The SAM/SAH Ratio is one of the most powerful functional indicators of methylation efficiency in the human body. It represents the balance between S-Adenosylmethionine (SAM)—the body’s primary methyl donor—and S-Adenosylhomocysteine (SAH)—a byproduct that accumulates when methylation reactions slow down.

On the Neurotransmitter XL panel, this ratio provides deep insight into the methylation cycle’s performance, influencing neurotransmitter metabolism, detoxification, DNA regulation, hormone balance, and energy production. A high SAM/SAH ratio reflects robust methylation activity, whereas a low ratio signals methylation inefficiency, often tied to nutrient deficiency, oxidative stress, or metabolic slowdown.

This marker functions as a metabolic checkpoint—showing whether the body is efficiently transferring methyl groups (-CH3) to sustain biochemical reactions essential for mental health, energy, and cellular repair.

The SAM/SAH ratio is commonly referred to as the “Methylation Index” in the literature and has well- documented clinical associations.

Global methylation is dependent on two key factors: adequate SAM supply and SAH removal.

The SAM/SAH ratio has been proposed to indicate the likelihood of hyper- or hypo-methylation. 

Overall, the SAM/SAH ratio is under tight homeostatic control. SAM levels remain fairly stable due to denovo synthesis and feedback mechanisms. Given this, alterations in the methylation index are more likely a result of SAH fluctuations.

The SAM/SAH Ratio is a key indicator of how efficiently your body performs methylation—the process that supports DNA repair, detoxification, neurotransmitter balance, hormone metabolism, and cellular energy. A higher ratio suggests stronger methylation activity, while a low ratio indicates reduced capacity, often due to nutrient deficiencies, metabolic stress, or folate-cycle imbalances. This marker provides one of the clearest overall snapshots of methylation health.

Sapovirus I, detected in a gut test, is a significant indicator of gastrointestinal health, particularly in the context of viral infections. Sapovirus, a member of the Caliciviridae family, is known for causing acute gastroenteritis, primarily in children and infants, but it can also affect adults. These viruses are typically transmitted through the fecal-oral route, often due to contaminated food or water, or close contact with infected individuals. The presence of Sapovirus I in a gut test indicates a recent or ongoing infection, which can be responsible for symptoms such as diarrhea, vomiting, abdominal pain, and sometimes fever and dehydration.

Sarcosine is an amino acid made within the methylation cycle when S-adenosylmethionine (SAM) is conjugated with glycine.

It can also be made by catabolism of dimethylglycine (DMG).

There are many dietary sources of sarcosine including eggs, legumes, nuts, and meats.

Sarcosine is also available as an over-the-counter supplement, and it is widely used in cosmetic formulations (toothpaste, creams, and soaps) and detergents.

In the methylation cycle, sarcosine is created by the GNMT enzyme, which functions to control SAM excess. Some clinicians use sarcosine elevation as a marker of ‘excess methyl supplementation’ or ‘over-methylation.’ Currently, there is no literature to support this hypothesis, but rather it is based on physiology.

Sarcosine is an amino acid made within the methylation cycle when S-adenosylmethionine (SAM) is conjugated with glycine. It can also be made by catabolism of dimethylglycine (DMG).

There are many dietary sources of sarcosine including eggs, legumes, nuts, and meats.

Sarcosine is also available as an over-the-counter supplement, and it is widely used in cosmetic formulations (toothpaste, creams, and soaps) and detergents. In the methylation cycle, sarcosine is created by the GNMT enzyme, which functions to control SAM excess.

Sarcosine is also known as N-methylglycine. It is an intermediate and byproduct in the glycine synthesis and degradation. Sarcosine is metabolized to glycine by the enzyme sarcosine dehydrogenase, while glycine-N-methyl transferase generates sarcosine from glycine.

Sarcosine is an amino acid made when SAM is conjugated with glycine by the glycine-N- methyltransferase (GNMT) enzyme. It can also be made by catabolism of DMG. There are many dietary sources of sarcosine including eggs, legumes, nuts, and meats. [L]

Sarcosine is also available as an over-the-counter supplement, and it is widely used in cosmetic formulations (toothpaste, creams, and soaps) and detergents. [L]

In the methylation cycle, sarcosine is created by the GNMT enzyme, which functions to control SAM excess. Disposal of excess SAM is seen in excess methyl donor supplementation, or SAM elevation due to adiposity/ obesity. Some clinicians use sarcosine elevation as a marker of ‘excess methyl supplementation’ or ‘over- methylation.’ Currently, there is no literature to support this hypothesis, but rather it is based on physiology. [L]

Sarcosine is an amino acid made within the methylation cycle when S-adenosylmethionine (SAM) is conjugated with glycine. It can also be made by catabolism of dimethylglycine (DMG).

There are many dietary sources of sarcosine including eggs, legumes, nuts, and meats.

Sarcosine is also available as an over-the-counter supplement, and it is widely used in cosmetic formulations (toothpaste, creams, and soaps) and detergents. In the methylation cycle, sarcosine is created by the GNMT enzyme, which functions to control SAM excess.

Sarcosine is an amino acid made within the methylation cycle when S-adenosylmethionine (SAM) is conjugated with glycine. It can also be made by catabolism of dimethylglycine (DMG).

There are many dietary sources of sarcosine including eggs, legumes, nuts, and meats.

Sarcosine is also available as an over-the-counter supplement, and it is widely used in cosmetic formulations (toothpaste, creams, and soaps) and detergents. In the methylation cycle, sarcosine is created by the GNMT enzyme, which functions to control SAM excess.

Sarcosine is an amino acid made within the methylation cycle when S-adenosylmethionine (SAM) is conjugated with glycine.

It can also be made by catabolism of dimethylglycine (DMG).

There are many dietary sources of sarcosine including eggs, legumes, nuts, and meats.

Sarcosine is also available as an over-the-counter supplement, and it is widely used in cosmetic formulations (toothpaste, creams, and soaps) and detergents.

In the methylation cycle, sarcosine is created by the GNMT enzyme, which functions to control SAM excess. Some clinicians use sarcosine elevation as a marker of ‘excess methyl supplementation’ or ‘over-methylation.’ Currently, there is no literature to support this hypothesis, but rather it is based on physiology.

Sarcosine is an amino acid made within the methylation cycle when S-adenosylmethionine (SAM) is conjugated with glycine. It can also be made by catabolism of dimethylglycine (DMG).

There are many dietary sources of sarcosine including eggs, legumes, nuts, and meats.

Sarcosine is also available as an over-the-counter supplement, and it is widely used in cosmetic formulations (toothpaste, creams, and soaps) and detergents. In the methylation cycle, sarcosine is created by the GNMT enzyme, which functions to control SAM excess.

Sarcosine is an amino acid made within the methylation cycle when S-adenosylmethionine (SAM) is conjugated with glycine. It can also be made by catabolism of dimethylglycine (DMG).

There are many dietary sources of sarcosine including eggs, legumes, nuts, and meats.

Sarcosine is also available as an over-the-counter supplement, and it is widely used in cosmetic formulations (toothpaste, creams, and soaps) and detergents. In the methylation cycle, sarcosine is created by the GNMT enzyme, which functions to control SAM excess.

Sarcosine is an amino acid made within the methylation cycle when S-adenosylmethionine (SAM) is conjugated with glycine.

It can also be made by catabolism of dimethylglycine (DMG).

There are many dietary sources of sarcosine including eggs, legumes, nuts, and meats.

Sarcosine is also available as an over-the-counter supplement, and it is widely used in cosmetic formulations (toothpaste, creams, and soaps) and detergents.

In the methylation cycle, sarcosine is created by the GNMT enzyme, which functions to control SAM excess. Some clinicians use sarcosine elevation as a marker of ‘excess methyl supplementation’ or ‘over-methylation.’ Currently, there is no literature to support this hypothesis, but rather it is based on physiology.

Sarcosine is also known as N-methylglycine. It is an intermediate and byproduct in the glycine synthesis and degradation. Sarcosine is metabolized to glycine by the enzyme sarcosine dehydrogenase, while glycine-N-methyl transferase generates sarcosine from glycine.