Abstract: Objective To investigate suppression effects of betaine-enriched beet on hyperhomocysteinemia induced by guanidine acetic acid(GAA)in rats.Methods Forty-eight Wistar rats were randomly divided into a control group(with 25% casein basal feed25c),a model group(25c+0.5% GAA);two betaine(Bet)groups(25c+0.5% GAA+0.05% or 0.1% Bet),and two beet powder groups(25c+0.5% GAA+3.94% or 7.88% beet).Ten days after the treatments,the rats were sacrificed by decapitation to collect blood and liver samples for the determination of intermediate metabolites of methionine and other biochemical indicators.Results Compared with the control group,the concentrations of homocysteine(Hcy)in plasma(32.2±0.4 μmol/L)and liver tissue (8.93±0.5 nmol/g)were significantly increased in the model group(all P< 0.05).Compared with the model group,the concentrations of Hcy in the plasma(21.5±0.7,21.1±0.6 μmol/L)and liver tissue(5.75±0.2,4.64±0.2 nmol/g)decreased significantly in the high dose Bet group and beet powder group.Compared with the control group,the concentration of S-adenosyl-L-methionie(SAM)was decreased to 59.7±1.3 nmol/L,but the concentration of S-adenosine homocysteine(SAH)was increased to 31.8±0.9 nmol/L in the liver tissue of the model group.The decreased SAM concentrations in liver tissue were increased to 71.4±1.4 nmol/L and 75.5±4.1 nmol/L in the rats treated with 0.10% betaine and 7.88% beet powder,while the increased SAH concentrations in the liver tissue were decreased to 27.1±0.7nmol/L and 26.5±1.6 nmol/L in the rats administrated with 0.10% betaine and 7.88% beet powder(all P< 0.05).The decrease in activity of betaine-homocysteine S-methyltransferase(BHMT)and cystathionine β-synthase(CBS)in the rats with GAA-induced hyperhomocysteinemia were recovered by supplementation of betaine or beet powder.For the rats treated with 7.88% beet powder,the activity of BHMT remarkably increased from 1.08±0.07 to 2.05±0.11 nmol/min/mg protein(P< 0.05).Conclusion The results indicate that betaine-enriched beet could decrease Hey concentration in plasma and liver and completely suppress the hyperhomocysteinemia induced by GAA in rats;the effect may relate to re-methylation of Hey and formation of cystathionine.