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November 1998

LE Magazine November 1998


Is Vegetarianism in Your Future?

Studies detail some of the benefits of a plant-based diet

Vegetarianism and arthritis

Uncooked, lactobacilli-rich, vegan food and rheumatoid arthritis
Nenonen MT Helve TA Rauma AL Hanninen OO. Br J Rheumatol
(1998 Mar) 37(3):274-81

We tested the effects of an uncooked vegan diet, rich in lactobacilli, in rheumatoid patients randomized into diet and control groups. The intervention group experienced subjective relief of rheumatic symptoms during intervention. A return to an omnivorous diet aggravated symptoms. Half of the patients experienced adverse effects (nausea, diarrhea) during the diet and stopped the experiment prematurely. Indicators of rheumatic disease activity did not differ statistically between groups. The positive subjective effect experienced by the patients was not discernible in the more objective measures of disease activity (Health Assessment Questionnaire, duration of morning stiffness, pain at rest and pain on movement). However, a composite index showed a higher number of patients with 3 to 5 improved disease activity measures in the intervention group. Stepwise regression analysis associated a decrease in the disease activity (measured as change in the Disease Activity Score, DAS) with lactobacilli-rich and chlorophyll-rich drinks, increase in fiber intake, and no need for gold, methotrexate or steroid medication (R2=0.48, P=0.02). The results showed that an uncooked vegan diet, rich in lactobacilli, decreased subjective symptoms of rheumatoid arthritis. Large amounts of living lactobacilli consumed daily may also have positive effects on objective measures of rheumatoid arthritis.

Vegetable intake and BMD

Bone mineral density in Chinese elderly female vegetarians, vegans, lacto-vegetarians and omnivores
Lau EM Kwok T Woo J Ho SC. Eur J Clin Nutr (1998 Jan) 52(1):60-4

Objectives: To compare the bone mineral density and dietary intake of elderly Chinese vegetarian women with omnivores, to compare the bone mineral density of Chinese vegans and lactovegetarians, and to study the relationship between nutrient intake and bone mineral density in vegetarians. Design: A cross-sectional survey. Setting and subjects: A community-based study. The vegetarian women (aged 70-89 y) (n = 76) were non-institutionalized subjects. All of them were Buddhists. Their bone mineral densities were compared with normal elderly volunteers (aged 70-89 y) (n = 109) who were recruited to establish normal ranges. Their dietary intake was compared with omnivorous subjects from a previous dietary survey (n = 250).

Methods: Dietary assessment was by the 24-hour recall method, and bone mineral density was measured by dual-X-ray-densitometry. The analysis of co-variance was used to compare the bone mineral density between vegetarians and omnivores, with adjustment for potential confounders. The bone mineral density in vegans and lactovegetarians were compared by similar methods. The t-test was used to compare dietary intake between omnivores and vegetarians. The relationship between nutrient intake and bone mineral density was studied by correlation and multiple regression. Results: The dietary calorie, protein and fat intake were much lower, but the sodium/creatinine ratio was much higher in vegetarians than omnivores. The bone mineral density at the spine was similar between vegetarians and omnivores. However, the bone mineral density at the hip was significantly lower in vegetarians at some sites (P < 0.05). There was no significant difference in bone mineral density between vegans and lactovegetarians. Bone mineral density in vegetarians appeared to be positively correlated with energy, protein and calcium intake, and negatively associated with urinary sodium/creatinine levels.

Conclusions: There is a relationship between diet and bone mineral density. The bone mineral density at the hip was lower in vegetarians than omnivores, but no difference was observed between vegans and lactovegetarians. There is a complex relationship between the intake of various nutrient and bone mineral density in vegetarians.

Vegetarianism and zinc absorption

Zinc absorption, mineral balance, and blood lipids in women consuming controlled lacto ovovegetarian and omnivorous diets for 8 weeks Hunt JR Matthys LA Johnson LK. Am J Clin Nutr (1998 Mar) 67(3):421-30

Zinc absorption, mineral balance, and blood lipid concentrations were measured in 21 women aged 20 to 42 years consuming controlled lacto ovovegetarian and nonvegetarians diets for 8 weeks each, in a crossover design. The lacto ovovegetarian and nonvegetarians diets, respectively, provided 973 and 995 mg calcium, 1.8 and 1.3 mg copper, 367 and 260 mg magnesium, 5.9 and 2.5 mg manganese, 1,457 and 1,667 mg phosphorus, 9.1 and 11.1 mg zinc, and (by calculation) 40 and 16 grams dietary fiber, 2.5 and 0.8 mmol phytic acid, molar ratios of phytate to zinc of 14 and 5, and millimolar ratios of (phytate x calcium) to zinc of 344 and 111. Dietary zinc absorption was measured by extrinsic isotopic labeling and whole-body counting. Plasma cholesterol, cholesterol fractions, and lipoproteins were reduced 7 to 12% with the lacto ovovegetarian diet, consistent with predictions based on dietary cholesterol and fat. Blood pressure was unaffected. Calcium, copper, magnesium and phosphorus balances were not different between diets; manganese balance tended to be greater with the lacto ovovegetarian diet (P < 0.07). The lacto ovovegetarian diet was associated with a 21% reduction in absorptive efficiency that, together with a 14% reduction in dietary zinc, reduced the amount of zinc absorbed by 35% (2.4 compared with 3.7 mg/d) and reduced plasma zinc by 5% within the normal range. Zinc balance was maintained with both diets. Although there is a greater risk of zinc deficiency in persons consuming lacto ovovegetarian compared with omnivorous diets, with inclusion of whole grains and legumes zinc requirements can be met and zinc balance maintained.

Perilla oil prevents colon cancer

Colon cancer prevention with a small amount of dietary perilla oil high in alpha-linolenic acid in an animal model
Narisawa T Fukaura Y Yazawa K Ishikawa C Isoda Y Nishizawa Y. Cancer (1994 Apr 15) 73(8):2069-75

Background: Epidemiologic and experimental studies suggest that dietary fish oil and vegetable oil high in omega-3 polyunsaturated fatty acids (PUFAs) suppress the risk of colon cancer. The optimal amount to prevent colon carcinogenesis with perilla oil high in omega- 3 PUFA alpha-linolenic acid in a 12% medium-fat diet was investigated in female F344 rats. For comparison, safflower oil high in omega-6 PUFA linoleic acid was used. Methods: 25 or 30 rats at 7 weeks of age in each group received an intrarectal dose of 2 mg N-methyl-N-nitrosourea 3 times weekly in weeks 1 and 2 and were fed the diets with various levels of perilla oil and safflower oil throughout the experiment.

Results: The incidence of colon cancer at the termination of the experiment at week 35 was 40%, 48% and 32% in the rats fed the diets with 3% perilla oil plus 9% safflower oil, 6% perilla oil plus 6% safflower oil, and 12% perilla oil plus 0% safflower oil, respectively, whereas it was 67% in the rats fed the control diet with 0% perilla oil plus 12% safflower oil. The amount of diet consumed and the body weight gain were identical in all of the dietary groups. The ratios of omega-3 PUFA to omega-6 PUFA in the serum and the colonic mucosa at week 35 were increased in parallel to the increased intake of perilla oil.

Conclusions: The results suggest that a relatively small fraction of perilla oil, 25% of total dietary fat, may provide an appreciable beneficial effect in lowering the risk of colon cancer.

Perilla oil and clotting

Possible mechanisms for the differential effects of high linoleate safflower oil and high alpha-linolenate perilla oil diets on platelet-activating factor production by rat polymorphonuclear leukocytes.
Oh-hashi K Takahashi T Watanabe S Kobayashi T Okuyama H. J Lipid Mediat Cell Signal (1997 Dec) 17(3):207-20

As compared with high dietary linoleate safflower oil, high dietary alpha-linolenate perilla oil decreased platelet-activating factor (PAF) production by nearly half in calcium ionophore (CaI)-stimulated rat polymorphonuclear leukocytes (PMN). In the CaI-stimulated PMN from the perilla oil group, the accumulated amount of arachidonate (AA) plus eicosapentaenoate (EPA) was 30% less and that of lyso-PAF was 50% less, indicating that the decreased availability of lyso-PAF is a factor contributing to the relatively low PAF production.

Consistently, eicosatetraynoic acid (ETYA), a dual inhibitor of cyclooxygenase and lipoxygenase, increased free fatty acids (FFA) and decreased PAF production possibly by decreasing the availability of lyso-PAF. Although, leukotrienes (LTs) have been proposed to stimulate PAF production synergistically, a potent LTB4 receptor antagonist, ONO-4057, decreased the formation of free fatty acids and LTB4, but stimulated PAF production somewhat, indicating that LTB4 may not stimulate PAF production in PMN. Lysophospholipid-induced transacylase (CoA-independent transacylase) activity in PMN homogenates was 25-30% lower in the perilla oil group but no significant differences were observed in the lyso-PAF acetyltransferase and PAF acetylhydrolase activities between the two dietary groups. Thus, decreased transacylase activity is another factor associated with the relatively low PAF production in the perilla oil group.

Fat formation

Perilla oil prevents the excessive growth of visceral adipose tissue in rats by down-regulating adipocyte differentiation.
Okuno M Kajiwara K Imai S Kobayashi T Honma N Maki T Suruga K Goda T Takase S Muto Y Moriwaki H. J Nutr (1997 Sep) 127(9):1752-7

We examined the effect of dietary oils with different fatty acid compositions on the growth of visceral adipose tissue in rats. For four months, starting at weaning, rats were fed a basal diet of perilla oil rich in omega-3 polyunsaturated fatty acids (PUFA), safflower oil rich in omega-6 PUFA, olive oil rich in monounsaturated fatty acid, or beef tallow rich in saturated fatty acids. The amount of food consumed and body weight gain did not differ among the four dietary groups. The weight of the epididymal fat pad and the serum triglyceride concentration in perilla oil-fed rats were significantly lower (P < 0.05) than those of olive oil- and beef tallow-fed groups. The product of [(volume of individual adipocytes) x (number of adipocytes in epididymal fat pad)], which presumably represents total adipocyte volume in the fat pad, was significantly lower (P < 0.05) in perilla oil-fed rats than in beef tallow- and olive oil-fed groups. Expression of the late genes of adipocyte differentiation, peroxisome proliferator-activated receptor alpha, adipocyte P2 and adipsin, was significantly (P < 0. 05) down-regulated in epididymal fat tissue of rats that had been fed perilla oil rather than beef tallow or olive oil, whereas expression of the early gene, lipoprotein lipase, was not significantly affected. Greater levels (P < 0.05) of (n-3) PUFA in the membrane phospholipid fraction of the fat tissue were observed in perilla oil-fed rats than in the other dietary groups. These results suggest that perilla oil or omega-3 PUFA prevents excessive growth of adipose tissue in rats, at least in part by suppressing the late phase of adipocyte differentiation.

Soy, postmenopausal women

Soy isoflavones improve systemic arterial compliance but not plasma lipids in menopausal and perimenopausal women
Nestel PJ Yamashita T Sasahara T Pomeroy S Dart A Komesaroff P Owen A Abbey M. Arterioscler Thromb Vasc Biol (1997 Dec) 17(12):3392-8

The possibility that the heightened cardiovascular risk associated with the menopause, which is said to be ameliorated by soybeans, can be reduced with soy isoflavones was tested in 21 women. Although several were perimenopausal, all have been included. A placebo-controlled crossover trial tested the effects of 80 mg daily of isoflavones (45 mg genistein) over 5- to 10-week periods. Systemic arterial compliance (arterial elasticity), which declined with age in this group, improved 26% (P < .001) compared with placebo. Arterial pressure and plasma lipids were unaffected. The vasodilatory capacity of the microcirculation was measured in nine women; high acetylcholine-mediated dilation in the forearm vasculature was similar with active and placebo treatments. LDL oxidizability measured in vitro was unchanged. Thus, one important measure of arterial health, systemic arterial compliance, was significantly improved in perimenopausal and menopausal women taking soy isoflavones to about the same extent as is achieved with conventional hormone replacement therapy.

Soy and bone loss

Modulation of age-related hyperparathyroidism and senile bone loss in Fischer rats by soy protein and food restriction
Kalu DN Masoro EJ Yu BP Hardin RR Hollis BW. Endocrinology (1988 May) 122(5):1847-54

Studies were carried out to explore the influence of soy protein and food restriction on age-related changes in serum PTH and bone. Three groups of male Fischer 344 rats were studied from 6 weeks of age. Group A rats were fed ad libitum diet A, which has casein as the protein source. Group B rats were fed diet B (with casein as protein source) at 60% of the mean ad libitum food intake. Group C rats were fed ad libitum diet C, which has soy protein as the protein source. Serum PTH, measured with an intact N- terminal-specific RIA, and immunoreactive calcitonin increased progressively with aging. The increase was markedly suppressed by food restriction, and in the case of PTH by the soy protein diet as well. Serum creatinine started to increase after 18 months of age, and both dietary regimens of groups 2 and 3 retarded the increase. Aging was associated with a fall in serum 25-hydroxyvitamin D, and loss of bone occurred during the terminal part of life in the ad libitum-fed animals. These were prevented by food restriction, while the soy protein diet delayed the onset of bone loss.

We conclude from these findings and other data from this study that in the male F344 rats 1) an age-related increase in serum PTH precedes an age-related increase in serum creatinine concentration; 2) an age-related decline in renal function probably contributes to age-related hyperparathyroidism, which, in turn, contributes to senile bone loss; 3) food restriction inhibits age-related hyperparathyroidism and senile bone loss; and 4) on the basis of the data from rats fed a soy protein-containing diet, a decline in renal function and progressive hyper parathyroidism are not inevitable consequences of aging in the ad libitum fed rats.

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