Intake of antioxidant vitamins and risk of death from stroke in postmenopausal women

Endothelium-Dependent Vasorelaxant Effect of Butanolic Fraction from Caryocar brasiliense Camb. Leaves in Rat Thoracic Aorta

Caryocar brasiliense Camb. “pequi” is a native plant from the Cerrado region of Brazil that contains bioactive components reported to be antioxidant agents. Previous work has demonstrated that dietary supplementation with pequi decreased the arterial pressure of volunteer athletes. We found that the crude hydroalcoholic extract (CHE) of C. brasiliense leaves relaxed, in a concentration-dependent manner, rat aortic rings precontracted with phenylephrine, and that the butanolic fraction (BF) produced an effect similar to that of the CHE. Aortic relaxation induced by BF was abolished by endothelium removal, by incubation of the nitric oxide synthase inhibitor L-NAME, or the soluble guanylatecyclase inhibitor ODQ. However, incubation with atropine and pyrilamine had no effect on the BF-induced vasorelaxation. Moreover, this effect was not inhibited by indomethacin and tetraethylammonium. The concentration-response curve to calcium in denuded-endothelium rings was not modified after incubation with BF, and the vasorelaxation by BF in endothelium-intact rings precontracted with KCl was abolished after incubation with L-NAME. In addition, administration of BF in anesthetized rats resulted in a reversible hypotension. The results reveal that C. brasiliense possesses both in vivo and in vitro activities and that the vascular effect of BF involves stimulation of the nitric oxide/cyclic GMP pathway.

Relation of serum α- and γ-tocopherol levels to cardiovascular disease-related mortality among Japanese men and women

Background

There is limited evidence regarding the relationship between serum tocopherol levels and cardiovascular disease.

Methods

We conducted a nested case-control study as part of the Japan Collaborative Cohort Study for evaluation of cancer risk (JACC Study). Baseline serum samples were collected from 39 242 participants (age range, 40–79 years) between 1988 and 1990. During the 13-year follow-up, there were 530 stroke deaths (302 ischemic strokes and 210 hemorrhagic strokes) and 211 deaths from coronary heart disease. Controls were matched for sex, age, and area of residence.

Results

Serum α-tocopherol level was not associated with any type of cardiovascular death in men; however, in women, it was inversely associated with total stroke mortality and hemorrhagic stroke mortality. The multivariate odds ratio (95% CI) for the highest versus the lowest quintile of serum α-tocopherol levels among women was 0.35 (0.16–0.77; P for trend = 0.009) for total stroke and 0.26 (0.07–0.97; P for trend = 0.048) for hemorrhagic stroke. Serum γ-tocopherol was inversely associated with ischemic stroke mortality in men but positively associated with hemorrhagic stroke mortality in women. The respective multivariate odds ratios (95% CI) for the highest versus the lowest quintile and for a 1-standard deviation increment in γ-tocopherol level were 0.48 (0.22–1.06; P for trend = 0.07) and 0.77 (0.58–1.02), respectively, for ischemic stroke in men and 3.10 (0.95–10.12; P for trend = 0.052) and 1.49 (1.04–2.13) for hemorrhagic stroke in women.

Conclusions

Among women, hemorrhagic stroke mortality was inversely associated with serum α-tocopherol and positively associated with serum γ-tocopherol. These findings are due in part to the antioxidative and antithrombotic activities of these tocopherols.

The antioxidant paradox in diabetes mellitus

There is ample empiric evidence to indicate that oxidative stress contributes to the pathogenesis of coronary artery disease and has a key role in the onset and progression of diabetes and its complications. Diabetes leads to depletion of the cellular antioxidant defense system and is associated with an increase in the production of free radicals. Oxidative stress can be the result of multiple pathways. Some of these are related to substrate-driven overproduction of mitochondrial reactive oxygen species, advanced glycation end product formation, glucose autoxidation, and depletion of micronutrients and cellular elements with antioxidative properties. There are numerous observational studies in the literature showing a beneficial outcome of the consumption of antioxidant vitamins. However, the interventional trials portray a different picture. The divide between the robust experimental evidence of the pathogenetic role of increased oxidative load in diabetes and the overwhelming failure of antioxidants to show any health benefits in clinical trials may well be characterized as the "antioxidant paradox."

Protective effects of vitamin E against hypercholesterolemia-induced age-related diseases

Hypercholesterolemia is a major risk factor for age-related diseases such as atherosclerosis and Alzheimer's disease (AD). Changes in human plasma cholesterol levels results from the interaction between multiple genetic and environmental factors. The accumulation of excess cholesterol in blood vessels leads to atherosclerosis. Many studies on this field show that differential expression of oxidative stress-related proteins, lipid metabolism-related enzymes, and receptors response to atherogenic diet. Additionally, excess brain cholesterol has been associated with increased formation and deposition of amyloid-β peptide from amyloid precursor protein which may contribute to the risk and pathogenesis of AD. To consider genetically, more than 50 genes have been reported to influence the risk of late-onset AD. Some of these genes might be also important in cholesterol metabolism and transport. Epidemiological studies have shown an association between high intake and high serum concentrations of antioxidant vitamins like vitamin E and lower rates of ischemic heart diseases. It has been known that vitamin E also inhibits smooth muscle cell proliferation by non-antioxidant mechanism. On the basis of the previous results, vitamin E has been accepted as an important protective factor against hypercholesterolemia-induced age-related diseases.

Intakes of vegetables and related nutrients such as vitamin B complex, potassium, and calcium, are negatively correlated with risk of stroke in Korea

Consumption of vegetables and fruits is associated with a reduced risk of stroke, but it is unclear whether their protective effects are due to antioxidant vitamins or folate and metabolically related B vitamins. The purpose of the study was to test the hypothesis that intake of fruits and vegetables, which are major sources of antioxidant and vitamin B complex vitamins, reduces the risk of stroke. Cases consisted of patients diagnosed with first event of stroke (n = 69). Controls (n = 69) were age-, sex-, and body mass index-matched to cases. Multivariable-adjusted regression analysis showed that subjects who ate four to six servings of vegetable per day had a 32% reduction in the risk of stroke, and those with more than six servings per day had a reduction of 69% after adjusting for age, sex, BMI, and family history of stroke. Intakes of total fat, plant fat, calcium, potassium, vitamin B(1), vitamin B(2), vitamin B(6), niacin, and folate were significantly and negatively associated with the risk of stroke. Although the trend was not significant, stroke risk was reduced in the second quartile (1.21-2.66 servings per week) of fish intake. However, intake of fruits (average daily intake of 1.0 serving) and antioxidant vitamins such as carotene, vitamin C, and vitamin E was not associated with the risk of stroke. In conclusion, our observational study suggests that intake of fat and vegetables, rich sources of vitamin B complex, calcium, and potassium may protect against stroke.

Vitamin E and risk of cardiovascular diseases: a review of epidemiologic and clinical trial studies

Cardiovascular diseases are the leading cause of worldwide mortality. There is strong epidemiologic evidence for a beneficial effect of vitamin E on cardiovascular disease risk. However, conflicting results have been reported by intervention studies. To assess the potential benefit of vitamin E intake on the risk of cardiovascular diseases, fifty-nine published reports from observational studies, retrospective and prospective, randomised clinical trials, meta-analyses as well as pooling analyses were reviewed. The paper provides a detailed discussion about design, quality and limitations of these studies with regard to the evidence of the hypothesized relationship between vitamin E and cardiovascular diseases.

Stroke: roles of B vitamins, homocysteine and antioxidants

In the present review concerning stroke, we evaluate the roles of B vitamins, homocysteine and antioxidant vitamins. Stroke is a leading cause of death in developed countries. However, current therapeutic strategies for stroke have been largely unsuccessful. Several studies have reported important benefits on reducing the risk of stroke and improving the post-stroke-associated functional declines in patients who ate foods rich in micronutrients, including B vitamins and antioxidant vitamins E and C. Folic acid, vitamin B6and vitamin B12are all cofactors in homocysteine metabolism. Growing interest has been paid to hyperhomocysteinaemia as a risk factor for CVD. Hyperhomocysteinaemia has been linked to inadequate intake of vitamins, particularly to B-group vitamins and therefore may be amenable to nutritional intervention. Hence, poor dietary intake of folate, vitamin B6and vitamin B12are associated with increased risk of stroke. Elevated consumption of fruits and vegetables appears to protect against stroke. Antioxidant nutrients have important roles in cell function and have been implicated in processes associated with ageing, including vascular, inflammatory and neurological damage. Plasma vitamin E and C concentrations may serve as a biological marker of lifestyle or other factors associated with reduced stroke risk and may be useful in identifying those at high risk of stroke. After reviewing the observational and intervention studies, there is an incomplete understanding of mechanisms and some conflicting findings; therefore the available evidence is insufficient to recommend the routine use of B vitamins, vitamin E and vitamin C for the prevention of stroke. A better understanding of mechanisms, along with well-designed controlled clinical trials will allow further progress in this area.

The response of gamma vitamin E to varying dosages of alpha vitamin E plus vitamin C

Vitamin E has been studied extensively in the prevention of atherosclerosis. Cross-sectional population studies as well as randomized controlled intervention trials have demonstrated conflicting results. A recent meta-analysis of these trials has emphasized the ineffectiveness of vitamin E in atherosclerosis prevention, with a possibility of harm at higher dosages. However, vitamin E has several isomers, with the alpha form being available via dietary supplements and the gamma form being available via dietary foodstuffs. The gamma form of vitamin E demonstrates several superior properties (such as trapping reactive nitrogen species and detoxifying nitrogen dioxide) compared with alpha vitamin E. All clinical trials have used the alpha isomer, with little concern that this isomer of vitamin E may actually suppress the gamma isomer of vitamin E. We undertook a dose-response study in volunteers with type 2 diabetes mellitus to include all the dosages of alpha vitamin E that have been used in cardiovascular prevention trials to determine the effect of alpha vitamin E on gamma vitamin E. We also assessed the effect of alpha vitamin E on several traditional markers of atherosclerotic risk. We added vitamin C to the vitamin E because several clinical trials included this vitamin to enhance the antioxidant effects of alpha vitamin E. Volunteers received, in randomized order for a 2-week period, one of the following vitamin dosage arms: (1) no vitamins, (2) low-dose supplemental vitamins E plus C, (3) medium-dose supplemental vitamins E plus C, and (4) high-dose supplemental vitamins E plus C. Blood levels of both alpha and gamma vitamin E were measured as well as surrogate markers of oxidative stress, hypercoagulation, and inflammation during a high-fat atherogenic meal (to increase the ambient oxidative stress level during the study). The results demonstrate that alpha vitamin E levels increased in proportion to the dose administered. However, at every dose of alpha vitamin E, gamma vitamin E concentration was significantly suppressed. No beneficial changes in surrogate markers of atherosclerosis were observed, consistent with the negative results of prospective clinical trials using alpha vitamin E. Our results suggest that all prospective cardiovascular clinical trials that used vitamin E supplementation actually suppressed the beneficial antioxidant gamma isomer of vitamin E. No beneficial effects on several potential cardiovascular risk factors were observed, even when the vitamin E was supplemented with vitamin C. If a standardized preparation of gamma vitamin E (without the alpha isomer) becomes available, the effects of gamma vitamin E on atherosclerotic risk will warrant additional studies.

Activation of muscarinic receptors by a hydroalcoholic extract of Dicksonia sellowiana Presl. HooK (Dicksoniaceae) induces vascular relaxation and hypotension in rats

Dicksonia sellowiana (Presl.) Hook is a native plant from the Central and South Americas that contain high levels of polyphenols, antioxidant compounds involved in protection against inflammation, cancer and cardiovascular risk. A phytomedicinal preparation obtained from aerial parts of D. sellowiana is currently under clinical evaluation in Brazil against asthma, and has been associated with several other beneficial effects. This study demonstrates that a hydroalcoholic extract obtained from D. sellowiana leaves (HEDS) fully relax, in a concentration-dependent manner, rat aortic rings precontracted with phenylephrine. Moreover, administration of HEDS (10, 20 and 40 mg/kg, i.v.) in anaesthetized rats resulted in a strong but reversible hypotension. Aortic relaxation induced by HEDS was abolished by endothelium removal, by incubation of the nitric oxide synthase inhibitor L-NAME, or the soluble guanylate cyclase inhibitor ODQ. In addition, this effect was partially inhibited by indomethacin (a cyclooxygenase inhibitor) and KT 5730 (a PKA inhibitor). The potassium channels blockade by either tetraethylammonium or charybdotoxin also resulted in a potent inhibition of HEDS-induced aortic relaxation, whereas apamine only slightly reduced it. In addition HEDS-induced relaxation was unchanged by 4-amynopiridine and glibenclamide. The selective muscarinic receptor antagonist atropine counteracted both aortic relaxation and blood pressure reduction generated by HEDS. Experiments using HPLC revealed the presence of high amounts of phenolic compounds in this extract. Taken together, our results reveal that the D. sellowiana possess substances with both in vivo and in vitro activities and that the vascular effect of HEDS involves activation of muscarinic receptors, stimulation of the nitric oxide pathway and opening of calcium-activated potassium channels.

Antioxidants and CVD

The involvement of free radicals and reactive oxygen and nitrogen species in the pathology of inflammatory and degenerative disease has been widely accepted, although the centrality of these species to the outcome of these diseases is still a matter for debate. In the case of CVD, and particularly the development of the atherosclerotic plaque, the oxidation of LDL is of particular importance and appears to explain many of the events that occur during the life history of the plaque. The corollary of this situation is that antioxidants must be a benign force to protect the population from the modern scourge of heart disease. In fact, recent evidence from intervention studies with large doses of the antioxidant vitamins and other antioxidants in foods has been very disappointing. Here, the background for the belief that antioxidants ought to be beneficial is examined and an attempt made to explain why the results of these intervention studies have been unsuccessful. It is agreed that a diet rich in fruit and vegetables is protective for both CVD and cancer, but the explanation for this effect may not necessarily lie with the presence of antioxidants.

Dietary supplement use and mortality in a cohort of Swedish men

The use of dietary supplements has increased substantially in most industrialized countries. The aim of this study was to prospectively examine the association between use of dietary supplements and all-cause mortality, cancer mortality and CVD mortality in men. We used the population-based prospective cohort of 38 994 men from central Sweden, 45–79 years of age, with no cancer or CVD at baseline and who completed a self-administered FFQ including questions on dietary supplement use and life-style factors in 1997. During average 7.7 years of follow-up, 3403 deaths were ascertained; among them, 771 due to cancer and 930 due to CVD (during 5.9 years of follow-up). In multivariate adjusted models including all men there was no association observed between use of any dietary supplement or of multivitamins, vitamin C, vitamin E or fish oil specifically and all-cause mortality, cancer or CVD mortality. Among current smokers, regular use of any supplement was associated with statistically significant increased risk of cancer mortality: relative risk (RR) 1·46 (95 % CI 1·06, 1·99). Among men reporting an inadequate diet at baseline (assessed by Recommended Food Score), there was a statistically significant inverse association between use of any dietary supplement and CVD mortality (RR 0·72; 95 % CI 0·57, 0·91), no associations were observed among men with adequate diets. In conclusion, we cannot exclude that the use of dietary supplements is harmful for smokers. On the other hand, among men with an insufficient diet, the use of supplements might be beneficial in reducing CVD mortality.

Role of oxidants and antioxidants in atherosclerosis: results of in vitro and in vivo investigations

Both in vitro and in vivo studies have shown that oxidants are central in the development of atherosclerosis. Consequently, additional studies evaluated the protective effects of various natural and synthetic antioxidants, alone and in combination, with most studies focusing on alpha-tocopherol (vitamin E). Here, we summarize the role of oxidants in the pathomechanism of atherosclerosis. We also discuss epidemiological studies and others focused on the protective effect of vitamin E against atherosclerosis. Other antioxidants are also considered if they were included in studies involving vitamin E. The protective effect of antioxidants on atherosclerotic pathomechanisms has been confirmed in vitro, but only in some animal studies. Various epidemiological and observational studies have produced conflicting results on the protective effect of antioxidants. Most studies of primary or secondary prevention failed to show a protective effect. These conflicting results are biased by a number of factors, including differences between the study groups. Therefore, we describe these studies in detail.

Association of dietary intake of soy, beans, and isoflavones with risk of cerebral and myocardial infarctions in Japanese populations: the Japan Public Health Center-based (JPHC) study cohort I

BACKGROUND

Soy and isoflavones have been proposed to reduce the risk of cardiovascular risk factors, but their potential as preventatives for cardiovascular disease remains uncertain. We investigated the association of soy and isoflavone intake with risk of cerebral and myocardial infarctions (CI and MI).

METHODS AND RESULTS

To examine the association of soy and isoflavone intake with the risk of CI and MI, we studied 40,462 Japanese (40 to 59 years old, without cardiovascular disease or cancer at baseline). They completed a food-frequency questionnaire (1990-1992) and received follow-up to 2002. After 503,998 person-years of follow-up, we documented incidence of CI (n=587) and MI (n=308) and of mortality for CI and MI combined (n=232). For women, the multivariable hazard ratios and 95% confidence limits for soy intake > or = 5 times per week versus 0 to 2 times per week were 0.64 (0.43 to 0.95) for risk of CI, 0.55 (0.26 to 1.09) for risk of MI, and 0.31 (0.13 to 0.74) for cardiovascular disease mortality. Similar but weaker inverse associations were observed between intake of miso soup and beans and risk of cardiovascular disease mortality. The multivariable hazard ratios for the highest versus the lowest quintiles of isoflavones in women were 0.35 (0.21 to 0.59) for CI, 0.37 (0.14 to 0.98) for MI, and 0.87 (0.29 to 2.52) for cardiovascular disease mortality. An inverse association between isoflavone intake and risk of CI and MI was observed primarily among postmenopausal women. No significant association of dietary intake of soy, miso soup, and beans and isoflavones with CI or MI was present in men.

CONCLUSIONS

High isoflavone intake was associated with reduced risk of CI and MI in Japanese women. The risk reduction was pronounced for postmenopausal women.

Adjunctive care with nutritional, herbal, and homeopathic complementary and alternative medicine modalities in stroke treatment and rehabilitation

This article presents an overview of nutritional, herbal, and homeopathic treatment options from complementary and alternative medicine (CAM) as adjuncts in stroke prevention, treatment, and rehabilitation. Despite many promising leads, the evidence does not favor recommendation of most of these treatments from a public health policy perspective. However, simple preventive interventions such as use of a high-quality multivitamin/multimineral supplement in patients with undernutrition may improve outcomes with minimal long-term risk. Natural agents such as the antioxidant alphalipoic acid, certain traditional Asian herbal mixtures, and some homeopathically prepared remedies show promise for reducing infarct size and associated impairments. A number of nutrients and herbs may assist in treatment of stroke-related complications such as pressure sores, urinary tract infections, and pneumonia. Individualized homeopathy may even play a helpful adjunctive role in treatment of sepsis. However, a great deal of systematic research effort lies ahead before most of the options discussed would meet mainstream medical standards for introduction into routine treatment regimens.

Vitamin E: inflammation and atherosclerosis

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in the western world with its incidence increasing lately in developing countries. Several lines of evidence support a role for inflammation in atherogenesis. Hence, dietary micronutrients having antiinflammatory properties may have a potential beneficial effect with regard to CVD. Vitamin E is a potent antioxidant with antiinflammatory properties. It comprises eight different isoforms: four tocopherols (T) (alpha, beta, gamma, and delta) and four tocotrienols (T3) (alpha, beta, gamma, and delta). A wealth of data is available for the preventive efficacy of alpha-T. alpha-T supplementation in human subjects and animal models has been shown to be antioxidant and antiinflammatory in terms of decreasing C-reactive protein (CRP) and release of proinflammatory cytokines, the chemokine IL-8 and PAI-1 levels especially at high doses. gamma-T is effective in decreasing reactive nitrogen species and also appears to have antiinflammatory properties; however, there are scanty data examining pure gamma-T preparations. Furthermore, tocotrienols (alpha and gamma) also have implications for prevention of CVD; however, there are conflicting and insufficient data in the literature with regards to their potency. In this chapter, we have gathered recent emerging data on alpha-T specifically and also have given a composite view of gamma-T and tocotrienols especially with regards to their effect on inflammation as it relates to CVD.

Does gamma-tocopherol play a role in the primary prevention of heart disease and cancer? A review

Vitamin E consists of a group of eight isomers, four tocopherols (alpha-, beta-, gamma-, delta-tocopherol) and four tocotrienols (alpha-, beta-, gamma-, delta-tocotrienol). While extensive literature has been published on the potential health benefits of alpha-tocopherol, little is known about gamma-tocopherol, the major form of vitamin E in food in the U.S. gamma-tocopherol has recently received more research attention based on findings from in vitro and animal studies indicating that it has potent anti-inflammatory and antioxidant properties. Based on these recent studies, it is important to investigate the possible health benefits of gamma-tocopherol in humans. In this article, we review publications on dietary gamma-tocopherol intake, plasma gamma-tocopherol levels, cardiovascular disease and cancer risk in humans.

Lower antioxidant vitamins (A, C and E) and trace minerals (Zn, Cu, Mn, Fe And Se) status in patients with cerebrovascular disease

The management of antioxidant micronutrient status in patients with chronic diseases may be an important step in controlling disease progression and preventing deterioration in patient quality of life. The objective of this study was to investigate the antioxidant micronutrient status and lipid profiles of cerebrovascular disease (CbVD) patients and to compare this information with an evaluation of normal healthy subjects. A total of 57 male subjects (26 patients with CbVD and 31 healthy subjects) and 65 female subjects (32 patients with CbVD and 33 healthy subjects) were included in this cross-sectional study. Plasma lipid profiles, thiobarbituric acid-reactive substances (TBARS), fasting plasma concentration of antioxidant vitamins (A, C, E) and trace minerals (Cu, Zn, Mn, Fe and Se) were measured. Compared to healthy subjects, male but not female CbVD patients showed a lower energy intake (p < 0.01) which was largely due to a lower intake of dietary carbohydrate. They also consumed a diet containing a higher level of vitamins A and C. Plasma vitamin C (p < 0.01, in women) and vitamin E (p < 0.05, both in men and women) concentrations were prominently lower in the patients compared to healthy subjects. Plasma levels of the two antioxidant minerals Zn and Se were found to be markedly lower in the patients with CbVD, both in men and women (p < 0.05). Despite consuming less energy and food with a higher vitamin A and C level than healthy subjects, antioxidant micronutrient status, lipid peroxidation levels and the atherogenic index of male CbVD patients suggested that their antioxidant micronutrient intake was in some respects nutritionally inadequate. A similar conclusion could be made regarding the nutritional inadequacy of female CbVD patient diets. Expert dietary advice and intervention should be given to CbVD patients in order to optimize micronutrient intake and status.

Carotenoids and cardiovascular disease: what research gaps remain?

PURPOSE OF REVIEW

Dietary and blood carotenoids, including alpha-carotene, beta-carotene, lycopene, lutein/zeaxanthin, and beta-cryptoxanthin, have been examined in a number of epidemiological studies in recent years for the risk of cardiovascular disease. This review assimilated the existing and recent literature on carotenoids and cardiovascular disease and considered what research gaps may remain.

RECENT FINDINGS

Numerous large cohort studies have been published in largely American men and women that have examined dietary intake or blood levels of total or individual carotenoids with the risk of various cardiovascular endpoints. Overall, early, promising results have grown increasingly inconsistent over time. More recently, studies examining lycopene and lutein/zeaxanthin have offered more promising data on a possible, but not yet established, inverse association with the risk of cardiovascular disease. Recent epidemiological data on beta-cryptoxanthin and cardiovascular disease are lacking. Primary and secondary prevention trials have extensively examined beta-carotene, but not other carotenoids, for the risk of cardiovascular disease as either the primary or secondary endpoint with largely null results. More recent studies have focused on individual carotenoids in relation to cardiovascular disease and require a more careful evaluation of potential mechanisms of effect.

SUMMARY

The promise of early epidemiological studies on carotenoids and cardiovascular disease paved the way to largely disappointing results from several large prevention trials of beta-carotene. Emerging recent evidence of potential cardioprotective effects for lycopene and other carotenoids besides beta-carotene in the diet and blood suggest that there is more to be learned in the story of carotenoids and both atherosclerotic progression and clinically manifested cardiovascular disease.

Nut and seed consumption and inflammatory markers in the multi-ethnic study of atherosclerosis

Nuts and seeds are rich in unsaturated fat and other nutrients that may reduce inflammation. Frequent nut consumption is associated with lower risk of cardiovascular disease and type 2 diabetes. The authors examined associations between nut and seed consumption and C-reactive protein, interleukin-6, and fibrinogen in the Multi-Ethnic Study of Atherosclerosis. This 2000 cross-sectional analysis included 6,080 US participants aged 45-84 years with adequate information on diet and biomarkers. Nut and seed consumption was categorized as never/rare, less than once/week, 1-4 times/week, and five or more times/week. After adjustment for age, gender, race/ethnicity, site, education, income, smoking, physical activity, use of fish oil supplements, and other dietary factors, mean biomarker levels in categories of increasing consumption were as follows: C-reactive protein-1.98, 1.97, 1.80, and 1.72 mg/liter; interleukin-6-1.25, 1.24, 1.21, and 1.15 pg/ml; and fibrinogen-343, 338, 338, and 331 mg/dl (all p's for trend < 0.01). Further adjustment for hypertension, diabetes, medication use, and lipid levels yielded similar results. Additional adjustment for body mass index moderately attenuated the magnitude of the associations, yielding borderline statistical significance. Associations of nut and seed consumption with these biomarkers were not modified by body mass index, waist:hip ratio, or race/ethnicity. Frequent nut and seed consumption was associated with lower levels of inflammatory markers, which may partially explain the inverse association of nut consumption with cardiovascular disease and diabetes risk.

Failure of vitamin E in clinical trials: is gamma-tocopherol the answer?

Oxidative stress and inflammation play a crucial role in atherosclerosis. However, prospective clinical trials of dietary antioxidants with anti-inflammatory properties, such as alpha-tocopherol (AT), have not yielded positive results. AT supplementation decreases gamma-tocopherol (GT) levels. GT is an antioxidant with potent anti-inflammatory activity, and plasma GT levels are inversely associated with cardiovascular diseases. Thus, studies using pure GT, alone or in conjunction with AT, will elucidate its utility in cardiovascular disease prevention.

Inter- and intra-individual vitamin E uptake in healthy subjects is highly repeatable across a wide supplementation dose range

Vitamin E uptake after supplementation varies widely in the healthy population, and preliminary studies have indicated that individual responses are relatively stable over periods in excess of 1 year. This phenotypic stability suggests a genetic basis to this observed variation. To examine this issue further, we examined the repeatability of both baseline plasma alpha-tocopherol and urinary alpha-tocopherol metabolite concentrations, as well as individual responses of these parameters after vitamin E supplementation. In the first study, 65 subjects (33 males, 32 females, aged 30.7 +/- 7.4 years) provided three plasma and urine samples for alpha-tocopherol and metabolite analysis with each collection separated by at least 2 weeks. Plasma alpha-tocopherol concentrations were found to be highly repeatable over this short interval (intra-class correlation coefficient [ICC] = 0.85), although the association deteriorated once values were corrected for plasma cholesterol (ICC = 0.64). Similarly, urinary alpha-tocopherol metabolites 2(2'-carboxyethyl)-6-hydroxychroman acid (alpha-CEHC) and quinone lactone (QL) concentration were found to display a moderate degree of intra-subject repeatability: ICC = 0.65 and 0.58, respectively. In a second study, plasma alpha-tocopherol and urinary metabolite responses were investigated in 18 healthy, nonsmoking subjects (12 males, 6 females, aged 33.1 +/- 9.1 years) after successive 6-week periods of vitamin E (RRR-alpha-tocopherol acetate) supplementation at 15, 100, 200, and 400 mg/day. Plasma and urine samples were obtained on days 0, 7, 14, 21, and 28 (7 days after the final supplement) of each dosing period and the strength of the underlying association between responses determined using Kendall's tau_b test. Individual plasma alpha-tocopherol responses at the 100, 200, and 400 mg/day doses were found to be highly associated: tau, 0.51, P = 0.02 [100 vs. 200] and tau, 0.49, P = 0.03 [100 vs. 400] and tau, 0.56, P = 0.005 [200 vs. 400]. Together these data support the contention that alpha-tocopherol uptake is a stable individual phenotype under genetic regulation.

Associations between plasma antioxidants and hypertension in a community-based sample of 415 Australians aged 60-64

It has been suggested that increased oxidative stress may be both a cause as well as a consequence of hypertension. In vivo oxidation of low-density lipoproteins by oxygen-free radicals may increase hypertension-related atherogenesis, and antioxidants may be beneficial in this regard. Previous findings concerning associations between serum measures of antioxidants and hypertension have however been inconsistent. Plasma levels of beta-carotene, Vitamin A, E, uric acid, homocysteine and total antioxidant capacity, as well as two markers of oxidative stress, malondialdehyde (MDA) and protein carbonyls, were measured in morning fasting blood samples provided by 415 Australians aged 60-64 years, selected randomly from the community. Participants also provided information on sociodemographic attributes, mental and physical health, and provided two measures of resting blood pressure, allowing a diagnosis of definite or borderline hypertension. Those with hypertension had lower levels of beta-carotene and higher levels of uric acid and MDA compared to normotensive participants. The last two of these associations persisted when the analyses controlled for lifestyle and health factors. The findings from this study offer limited support for the proposition that lower antioxidant status and higher oxidative stress are associated with hypertension, and suggest the need for longitudinal studies to examine causality and intervention studies to determine the benefit of antioxidants in this group.

Improved diet quality with peanut consumption

OBJECTIVE

To evaluate the diet quality of free-living men, women, and children choosing peanuts and peanut products.

DESIGN

Using data reported in the Continuing Survey of Food Intake by Individuals and Diet and Health Knowledge Survey (CSFII/DHKS) from 1994-1996, food codes were used to sort respondents by use or nonuse of peanuts.

SUBJECTS

A nationally representative sample of 4,751 men, 4,572 women, and 4,939 children (boys and girls, 2-19 yrs) who completed 2-day intake records.

MEASURES OF OUTCOME

The two-sample t test was used to analyze differences between peanut users and nonusers for energy, nutrient intakes, Health Eating Index (HEI) scores, and body mass index (BMI).

RESULTS

Peanut users (24% of CSFII/DHKS) had higher intakes (p < 0.001) of protein, total fat, polyunsaturated fat (PUFA), monounsaturated fat, (MUFA) (p < 0.01), fiber, vitamin A, vitamin E, folate, calcium, magnesium, zinc, and iron. Percent of energy from saturated fat was not significantly different for men, women or girls and was slightly lower (p < 0.01) for boys. Dietary cholesterol of peanut users was lower for all population groups; this decrease was significant for both men (p < 0.01) and children (p < 0.001). The HEI was calculated as a measure of overall nutrient profile of the diets and was significantly greater for peanut users (men 61.4, women, 65.1, children 66.8) compared to nonusers (men 59.9, women 64.1, children 64.7) for men (p = 0.0074) and children (p < 0.001). Energy intake was significantly higher in all population groups of peanut users (p < 0.001; boys: p < 0.01); however mean BMI for peanut users was lower for all gender/age categories (women: p < 0.05; children: p < 0.001).

CONCLUSIONS

These results demonstrate improved diet quality of peanut users, indicated by the higher intake of the micronutrients vitamin A, vitamin E, folate, calcium, magnesium, zinc, and iron and dietary fiber, and by the lower intake of saturated fat and cholesterol. Despite a higher energy intake over a two-day period, peanut consumption was not associated with a higher BMI.

Fruit, vegetable, and antioxidant intake and all-cause, cancer, and cardiovascular disease mortality in a community-dwelling population in Washington County, Maryland

Higher intake of fruits, vegetables, and antioxidants may help protect against oxidative damage, thus lowering cancer and cardiovascular disease risk. This Washington County, Maryland, prospective study examined the association of fruit, vegetable, and antioxidant intake with all-cause, cancer, and cardiovascular disease death. CLUE participants who donated a blood sample in 1974 and 1989 and completed a food frequency questionnaire in 1989 (N = 6,151) were included in the analysis. Participants were followed to date of death or January 1, 2002. Compared with those in the bottom fifth, participants in the highest fifth of fruit and vegetable intake had a lower risk of all-cause (cases = 910; hazard ratio (HR) = 0.63, 95% confidence interval (CI): 0.51, 0.78; p-trend = 0.0004), cancer (cases = 307; HR = 0.65, 95% CI: 0.45, 0.93; p-trend = 0.08), and cardiovascular disease (cases = 225; HR = 0.76, 95% CI: 0.54, 1.06; p-trend = 0.15) mortality. Higher intake of cruciferous vegetables was associated with lower risk of all-cause mortality (HR = 0.74, 95% CI: 0.60, 0.91; p-trend = 0.04). No statistically significant associations were observed between dietary vitamin C, vitamin E, and beta-carotene intake and mortality. Overall, greater intake of fruits and vegetables was associated with lower risk of all-cause, cancer, and cardiovascular disease death. These findings support the general health recommendation to consume multiple servings of fruits and vegetables (5-9/day).

Does supplemental vitamin C increase cardiovascular disease risk in women with diabetes?

BACKGROUND

Vitamin C acts as a potent antioxidant; however, it can also be a prooxidant and glycate protein under certain circumstances in vitro. These observations led us to hypothesize that a high intake of vitamin C in diabetic persons might promote atherosclerosis.

OBJECTIVE

The objective was to examine the relation between vitamin C intake and mortality from cardiovascular disease.

DESIGN

We studied the relation between vitamin C intake and mortality from total cardiovascular disease (n = 281), coronary artery disease (n = 175), and stroke (n = 57) in 1923 postmenopausal women who reported being diabetic at baseline. Diet was assessed with a food-frequency questionnaire at baseline, and subjects initially free of coronary artery disease were prospectively followed for 15 y.

RESULTS

After adjustment for cardiovascular disease risk factors, type of diabetes medication used, duration of diabetes, and intakes of folate, vitamin E, and beta-carotene, the adjusted relative risks of total cardiovascular disease mortality were 1.0, 0.97, 1.11, 1.47, and 1.84 (P for trend < 0.01) across quintiles of total vitamin C intake from food and supplements. Adjusted relative risks of coronary artery disease were 1.0, 0.81, 0.99, 1.26, and 1.91 (P for trend = 0.01) and of stroke were 1.0, 0.52, 1.23, 2.22, and 2.57 (P for trend < 0.01). When dietary and supplemental vitamin C were analyzed separately, only supplemental vitamin C showed a positive association with mortality endpoints. Vitamin C intake was unrelated to mortality from cardiovascular disease in the nondiabetic subjects at baseline.

CONCLUSION

A high vitamin C intake from supplements is associated with an increased risk of cardiovascular disease mortality in postmenopausal women with diabetes.

Sujets hyperlipidémiques, des apports nutritionnels inappropriés

OBJECTIVE

Gather knowledge on nutritional supplementation in patients with hyperlipidemia.

METHODS

In an observational study on patients with hyperlipidemia, nutritional intake was assessed using a 7-day dietary questionnaire, provided on the first visit to a lipid clinic.

RESULTS

291 patients (201 men and 90 women) were studied. Calorie intake and proportion of energetic nutrients revealed low carbohydrate intake, low intake of dietary fibres, and excessive lipid and saturated fatty acid intakes. Patients with isolated hypercholesterolemia had nutritional intake very similar to the daily allowances recommended in France. Men with type III hyperlipidemia had the highest calorie intake and those with type IV dyslipidemia had the highest alcohol intake. Triglycerides increased with total energy intake and with fat intake (%). Body mass index was inversely correlated to carbohydrate intake. The duration of dyslipidemia was related to low vitamin C and B9 intake. The existence of risk factors (type 2 diabetes, hypertension, smoking or inactivity) was associated with less well-balanced diet and low protective micronutrient status. In the case of atherosclerosis, vitamin B9, C, E and beta-carotene intake was insufficient. Interactions existed between nutrient intake with correlations between fibres, vitamin B9, C and beta-carotene, suggesting that nutritional education should favour foodstuffs that provide them simultaneously.

CONCLUSION

Nutritional intake in patients with hyperlipidemia is often far from that recommended and does not greatly differ from that in large non-selected populations. It can be considered as inappropriate because of the metabolic and cardiovascular risks in these patients. Adapted nutritional management is crucial.

Studies of various elements of nutritional and toxicological interest associated with different molecular weight fractions in Brazil nuts

On-line hyphenation of size exclusion chromatography (SEC), UV, and inductively coupled plasma mass spectrometry (ICP-MS) was used to study the molecular weight distribution patterns of several elements in Brazil nuts (Bertholletia excelsa). This technique was used for the elemental speciation of different elements of nutritional and toxicological interests such as Mg, Fe, Co, Mo, Ag, Hg, and Pb. Elemental fractionation in Brazil nuts was studied using a Superdex peptide column with resolving capacity in the range of 14 to 0.18 kDa. Three different mobile phases, Tris buffer solution (pH 8.0), phosphate buffer (pH 7.5), and CAPS buffer solution (pH 10.0), were tried for the SEC fractionation. Size exclusion fractionation of all the extracted solutions was performed using a 50 mmol L(-)(1) Tris buffer (pH 8) as the mobile phase at a flow rate of 0.6 mL min(-)(1). Three different extractions, 0.05 mol L(-)(1) NaOH, 0.05 mol L(-)(1) HCl, and hot water at 60 degrees C, were performed, and the association of elements with various molecular weight fractions was evaluated. Total elemental concentrations in the extracted samples were determined and compared with the values obtained after total digestion to calculate the recovery values. Generally, high extraction efficiency was obtained with the NaOH solution as compared with HCl and hot water except in the case of magnesium, for which HCl was found to be a good extractant. Chromatographic elution profiles for these extractions were quite distinct from each other in most cases. Most of the elemental species were found to be associated with high molecular weight fractions. To study the differences obtained during the sample-processing step, the results obtained for nuts with shell were treated differently from those obtained for nuts purchased without shell and were compared.

A review of the epidemiological evidence for the 'antioxidant hypothesis'

OBJECTIVE

The British Nutrition Foundation was recently commissioned by the Food Standards Agency to conduct a review of the government's research programme on Antioxidants in Food. Part of this work involved an independent review of the scientific literature on the role of antioxidants in chronic disease prevention, which is presented in this paper.

BACKGROUND

There is consistent evidence that diets rich in fruit and vegetables and other plant foods are associated with moderately lower overall mortality rates and lower death rates from cardiovascular disease and some types of cancer. The 'antioxidant hypothesis' proposes that vitamin C, vitamin E, carotenoids and other antioxidant nutrients afford protection against chronic diseases by decreasing oxidative damage.

RESULTS

Although scientific rationale and observational studies have been convincing, randomised primary and secondary intervention trials have failed to show any consistent benefit from the use of antioxidant supplements on cardiovascular disease or cancer risk, with some trials even suggesting possible harm in certain subgroups. These trials have usually involved the administration of single antioxidant nutrients given at relatively high doses. The results of trials investigating the effect of a balanced combination of antioxidants at levels achievable by diet are awaited.

CONCLUSION

The suggestion that antioxidant supplements can prevent chronic diseases has not been proved or consistently supported by the findings of published intervention trials. Further evidence regarding the efficacy, safety and appropriate dosage of antioxidants in relation to chronic disease is needed. The most prudent public health advice remains to increase the consumption of plant foods, as such dietary patterns are associated with reduced risk of chronic disease.

Gamma-tocopherol--an underestimated vitamin?

The main research activities of the last decades on tocopherols were mainly focused on alpha-tocopherol, in particular when considering the biological activities. However, recent studies have increased the knowledge on gamma-tocopherol, which is the major form of vitamin E in the diet in the USA, but not in Europe. gamma-Tocopherol provides different antioxidant activities in food and in-vitro studies and showed higher activity in trapping lipophilic electrophiles and reactive nitrogen and oxygen species. The lower plasma levels of gamma- compared to alpha-tocopherol might be discussed in the light of different bioavailability, but also in a potential transformation from gamma- into alpha-tocopherol. From the metabolism end product, only that of gamma-tocopherol (2,7,8-trimethyl-2-(beta-carboxyethyl)-6-hydroxychroman), but not that of alpha-tocopherol, was identified to provide natriuretic activity. Studies also indicate that only the gamma-tocopherol plasma level served as biomarker for cancer and cardiovascular risk. Therefore, this paper provides a comprehensive review on gamma-tocopherol with emphasis on its chemistry, biosynthesis, occurrence in food, different intake linking to different plasma levels in USA and Europe, absorption and metabolism, biological activities, and possible role in human health.

Prospective study of plasma carotenoids and tocopherols in relation to risk of ischemic stroke

BACKGROUND AND PURPOSE

Intake of fruits and vegetables has been related to lower risk of ischemic stroke, but nutrients responsible for this apparent benefit remain ill-defined. Tocopherols (vitamin E) have also been proposed to be protective.

METHODS

We conducted a prospective, nested case-control analysis among male physicians without diagnosed cardiovascular disease followed-up for up to 13 years in the Physicians' Health Study. Samples from 297 physicians with ischemic stroke were analyzed with paired controls, matched for age and smoking, for 5 major carotenoids (alpha- and beta-carotene, beta-cryptoxanthin, lutein, and lycopene), retinol, and alpha- and gamma-tocopherol.

RESULTS

Baseline plasma levels of alpha-carotene and beta-carotene and lycopene tended to be inversely related to risk of ischemic stroke with an apparent threshold effect. As compared with men whose plasma levels were in the lowest quintile, the multivariate adjusted odds ratios (ORs) of ischemic stroke among men with levels in the second through fifth quintiles were 0.59 (95% CI, 0.36 to 0.98) for alpha-carotene, 0.62 (95% CI, 0.38 to 1.01) for beta-carotene, and 0.61 (95% CI, 0.37 to 1.00) for lycopene. A tendency toward an inverse association was found for beta-cryptoxanthin, but the result was not statistically significant. No association was found for lutein, retinol, and tocopherols.

CONCLUSIONS

Our data suggest that higher plasma levels of carotenoids, as markers of fruit and vegetable intake, are inversely related to risk of ischemic stroke and provide support for recommendations to consume fruits and vegetables regularly.

Nutrition and prevention of ischemic stroke: present knowledge, limitations and future perspectives

Stroke, particularly ischemic stroke, has a major impact on public health due to its high incidence, prevalence and rate of subsequent disability in Italy as in most industrialised countries. Apart from age, many modifiable factors, such as hypertension, smoking, diabetes, dyslipidemia, obesity, physical inactivity, alcohol abuse and hyperhomocysteinemia, have been recognised as playing a role in the pathogenesis of this disease. While appropriate pharmacological therapy has proven effective in the prevention of stroke in particular categories of patients, most of the above mentioned predisposing conditions are amenable to be affected by nutrition. Unequivocal demonstration of a protective or adverse role of single foods and nutrients against the risk of stroke has been however difficult to achieve due to confounding by biological variability, methodological inadequacies in the assessment of individual nutritional habits and difficulty to carry out long-term randomised controlled trials in the nutritional area. Notwithstanding, in several cases, causal relationships could be inferred from case-control and cohort studies in the presence of plausible and reproducible associations, evidence of dose-dependent effects and consistency in the results of different studies. The aim of this paper was to review present knowledge and highlight limitations and future perspectives about the role of nutrition in the prevention of ischemic stroke.

Age-related changes of serum lipoprotein oxidation in rats

Oxidation of low-density lipoprotein (LDL) may be a prelude to atherogenesis and directly age related. To assess whether there may be relationship between age and plasma lipoprotein (LP) oxidation, we studied copper-mediated LP oxidation isolated from the blood of 2 months, 7 months, and 15 months old rats. We determined whether the susceptibility of LP to oxidation might be related to vitamin C levels in serum, vitamin E levels in LP, or the total antioxidant capacity (TAC) of serum or LP. Serum vitamin C content was inversely related to age, malondialdehyde (MDA) propagation rate, and maximum change of MDA concentrations. However, there were no significant relationships between age and serum TAC, LP TAC, serum vitamin E, or the ratio of LP vitamin E to serum vitamin C content. The lag phase of MDA formation was significantly decreased with age and the ratio of LP vitamin E content to serum vitamin C content, increased with age. Maximum change of MDA concentration was positively correlated with the ratio of LP vitamin E contents to serum vitamin C concentration. Thus, as the rat ages, vitamin C status decreases with an increased LP susceptibility to oxidation. It is tempting to speculate that enhanced LP oxidation in older rats may reflect a reduced amount of recycling of LDL vitamin E by serum vitamin C.

Vegetable and Fruit Intake and Stroke Mortality in the Hiroshima/Nagasaki Life Span Study

BACKGROUND AND PURPOSE

Fruits and vegetables are known for their beneficial effects on chronic diseases. The purpose of the present study was to investigate the protective effect of a diet rich in fruits and vegetables on total stroke mortality and its 2 main subtypes in men and women separately.

METHODS

A prospective cohort study of 40 349 Japanese men and women was initiated in 1980-1981 and followed until 1998. Fruit and vegetable intake was assessed at baseline on the basis of the response to a food frequency questionnaire. During the 18-year follow-up period, deaths from stroke were registered.

RESULTS

A total of 1926 stroke deaths were identified during the follow-up period. An increasing frequency of intake of green-yellow vegetables and fruit was associated with a reduced risk of death from intracerebral hemorrhage and cerebral infarction. Daily intake of green-yellow vegetables was associated with a significant 26% reduction in the risk of death from total stroke in men and women compared with an intake of once or less per week. The protective effect associated with daily fruit and vegetable intake was observed for both cerebral infarction and intracerebral hemorrhage mortality but was slightly stronger and clearer for infarction than for hemorrhage, with a 32% reduction in men and a 30% reduction in women. Daily fruit intake was associated with a significant 35% reduction in risk of total stroke in men and a 25% reduction in women and was equally strong for both intracerebral hemorrhage and cerebral infarction.

CONCLUSIONS

Daily consumption of green-yellow vegetables and fruits is associated with a lower risk of total stroke, intracerebral hemorrhage, and cerebral infarction mortality. The protective effects are similar in both men and women.

Plasma carotenoids and tocopherols and risk of myocardial infarction in a low-risk population of US male physicians

BACKGROUND

Increased intake of carotenoids and vitamin E may protect against myocardial infarction (MI). However, prospective data on blood levels of carotenoids other than beta-carotene and vitamin E (tocopherol) and risk of MI are sparse.

METHODS AND RESULTS

We conducted a prospective, nested case-control analysis among male physicians without prior history of cardiovascular disease who were followed for up to 13 years in the Physicians' Health Study. Samples from 531 physicians diagnosed with MI were analyzed together with samples from paired control subjects, matched for age and smoking, for 5 major carotenoids (alpha- and beta-carotene, beta-cryptoxanthin, lutein, and lycopene), retinol, and alpha- and gamma-tocopherol. Overall, we found no evidence for a protective effect against MI for higher baseline plasma levels of retinol or any of the carotenoids measured. Among current and former smokers but not among never-smokers, higher baseline plasma levels of beta-carotene tended to be associated with lower risk (P for interaction=0.02). Men with higher plasma levels of gamma-tocopherol tended to have an increased risk of MI (P for trend=0.01).

CONCLUSIONS

These prospective data do not support an overall protective relation between plasma carotenoids or tocopherols and future MI risk among men without a history of prior cardiovascular disease.

Drug therapy of neurovascular disease

Recent advances in the prevention and pharmacotherapy of cerebrovascular disease have provided more favorable clinical outcomes. For the treatment of an acute ischemic stroke, the early use of thrombolytic agents can reduce the degree of brain damage while improving functional outcomes. However, trials evaluating various classes of other neuroprotective agents have not shown benefit to date. For the prevention of second stroke, the use of antiplatelet drugs, HMG-CoA reductase inhibitors, and angiotensin-converting enzyme inhibitors with a diuretic have shown benefit in reducing new events. In patients with underlying heart disease or atrial fibrillation, warfarin appears to be the drug of choice in preventing stroke. Early treatment of hemorrhagic stroke with calcium channel blockers can improve the functional outcome. Innovative therapies are now available for the treatment of migraine and vascular dementia. Primary prevention of stroke remains the optimal therapeutic strategy and includes treatment of systemic hypertension and hypercholesterolemia.

Oxidative stress in neurodegenerative diseases: therapeutic implications for superoxide dismutase mimetics

Evidence of oxidative stress is apparent in both acute and chronic neurodegenerative diseases, such as stroke, Parkinson's disease (PD) and amyotrophic lateral sclerosis (ALS). Increased generation of reactive oxygen species simply overwhelm endogenous antioxidant defences, leading to subsequent oxidative damage and cell death. Tissue culture and animal models have been developed to mimic some of the biochemical changes and neuropathology found in these diseases. In doing so, it has been experimentally demonstrated that oxidative stress plays a critical role in neuronal cell death. Antioxidant enzymes, such as superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx) have demonstrated therapeutic efficacy in models of neurodegeneration. However, delivery and stability issues have reduced the enthusiasm to clinically develop these proteins. Most recently, SOD mimetics, small molecules which mimic the activity of endogenous superoxide dismutase, have come to the forefront of antioxidant therapeutics. This review will examine the experimental evidence supporting the use of scavengers of superoxide anions in treating some neurodegenerative diseases, such as stroke, PD and ALS, but also the pitfalls that have met antioxidant molecules in clinical trials.

Mediterranean diet and stroke: objectives and design of the SUN project. Seguimiento Universidad de Navarra

PURPOSE

The Mediterranean diet has been postulated as a protective factor against different diseases including stroke. Thus, an epidemiological study in a Mediterranean country, such as Spain, focused on diet may offer new insights of the potential benefits of this nutritional pattern to prevent the onset of cerebrovascular diseases.

METHODS

The SUN ("Seguimiento Universidad de Navarra") project is a prospective study among Spanish university alumni, aimed to identify the dietary determinants of stroke, coronary disease and other disorders. Two pilot studies have been developed. The first pilot study was focused on the understanding of the questionnaire. The second study used a random sample to assess the response proportion and the feasibility of using a mailing system for following-up the cohort. The first informative results are expected to be available after the first four years of following-up the cohort (2005). Here, we report the description of the baseline diet of the first participants in the cohort using data from 1,587 men and 2,260 women.

RESULTS

The outcome of our pilot studies ensure the feasibility of a mail-based cohort. In the baseline assessment, we found a high consumption of olive oil (18.5 g/person/day), red wine (28.8 g/person/day), legumes (102.5 g/person/day), vegetables (507.8 g/person/ day) and fruits (316.7 g/person/day), with a great between-subject variability. Also, the values for cereals (170.4g/person/day), dairy products (239.3 g/person/day) and meat and meat products consumption (186 g/person/ day) in this cohort were estimated. The coefficients of variation ranged in women from 56 (for vegetables) to 240% (for red wine) and in men from 62 to 180% (for these same two items), reflecting a wide heterogeneity in the diet of participants.

CONCLUSIONS

Although the participation was not high (22% according to the estimates of the pilot study), it was comparable to the proportion found in large previous cohorts such as the Nurses-II Health Study (24%). The sharp contrast in dietary habits between the US and Spain together with the high between-subjects variability we have found in our Spanish cohort provides an exceptional opportunity to assess the aspects of the Mediterranean diet, which may be protective against stroke and other neurological disorders.

gamma-tocopherol, the major form of vitamin E in the US diet, deserves more attention

gamma-tocopherol is the major form of vitamin E in many plant seeds and in the US diet, but has drawn little attention compared with alpha-tocopherol, the predominant form of vitamin E in tissues and the primary form in supplements. However, recent studies indicate that gamma-tocopherol may be important to human health and that it possesses unique features that distinguish it from alpha-tocopherol. gamma-Tocopherol appears to be a more effective trap for lipophilic electrophiles than is alpha-tocopherol. gamma-Tocopherol is well absorbed and accumulates to a significant degree in some human tissues; it is metabolized, however, largely to 2,7,8-trimethyl-2-(beta-carboxyethyl)-6-hydroxychroman (gamma-CEHC), which is mainly excreted in the urine. gamma-CEHC, but not the corresponding metabolite derived from alpha-tocopherol, has natriuretic activity that may be of physiologic importance. Both gamma-tocopherol and gamma-CEHC, but not alpha-tocopherol, inhibit cyclooxygenase activity and, thus, possess antiinflammatory properties. Some human and animal studies indicate that plasma concentrations of gamma-tocopherol are inversely associated with the incidence of cardiovascular disease and prostate cancer. These distinguishing features of gamma-tocopherol and its metabolite suggest that gamma-tocopherol may contribute significantly to human health in ways not recognized previously. This possibility should be further evaluated, especially considering that high doses of alpha-tocopherol deplete plasma and tissue gamma-tocopherol, in contrast with supplementation with gamma-tocopherol, which increases both. We review current information on the bioavailability, metabolism, chemistry, and nonantioxidant activities of gamma-tocopherol and epidemiologic data concerning the relation between gamma-tocopherol and cardiovascular disease and cancer.

Whole grain intake and risk of ischemic stroke in women

In a recent prospective study, whole grain intake was associated with a reduced risk of ischemic stroke. Refined grain, however, did not elicit such protection. Given the potential health benefits associated with whole grain diets, further exploration on the effects of whole grains on health and risk of chronic disease is warranted.

Therapeutic potential of vitamin E in heart disease

Low density lipoprotein (LDL) oxidation is considered an important step in the atherogenic process. Oxidatively modified particles induce the expression of adhesion molecules, stimulate the production of inflammatory cytokines and impair endothelial function. The measurement of oxidised LDLs in vivo is very difficult, therefore most investigators rely on the measurement of in vitro oxidability of these particles to evaluate their deleterious effects. Supplementation with water and lipid soluble anti-oxidant vitamins, especially vitamin C and E, significantly increase the resistance to LDL oxidation. Vitamin E supplementation also improves endothelium-dependent vasodilation in hypercholesterolaemic and subjects who smoke cigarettes. Epidemiological studies have not consistently demonstrated a protective effect of vitamin E consumption as food or supplements on coronary events or stroke. Likewise, only one of five large prospective trials has shown a beneficial effect of vitamin E supplementation on cardiovascular events or mortality. One report showed that supplemented haemodialysed patients had a lower incidence of cardiovascular events. Thus, presently, there is not enough evidence to widely recommend the use of vitamin E supplements for vascular protection.