Meet Dr. B

Dr. Will Bulsiewicz (or "Dr. B") is an award winning gastroenterologist, internationally recognized gut health expert, the New York Times-bestselling author of Fiber Fueled and The Fiber Fueled Cookbook, and the Founder of 38TERA. His research has been published in Nature Medicine, Gastroenterology and more. He has given more than forty presentations at scientific meetings, spoken to Congress and the USDA, and through social media, podcasts, his books and courses he has educated millions on the importance of gut health.

Dr. Will Bulsiewicz, MD, MSCI

Education, training, and awards

Why 38TERA?

Revolutionizing gut health

Going back more than 10 years, supplements played an important role in my gastroenterology clinic. Prebiotics and probiotics were a routine part of how I cared for my patients, but as a gastroenterologist, I struggled to find trustworthy, well-formulated supplements that I believed in.

Many supplements had outdated formulas or weak science with exaggerated claims, lacking transparency and third-party testing.

My frustration motivated me to do something radical.
Introducing 38TERA.

Inspired by patients

As a gastroenterologist, I am creating solutions to the very real problems many people experience as the result of a damaged gut microbiome.

Guided by science

38TERA products are formulated at the intersection of advanced science, clinical experience and gut health expertise, delivering effective solutions powered by the latest research and innovation.

Designed for you and your microbes

Your gut microbes are central to your health and 38TERA is designed to nourish and enhance your gut microbiome to elevate your health.

The vision

Premium quality

Crafted from the finest ingredients based on the latest gut health science.

Certified Manufacturing

Produced in an FDA- and GMP-certified facility ensuring top-notch quality.

Rigorous testing

Every lot is third-party tested for 100+ substances to ensure purity and safety.

Continuous improvement

Committed to further testing, research, and certifications to enhance product quality.

Educational support

Offer valuable resources for maximizing benefits from our supplements AND improving diet and lifestyle.

Community building

Foster a supportive network of gut health enthusiasts for mutual encouragement and growth.

Exceptional service

Provide friendly and supportive customer care.

Customer satisfaction

Dedicated to consistently going above and beyond customer expectations.

Your daily gut ‘multi-vitamin’

Your gut's new best friend.

Shop now
Drawing from my experience with tens of thousands of patients and my gut microbiome expertise, 38TERA is here to offer superior supplements to help you take your gut health to the next level.

Dr. Will Bulsiewicz, MD, MSCI