What is choline and what are its benefits?

Choline: Essential Nutrient with Multiple Health Benefits

Choline is an essential nutrient that functions as a component of structural lipoproteins, blood and membrane lipids, and serves as a precursor for the neurotransmitter acetylcholine, with benefits for liver health, muscle function, and neurocognitive development. 1

What is Choline?

Choline is a quaternary amine that was recognized as an essential nutrient by the Institute of Medicine in 1998. While humans can produce small amounts of choline endogenously through the hepatic phosphatidylethanolamine N-methyltransferase pathway, this production is insufficient to meet bodily needs, making dietary consumption necessary. 1, 2

Key characteristics of choline include:

• It is hydrophilic and requires specific active transporters to move into different tissues
• Its availability is partially dependent on intestinal microbiota
• It serves multiple critical functions in the body
• Plasma choline levels are not a reliable reflection of tissue levels 1

Primary Functions of Choline

Choline plays several vital roles in human health:

1. Structural component: Forms part of cell membranes and lipoproteins 1
2. Neurotransmitter precursor: Essential for the synthesis of acetylcholine, a neurotransmitter crucial for brain function 1, 3
3. Metabolic functions:
   • Supports lipid metabolism and transport
   • Involved in homocysteine metabolism through conversion to betaine
   • Contributes to one-carbon metabolism 3, 4
4. Anti-inflammatory properties: Demonstrated in animal and in vitro studies 1

Health Benefits of Choline

Liver Health

• Prevents non-alcoholic liver steatosis
• Supports lipid metabolism and transport
• Deficiency can lead to liver damage with elevated liver enzymes (GGT, AST, ALT) 1

Neurocognitive Development and Function

• Critical during perinatal development for optimal cognitive outcomes
• Essential for proper brain development in infants
• Associated with better cognitive performance in adults and the elderly
• May help prevent neural tube defects during pregnancy 3, 4

Muscle Function

• Prevents subclinical muscle damage
• Deficiency can lead to elevated creatine phosphokinase levels 1

Other Benefits

• May play a role in preventing age-related macular degeneration (though this requires further research) 1
• Important for cellular membrane composition and repair 4
• Supports proper homocysteine metabolism 3

Choline Requirements and Deficiency

Despite its importance, approximately 90% of Americans consume less than the Adequate Intake (AI) for choline. 2

Groups at higher risk for choline deficiency include:

• Pregnant and lactating women
• Growing infants
• Patients with cirrhosis
• Individuals receiving intravenous feeding
• Vegetarians and vegans (as choline is predominantly found in animal-derived foods) 2, 5

Signs of choline deficiency may include:

1. Non-alcoholic liver steatosis
2. Subclinical muscle damage with elevated creatine kinase levels
3. Potential neurocognitive impacts, especially during development 1

Recommended Intake

Although choline is not classified as an essential nutrient in all contexts, the following intake guidelines are suggested:

• For general population: 400-550 mg per day to support lipid metabolism 1
• For patients with suspected deficiency: 550 mg to 2 g per day 1
• For pregnant women: Higher intakes are recommended due to increased demands 4

Potential Risks of Excess Intake

Excessive choline intake may cause:

• Hypotension
• Fishy body odor
• Conversion to trimethylamine-N-oxide (TMAO), which may have negative cardiovascular effects 1

The Upper Limit (UL) for adults is defined as 3.5 g/day. 1

Clinical Considerations

• Plasma free choline measurement should be considered in patients on home parenteral nutrition who develop unexplained liver steatosis or muscle damage 1
• No routinely accessible biomarker exists for choline status, though specialized techniques can measure choline and its metabolites 1
• Genetic variants in genes related to choline, folate, and one-carbon metabolism can affect an individual's choline requirement 2, 4

Choline's importance has been reaffirmed by both the American Medical Association and American Academy of Pediatrics, particularly during pregnancy and lactation for optimal neurocognitive development in offspring. 2, 4