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Functional Hyperhomocysteinemia in Healthy Vegetarians: No Association with Advanced Glycation End Products, Markers of Protein Oxidation, or Lipid Peroxidation after Correction with Vitamin B₁₂

Katarína ebeková^1,a, Marica Krajoviová-Kudláková¹, Pavol Blaíek², Vojtech Parrák³, Reinhard Schinzel⁴ and August Heidland⁴

¹ Institute of Preventive and Clinical Medicine,
² Hospital of Ministry of Defense of Slovak Republic, and
³ St. Cyril and Method Hospital, 833 01 Bratislava, Slovakia

⁴ University of Wuerzburg, 97070 Wuerzburg, Germany

^aaddress correspondence to this author at: Institute of Preventive and Clinical Medicine, Limbová 14, 833 01 Bratislava, Slovakia; fax 421-2-59369-170, e-mail sebekova@upkm.sk

The first 300 words of the full text of this article appear below.

Vegetarians are at risk of developing hyperhomocysteinemia (HHcy). The predominant or selective consumption of proteins of plant origin shifts homocysteine (Hcy) metabolism to the remethylation pathway (1), which requires vitamin B₁₂ as a cofactor and methyltetrahydrofolate as a substrate. In the vegetarian diet, the intake of folic acid exceeds the recommended dietary allowance (RDA), whereas intake of vitamin B₁₂ is inadequate or even absent (2).

HHcy represents an independent risk factor for cardiovascular disease (3). Autooxidation of Hcy produces reactive oxygen species (ROS) (4), which may stimulate lipid peroxidation and formation of advanced oxidation protein products (AOPPs) and advanced glycation end products (AGEs). Interaction of AGEs with their specific receptor, RAGE, induces formation of ROS (5). In mice, HHcy was shown to enhance the expression of RAGE (6). AGEs, AOPPs, and lipid peroxidation products are implicated in the pathogenesis of degenerative and inflammatory diseases, including atherosclerosis (7).

In vegetarians, plasma concentrations of AGEs are mildly but significantly increased compared with populations on a Western mixed diet (8). We therefore investigated (a) whether there is an association between Hcy and plasma AGE concentrations or markers of protein oxidation and lipid peroxidation, and (b) whether supplementation of vitamin B₁₂ affects the mentioned analytes in vegetarians with HHcy produced by a potential vitamin B₁₂ deficit.

The study was approved by the Institutional Ethics Board and was conducted according to the Declaration of Helsinki. All participants gave written consent to participate.

We investigated 63 healthy vegetarians in whom HHcy had been revealed previously. The normohomocysteinemic (NHcy; Hcy <12.0 µmol/L) subgroup (with plasma folate and vitamin B₁₂ concentrations within the appropriate reference intervals) was compared with the subgroup with functional HHcy (Hcy >12.0 µmol/L) attributable . . . [Full Text of this Article]