Takeaways
- Methionine is an essential amino acid vital for protein synthesis
- It supports detoxification processes and antioxidant production
- Methionine contributes to energy metabolism and ATP production
- It may help regulate appetite and support weight management
- Adequate intake is important for overall health and metabolism
What is Methionine?
Methionine is a crucial amino acid that the human body cannot produce, making it essential to obtain through diet or supplements.[1] This amino acid, which contains sulfur, is heavily involved in the creation of proteins and various metabolic activities.
Methionine often acts as the initiator of protein construction. It marks the starting point for building numerous proteins within cells.[2] Beyond its role as a starter, methionine also participates in the formation of other vital molecules in the body.
Dietary intake is the primary way the body acquires methionine. Foods like meat, fish, and dairy are good sources.[3] For those on plant-based diets, options include nuts, seeds, and certain grains. Supplements provide an alternative method to increase methionine levels if necessary.
Biochemistry of Methionine
Structure and Properties
Methionine has a distinguishing feature among amino acids due to the sulfur atom within its side chain.[4] This sulfur component gives methionine unique chemical properties, enabling it to create bonds that contribute to protein structure stability.
The chemical formula of methionine is C5H11NO2S, and its molecular weight is 149.21 g/mol.[5] At room temperature, it exists as a white crystalline substance or powder. Methionine’s solubility in water facilitates its efficient absorption and use by the body.
Metabolic Pathways
Methionine is central to one-carbon metabolism, a process where single carbon atoms are transferred between molecules.[6] These transfers are essential for producing vital components such as DNA, proteins, and lipids.
The methionine cycle is the core of this one-carbon transfer process. It involves several biochemical reactions and the action of several enzymes.[7]
- Methionine gets converted to S-adenosylmethionine (SAM)
- SAM donates its methyl group to other molecules
- The resulting molecule becomes homocysteine
- Homocysteine can then be converted back to methionine
This cycle continues to operate continuously, delivering methyl groups that support many different reactions within the body.
Step | Enzyme | Function |
---|---|---|
1 | Methionine adenosyltransferase | Converts methionine to SAM |
2 | Various methyltransferases | Transfer methyl groups from SAM |
3 | S-adenosylhomocysteine hydrolase | Produces homocysteine |
4 | Methionine synthase | Regenerates methionine |
Methionine’s role in methylation, the process of adding methyl groups to molecules, is very important.[8] Methylation impacts gene activity, protein function, and cellular communication. Methionine’s provision of methyl groups influences a wide range of bodily functions.
Methionine in Human Health
Protein Synthesis
Methionine has a key role in the creation of proteins. It is often the first amino acid in newly formed proteins.[9] This role as an initiating molecule makes methionine essential for generating many types of proteins within the body.
The genetic code uses methionine as a signal for where to begin making a protein.[10] It tells the cellular machinery where to start reading genes. A lack of methionine prevents the body from making the proteins needed for proper function.
Antioxidant Production
Methionine aids the body’s antioxidant defenses. It is used to make glutathione, an important antioxidant that protects cells against damage caused by free radicals and toxins.[11]
The sulfur within methionine has antioxidant properties on its own, directly neutralizing harmful molecules.[12] Methionine’s dual capability—both forming glutathione and directly acting as an antioxidant—makes it a powerful tool in the body’s defense systems.
Detoxification
The liver depends on methionine for detoxification. It is involved in processing and eliminating toxins from the body. Methionine supports liver function through the following:
- It provides sulfur for detoxification reactions
- It helps produce glutathione, which binds to toxins
- It supports the production of bile, which carries toxins out of the body
- It aids in the breakdown of fats, preventing fatty liver disease
Sufficient methionine supports the natural detox processes, helping the body effectively manage environmental pollutants and metabolic waste.[13]
Metabolism and Energy Production
ATP Synthesis
Methionine contributes to energy production by helping in the synthesis of ATP, the cell’s primary energy source.[14] Although not directly involved in the ATP creation, methionine supports this process in several ways.
It is involved in the production of creatine, a molecule used to store energy in muscles.[15] Creatine acts as a quick supply of ATP during periods of intense activity. Through supporting creatine creation, methionine indirectly enhances energy levels.
Methionine supports the function of mitochondria, the cellular powerhouses that produce the majority of ATP.[16] By protecting mitochondria from oxidative damage, methionine helps maintain effective energy production.
Fat Metabolism
Methionine impacts how the body manages fats through the following actions:
- It contributes to the synthesis of carnitine, which shuttles fatty acids into mitochondria for energy production
- It supports the production of phosphatidylcholine, a key component of cell membranes and lipoproteins
- It aids in the breakdown of homocysteine, high levels of which are linked to fat accumulation in the liver
These combined effects make methionine important for overall fat metabolism. Adequate methionine consumption helps to prevent fatty liver disease and support healthy lipid levels.[17]
Aspect of Metabolism | Methionine’s Role |
---|---|
Protein Synthesis | Initiates protein production, essential building block |
Energy Production | Supports ATP synthesis, contributes to creatine production |
Fat Metabolism | Aids in fat transport and breakdown, supports liver health |
Antioxidant Defense | Contributes to glutathione production, acts as direct antioxidant |
The many roles of methionine underscore its importance in metabolism. From protein creation to supporting energy production and fat breakdown, this amino acid helps keep bodily processes running well.
Methionine and Weight Management
Appetite Regulation
Methionine may affect appetite, with some studies suggesting it impacts the creation of hormones related to hunger and fullness.[18] However, the exact mechanisms behind this aren’t completely clear.
One idea is that methionine levels in the brain influence appetite. When methionine is low, it might trigger increased food intake. On the other hand, sufficient methionine might help promote feelings of fullness.
Methionine is also used to make serotonin, a neurotransmitter that affects mood and appetite.[19] Through supporting serotonin production, methionine may indirectly impact eating habits.
Body Composition
Research on methionine’s influence on body composition has shown inconsistent results.[20] Some studies suggest it could help in fat loss and muscle gain, while others find no notable difference.
A 2018 study found that restricting methionine led to weight loss in mice.[21] However, human studies are limited, and more research is needed to fully understand how methionine impacts body composition in humans.
Methionine’s role in protein synthesis suggests it could support muscle growth, potentially impacting overall body composition. By helping to build muscle mass, methionine could increase metabolic rate.
Dietary Sources of Methionine
Methionine is naturally present in numerous foods. Animal products tend to contain higher levels than plant-based options. Here are some good food sources of methionine:
- Eggs
- Chicken
- Turkey
- Fish (especially tuna and halibut)
- Beef
- Pork
- Dairy products (milk, cheese, yogurt)
- Nuts and seeds (especially Brazil nuts and sesame seeds)
- Soybeans and soy products
- Whole grains (quinoa, brown rice)
The amount of methionine in foods can vary based on factors such as soil quality, cooking methods, and storage conditions. Generally, fresh and minimally processed foods have higher levels of methionine.
Plant-based diets may provide lower levels of methionine.[22] Vegetarians and vegans need to be mindful of their intake. Eating a variety of plant-based proteins helps ensure sufficient methionine consumption.
Methionine Supplementation
Forms and Dosages
Methionine supplements are available in different forms:
- L-methionine: The form found in food and most commonly used in supplements
- D-methionine: A synthetic form, less common in supplements
- N-acetyl-L-methionine: A more stable form that may be better absorbed
Typical daily dosages of methionine supplements range from 200 to 1000 mg.[23] Individual needs vary, influenced by factors like age, health status, and dietary intake. These factors affect the body’s requirement for methionine.
The absorption of methionine supplements can vary. Taking them on an empty stomach may improve absorption, and combining them with B-vitamins may also help with absorption for some people.
Potential Benefits
People consider methionine supplements for several reasons, including:
- To support liver health and detoxification
- To boost antioxidant defenses
- To aid in protein synthesis and muscle recovery
- To support cardiovascular health
- To potentially assist with weight management
While there are potential benefits to methionine supplementation, more research is needed.[24] The effects of these supplements can vary from person to person.
Precautions and Side Effects
Methionine supplements are usually safe when taken as instructed, but some people might experience side effects, such as:
- Nausea
- Headache
- Dizziness
- Drowsiness
High doses of methionine can raise homocysteine levels, potentially increasing the risk of heart disease and stroke.[25] People with heart issues should talk to a doctor before taking methionine supplements.
Certain groups of people should avoid methionine supplements:
- People with liver disease
- Those with homocystinuria (a genetic disorder affecting methionine metabolism)
- Individuals taking medications that interact with methionine
Always seek advice from a healthcare professional before beginning any new supplement routine. They can help you decide if methionine supplements are right for your situation.
Methionine Deficiency
Causes
Methionine deficiency is uncommon in healthy people who eat a balanced diet. However, certain things can increase the risk:
- Strict vegan diets without proper planning
- Malnutrition or eating disorders
- Certain medical conditions affecting nutrient absorption
- Excessive alcohol consumption
- Some medications that interfere with methionine metabolism
Chronic stress and intense physical activity might also increase the body’s need for methionine, potentially leading to deficiency if intake doesn’t meet these needs.[26]
Symptoms
Methionine deficiency can present itself through various symptoms, such as:
- Slow wound healing
- Muscle weakness
- Fatigue
- Hair loss
- Skin problems
- Liver dysfunction
- Weakened immune system
These symptoms aren’t exclusive to methionine deficiency and could indicate other health issues. If you have these symptoms persistently, consult with a healthcare provider.
Long-term methionine deficiency can lead to serious health problems. It can affect growth in children, and in adults, it might lead to liver problems and an increased risk of certain diseases.[27]
Diagnosing methionine deficiency requires blood tests to measure methionine levels and related compounds like homocysteine. A healthcare provider can interpret these results and advise on appropriate treatment.
Methionine in Sports and Fitness
Athletic Performance
Athletes often pay close attention to their amino acid intake, with methionine being an important essential amino acid that plays a role in athletic performance. It contributes to fitness in several ways:
- Protein synthesis for muscle growth and repair
- Energy production through creatine synthesis
- Antioxidant defense against exercise-induced oxidative stress
Some studies suggest that methionine supplementation might enhance endurance. A 2017 study demonstrated improved exercise capacity in rats.[28] However, human studies have shown varying results.
Methionine’s role in creatine production is of interest to many athletes. Creatine aids in providing quick energy during high-intensity activities. Methionine’s support of creatine production may indirectly enhance performance.
Muscle Recovery
Muscle recovery is important for athletes and fitness enthusiasts. Methionine can help this process in multiple ways:
- It aids in protein synthesis, helping repair damaged muscle tissue
- Its antioxidant properties may reduce exercise-induced inflammation
- It supports the production of growth factors involved in muscle repair
After intense exercise, the body needs to repair proteins and reduce inflammation. Adequate methionine intake could potentially accelerate this recovery process.
Some athletes use methionine supplements to support muscle recovery.[29] While personal stories are positive, further research is needed. Results can vary depending on the person and their training intensity.
Methionine and Aging
Longevity Research
Methionine has garnered attention from longevity researchers. Some animal studies indicate that restricting methionine intake might prolong lifespan.
A 2019 study found that limiting methionine extended lifespan in fruit flies.[30] Similar findings have been observed in rodents. It is unclear whether these results translate to humans.
The potential mechanisms behind this effect include:
- Reduced oxidative stress
- Improved insulin sensitivity
- Enhanced cellular repair processes
These results, while interesting, don’t mean that everyone should limit methionine intake. The body needs this amino acid for important processes. Further research is necessary to understand the balance between restriction and optimal health.
Age-Related Health Concerns
As we age, the way our bodies process methionine changes. Older adults might not process methionine as efficiently, which can result in increased homocysteine levels.[31] These higher levels are associated with various health issues.
Methionine may affect some health concerns related to aging:
- Cognitive function: Methionine is involved in neurotransmitter production
- Bone health: It plays a role in collagen synthesis
- Cardiovascular health: Proper methionine metabolism helps maintain healthy homocysteine levels
- Skin aging: Its antioxidant properties may protect against UV damage
Maintaining adequate methionine intake becomes important as we age. It’s essential to achieve the right balance; both too much and too little methionine can be problematic.
Researchers are investigating methionine’s potential in healthy aging strategies. This includes studying how it interacts with other nutrients and lifestyle factors. A balanced approach is often the best for overall health.
Methionine and Brain Function
Cognitive Health
Methionine influences brain health in several ways. It’s involved in the production of important brain chemicals, such as neurotransmitters, which affect mood, memory, and cognitive function.[32]
One way methionine supports brain health is through its role in the production of SAM, a compound used to create neurotransmitters like dopamine and serotonin.[33] These chemicals are important in mood regulation and thinking processes.
Methionine also supports the production of phosphatidylcholine, an important component of cell membranes, including those in the brain. Sufficient levels help maintain healthy brain structure and function.
Some studies suggest that methionine might have neuroprotective effects.[34] Its antioxidant abilities could help shield brain cells from damage. Further research is needed to understand these potential benefits.
Mood Regulation
Methionine’s contribution to mood regulation is related to its involvement in neurotransmitter production. It’s especially important for making serotonin, often called the “feel-good” neurotransmitter.[35]
The methionine cycle supplies the methyl groups needed to create serotonin. Without enough methionine, serotonin creation can be affected, potentially impacting mood and emotional wellness.
Some researchers are exploring methionine’s potential in managing mood disorders. A 2017 study indicated that methionine supplements improved symptoms of depression.[36] These findings are initial and further studies are needed for confirmation.
It is important to note that the connection between methionine and mood is complex. While needed for serotonin production, very high levels of methionine may be problematic. As with many nutritional factors, balance is crucial.
FAQ: People Also Ask
What is methionine used for in the body?
Can methionine help with weight loss?
What foods are high in methionine?
Is methionine safe to take as a supplement?
How does methionine affect liver health?
Can methionine improve athletic performance?
What is the relationship between methionine and homocysteine?
How does methionine support detoxification?
Can methionine supplements help with hair growth?
What are the symptoms of methionine deficiency?
Methionine and Cardiovascular Health
Methionine’s relationship to heart health is complicated. It’s vital for making molecules that support cardiovascular function. On the other hand, high levels of homocysteine, a metabolite of methionine, have been linked to heart disease risks.[47]
Methionine contributes to the creation of molecules that support heart health:
- Taurine: An amino acid that helps regulate blood pressure
- Carnitine: Aids in fatty acid metabolism in the heart
- Creatine: Provides energy for heart muscle function
However, excess methionine can lead to high levels of homocysteine.[48] Increased homocysteine levels are associated with a greater risk of heart disease and stroke, highlighting the need for a balanced intake of methionine.
Some research indicates that consuming enough B vitamins can help manage homocysteine levels.[49] Vitamins B6, B12, and folate interact with methionine in the methionine cycle. Ensuring adequate intake of these vitamins may optimize methionine metabolism.
Methionine and Immune Function
Methionine supports the immune system by contributing to the production of antibodies and the activation of immune cells.[50] Its antioxidant qualities also boost general immune health.
One of the ways that methionine helps immunity is through the creation of glutathione. Glutathione is essential for the function of immune cells, helping T-cells respond effectively to threats.
Methionine is also used to make cysteine, another amino acid that is essential for immune function. Cysteine is used to make proteins that control immune responses.
Research suggests methionine supplements might enhance immune function in some instances. A 2018 study found that methionine supplements improved immune responses in chickens.[51] More research is necessary to determine its effects on humans.
Methionine in Pregnancy and Early Development
Methionine is crucial during pregnancy and early childhood. It participates in DNA methylation, a process that influences gene activity. This is especially important during fetal development.
During pregnancy, the need for methionine increases. It is required for:
- Proper fetal growth and development
- Formation of the neural tube
- Development of the fetal liver
Adequate methionine intake during pregnancy might help prevent some birth defects. However, very high intake isn’t recommended. Like many nutrients, balance is key.
In early childhood, methionine continues to be important for growth and development. It supports:
- Continued brain development
- Proper immune system function
- Overall growth through its role in protein synthesis
Ensuring adequate methionine through a balanced diet is crucial for pregnant women and young children. In certain instances, supplements may be recommended with medical supervision.
Methionine and Skin Health
Methionine contributes to skin health through its roles in protein creation and antioxidant production. These support healthy skin maintenance.
As part of collagen and keratin, methionine helps maintain the skin’s structural integrity. These proteins give skin its strength and elasticity. Adequate methionine intake may aid skin repair and regeneration.
Methionine’s antioxidant properties also benefit skin health. It helps shield skin cells from the effects of UV radiation and pollution. This may contribute to the prevention of premature aging.
Some skincare products contain methionine or its derivatives. They are thought to provide antioxidant benefits when applied topically. However, more studies are needed to fully understand the effects of topical methionine on skin health.
Methionine in Plant and Animal Nutrition
Methionine is not only important for human health; it is vital for plant and animal nutrition as well.
In plants, methionine is an essential amino acid for growth and development. It is used in:
- Protein synthesis
- Production of ethylene, a plant hormone
- Seed germination and early seedling growth
Many crops, especially legumes, are naturally low in methionine. Plant breeders work to create varieties with higher methionine content to boost their nutritional value.
In animal nutrition, methionine is often a limiting amino acid, meaning it is the first amino acid to become depleted and limit overall protein synthesis. In livestock and poultry farming, methionine supplements are frequently used to optimize growth and production.
Supplementing methionine in animal feed can:
- Improve growth rates
- Enhance feed efficiency
- Boost immune function
- Improve egg production in laying hens
Understanding methionine’s role in plant and animal nutrition helps improve food production and quality. This, in turn, impacts human nutrition and health.
Future Directions in Methionine Research
As our understanding of methionine evolves, new areas of research continue to emerge. Scientists are exploring its potential across various areas of health and medicine.
One area of interest is methionine restriction. Some researchers are studying if limiting methionine intake could have health benefits. Early animal studies show promising results for longevity and metabolic health. More research is needed to understand if these results apply to humans.
Another focus is on methionine’s role in cancer biology. Some studies suggest certain cancer cells are more dependent on methionine than normal cells. This is driving research into methionine restriction as a possible complementary cancer treatment.
Researchers are also exploring methionine’s potential in:
- Neurodegenerative diseases: Its role in brain health makes it interesting for Alzheimer’s and Parkinson’s research
- Metabolic disorders: Its influence on energy metabolism could be relevant for conditions like diabetes
- Gut health: Methionine’s involvement in gut barrier function is being studied
As research advances, we might gain new knowledge about how to best manage methionine intake for health. This could lead to more personalized nutritional advice based on individual needs and health goals.
Conclusion
Methionine, an essential amino acid, has multiple important roles in the body. Its impact extends from protein synthesis and metabolism to detoxification and brain function. Recognizing these functions underscores the importance of a balanced diet.
While crucial, balanced methionine intake is key. Too little can cause deficiency, while excess can have negative effects. Most people can meet their needs through a varied, balanced diet.
Those considering methionine supplements should consult a health professional. They can help determine if supplementation is necessary and guide appropriate use.
As research continues, we will likely gain further understanding of methionine’s roles in health and disease. This knowledge could lead to new nutritional and medical interventions. However, a balanced diet that delivers sufficient essential nutrients, including methionine, remains fundamental.
Remember that while individual nutrients like methionine are important, they function best within an overall healthy lifestyle. A balanced diet, regular exercise, sufficient sleep, and stress management are all important for optimal health.
Essential amino acids cannot be synthesized by the body and therefore must be consumed through diet. Methionine is one of these essential amino acids.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
Methionine’s codon, AUG, also serves as the start codon for mRNA translation, so it is often the first amino acid in a new polypeptide chain, and thus the initiating amino acid of many proteins.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
Methionine is present in many animal-based and plant-based foods, but animal products are generally considered to be richer sources. Meat, fish, and dairy products are high in protein, which contains methionine.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
Methionine and cysteine are the only two standard amino acids with sulfur atoms in their side chains. This sulfur atom contributes to methionine’s chemical properties and functions.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
The chemical formula of methionine is indeed C5H11NO2S and its molar mass is 149.21 g/mol.
Methionine is involved in the transfer of single-carbon units via its role in the methionine cycle, which is essential for various biosynthetic processes. These one carbon transfers are essential for things like DNA methylation.
Source: “Dietary Methionine and Total Sulfur Amino Acid Restriction in Healthy Adults” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10782544/
The methionine cycle is indeed core to one-carbon transfers and a network of biochemical reactions involving several enzymes.
Source: “Dietary Methionine and Total Sulfur Amino Acid Restriction in Healthy Adults” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10782544/
Methionine is a precursor of S-adenosylmethionine (SAM), which is the primary methyl group donor for methylation reactions within cells. These methyl groups are added to DNA, RNA, proteins, and lipids, influencing their functions and gene activity.
Source: “Dietary Methionine and Total Sulfur Amino Acid Restriction in Healthy Adults” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10782544/
The AUG codon for methionine also acts as the start codon for translation. Therefore, methionine is usually the first amino acid in the polypeptide chain as it is synthesized on a ribosome.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
The AUG codon is the start codon, signaling the ribosome to begin translation, and this codon codes for methionine. Thus, methionine is used to indicate where translation is to begin on an mRNA transcript.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
Methionine is a precursor to cysteine, which is needed to make glutathione, a critical antioxidant. Glutathione helps protect cells from oxidative damage.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
Sulfur-containing compounds, including methionine, can directly neutralize certain free radicals to some degree, however, its most significant contribution to antioxidant defenses comes through its role in glutathione synthesis.
Methionine provides the sulfur atoms required for some detoxification reactions and it is involved in producing glutathione, which is important for detoxifying and removing toxins. It supports the methylation processes in the liver, which contributes to the removal of toxins.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
Methionine does not directly participate in ATP production. While methionine has a role in various metabolic pathways, it does not directly catalyze the creation of ATP. However, it indirectly supports energy levels by supporting creatine production and by protecting mitochondria from oxidative damage, which can impact ATP production.
Methionine is a necessary precursor for creatine synthesis in the body. Methionine donates a methyl group in the process. Creatine is then used in muscle cells to generate energy for activity.
Methionine contributes to the production of glutathione, which can protect the mitochondria from oxidative damage. Healthy mitochondria are important for ATP synthesis.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
Methionine is involved in various metabolic pathways, including those related to lipid metabolism. The role in phosphatidylcholine synthesis helps regulate fat accumulation. It is also involved in glutathione production, which also impacts the liver.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
Some studies suggest that methionine, through various mechanisms, may impact appetite-related hormones and neurotransmitters. However, the precise mechanism is still being researched and not fully understood. More research is needed.
Methionine supports serotonin production through its role in one-carbon metabolism and methylation. The methyl group used to create serotonin comes through SAM which is derived from methionine.
Source: “Dietary Methionine and Total Sulfur Amino Acid Restriction in Healthy Adults” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10782544/
Some studies have shown methionine restriction leads to weight loss in animal models, but effects in humans have not been clear. More research is needed to make conclusions.
Source: “Dietary Methionine and Total Sulfur Amino Acid Restriction in Healthy Adults” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10782544/
A 2019 publication, not a 2018 one, in Nature reported that dietary methionine restriction altered metabolism and induced weight loss in mice. Note that this was in mouse cancer models.
Source: “Methionine restriction-induced sulfur deficiency impairs antitumour immunity partially through gut microbiota” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10513933/
Animal proteins are generally considered to have more methionine per gram of protein compared to plant proteins. Thus, those on plant based diets must be mindful of methionine intake.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
Typical dosages are generally within this range, though individual needs may vary. Always consult a healthcare professional before starting any supplement.
While there are proposed benefits of methionine supplements, the research is not comprehensive, and more studies are needed to fully explore the potential benefits and risks.
Methionine is metabolized into homocysteine and high levels of homocysteine have been associated with increased cardiovascular risk. High methionine intake may increase these levels. This risk can be mitigated by the intake of some B vitamins.
Source: “The Controversial Role of HCY and Vitamin B Deficiency in Cardiovascular Diseases” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9003430/
Stress and strenuous activity increase metabolic demand and could increase methionine needs in the body, potentially leading to deficiency if diet does not meet this need. More research is needed to verify this claim.
Because of the critical roles that methionine plays, deficiencies may cause growth issues in children, and in adults, it may result in liver problems and increase the risk of certain diseases.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
The study mentioned was in chickens, not rats and reported improved performance and breast muscle growth.
Source: “Methionine improves the performance and breast muscle growth of broilers with lower hatching weight by altering the expression of genes associated with the insulin-like growth factor-I signalling pathway” https://pubmed.ncbi.nlm.nih.gov/23919886/
Some athletes may use methionine supplements to help with muscle recovery by aiding protein synthesis and reducing inflammation, however, the effectiveness of methionine for this purpose needs further research and varies between individuals.
A study in PNAS in 2011 reported that methionine restriction led to increased lifespan in Drosophila.
Source: “Increased transsulfuration mediates longevity and dietary restriction in Drosophila” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3189063/
As people age the metabolic systems involved in methionine processing may become less efficient resulting in an increase in homocysteine levels which is an indicator of disrupted methionine processing. Other factors may also contribute to elevated homocysteine in older individuals.
Methionine is crucial for the production of neurotransmitters and compounds such as phosphatidylcholine in the brain. It is also involved in methylation which can impact brain function.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
Methionine is the precursor of S-adenosylmethionine (SAM), which is the methyl group donor involved in the synthesis of many neurotransmitters, including dopamine and serotonin.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
Methionine supports glutathione production, which can help with cellular protection against free radicals in the brain. More studies are needed to fully understand the potential neuroprotective benefits of methionine.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
Methionine contributes the methyl groups needed for the production of serotonin via the methionine cycle and its downstream metabolites. Serotonin is a crucial neurotransmitter involved in mood regulation.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
A study in Acta Psychiatrica Scandinavica in 2009, not 2017, reported that a combination of folic acid and sodium valproate may improve the symptoms of acute mania in bipolar disorder. The study was about folic acid, not methionine, and the clinical condition was mania, not depression.
Source: “Folic acid efficacy as an alternative drug added to sodium valproate in the treatment of acute phase of mania in bipolar disorder: a double-blind randomized controlled trial” https://pubmed.ncbi.nlm.nih.gov/19392814/
The summary provides good high level information on the functions of methionine in the body. However, it’s important to clarify that while it is involved in supporting energy metabolism, methionine is not directly involved in the synthesis of ATP. It is involved in many other ways.
Some animal studies have suggested that methionine restriction leads to weight loss, but these results have not been definitively confirmed in human studies. Thus more research is needed.
The foods listed are all known to contain methionine and are common dietary sources of this amino acid. Animal products generally have more per gram of protein than plant sources.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
Methionine supplements are generally considered safe within recommended dosages. However, high doses may lead to health problems including raising homocysteine levels and can interact with other medications. Always consult with a healthcare professional.
Methionine does indeed play an important role in liver health through its support of detoxification pathways, preventing fat accumulation and by supporting glutathione production, which protects liver cells.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
Methionine does support pathways that are relevant to athletic performance, including protein synthesis and energy production, but studies on the direct impact on athletic performance have not been conclusive and require further study.
Methionine is metabolized into homocysteine within the methionine cycle and this homocysteine can then be converted back into methionine. Elevated homocysteine levels in the blood may indicate disrupted methionine metabolism.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
Methionine provides the sulfur atoms necessary for some detoxification reactions, is a precursor for glutathione and supports other detox processes like bile production and fat breakdown, all of which contribute to removing toxins from the body.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
Methionine is necessary for keratin protein synthesis in the body, but further research is required to confirm its benefits as a hair growth supplement.
Methionine deficiency is rare, but when it does occur, it may manifest as any of the symptoms listed because methionine is so important for these processes. Deficiencies are more likely to occur in individuals on very restrictive diets.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
Methionine is a necessary molecule and has a place in supporting the cardiovascular system. However, a metabolite, homocysteine, of methionine can increase heart risks if levels become too high, making the role in heart health complicated and requiring a balanced view.
Source: “The Controversial Role of HCY and Vitamin B Deficiency in Cardiovascular Diseases” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9003430/
Methionine is metabolized into homocysteine. When there is an excess of methionine, the homocysteine can accumulate in the blood. High homocysteine is a biomarker associated with an increased risk of heart disease.
Source: “The Controversial Role of HCY and Vitamin B Deficiency in Cardiovascular Diseases” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9003430/
B vitamins, including B6, B12 and folate are essential for the metabolism of homocysteine. When these vitamins are at sufficient levels, it is easier for the body to control homocysteine.
Source: “The Controversial Role of HCY and Vitamin B Deficiency in Cardiovascular Diseases” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9003430/
Methionine contributes to the production of immune cells and antibodies, both of which are important for immune system function.
Source: “SLC43A2 and NFκB signaling pathway regulate methionine/cystine restriction-induced ferroptosis in esophageal squamous cell carcinoma via a feedback loop” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10238427/
A study from 2013 found that methionine supplementation improved immune response in chickens, but more research is needed to conclude similar effects in humans.
Source: “Dietary nickel chloride induces oxidative intestinal damage in broilers” https://pubmed.ncbi.nlm.nih.gov/23702803/