Thiamin is a vitamin (B1) found in a variety of foods including meat, legumes, and whole, fortified and enriched grain products. Thiamin’s main role in the body is to act as a helper to enzymes used to release energy from foods. Thiamin also plays a role in fatty acid synthesis, membrane and nerve conduction and amino acid metabolism.

The metabolism of branched-chain amino acids (BCAA) involves several enzymatic steps and complexes. The first step involves removing the amino group to create a-ketoacids. This step is catalyzed by an enzyme known as branched chain aminotransferase (BCAT), and occurs normally in MSUD. The next step involves a branched-chain a-ketoacid dehydrogenase complex (BCKAD). MSUD is caused by a defect in this enzyme complex, resulting in a buildup of BCAAs and their a-ketoacids. Thiamin is part of a cofactor needed for this enzyme to work.

One form of MSUD is considered to be thiamin-responsive. This variant of the disease is less severe than the classic form, and has some enzyme activity.  The daily requirement for thiamin in healthy people is approximately 1.1 mg daily for adults, but the amount needed to improve enzyme function is much greater and depends on the amount of enzyme activity present. Thiamin dosages used to treat MSUD range from 10-100mg each day. Individuals who have thiamin-responsive MSUD can also tolerate more protein in their diet as compared with other more severe types of the disease.

The first observed thiamin-responsive patient was reported by Scriver and associates in 1971.  This French Canadian female infant was admitted to Montreal Children's Hospital with moderately elevated plasma BCAA concentrations. She was provided with a 10 mg per day oral supplement of thiamin hydrochloride and her plasma BCAA concentrations were drastically reduced to normal levels without the restricting BCAA intake. The withdrawal of the vitamin supplement caused a fast return of plasma BCAA concentrations to the pre-thiamin levels. This was followed by another sharp decline of BCAA concentrations upon reintroduction of the thiamin supplement (Chuang, 2006).

Researchers hypothesize that large doses of thiamin increase the amount of the cofactor which is needed for proper enzyme function, allowing the enzyme to function normally (Rosenberg 2008 pg 669). Large doses are safe as they do not cause toxicity and excess amounts are excreted in the urine.

This method of treatment only works for MSUD individuals who are thiamin-responsive. Those with classic MSUD do not respond as they have minimal or no enzyme activity of the BCKAD complex. Thiamine supplementation is not an alternative to diet for individuals with this type of MSUD.  It should be understood that while thiamine is a vitamin, when administered in these very large doses it acts more as a drug making monitoring by a physician essential.

Chuang, D., Chuang, J., & Wynn, R. (2006). Lessons from genetic disorders of branched chain amino acid metabolism. The Journal of Nutrition, 136(1), 2435-2495.

Rosenberg, R., DiMauro, S., Paulson, H., Ptacek, L., & Nestler, E. (2008). The Molecular and Genetic Basis of Neurologic and Psychiatric disease. (4th ed., p. 669). Philadelphia: Lippincott Williams & Wilkins.

Melvin Carruth

This letter is a tribute to my brother Melvin Carruth! We believe he is one of the oldest living African Americans with Maple Syrup Urine Disease.

Read More

NBS-MSUD Connect: Your One-Stop Shop For MSUD Resources

NBS-MSUD Connect was launched as part of the Newborn Screening Connect patient registry (NBS Connect) in 2013 through a partnership between the Department of Human Genetics at Emory University, the Maple Syrup Urine Disease (MSUD) Family Support Group and other key stakeholders.

Read More

Cambrooke Therapeutics

Cambrooke Therapeutics continues to expand its line of delicious and nutritious low protein foods to help improve the lives of individuals with Inborn Errors of Metabolism such as MSUD.

Read More

Updates To Nutrition Management Guidelines

The Nutrition Management Guideline for MSUD was first published in 2014. Since that time, there have been reports of new research and experiences that have prompted updates of the guideline.

Read More

Emory Metabolic Camp 2018 Announcement

Join us June 18-23, 2018 for the 24th Annual Metabolic Camp at Emory University in Atlanta, GA!

Read More

From The Chairman’s Desk

As I sit here reflecting on how much the care and treatment of MSUD has changed over the years, my mind goes back to 1978 when our son Keith was born.

Read More

MSUD Advocacy Report

Medical Nutrition Equity Act

The Medical Nutrition Equity Act (MNEA) would require all private insurance plans (state regulated or self-insured/self-funded) and federal health programs, including Children’s Health Insurance Program, Tricare, Medicaid, Medicare, and Federal Employee Health Benefit Plans, to provide coverage for formula and low-protein foods for all children and adults with MSUD.

Read More

The MSUD Family Support Group Is Excited To Announce Their Participation In The Million Dollar Bike Ride

The MSUD Family Support Group is excited to announce their participation in The Million Dollar Bike Ride

Read More

19th Biennial MSUD Symposium

I can’t believe that almost two years have passed and it is time for another MSUD Symposium! I am especially excited about this conference because I’ve built in extra time for social interaction.

Read More


A Child's Life

Subscribe to our mailing list

Signup To Our Newsletter Signup with your email address to receive news and updates