well as non-medicated Intra-uterine Inseminations (IUI).  Dr. Stefani’s passion is assisting all types of families in realizing their goals of pregnancy.  Her favorite experience is supporting single women and all types of couples through their preconception and fertility journey, adjunctively throughout pregnancy, and into a vital postpartum time.  For more information about Dr. Stefani’s practice, visit www.kwanyinhealingarts.com


Gary Weiner, N.D., LAc, balances the art and science of medicine.  A primary care naturopathic physician and acupuncturist, Dr. Weiner blends fifteen years of clinical experience with natural therapies to create individual treatment plans that are effective and safe.  Transforming his own health through diet motivated Dr. Weiner to change from a successful career as writer and producer for public television and film to a career in medicine. Committed to using all of his skills and knowledge and the best medicine has to offer, Dr. Weiner trained in family medicine while specializing in the treatment of endocrine and auto-immune disorders.  He lectures frequently and is a member of the Advisory Committee to the Crohn’s and Colitits Foundation as well as a member of the Oregon and American Associations of Naturopathic Physicians.


Ilana Gurevich, N.D., L.Ac. is a board-certified naturopathic physician and acupuncturist who graduated from the oldest accredited naturopathic medical school in the country, the National College of Natural Medicine. She uses individualized natural therapies to address the underlying cause of disease. Her Chinese medicine training is in Classical Chinese medicine, which uses the ancient texts of China as the foundation of education. She integrates the healing powers of the mind, body and spirit to provide holistic healthcare for her patients. Dr. Gurevich combines conventional medical diagnostics with effective natural therapies to restore the body’s innate ability to heal. She believes that the body has an inherent ability to cure itself, and she views her role as an assistant in that process. She can support the body’s natural balance, as well as remove obstacles to health. Dr. Gurevich relies heavily on her Chinese medicine training to provide further care for her patients.