Polyunsaturated Fatty Acid Plasma Content in Groups of General Population with lowvitamin B6 or low iron serum levels

Experimental and human studies describe the adverse effect of iron or vitamin B6 deficiencies on polyunsaturated fatty acid metabolism. Iron is present in end proteins of the delta6-desaturase enzyme complex, and vitamin B6 deficiency can affect the transmethylation reaction of proteins. Plasma polyunsaturated fatty acid content was estimated in apparently healthy subjects of the general population with no consumption of fish and low vitamin B6 serum levels (< 3 microg/l; n = 21) or with low iron serum levels (men: < 12 micromol/l; women: < 10 micromol/l; n = 16) and compared to a control group (n = 22) with normal vitamin B6 and iron serum levels (in reference range). The activities of the delta6-desaturase enzyme complex were calculated as product/precursor (conversion indices). In groups of subjects with low vitamin B6 and low iron levels, delta6-desaturase activity together with delta5-desaturase activity (conversion of alpha-linolenic/18:3,n-3/ into eicosapentaenoic acid/20:5,n-3/) as well as the conversion index of docosahexaenoic acid formation (22:6,n-3) from 22:5,n-3 (second delta6-desaturase activity) were significantly reduced. The inhibition effect on fatty acid synthesis was more pronounced in subjects with low iron levels than in those with low vitamin B6 levels. The conversion indices correlated significantly positively with vitamin B6 or iron levels.

Advanced glycation end products and nutrition

Advanced glycation end products (AGEs) may play an important adverse role in process of atherosclerosis, diabetes, aging and chronic renal failure. Levels of N(epsilon)-carboxymethyllysine and fluorescent AGE values were estimated in two nutritional population groups--alternative group (vegetarians--plant food, milk products, eggs) and traditional group (omnivorous subjects). Vegetarians have a significantly higher carboxymethyllysine content in plasma and fluorescent AGE values. Intake of proteins, lysine and monosaccharides as well as culinary treatment, consumption of food AGEs (mainly from technologically processed products) and the routes of Maillard reaction in organism are the substantial sources of plasma AGEs. Vegetarians consume less proteins and saccharides. Lysine intake is significantly reduced (low content in plant proteins). Subjects on alternative nutrition do not use high temperature for culinary treatment and consume low amount of technologically processed food. Fructation induced AGE fluorescence is greater as compared with that induced by glucose. It is due to higher participation of a more reactive acyclic form of fructose. Intake of vegetables and fruit with predominance of fructose is significantly higher in vegetarians. Comparison of nutrition and plasma AGEs in vegetarian and omnivorous groups shows that the higher intake of fructose in alternative nutrition of healthy subjects may cause an increase of AGE levels.

Plasma levels of advanced glycation end products in healthy, long-term vegetarians and subjects on a western mixed diet

BACKGROUND

Evidence indicates that food-derived Maillard's reaction products are absorbed and yet can be detected in the circulation.

AIM OF THE STUDY

We postulated that consumption of the heat-treated food by omnivores could be reflected by higher plasma levels of advanced glycation end products (AGEs) in comparison with vegetarians, who in cooking (by keeping away from meat) use lower temperatures and less time for heating.

METHODS

Plasma fluorescent AGEs (350/450 nm) and N(epsilon)-(carboxymethyl)lysine (CML, competitive ELISA) levels were investigated in 3 groups of healthy vegetarians (9 vegans-V, 19 lactoovo-vegetarians--VLO and 14 semi-vegetarians--VS) and compared with those of age-matched omnivores (O, n=19). Mean duration of vegetarian diet was V: 7.2 +/- 1.0,VLO: 8.2 +/- 0.8 and VS: 7.9 +/- 1.1 years.

RESULTS

Both fluorescent AGE (O: 9.9 +/- 0.5; V: 10.8 +/- 0.7, LO: 13.1 +/- 0.8* and SV: 11.6 +/- 1.2 x 10(3) AU), and CML levels (O: 427.1 +/- 15.0,V: 514.8 +/- 24.6*, LO: 525.7 +/- 29.5**, SV: 492.6 +/- 18.0* ng/ml) were significantly lower in omnivores than in vegetarians. Plasma glucose, parameters of renal function (plasma concentration of creatinine and cystatin C, calculated glomerular filtration rate--GFR) as well as C-reactive protein levels were within the normal range and did not differ significantly between the groups. Thus, neither decline of kidney function nor inflammatory processes contributed to the rise in plasma AGEs.

CONCLUSION

Enhanced plasma AGE levels in vegetarians in comparison to omnivores are herein presented for the first time. Mechanisms of AGE elevation and potential pathophysiological relevance of this finding are to be elucidated in prospective studies.

LDL and HDL oxidation and fatty acid composition in vegetarians

The oxidation of low-density lipoproteins (LDL) and high-density lipoproteins (HDL) and fatty acid composition, which may affect the resistance of lipoproteins to oxidation, were determined in 24 lacto-ovo vegetarians. Vegetarian diets contain more essential polyunsaturated fatty acids (PUFAs). Therefore, the relationship between LDL and HDL oxidation resistance measured by the kinetics of the formation of fatty acid conjugated dienes (lag time, maximal rate of oxidation and maximal amount of conjugated dienes), LDL and HDL fatty acid composition and vitamin E content were evaluated. All parameters of in vitro oxidation were significantly lower in HDL when compared with LDL. The relative values of arachidonic, dihomo-gamma-linoleic and docosahexaenoic acid were significantly higher in HDL, alpha-linolenic acid content significantly lower, when compared with LDL; the peroxidizability index was significantly higher in HDL. The content of vitamin E was found more than 2-fold lower in HDL particles. The results show the importance of fatty acid composition in the resistance of LDL and HDL to oxidation and from this aspect, the composition of LDL isolated from vegetarians seems to be more favourable compared to HDL.

[Nutritional status in adults on an alternative or traditional diet]

BACKGROUND

Plant food lacks vitamin B12, vitamin D and higher n-3 polyunsaturated fatty acids. Essential aminoacids methionine and lysine can be found in significantly lower amounts. On the contrary, the culinary and technologically non-processed plant food and whole-grain products contain essential nutrients in a highly condensed form. The aim of the study was to compare nutritional status of adults on alternative or on traditional diet and sequels of the diet to body metabolism.

METHODS AND RESULTS

The group on alternative diet consisted of 89 lacto-ovo-vegetarians (age 38.7 +/- 0.6 years, average duration of vegetarianism 7.8 years). Control group on traditional diet (omnivores, n = 84) was formed as an average sample. Nutritional regime was determined using dietetic questionnaire on the food intake regularity. Vegetarians consume optimal amount of fat (along with recommendations of OVD) with predominance of vegetal lipids. They have low intake of cholesterol (62.8 mg), recommended ratio of saturated fatty acids (SFA), monounsaturated (MUFA), and polyunsaturated (PUFA) 6.5:10.6:8.9 energetic percent. Their ratio of linolic:alpha-linolenic acid (10.4:1) also corresponds with recommendations. In traditional diet, the content of lipids and energy usually exceeds the norm of OVD (by 33% or 19% respectively), cholesterol intake is much higher (512.2 mg, 200 mg is recommended as a maximum). Higher is the amount taken of SFA (11.2 energetic %, recommended 7%), and not sufficient is the intake of alpha-linolenic acid (68% of OVD). People on alternative diet have low plasma levels of risk lipid parameters and significantly higher levels of antisclerotic substances. As a result of significantly higher intake of fruits and vegetables, plant oil, sprouts, seeds, and whole-grain food the plasma levels of antioxidative vitamins are in vegetarians higher then threshold. It reduces the risk of the free-radical disease. On the contrary, vegetarians have deficits in methionine intake, and 15% of them have hypoproteinemia is (0% in omnivores). Low plasma levels of iron and calcium, occurrence of hyposideremia (16% versus 2%) and hypocalcemia (21% versus 8%) corresponds with intake of vegetal absorption inhibitors (fytolic acid, oxalic acid, roughage). Frequently a mild form of hyperhomocysteinemia is found (28% versus 5%), resulting vitamin B12 deficit.

CONCLUSIONS

Vegetarian diet is optimal for prevention of free-radical diseases, especially those of the cardiovascular system. It may bring a risk from the point of view of low iron and calcium absorption, low intake of methionine and occurrence of mild forms of hyperhomocysteinemia. In traditional diet, total lipid content should be lowered, amount of vegetable oil with alpha-linolenic acid should be elevated as well as fruit and vegetable consummation. Whole grain food and oily seeds should be included into the daily food.

Traditional and alternative nutrition--levels of homocysteine and lipid parameters in adults

Values of homocysteine and lipid parameters were measured in groups of adults consuming alternative nutrition (vegetarians/lactoovo/, vegans) and compared with a group consuming traditional diet (omnivores, general population). Frequency of hyperhomocysteinemia was 53% in the vegans group, 28% in vegetarians vs. 5% in omnivores. In conditions of lower methionine intake (reduced content in plant proteins), the remethylation pathway of homocysteine metabolism prevails and it is vitamin B12 and folate-dependent. The intake of vitamin B12 is equal to zero in vegans; vegetarians consume 124% of the RDA vs. 383% in omnivores. Serum vitamin levels are significantly lower in subjects consuming alternative nutrition with deficiency observed in 24% of vegetarians, 78% of vegans vs. 0% in omnivores. Serum folate levels are within the reference range in all groups. Mild hyperhomocysteinemia in the groups consuming alternative diet is a consequence of vitamin B12 deficiency. Vegetarians and vegans meet the RDA for energy and fat, and have a favourable proportion of saturated, mono- and polyunsaturated fatty acids on total energy intake; the ratio of linoleic/alpha-linolenic acid in their diet corresponds with the recommendations. They have low cholesterol consumption and higher vitamin E and C intake. Optimal fat intake of correct composition is reflected in lower values of atherosclerosis risk factors (cholesterol, LDL-cholesterol, atherogenic index, saturated fatty acids, triacylglycerols), and significantly higher levels of protective substances (linoleic acid, alpha-linolenic acid, HDL-cholesterol, vitamin E, vitamin E/cholesterol, vitamin C). Low lipid risk factors but higher findings of mild hyperhomocysteinemia in vegetarians mean a diminished protective effect of alternative nutrition in cardiovascular disease prevention.

Oleic acid serum phospholipid content is linked with the serum total- and LDL-cholesterol in elderly subjects

INTRODUCTION

Increased dietary intake of the olive oil has been found to lower several cardiovascular risk factors. Aim of our study was to check if there is any link between the oleic acid (OL-18:1n9) serum phospholipid (SPL) content and some of these factors in subjects living relatively far from the Mediterranean region and in habitual conditions, i.e. without any dietary intervention.

MATERIAL AND METHODS

The investigated group included 62 out-patients older than 51 yr. Serum lipids were measured using standard hospital laboratory methods, the LDL-cholesterol was calculated using Friedewald's formula. Gas chromatography was used for estimation of fatty acids (FA) in SPL, their values were calculated as relative percentages of all FA.

RESULTS

There was a statistically significant inverse correlation between the OL SPL content and the serum total cholesterol (TCHOL) in all 62 patients (r = -0.294; p = 0.020). Analogous correlation was marginally significant for the LDL (r = -0.245; p = 0.055). After a division into 2 groups based on the median of the OL, the group with OL higher than median had significantly lower both TCHOL and LDL (p = 0.014; p = 0.033, respectively). OL correlated positively with the alpha-linolenic acid (18:3n3; r = 0.281; p = 0.027) but inversely with the stearic acid (18:0; r = -0.303; p = 0.017).

CONCLUSION

The subjects with less OL in their SPL had higher TCHOL and LDL serum levels and also their fatty acid SPL spectrum showed some other features which may be characterized as undesirable. This is an independent argument emphasizing the need for enhancing OL dietary intake.

Blood levels of natural antioxidants in gastric and colorectal precancerous lesions and cancers in Slovakia

A long-term sufficient intake of fruits and vegetables reduces significantly the risk of gastric and colorectal carcinoma. It is anticipated that natural antioxidants are involved in this effect in addition to other substances. The aim of this study was to determine levels of vitamins A, C and E, as well as beta-carotene, selenium, zinc and copper in blood of 249 patients with precancerous lesions (atrophic gastritis, gastric hyperplastic polyp, gastric, colonic and rectal adenoma, chronic ulcerative colitis) and in 96 individuals with gastric, colonic or rectal carcinoma and to compare these levels with the values of a control group of 130 healthy individuals. We have found that the frequency of average values of analyzed micronutrients in precancerous groups was decreasing in the order vit C > vit E/vit A > Se > beta-car. The average levels of vitamins and beta-carotene were significantly reduced in all carcinoma groups, while selenium level showed a decrease only in the gastric carcinoma group. Copper level was elevated in the ulcerative colitis group and in all groups with carcinoma. The results indicate a frequent insufficient saturation of organism by natural antioxidants in groups with precancerous lesions and carcinomas of stomach and colorectum. Therefore, it is necessary to increase the general consumption of fruits and vegetables in Slovakia as a part of primary prevention of malignant diseases in these organs. Chemoprevention may be recommended in individuals with precancerous lesions.

[Comparison of nutrient intake and corresponding biochemical parameters in adolescent vegetarians and non-vegetarians]

BACKGROUND

In comparison to food habits of non-vegetarians alternative nutrition bears several risks, but it also has beneficial effects. Considering risks represent a significant age aspect. Nutritional risk and protective factors were evaluated in a adolescent group.

METHODS AND RESULTS

Food habits of 53 lactoovovegetarians (mean duration of vegetarianism 3.2 y) assessed by analysis of dietary questionnaires were compared to those of 55 nonvegetarians and evaluated with respect to basic biochemical indicators (iron, hemoglobin, calcium, total protein, cholesterol, fatty acids, vitamin A, beta-carotene, vitamin C, vitamin 3). Vegetarians consume less fat, and they have higher intake of plant fat, which is reflected din more favourable lipid levels, i.e. lower risk parameters of atherosclerosis (cholesterol, LDL-cholesterol, atherogenic index, saturated fatty acids) and higher values of factors with antisclerotic effect (32.9% ratio of HDL-cholesterol vs. 30.6% in non-vegetarians, polyunsaturated fatty acids, vitamin E/cholesterol ratio, vitamin C). Total plasma protein levels are balanced in both groups (intake of full value mixture of amino acids from grains, legumes (soya), and mild in vegetarians, similar intake of total proteins with a small difference in plant protein consumption). Iron and calcium absorption is inhibited in vegetarians as a consequence of presence of plant food--physic acid, oxaloacetic acid (20.7% hyposiderinemia vs. 0% in non-vegetarians, high iron intake in both groups, iron from plant sources represented 82% in vegetarian boys and 95% in vegetarian girls, hypocalcemia in 28% of vegetarians vs. 7.3% of non-vegetarians). Vegetarians have significantly higher levels of all antioxidant vitamins. This is result of higher consumption of vegetables, fruit, plant fat and sprouts. Higher intake and higher levels of antioxidants are reflected in significantly lower lipoperoxidation values.

CONCLUSIONS

Lactoovovegetarian nutrition represents risk for adolescents if the values of iron and calcium are considered, however it has positive aspects on lipid parameters, protein values, and antioxidant parameters.

[Relation between fatty acid composition, vitamin e and malondialdehyde levels, and activity of antioxidant enzymes in the blood]

The aim of our study was to determine the composition of saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) in erythrocytes and to investigate their relation to the concentration of vitamin E (Vit E) in the plasma, level of malondialdehyde (MDA) in the serum and activities of antioxidant enzymes (AE) in erythrocytes. We examined 128 healthy volunteers (57 men and 71 women) at the ages ranging between 20 and 72. Fatty acids were assessed by gas chromatography, vitamin E by the HPLC method, MDA by the spectrophotometric method, GSH-Px by the kinetic method, CU, Zn-SOD by the Randox test. We have detected the following order in the proportion of fatty acids: SFA > PUFA > MUFA. The increase in PUFA and MUFA was in direct correlation with the concentration of MDA and AE activity, however in reverse correlation with Vit E. A reverse correlation was observed in the increase in SFA. We have found an increase in lipoperoxidation due to the increase in PUFA in erythrocytes in the group of healthy people. This state is concommited by an increase in the activity of antioxidant protection for the maintenance of the balance state. The authors assume that a decrease in Vit E can be caused by its increased "consumption" as the most effective antioxidant in lipid environment. (Tab. 2, Fig. 1, Ref. 27.)

Plasma fatty acid profile and alternative nutrition

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.

[The plasma profile of fatty acids in vegetarians]

The plasma profile of fatty acids has been observed in 27 vegetarian adults, their age ranging from 20 to 63 years (13 men, 14 women) with the average period of vegetarian dietary pattern being 8.8 years. A third of the men and a half of the women were lacto-vegetarians, the rest of them were lacto-ovo-vegetarians. The contents of saturated and monounsaturated fatty acids insignificantly decreased in vegetarians when compared with non-vegetarians (n = 26, 12 men, 14 women, average group of non-smokers with mixed nutrition). The results of parameters regarded as positive factors in vegetarian diet and effective in prevention of atherosclerosis are as follows: significantly higher values of linoliec acid C 18:2, a significantly higher ratio of linoliec/leic acids C 18:2/C18:1 and insignificantly higher value of linolenic acid C 18:3, together with an unchanged, or moderately decreased contents of poly-unsaturated fatty acids C 20:4 (arachidonic acid) and C 22:6 (n3; docosahexaenoic acid). Further prooxidative-antioxidative parameters were selected in regard to the theoretical anticipation of risk brought about by increased lipoperoxidation in vegetarians (poly-unsaturated fatty acids-substrate of the process) which is significant in the etiology of cardio-vascular and oncologic diseases. Their favourable values (significantly lower plasma contents of conjugated dienes of fatty acids, significantly higher plasma value of vitamin C, Beta-carotene, vitamin E/cholesterol-protection of LDL, vitamin E/triacylglycerols-protection of fatty acids, 3.5 times more significant positive linear correlation of vitamin E/triacylglycerol versus plasma contents of C 18:2) eliminate the risk of increased lipoperoxidation in vegetarians. (Tab. 3, Fig. 1, Ref. 29.)

Lipid and antioxidant blood levels in vegetarians

Parameters of lipid metabolism (triacylglycerols TG, cholesterol CH, HDL-CH, LDL-CH, atherogenic index AI, profile of fatty acids) were measured in blood samples of 81 healthy lacto and lacto-ovo vegetarians (42 males, 39 females; age range 19-39 years). The average period of being on a vegetarian diet was 6.2 years. Low levels of TG, CH, LDL-CH, AI and HDL-CH values on the borderline between standard and reduced risk (1.4 mmol.l-1) can be considered as favourable from the atherosclerosis prevention aspect. Compared with non-vegetarians (n = 62), the levels of TG, CH, LDL-CH, and AI are significantly reduced in the vegetarian group. As opposed to non-vegetarians, vegetarians showed a higher total sum of polyunsaturated fatty acids, a significantly higher content of linoleic acid (C 18:2) and linolenic acid (C 18:3), unchanged content of oleic acid (C 18:1), stearic acid (C 18:0) and other polyunsaturated fatty acids. The process of lipoperoxidation (with polyunsaturated fatty acids as substrate) is involved in the etiology of cardiovascular and oncological diseases. Favourable values of prooxidative-antioxidative parameters demonstrated a reduced risk of lipoperoxidation in vegetarians, compared to non-vegetarians (significantly reduced content of conjugated dienes of fatty acids in plasma, significantly higher plasma levels of vitamin C, beta-carotene, vitamin E/cholesterol ratio--and indicator of LDL protection, vitamin E/triacylglycerols ratio--an indicator of fatty acid protection--, selenium and glutathione-peroxidase activity).

Plasma fatty acid profile and prooxidative-antioxidative parameters in vegetarians

Fatty acid profile in plasma was examined in 12 adult vegetarians (lacto and lacto-ovo) aged 41-63 years with an average period of vegetarian nutrition of 9.8 years. Difference in the content of saturated and monounsaturated fatty acids in vegetarians was insignificant (compared to non-vegetarians). Positive factor of vegetarian nutritional habit with respect to atherosclerosis included significantly elevated content of linoleic acid (C 18:2) and linolenic acid (C 18:3), as well as unchanged or only slightly reduced content of polyunsaturated fatty acids--arachidonic acid (C 20:4) and docosahexaenoic acid (C 22:6, n = 3). Favourable values of prooxidative-antioxidative parameters (significantly reduced content of conjugated dienes of fatty acids in plasma, significantly higher plasma levels of vitamin C, beta-carotene, vitamin E/cholesterol--indicator of LDL protection and vitamin E/triacylglycerols--indicator of fatty acid protection) demonstrated a reduced risk of lipoperoxidation in vegetarians.

Effect of intake of exogenous vitamins C, E and beta-carotene on the antioxidative status in kidneys of rats with streptozotocin-induced diabetes

We studied the effect of supplementation with vitamins C, E and beta-carotene (PARABION, produced by Syndipharma) on antioxidative status in kidneys of male Wistar rats with diabetes induced by intravenous application of streptozotocin (45 mg.kg-1 of body weight). The animals received subtherapeutic doses of Insulin Interdep (6 U.kg-1 of body weight). A significant decrease of malondialdehyde (MDA), reduced (GSH) and oxidized (GSSG) glutathione and reduction of the activities of Se-glutathione peroxidase (Se-GSH-PX, EC. 1.11.1.9.) and glutathione S-transferase (GST, EC. 2.5.1.18.) were observed in kidneys of diabetic rats treated with these vitamins. On the contrary, the activity of CuZn-superoxide dismutase (CuZn-SOD, EC. 1.15.1.1) and the level of vitamin C (vit. C) increased significantly. No changes were observed for vitamin E (vit. E), beta-carotene and catalase (CAT, EC. 1.11.1.6). Supplementation with vitamins C, E and beta-carotene resulted in an improvement of antioxidative status of kidneys of rats with streptozotocin-induced diabetes.

Selected parameters of lipid metabolism in young vegetarians

Selected parameters of lipid metabolism (cholesterol, HDL cholesterol, LDL cholesterol, atherogenic index, triacylglycerols, vitamin C, vitamin E, vitamin E/cholesterol, plasma fatty acid profile) and pro-oxidative/anti-oxidative parameters (conjugated dienes of fatty acids, activity of catalase and glutathione peroxidase) were estimated in blood of 59 healthy vegetarians aged 19-30 years. When compared to non-vegetarians, no incidence of obesity, low levels of cholesterol, LDL cholesterol, atherogenic index or triacylglycerols, HDL cholesterol levels on the margin of 1.4 mmol/l (boundary level between standard and reduced risk) as well as a higher plasma content of polyunsaturated fatty acids and a higher 18:2/18:1 ratio were all favourable consequences of vegetarianism with respect to atherosclerosis prevention. These factors are completed by higher levels of protective compounds with antisclerotic activity (vitamin C, vitamin E/cholesterol--protecting LDL from lipoperoxidation) as well as by beneficial pro-oxidative/anti-oxidative parameters (low values of conjugated dienes, significantly higher activity of catalase, higher level of vitamin C).