Anthocyanin administration elevates plasma homocysteine in rats

The data accumulated from epidemiological studies suggests that individuals with elevated blood levels of homocysteine have an increased risk of cardiovascular disease. However, little is known of the food factor that may affect the homocysteine status, except for folate and B-vitamins. Here, we tested the effect of dietary phenolics (i.e., anthocyanin of food colorant) administration on plasma homocysteine concentration in a rat study, since a profound effect on the methionine metabolism was speculated from the 3',4'-catechol skeletal structure of anthocyanin. Female Sprague-Dawley rats (body weight 100 g) orally ingested a single dose of anthocyanin mixture (total 100 mg) composed of cyanidin-3-glucoside (50mg), cyanidin-3-sambubioside (48 mg), and cyanidin-3,5-diglucoside (2 mg). The total homocysteine in the plasma collected 90-240 min after anthocyanin intake was 1.4 to 1.8-fold (5.2-6.7 micromol/L) higher than the basal homocysteine level (3.7 micromol/L). In the liver and kidney, anthocyanin significantly affects sulfur amino acid (S-adenosylmethionine, SAM, and S-adenosylhomocysteine, SAH) levels, both of which are precursors of plasma homocysteine, and the SAH/SAM ratio showed a significant increase in the liver and kidney. Accordingly, these results suggest that dietary anthocyanin stimulates homocysteine synthesis from SAH in the liver and kidney, and the homocysteine yielded transfers into the blood stream. The intake of anthocyanin and its structural homologues may have an effect on the metabolic regulation of sulfur amino acids and possibly increase the risk of vascular disease in humans.