Vitamin B₁₂, folate, and vitamin B₆ are the main determinants of homocysteinemia. The vegan diet provides no vitamin B₁₂, but also less strict forms of alternative nutrition may suffer from a deficit of this vitamin. The plasma homocysteine level was measured in alternative nutrition groups of adults (lacto- and lactoovovegetarians, n = 62; vegans, n = 32) and compared with the levels in a group consuming traditional diet (n = 59), omnivores). In the group of vegetarians the average homocysteine level is 13.18 vs. 10.19 μmol/l in omnivores; the frequency of hyperhomocysteinemia is 29 vs. 5% in omnivores. In the group of vegans the average homocysteine value is 15.79 μmol/l (53% of the individual values exceeded 15 μmol/l). Omnivores consume the recommended amount of methionine; however, in individuals consuming an alternative diet, the intake of methionine is deficient (assessed by food frequency questionnaire; lower content of methionine in plant proteins). Under conditions of lower methionine availability the remethylation pathway prevails; therefore, vitamin B₁₂ and folate were evaluated in relation to the homocysteine level. The serum vitamin B₁₂ levels are significantly lower in the alternative nutrition groups (214.8 pmol/l in vegetarians, 140.1 pmol/l in vegans vs. 344.7 pmol/l in omnivores); a deficit (<179.0 pmol/l) was found in 26% of the vegetarians and in 78% of the vegans vs. 0% in omnivores. The serum folate levels were within the range of reference values in all groups; however, they were significantly lower in omnivores. The results show that the mild hyperhomocysteinemia in alternative nutrition is a consequence of vitamin B₁₂ deficiency.

To evaluate the health and nutritional status of children with two different nutritional habits, the authors examined 26 vegetarians (lacto- and lacto-ovo; an average period of vegetarianism 2.8 years) and 32 individuals on mixed diet (omnivores) in the age range 11-14 years. Vegetarian children had significantly lower erythrocyte number as well as reduced levels of haemoglobin and iron compared to omnivores. The average level of iron did not reach the lower limit of the physiological range and hyposiderinemia was found in 58% of vegetarians vs 9% of omnivores. Reduced iron levels were observed in spite of increased intake of vegetable iron sources and vitamin C (which facilitates the conversion to ferro-form). This reduction can be attributed to the absence of animal iron sources with high utilizability and to lower iron utilization in the presence of phytic acid (higher intake of grains compared to omnivores). The incidence of hypoalbuminemia and hypoproteinemia in vegetarian children was 38 and 12%, respectively, compared to 0% in omnivores. The protein mixture from milk, eggs and vegetable sources is complete, but vegetarian children had significantly reduced intake of milk and dairy products. Favourable lipid and antioxidant parameters in vegetarian children reflect the optimal nutrition composition with respect to the prevention of free radical diseases. Such a nutrition results in significantly lower levels of cholesterol and LDL-cholesterol compared to omnivores and significantly higher and over threshold values of essential antioxidants--vitamin C, vitamin E/cholesterol (more effective protection against LDL oxidation), beta-carotene, vitamin A.

Plasma profile of fatty acids was examined in a group of children consisting of 7 vegans, 15 lactoovovegetarians and 10 semivegetarians. The children were 11-15 years old and the average period of alternative nutrition was 3.4 years. The results were compared with a group of 19 omnivores that constituted an average sample with respect to biochemical and hematological parameters from a larger study of health and nutritional status of children in Slovakia. Alternative nutrition groups had significantly lower values of saturated fatty acids. The content of oleic acid was identical to omnivores. A significant increase was observed for linoleic and alpha-linolenic (n-3) acids. The dihomo-gamma-linolenic (n-6) acid and arachidonic (n-6) acid values were comparable to omnivores for all alternative nutrition groups. Values of n-3 polyunsaturated fatty acids in lactoovovegetarians were identical to those of omnivores whereas they were significantly increased in semivegetarians consuming fish twice a week. Due to the total exclusion of animal fats from the diet, vegans had significantly reduced values of palmitoleic acid as well as eicosapentaenoic (n-3) acid and docosahexaenoic (n-3) acid resulting in an increased n-6/n-3 ratio. Values of plasma fatty acids found in alternative nutrition groups can be explained by the higher intake of common vegetable oils (high content of linoleic acid), oils rich in alpha-linolenic acid (cereal germs, soybean oil, walnuts), as well as in n-3 polyunsaturated fatty acids (fish). The results of fatty acids (except n-3 in vegans) and other lipid parameters confirm the beneficial effect of vegetarian nutrition in the prevention of cardiovascular diseases.

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Selected vitamin (A, C, E, β-carotene) and trace element (selenium, zinc, copper) levels were estimated in the blood of 67 vegetarian nonsmokers aged 34-60 years. The average period of lacto- or lacto-ovovegetarianism was 6.2 years. The results were compared with those of 75 nonvegetarians of the same age and living in the same region. Vegetarians had significantly higher plasma levels of essential antioxidants: vitamin C, β-carotene, and vitamin A. A significantly higher molar ratio vitamin E/cholesterol indicates a more effective protection especially of low-density lipoproteins against peroxidation. Oxidation of low-density lipoproteins represents one of the key factors in the pathogenesis of atherosclerosis. The molar ratio vitamin E/total lipids was significantly higher in plasma of vegetarians, demonstrating a more effective protection of polyunsaturated fatty acids against peroxidation. Vegetarians had significantly higher plasma levels of selenium and similar levels of zinc and copper when compared to nonvegetarians. These trace elements are important for the activity of antioxidant enzymes. The results document a beneficial effect of vegetarian nutritional habits on antioxidative parameters and thus on the reduction of cardiovascular diseases and cancer risk. Reactive products of oxygen metabolism and subsequent toxic products of lipid peroxidation play an important role in the etiology of these diseases.