Choline

Choline is an essential, water‑soluble nutrient that serves as a precursor for:
- The neurotransmitter acetylcholine
- The phospholipid phosphatidylcholine, a major component of cell membranes.

Its primary physiological roles include:
- Supporting neuronal signaling
- Maintaining membrane integrity
- Providing methyl groups for epigenetic and metabolic processes.

• Cognitive function: Randomized trials show that choline supplementation improves memory performance and attention, especially in populations with low baseline intake (e.g., older adults, pregnant women).
• Neurodevelopment: Adequate maternal choline reduces neural tube defects and enhances offspring hippocampal development, as demonstrated in animal models and human cohort studies.
• Liver health: Choline deficiency leads to hepatic steatosis; supplementation reduces liver fat accumulation and improves liver enzyme profiles in non‑alcoholic fatty liver disease (NAFLD) trials.
• Cardiovascular/metabolic: As a methyl donor, choline supports homocysteine metabolism, lowering plasma homocysteine and potentially reducing cardiovascular risk.
• Physical performance: Choline’s role in acetylcholine synthesis aids neuromuscular transmission, which can enhance endurance and reduce fatigue in athletes.

• Choline enters cells via high‑affinity transporters (e.g., CHT1).
• It is phosphorylated by choline kinase to phosphocholine, then converted to phosphatidylcholine via the Kennedy pathway, forming cellular membranes and lipoproteins.
• In the brain, choline is acetylated by choline acetyltransferase to produce acetylcholine, a key neurotransmitter for memory, muscle contraction, and autonomic regulation.
• Choline also serves as a methyl‑group donor after oxidation to betaine, which donates methyl groups to homocysteine via betaine‑homocysteine S‑methyltransferase, thereby supporting the methylation cycle, DNA methylation, and lipid metabolism.

• Choline is a quaternary ammonium compound with the formula C₅H₁₄NO⁺.
• Its IUPAC name is 2‑hydroxy‑N,N,N‑trimethylethanaminium.
• The neutral salt is often presented as choline chloride (C₅H₁₄ClNO).
• The molecule contains:
  • A positively charged nitrogen atom attached to three methyl groups
  • A hydroxy‑ethyl side chain, conferring high water solubility and a strong dipole moment.
• It is a zwitterionic compound at physiological pH.
• Readily soluble in water and ethanol.
• Stable under standard storage conditions (20‑25 °C, protected from moisture).

• Dietary choline is abundant in:
  • Egg yolk
  • Liver
  • Soybeans
  • Cruciferous vegetables (e.g., broccoli).
• Commercial supplements are primarily derived from:
  • Choline chloride, produced by reacting ethylene oxide with trimethylamine
  • Phosphatidylcholine extracted from soy lecithin.
• Synthetic choline chloride is the most common, offering high purity (>99 %).
• Quality considerations:
  • Verification of the absence of heavy metals, residual solvents, and microbial contaminants.
  • Look for products certified by third‑party labs (e.g., USP, NSF).
  • Look for products derived from non‑GMO, organic sources when using phosphatidylcholine from natural lecithin.