Choline supplementation is important because low intake levels can lead to fatigue, muscle dysfunction, and can also impair brain function and memory.1 Dietary supplement sources include krill oil, which is a rich source of the phospholipid phosphatidylcholine and free choline from choline salts such as choline bitartrate or choline chloride. Phosphatidylcholine is either absorbed intact or after hydrolysis by phospholipase D, by which free choline is liberated from the structure. Free choline doesn’t require an enzymatic conversion step.
Choline from dietary supplements are then converted into different metabolites such as betaine, an oxidation product of free choline, and dimethylglycine (DMG), a metabolite of betaine. Trimethylamine N-oxide (TMAO) is metabolized in the host liver from trimethylamine (TMA), which is, in turn, primarily generated from dietary choline, betaine, L-carnitine, and its metabolite y-butyrobetaine, by the action of gut microbiota.1
TMAO is a waste product of choline metabolism, but it may also be a risk factor and prognostic marker in the development of diseases and outcome of disorders such as cardiovascular disease, renal disease, type II diabetes, colorectal cancer, and neurological disorders.1 A study published in Nutrients1 compared the pharmacokinetics of free choline and of selected choline metabolites from a single dose of phosphatidylcholine present in the branded SuperbaBoost krill oil (from Aker BioMarine; Lysaker, Norway), and choline bitartrate salts. Fish oil was used as placebo.
Results showed that both products significantly increased choline concentrations up to the eight-hour time point, compared to placebo. The metabolite betaine also increased significantly for both choline bitartrate and krill oil, compared to placebo, but at its peak at the eight-hour point, concentrations of betaine were significantly higher after krill oil consumptions. Betaine is important for the formation of the essential amino acid methionine.
Concentrations of the metabolite DMG were significantly higher for both choline bitartrate and krill oil, compared to placebo. DMG is a metabolite of betaine that is an important source of the amino acid glycine and methyl groups for biochemical reactions. The study also found that while both choline bitartrate and krill oil significantly increased levels of TMAO, compared to placebo, the concentrations of TMAO following choline bitartrate were about 13 times higher compared to krill oil.
“That is the main finding in the paper is that you get phosphatidylcholine while getting omegas, and you get your choline without feeding bacteria,” said Nils Hoem, chief scientist for Aker BioMarine to Nutritional Outlook. Considering concerns about the effects of TMAO, the study shows that krill oil may be a safer source of choline.
1. Mödinger Y et al. “Plasma kinetics of choline and choline metabolites after a single dose of SuperbaBoost krill oil or choline bitartrate in healthy volunteers.” Nutrients, vol. 11 (2019): 2548