Methyl Donor Deficiency

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    Methyl Donor Deficiency refers to a lack of certain nutrients in the body that provide methyl groups, which are essential for many cellular functions. These functions include making DNA, creating certain fats in the body, and building proteins. Methyl groups come from what we eat, including nutrients like methionine, folate, betaine, and choline, which are found in various foods.[1]

    The body uses a substance called S-Adenosylmethionine (SAMe) to transfer methyl groups in many important reactions. SAMe is made from methionine, which we can get from our diet or from recycling a substance called homocysteine in our body. The liver and kidneys are especially good at storing betaine, which helps in this recycling process. However, if there's too much SAMe, it can actually slow down its own production by affecting other enzymes related to methyl group metabolism.[1]


    Methyl donor deficiency can lead to a range of physiological and metabolic disturbances due to its impact on essential cellular functions, including DNA methylation [2], phosphatidylcholine synthesis, and protein synthesis. Below are some of the symptoms and consequences associated with this condition:

    Energy Metabolism and Muscle Disorders

    • Fatigue and weakness due to disturbances in energy metabolism.
    • Muscle disorders, potentially linked to impaired protein synthesis.

    Hepatic Effects

    • Fatty liver (hepatic steatosis), which can occur due to disrupted lipid metabolism.
    • Increased risk of liver inflammation and liver disease.

    Cardiovascular Symptoms

    • Elevated levels of plasma total homocysteine (tHcy), which is a risk factor for cardiovascular diseases.
    • Potential increase in cardiovascular risk factors, possibly leading to cardiovascular events.

    Neurological and Cognitive Symptoms

    • Impaired cognitive function and potential developmental delays.
    • Increased risk of neurodegenerative diseases due to disrupted brain methylation processes.

    Pregnancy and Developmental Issues

    • During pregnancy, increased risk of complications and birth defects due to impaired DNA methylation.
    • Potential for neural tube defects and other developmental anomalies in the fetus.

    Psychological Symptoms

    • Mood disturbances, including depression, possibly related to altered neurotransmitter synthesis.
    • Behavioral changes due to imbalances in epigenetic regulation of gene expression.


    Methyl donor deficiency is often diagnosed through a combination of clinical evaluations, assessment of dietary intake, and biochemical tests. The following approaches are used to diagnose this deficiency:

    Clinical Evaluation

    • Assessment of symptoms that may suggest a deficiency in methyl donors, such as fatigue, muscle weakness, or cognitive changes.
    • Evaluation of medical history and physical examination for signs of liver dysfunction or cardiovascular issues.

    Dietary Assessment

    • Detailed dietary history to assess the intake of key nutrients involved in methylation processes, including folate, betaine, choline, and B-vitamins.

    Laboratory Tests

    • Measurement of plasma total homocysteine (tHcy) levels, which can be elevated in cases of methyl donor deficiency.
    • Blood tests for levels of S-Adenosylmethionine (SAMe) and S-adenosylhomocysteine (SAH), with a low SAM/SAH ratio indicating potential deficiency.
    • Plasma concentrations of folate, betaine, and choline, as well as vitamin B12 and B6 levels.
    • Genetic testing for polymorphisms in enzymes such as MTHFR that may affect methylation pathways.

    Specialized Tests

    • Liver function tests, since methyl donor deficiency can affect liver health.
    • In pregnant women, assessment of fetal development and monitoring for any complications that could be related to methyl donor deficiency.

    It is essential to consider that these tests may not directly confirm a methyl donor deficiency but may indicate a potential problem in the methylation cycle that could be linked to dietary inadequacies or genetic factors. Consultation with a healthcare provider specializing in metabolic disorders is recommended for a definitive diagnosis and appropriate treatment plan.

    See Also


    1. 1.0 1.1 Obeid R: The metabolic burden of methyl donor deficiency with focus on the betaine homocysteine methyltransferase pathway. Nutrients 2013. (PMID 24022817) [PubMed] [DOI] [Full text] Methyl groups are important for numerous cellular functions such as DNA methylation, phosphatidylcholine synthesis, and protein synthesis. The methyl group can directly be delivered by dietary methyl donors, including methionine, folate, betaine, and choline. The liver and the muscles appear to be the major organs for methyl group metabolism. Choline can be synthesized from phosphatidylcholine via the cytidine-diphosphate (CDP) pathway. Low dietary choline loweres methionine formation and causes a marked increase in S-adenosylmethionine utilization in the liver. The link between choline, betaine, and energy metabolism in humans indicates novel functions for these nutrients. This function appears to goes beyond the role of the nutrients in gene methylation and epigenetic control. Studies that simulated methyl-deficient diets reported disturbances in energy metabolism and protein synthesis in the liver, fatty liver, or muscle disorders. Changes in plasma concentrations of total homocysteine (tHcy) reflect one aspect of the metabolic consequences of methyl group deficiency or nutrient supplementations. Folic acid supplementation spares betaine as a methyl donor. Betaine is a significant determinant of plasma tHcy, particularly in case of folate deficiency, methionine load, or alcohol consumption. Betaine supplementation has a lowering effect on post-methionine load tHcy. Hypomethylation and tHcy elevation can be attenuated when choline or betaine is available.