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What is Glycine? Why Do I Need Glycine During Pregnancy?

Updated

pregnancy, healthy outcomes, healthy pregnancy, protein, enough protein, protein during pregnancy

Abstract: 

Protein is crucial for your health, and the growth and development of your baby. Glycine is a protein found in food and synthesized by your body. It is essential for many metabolic functions including muscle, brain, gut, and skin health. During pregnancy, glycine may reduce risk of preeclampsia and high blood pressure and support the development of DNA, neurotransmitters, and the placenta. General guidelines do not recommend supplementation of glycine during pregnancy as there is limited evidence supporting benefits.   

What is glycine and why do I need it? 

Adequate amount of protein is essential for prenatal nutrition and fetal development. Glycine is a protein your body can synthesize, it is also found in many food products. Although your body can synthesize it, glycine from the diet can contribute to the many metabolic effects of this amino acid. 

Glycine is found to support your body in a great many ways including:

      • Muscle function
      • Cognitive function and development 
      • Skin health and beauty 
      • Protecting the liver from toxins
      • By acting as a powerful antioxidant 
      • Aiding in fat digestion
      • Supporting intestinal lining

In this article we will:

  • Review glycines role in pregnancy 
  • Introduce the biology of glycine metabolism in the body
  • Discuss glycines role in collagen and mental health
  • Explore supplementation recommendations regarding glycine and pregnancy 
  • Learn foods high in glycine 
  • Define recommended intake, toxicity, and deficiency 

How Does Glycine Help In Pregnancy?

Glycine can play many roles in pregnancy and fetal development however more research is needed. Current research finds that in mothers, glycine may reduce risk of preeclampsia and high blood pressure. Additionally, it is found to support the development of connective tissue which can reduce stretch marks and allow for the expansion of the uterus. 

For babies, glycine is found to support the development of DNA, neurotransmitters, and the placenta all of which are essential for short term and long term health outcomes. 

Particularly in the 3rd trimester of pregnancy, research finds low glycine levels can reduce overall protein synthesis for mom and increase risk of oxidative stress due to lower glutathione (GSH). 

Did you know? Research finds that pregnant adolescents have higher needs for glycine during the 3rd trimester compared to adult women .

Glycine in action: What does it do in the body?

Glycine is synthesized from choline, threonine, and serine and is a main component of bile acids.

It is used for synthesis of glutathione, heme, creatine, nucleic acid, and uric acid. This means it is essential for antioxidant defense, DNA expression, neurotransmission, blood cell structure, and muscular function.

Glycine supports the methylation process which is important for gene expression and reduced oxidative stress, tumor necrosis factor, inflammation, and activation of macrophages. Additionally, it has been found to reduce the accumulation of free fatty acids and regulate the individual free fatty acid composition in the brain and liver particularly among alcoholics.  

Glycine and Collagen

Glycine is found to make up about one-third of the amino acids in collagen, the most abundant protein in the human body. Collagen is needed for the maintenance of tissues and the production of enzymes and hormones.

Researchers find that adequate amounts of glycine may reduce stretch marks, improve uterus expansion, and support muscular and ligament changes during pregnancy.

Additionally, not related to pregnancy, collagen is essential for skin firmness and elasticity. Proper collagen is associated with decreased aging and wrinkles of skin, less sagging below eyes, and plumper, more hydrated skin.

Glycine and Mental Health

Due to its role in DNA methylation and neurotransmission, glycine is found to play an interesting role in mental health. Research finds adequate glycine levels are associated with reduced risk of schizophrenia, mood and memory, and support sleep.

Within neurotransmission, glycine is found to stimulate the production of serotonin. This neurotransmitter has been found to play a critical role in your reward and pleasure systems. Those with low levels of serotonin are more likely to experience anxiety, depression, and even GI distress.

How Much Glycine Should I Have Per Day?

food sources, foods high in protein, essential amino acids, balanced diet, protein supplementation

Typically amino acid supplements are not recommended during pregnancy, this include glycine.

Supplementation can be taken as a single amino acid, or an amino acid combination, however neither are recommended during pregnancy. This is beaucuse supplements deliver nutrients to your body differently than food, and not enough research has conclusive evidence on health effects during pregnancy. 

Supplements are concentrated and may be in higher amounts than food therefore acting differently when metabolized. Additionally, unregulated substances might also have unlisted additives that might not be safe including heavy metals such as lead and arsenic which can severely damage fetal development and lead to long term health consequences. 

It is recommended that if you are currently taking glycine supplements prior to conception, to pause supplementation once you are aware you are pregnant.

New research finds that even with adequate protein intake, during late stage pregnancy glycine levels may still be inadequate in pregnant mothers. This newer research warrants further investigation in order to set more accurate recommendations of this amino acid during pregnancy. 

Remember to talk to your healthcare provider about any supplementation prior to use.

Glycine rich foods:

  • Gelatin 
  • Bone broth 
  • Seafood
  • Spinach 
  • Legumes 
  • Dairy products

How Much is Too Much Glycine?

Glycine toxicity is rare, however it can occur through large amounts of supplementation. Toxicity could cause seizures or developmental delay in children.

Signs of glycine toxicity include:

  • Visual disturbances
  • Drowsiness
  • Vomiting
  • Weakness
  • Prickling skin sensations
  • Skin flushing

What Happens If I Don’t Have Enough Glycine?

Complications of low glycine are also associated with oxidative stress, which can impair brain function and overall development. Glycine is a precursor for a powerful antioxidant called glutathione, GSH.

Researchers have found that those with higher oxidative stress while pregnant were more likely to experience a range of unfavorable symptoms and possible disease for both mom and baby. For mom, there is increased risk of preeclampsia, preterm labor, or misscarriage. And for baby issues could be immediate consequences such as low birth weight and length, to long term consequences such as depression, cardiovascular disease, diabetes, and even alzheimers. 

High risk populations for low glycine levels include those with diabetes, hypothyroidism, obesity, and after intense exercise. Clinically, low glycine levels are also suspected in depression and schizophrenia.

Summary

Protein is critical for your health, and the growth and development of your baby. Glycine is a protein found in food and synthesized by your body. It is essential for many metabolic functions including muscle, brain, gut, and skin health. During pregnancy, glycine may reduce risk of preeclampsia and high blood pressure and support the development of DNA, neurotransmitters, and the placenta. General guidelines do not recommend supplementation of glycine during pregnancy as there is limited evidence supporting benefits.   

 


References:

  1. Determination of glycine requirement in pregnancy - full text view. Full Text View - ClinicalTrials.gov. https://clinicaltrials.gov/ct2/show/NCT02149953. Accessed May 13, 2022. 
  2. F, Turner N. Glycine becomes conditionally indispensable during late gestation. American Society for Nutrition. https://nutrition.org/glycine-becomes-conditionally-indispensable-during-late-gestation/. Published January 12, 2022. Accessed May 12, 2022. 
  3. Hsu, J., Thame, M., Gibson, R., Baker, T., Tang, G., Chacko, S., . . . Jahoor, F. (2016). Unlike pregnant adult women, pregnant adolescent girls cannot maintain glycine flux during late pregnancy because of decreased synthesis from serine. British Journal of Nutrition, 115(5), 759-763. doi:10.1017/S0007114515005279
  4. Rasmussen BF, Ennis MA, Dyer RA, Lim K, Elango R. Glycine, a Dispensable Amino Acid, Is Conditionally Indispensable in Late Stages of Human Pregnancy. J Nutr. 2021;151(2):361-369. doi:10.1093/jn/nxaa263
  5. Razak MA, Begum PS, Viswanath B, Rajagopal S. Multifarious Beneficial Effect of Nonessential Amino Acid, Glycine: A Review [published correction appears in Oxid Med Cell Longev. 2022 Feb 23;2022:9857645]. Oxid Med Cell Longev. 2017;2017:1716701. doi:10.1155/2017/1716701
    Sekhar RV, Patel SG, Guthikonda AP, et al. Deficient synthesis of glutathione underlies oxidative stress in aging and can be corrected by dietary cysteine and glycine supplementation. Am J Clin Nutr. 2011;94(3):847-853. doi:10.3945/ajcn.110.003483
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