Oxidative stress is implicated in atherogenesis; however most clinical trials with dietary antioxidants failed to show marked Success in preventing atherosclerotic diseases. We have found that hydrogen (dihydrogen; H-2) acts as an effective antioxidant to reduce oxidative stress [I. Ohsawa, M. Ishikawa, K. Takahashi, M. Watanabe, K Nishimaki, K Yamagata, K Katsura, Y. Katayama, S, Asoh, S. Ohta, Hydrogen acts as a therapeutic antioxidant by selectively reducing cytotoxic oxygen radicals, Nat. Med. 13 (2007) 688-694]. Here, we investigated whether drinking H-2-dissolved water at a saturated level (H-2-Water) ad libitum prevents arteriosclerosis using an apolipoprotein E knockout mouse (apoE(-/-)), a model of the spontaneous development of atherosclerosis. ApoE(-/-) mice drank H-2-water ad libitum from 2 to 6 month old throughout the whole period. Atherosclerotic lesions were significantly reduced by ad libitum drinking of H-2-water (p = 0.0069) as Judged by Oil-Red-O staining series of sections of aorta. The oxidative stress level Of aorta was decreased. Accumulation of macrophages in atherosclerotic lesions was confirmed. Thus, consumption of H-2-dissolved Water has the potential to prevent arteriosclerosis. (C) 2008 Elsevier Inc. All rights reserved.