Cereal foods are the major source of betaine in the Western diet

Betaine and its precursor choline are important components of one-carbon metabolism, remethylating homocysteine into methionine and providing methyl groups for DNA methylation. Cereals are the main source of betaine in the diet, though there is little literature available on the content of betaine in cereal products, nor on betaine intake from cereals. Betaine and free-choline concentrations were measured by liquid-chromatography with tandem mass spectrometry in a wide range of commercially available cereal foods and cereal fractions. Whole grain wheat and related fractions were the best overall common source of betaine, while the pseudocereal quinoa had the highest amount of betaine measured (3900mug/g). Based on estimates of dietary intake data cereal foods provide approximately 60-67% of betaine in Western diets, and 20-40% of betaine in South-East Asian diets. Average intake of betaine was 131mg/d, well below those used in intervention studies using betaine to lower blood homocysteine.

Ross, A.B., A. Zangger, and S.P. Guiraud, Cereal foods are the major source of betaine in the Western diet - Analysis of betaine and free choline in cereal foods and updated assessments of betaine intake. Food Chem, 2014. 145C: p. 859-865