Vegetarians have higher plasma alpha-tocopherol relative to cholesterol than do nonvegetarians

Effects of a low-fat vegan diet and a Step II diet on macro- and micronutrient intakes in overweight postmenopausal women

OBJECTIVE

This study investigated the nutrient intake of overweight postmenopausal women assigned to a low-fat vegan diet or a Step II diet.

METHODS

Fifty-nine overweight (body mass index, 26 to 44 kg/m2) postmenopausal women were randomly assigned to a self-selected low-fat vegan or a National Cholesterol Education Program Step II diet in a 14-wk controlled trial on weight loss and metabolism. Nutrient intake, which was measured per 1000 kcal, was the main outcome measure. Statistical analyses included within-group and between-group t tests examining changes associated with each diet.

RESULTS

Consumption of a low-fat vegan diet was associated with greater decreases in fat, saturated fat, protein, and cholesterol intakes and greater increases in carbohydrate, fiber, beta-carotene, and total vitamin A intakes than was a Step II diet. The low-fat vegan group also increased thiamin, vitamin B6, and magnesium intakes more than the Step II group, and both groups increased folic acid, vitamin C, and potassium intakes. If considering only food sources of micronutrients, the low-fat vegan group decreased vitamin D, vitamin B12, calcium, selenium, phosphorous, and zinc intakes compared with baseline. However, with incidental supplements included, decreases were evident only in phosphorous and selenium intakes. No micronutrient decreases were found in the Step II group.

CONCLUSIONS

Individuals on a low-fat vegan or Step II diet should take steps to meet the recommended intakes of vitamin D, vitamin K, folic acid, calcium, magnesium, and zinc. Individuals on a low-fat vegan diet should also ensure adequate intakes of vitamin B12, phosphorous, and selenium.

The macrobiotic diet in cancer

Macrobiotics is one of the most popular alternative or complementary comprehensive lifestyle approaches to cancer. The centerpiece of macrobiotics is a predominantly vegetarian, whole-foods diet that has gained popularity because of remarkable case reports of individuals who attributed recoveries from cancers with poor prognoses to macrobiotics and the substantial evidence that the many dietary factors recommended by macrobiotics are associated with decreased cancer risk. Women consuming macrobiotic diets have modestly lower circulating estrogen levels, suggesting a lower risk of breast cancer. This may be due in part to the high phytoestrogen content of the macrobiotic diet. As with most aspects of diet in cancer therapy, there has been limited research evaluating the effectiveness of the macrobiotic diet in alleviating suffering or prolonging survival of cancer patients. The few studies have compared the experience of cancer patients who tried macrobiotics with expected survival rates or assembled series of cases that may justify more rigorous research. On the basis of available evidence and its similarity to dietary recommendations for chronic disease prevention, the macrobiotic diet probably carries a reduced cancer risk. However, at present, the empirical scientific basis for or against recommendations for use of macrobiotics for cancer therapy is limited. Any such recommendations are likely to reflect biases of the recommender. Because of its popularity and the compelling evidence that dietary factors are important in cancer etiology and survival, further research to clarify whether the macrobiotic diet or similar dietary patterns are effective in cancer prevention and treatment is warranted.

Antioxidant status in vegetarians versus omnivores

Every day, vegetarians consume many carbohydrate-rich plant foods such as fruits and vegetables, cereals, pulses, and nuts. As a consequence, their diet contains more antioxidant vitamins (vitamin C, vitamin E, and beta-carotene) and copper than that of omnivores. Intake of zinc is generally comparable to that by omnivores. However, the bioavailability of zinc in vegetarian diets is generally lower than that of omnivores. Dietary intake of selenium is variable in both groups and depends on the selenium content of the soil. Measurements of antioxidant body levels in vegetarians show that a vegetarian diet maintains higher antioxidant vitamin status (vitamin C, vitamin E, beta-carotene) but variable antioxidant trace element status as compared with an omnivorous diet. To evaluate the antioxidative potential of a vegetarian diet versus an omnivorous diet, more studies are needed in which the total antioxidant capacity is determined rather than the status of a single antioxidant nutrient.

Vitamins E plus C and interacting conutrients required for optimal health. A critical and constructive review of epidemiology and supplementation data regarding cardiovascular disease and cancer

Antioxidants are crucial components of fruit/vegetable rich diets preventing cardiovascular disease (CVD) and cancer: plasma vitamins C, E, carotenoids from diet correlate prevalence of CVD and cancer inversely, low levels predict an increased risk of individuals which is potentiated by combined inadequacy (e.g., vitamins C + E, C + carotene, A + carotene); self-prescribed rectification of vitamins C and E at adequacy of other micronutrients reduce forthcoming CVD, of vitamins A, C, E, carotene and conutrients also cancer; randomized exclusive supplementation of beta-carotene +/- vitamin A or E lack benefits except prostate cancer reduction by vitamin E, and overall cancer reduction by selenium; randomized intervention with synchronous rectification of vitamins A + C + E + B + minerals reduces CVD and counteracts precancerous lesions; high vitamin E supplements reveal potentials in secondary CVD prevention. Plasma values desirable for primary prevention: > or = 30 mumol/l lipid-standardized vitamin E (alpha-tocopherol/cholesterol > or = 5.0 mumol/mmol); > or = 50 mumol/l vitamin C aiming at vitamin C/vitamin E ratio > 1.3-1.5; > or = 0.4 mumol/l beta- (> or = 0.5 mumol/l alpha+ beta-) carotene.

CONCLUSIONS

In CVD vitamin E acts as first risk discriminator, vitamin C as second one; optimal health requires synchronously optimized vitamins C + E, A, carotenoids and vegetable conutrients.

Influence of vegetarian and mixed nutrition on selected haematological and biochemical parameters in children

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.

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.

Modulation of infant formula fat profile alters the low-density lipoprotein/high-density lipoprotein ratio and plasma fatty acid distribution relative to those with breast-feeding

The effect of breast-feeding was compared with that of two fat-modified milk formulas in 45 infants (15 per group) studied by assessing body weight gain for 4 months and plasma lipids, lipoprotein profiles, fatty acid profiles of plasma and red blood cells, and plasma tocopherol status 3 months after birth. A saturated fat formula with coconut oil/soybean oil (COCO/SOY) had a fatty acid content and polyunsaturated/saturated ratio (P/S, 0.55) comparable with that of human milk fat (P/S, 0.39) and had the same fat energy content (50% kcal). The second formula, with corn oil/soybean oil (CORN/SOY), was highly unsaturated (P/S, 4.6), with only 35% kcal from fat. Energy intake and body weight gain were similar for all groups. Plasma total cholesterol, triglyceride, and phospholipid levels were significantly lower (greater than 20% on average) in infants fed the CORN/SOY formula than in infants fed either the COCO/SOY formula or human milk. Infants fed the CORN/SOY formula also had lower (25% to 35%) plasma low-density lipoprotein cholesterol and apolipoprotein B levels and low-density lipoprotein/high-density lipoprotein and apolipoprotein B/apolipoprotein A-I ratios. Plasma, red blood cell, and cholesteryl ester fatty acids from infants fed COCO/SOY contained less 18:1 and more 18:2; cholesterol esters in plasma from breast-fed infants had the highest 20:4n-6 levels. Plasma tocopherol levels were higher in infants consuming formulas. The presence of cholesterol in human milk appeared to expand the low-density lipoprotein pool and exert an "unfavorable" increase in the low-density lipoprotein/high-density lipoprotein ratio. Thus modulation of infant lipoproteins by changing dietary fat and cholesterol is feasible and in keeping with the known response in adults.