Deadlock quartet

The deadlock quartet is a combination of four nutrients used to overcome a proposed "deadlock" in the methylation cycle.

The deadlock quartet consists of:
 * cyanocobalamin - a form of vitamin B12
 * Hydroxocobalamin - a form of vitamin B12
 * Folic acid
 * Folinic acid

Theory
A hypotheical four-way "deadlock" in the methylation process is believed to cause energy limitations due to impaired metabolism.

Evidence
There is no peer-reviewed evidence in support of either a four-way deadlock in methylation or in the use of the deadlock quartet to treat it. The deadlock quartet was developed by Phoenix Rising forum member Freddd, based on work by ME/CFS patient Rich Van Konynenburg.

The concept of a block or deadlock affecting energy metabolism is also part of the metabolic trap hypothesis, which was developed independently using the ME/CFS Severely Ill, Big Data Study, and which has different proposed treatments.

Risks and safety
Largely unknown since clinicial trials have not taken place. Cyanocobalamin has significant safety risks, including the loading of potassium levels. Both cyanocobalamin and hydroxocobalamin are available as supplements and in other forms, including injections of higher doses as a perscription drug. Allergies and anaphylatic shock also occur in some people given cyanocobalamin or other B12 forms.

Learn more

 * Vitamin B12 - Office of Dietary Supplements
 * Cyanocobalamin - FDA prescribing information, side effects - drugs.com
 * Hydroxocobalamin (injection): Uses, Side Effects & Warnings - drugs.com