What is L-serine?
L-serine is an amino acid that plays an important role in the production of proteins, DNA, and cell membranes. It is a nonessential amino acid, meaning that we do not have to obtain it from the diet. The body can make enough serine on its own.
However, because of the diverse roles that serine plays in the body, many find it useful to include it in their diet .
Serine is often taken with other amino acids such as glycine, arginine, tyrosine, and leucine. In patients suffering from seizures, glycine and serine may be taken together for their mutually beneficial interaction [3, 4].
Serine is produced from the amino acid glycine and can exist as L-serine and D-serine. D-serine is formed internally from L-serine and has a slightly different structure.
L-serine is still being researched in clinical trials for its effects but may be recommended or prescribed by doctors and purchased as a supplement.
D-serine is a neurotransmitter that plays a central role in information processing. Although it can also be purchased as a supplement, D-serine has poor absorption when taken orally. L-serine is more commonly taken in supplemental form.
Although L-serine is not FDA approved to treat these diseases, it is still regarded as safe to consume as an additive .
Natural Sources and Forms of Supplementation
Foods that are high in protein contain L-serine. The following foods contain a high amount:
- Soy protein
Phosphatidylserine is a common supplement formed from L-serine and 2 fatty acid molecules. It can provide similar effects as a basic L-serine supplement. Although each supplements’ effects are related, this article focuses on the benefits of L-serine alone .
Mechanism of Action
L-serine plays a role in forming of all four bases of DNA and RNA (adenine, guanine, cytosine, thymine, and uracil) .
L-serine is converted to D-serine by an enzyme called serine-racemase. D-serine is mainly found in the brain. It assists in stimulating the nervous system. It is important in cell communication within the brain .
It is also involved in the production of antibodies (immunoglobulins) and is a precursor to other amino acids like glycine and cysteine .
Phosphatidylserine, formed by L-serine and 2 fatty acid molecules, is one of the main neuroprotective agents in nerve cells. It is vital for the maintenance of brain health .
Phosphatidylserine is a key component of the cell membrane and regulates what molecules can enter and leave the cell .
Health Benefits of Serine
L-serine and D-serine have different benefits in the body that are only seen when taking one specific form over the other.
1) L-serine May Treat Amyotrophic Lateral Sclerosis
L-serine has recently been studied for the treatment of amyotrophic lateral sclerosis (ALS). ALS is caused by the breakdown of nerve cells and ultimately results in fatal muscle weakness.
In a study of 20 patients with ALS, daily intake of L-serine for 6 months slowed the progression of the disease .
2) L-serine Can Reduce Symptoms of Chronic Fatigue Syndrome
Chronic fatigue syndrome (CFS) causes symptoms such as extreme tiredness, pain, and discomfort throughout the body. These symptoms may be linked to low blood levels of serine. Supplementing L-serine may reduce symptoms by restoring L-serine back to healthy levels .
Supplementing L-serine in 28 patients with chronic fatigue syndrome (DB-RCT) significantly reduced physical symptoms after 15 weeks of treatment .
3) L-serine Can Reduce Symptoms of HSAN1
HSAN1 is a brain disease that causes loss of sensation in the legs and feet.
A study of 14 patients with HSAN1 (RCT) taking L-serine for 10 weeks prevented progression of the disease. It also improved sensation in the legs .
4) L-serine May Help You Sleep
Small doses of L-serine before sleep may improve sleep quality.
5) L-serine May Treat Seizures
Serine deficiency is linked to seizures .
Patients suffering from seizures have low levels of L-serine. 1 week of L-serine treatment reduced seizures. It also reduced involuntary movements, muscle spasms, and uncontrolled muscle stiffness .
On the other hand, in 13 patients with non-cancerous brain tumors (angiomas) and recurrent seizures, high levels of serine were found within the tumors .
L-serine treatments may not be completely effective in certain seizure-inducing diseases such as 3-phosphoglycerate dehydrogenase deficiency, where 500 mg/kg of L-serine was ineffective to control seizures .
6) L-serine May Reduce the Risk of Alzheimer’s
L-serine reduced the buildup of proteins (neurofibrillary tangles) in the brain that are associated with Alzheimer’s disease. Cell studies show that these tangles can be reduced through exposure to L-serine [28, 15].
In monkeys (vervets) with neurofibrillary tangles, 4 months of daily L-serine intake greatly reduced the number of proteins associated with Alzheimer’s .
D-serine may also play a role in identifying Alzheimer’s disease. Low levels of D-serine are found in patients with Alzheimer’s. The enzyme important in forming D-serine (serine racemase) in the body may not be working correctly, which may be associated with the disease .
However, other studies have found no significant difference in the amount of D-serine in a brain with Alzheimer’s compared to one without .
7) L-serine May Increase Blood Flow to the Brain
In rats, supplementing L-serine increased blood flow to the brain and protected brain cells .
8) L-serine May Improve Huntington’s Disease
L-serine may reduce some of the symptoms associated with Huntington’s disease, where nerve cells break down in the brain.
In cells, the addition of L-serine improved nerve function in the brain associated with Huntington’s .
9) L-serine May Benefit the Skin
L-serine, when applied in lotions, can reduce wrinkles caused by UV radiation. In hairless mice, the application of an L-serine-based cream slowed the appearance of wrinkles and decreased the presence of pre-existing wrinkles .
10) L-serine and Fibromyalgia
In 2o patients suffering from fibromyalgia, low levels of tryptophan, serine, lysine, and 3 other amino acids were found. This indicates that fibromyalgia may be linked to an imbalance of amino acids .
11) D-serine Can Help Schizophrenia
A study of 42 schizophrenic patients (DB-RTC) taking high doses of D-serine (120 mg) for 4 weeks saw significant improvements in symptoms such as hallucinations, delusions, mood disturbances and cognition .
Similarly, 44 patients (DB-RCT) taking D-serine (120 mg) for 16 weeks had improved symptoms of schizophrenia .
It is unclear whether supplementing L-serine will provide the same benefits for schizophrenic patients.
12) D-serine Can Help with PTSD
13) D-serine May Combat Depression
However, a study of 148 patients with depression exhibited higher levels of both L-serine and D-serine than patients without depression .
However, the mixed results seen with D-serine in humans and rodents require further research.
Similarly, the effects of supplementing L-serine for depression should be investigated as well. A study of rats suggests L-serine may reduce depression by increasing levels of both L-serine and D-serine in the brain .
14) D-serine May Help Relieve Anxiety
Serine levels are linked to anxiety. In mice, deficiency of D-serine was linked to increased anxiety .
Supplementing D-serine in mice greatly improved emotional behavior and anxiety-like behaviors.
L-serine and glycine, an amino acid that is converted to serine in the body, had no specific impact on mood disorders of mice .
Using Serine as a Supplement
The recommended dosage for L-serine supplementation is between 500 and 2,000 mg. Doses up to 30 grams are well tolerated and have a low risk of toxicity .
People with gluten and soy allergies should be cautious when supplementing L-serine because certain manufacturers may include those allergens.
- Frequent urination
Taking too much serine can be toxic. It is also one of the main amino acids necessary for cancer growth and raising serine levels excessively could promote the spread of cancer .
Limitations and Caveats
Studies on D-serine and L-serine have indicated that there may be a potential benefit of supplementing with these amino acids. However, further clinical research is required to validate these benefits.
The benefits of D-serine and L-serine differ despite their similarity; most studies of serine are done on only one form of the substance.
There is minimal research on the effects of combining the two forms of serine, and D-serine has only recently become an area of interest in clinical research .
Serine levels are slightly lower in pregnant women. However, there is no research that recommends the use of L-serine supplements in pregnancy and the safety of these supplements has not been evaluated .
L-serine is considered a safe supplement to add to the diet. D-serine is more commonly recommended for older patients to improve general mental clarity .
There have been no reported drug interactions with L-serine. Consult your doctor before adding L-serine to your diet.
Genetic Variations That Might Influence Your Response to L-serine
Certain gene variations may influence your response to L-serine, resulting in different total serine levels amongst individuals:
- RS1163251: variations at this point in the genome are associated with a slight increase in total serine .
- RS715: variations at this point in the genome are associated with a decrease in total serine levels .
- RS477992: variations at this point in the genome are associated with a decrease in total serine .
- RS4947534: variations at this point in the genome are associated with a decrease in total serine .
- RS259842: variations at this point in the genome are associated with an increase in total serine .
To learn more about your genetic variations and how beneficial supplementing L-serine can be for you, check out SelfDecode.
Patients that use L-serine for neurological diseases have found that it eases their symptoms and helps to clear their mind.
A patient with both amyotrophic lateral sclerosis and chronic fatigue syndrome reported that using L-serine improved [her] energy levels.
Although rare, the most common side effect that people experience with L-serine is nausea.
A user taking L-serine began to develop significant headaches. The headaches went away a few days after stopping L-serine supplements.
Many people that take L-serine for its general benefits have seen a positive change in:
- Sleeping habits
- General cognitive capabilities
One found after three months of taking L-serine powder that her mental clarity, focus, sharpness significantly improved.
D-serine is taken less commonly as a supplement, but one person reported that supplementing D-serine reduced [his] schizophrenia symptoms.