Determinants of the Nutritional Status of Vitamin E in a Non- Smoking Mediterranean Population

Home , Vitamin E

Determinants of the nutritional status of vitamin E in a non- smoking Mediterranean population. Analysis of the effect of vitamin E intake, alcohol consumption and body mass index on the serum alpha-tocopherol concentration

P GascoÂn-Vila1, R Garcia-Closas1, L Serra-Majem1,2, MC Pastor3, L Ribas1, JM Ramon1, A MarineÂ-Font4 and L Salleras5

1Community Nutrition Research Unit, Institute of Public Health, Campus de Bellvitge, University of Barcelona, Ctra. de la Feixa Llarga, s/n 08907 L'Hospitalet, Spain; 2Department of Preventive Medicine and Public Health, Faculty of Health Sciences, University of Las Palmas, 35080 Las Palmas, de Gran Canaria; 3Laboratory of Biochemistry, Germans Trias i Pujol Hospital, 08910, Badalona; 4Department of Nutrition and Bromatology, Faculty of Pharmacy, University of Barcelona, 08028 Barcelona; and 5Department of Health and Social Security, Autonomous Government of Catalonia, 08028 Barcelona

Objectives: Study was conducted in order to investigate the association of vitamin E intake and other factors with plasma a-tocopherol concentration in a non-smoking Mediterranean population. Design: A cross-sectional study was conducted in a subsample of a representative sample of the Catalan population. Subjects: Sample size was 143 men and women, aged between 18 and 75 y, and ®nal response rate reached 61.9% of the initial sample. Interventions: Serum alpha-tocopherol concentration standardized by serum total lipids was used as a proxy of the nutritional status of vitamin E. Vitamin E intake and alcohol consumption were estimated by a replicated 24 h recall method. Dietary data were collected in two different periods, winter and summer, in order to account for seasonal variation in nutrient intake, and were corrected for random within-person variability in order to account for day-to-day variation in nutrient intake. Multivariate linear regression models were ®tted in order to estimate the determinants of serum a-tocopherol concentration. Results: In this population study, for each one mg increase in vitamin E intake, serum a-tocopherol concentration increased, on average, 0.66 micromol/L, after adjusting for age, gender, Body Mass Index (BMI), alcohol consumption and energy intake. BMI also in¯uenced signi®cantly serum a-tocopherol concentration, whereas alcohol intake, age and gender did not show signi®cant associations with serum a-tocopherol. Conclusions: The study showed that vitamin E nutritional status was associated to vitamin E intake and BMI in non-smokers. Sponsorship: This study was supported by a research agreement between the Department of Health of the Autonomous Government of Catalonia and the Bosch Gimpera Foundation of the University of Barcelona (Contract 2415/95). Descriptors: vitamin E; BMI; alcohol; intake; a-tocopherol and nutritional status

Introduction the vitamin E nutritional status is, therefore, useful for epidemiologic studies of chronic disease. The concentration Vitamin E is an essential micronutrient which may have of total vitamin E or a-tocopherol in serum is the most protective effects against cardiovascular diseases and sev- frequently used biochemical index of the nutritional status eral cancers through different biological mechanisms of vitamin E (Gibson, 1990; Hunter, 1990). It does appear (Grant & De Hoog, 1985; Willett, 1986; Diplock, 1991; that a single measurement of plasma or serum a-tocopherol Stahelin et al, 1991; Ashwell, 1993; Rimm et al, 1993; standardized by lipid concentration can reasonably repre- Stampfer et al, 1993; Bellizzi et al, 1994; Kushi et al, sent long-term vitamin E intake and could be used in 1996). It has antioxidant properties, which may prevent epidemiological studies of diet and disease (Gibson, cellular damage (Bieri, 1984; Ames, 1983). It may also 1990; Hunter, 1990). have antiaggregant effects (Gey, 1989) and inhibit carci- Factors such as tobacco and alcohol consumption do nogenesis (Ames, 1983). Knowledge of the determinants of appear to be determinants of plasma a-tocopherol levels in some epidemiologic studies (Buiatti et al, 1996), but not in others (Stryker et al, 1988; Comstock et al, 1988). Previous studies have found a relationship between concentration of Correspondence: Prof LluõÂs Serra-Majem, Institut de Salut PuÂblica de vitamin E in the adipose tissue and plasma concentration of Catalunya, Camput de Bellvitge, Universitat de Barcelona, Ctra. de la Feixa Llarga, s/n. 08907 L'Hospitalet, Spain. a-tocopherol (Kayden et al, 1983; Traber & Kayden, 1987; Received 19 January 1997; revised 12 June 1997; accepted 26 June 1997 Kaardinal et al, 1995). Determinants of the nutritional status of vitamin E P GascoÂn-Vila et al 724 The aim of the present investigation is to study vitamin et al, 1991). We chose this source of food composition data E dietary intake, body mass index (BMI), and alcohol because of its accuracy, speci®city, and comprehensiveness consumption as possible determinants of serum a-toco- in foods and nutrients, and because of the similarities in the pherol concentration in a non-smoking Mediterranean composition and types of food consumed in Catalonia and population. in France (Farran et al, 1994).

Methods Statistical analyses Data analyses were performed using the statistical package Sample STATA 4.0 for Windows (Statistics and Data Analysis, The representativeness of the Catalan population sample Stata Corporation, College Station, Texas). In order to was assured by the sampling process. The sample was account for day-to-day variation in nutrient intake, the strati®ed according to household and randomized into estimated nutrient intakes were corrected for random subgroupings where municipalities constituted the primary within-person error (Beaton et al, 1979). Correction for sampling units, and the individuals within these municipa- random within-person error enabled us to estimate usual lities constituted the ®nal sample units. intake. Usual intake is an estimation of long term intake, The sample distribution according to strati®cation by and long term intake is correlated with nutritional status household was as follows: 46 municipalities with less than biomarker (Willett, 1990). Means, standard deviations and 10000 inhabitants, 28 municipalities with more than 10000 medians were estimated for continuous variables, and and less than 100000 inhabitants, and 8 municipalities frequency distributions were examined for categorical vari- consisting of more than 100000 inhabitants (Serra-Majem ables. et al, 1996). For biochemical assessment a random sub- The residual standard multivariate method was used to sample was obtained from the representative sample of the adjust nutrient intake for total energy intake (Willett & Catalan population aged between 18 and 75 y, previously Stampfer, 1986). This method enabled us to isolate the selected for the Nutritional Survey of the Catalan Popula- effect of total energy intake on the dependent variable. It tion (1992±93) carried out by the Department of Health and overcomes the added variation of nutrient intake related to Social Security of the Government of Catalonia and the total energy intake, but unrelated to dietary composition University of Barcelona (Serra-Majem et al, 1996). After (Willett, 1990; Willett & Stampfer, 1986). exclusion of smokers, the study sample was 143 subjects: Energy-adjusted vitamin E intake, energy-adjusted alco- 45.4% men, 54.6% women. hol consumption and BMI were categorized in tertiles. Serum a-tocopherol levels and other characteristics of the Dietary assessment method sample were explored by levels of vitamin E intake, alcohol Two 24 h recalls per subject collected in two different consumption and BMI. The Kruskall±Wallis test was used periods (June±July 1992 and November±December 1992) to assess mean differences between categories. Crude were used to estimate nutrient intake. Thirty-six previously associations between serum alpha-tocopherol concentration trained dieticians using standard protocol obtained the and the independent covariates were explored by correla- information in the participants homes. Each subject was tion and linear regression coef®cients. Multivariate linear visited by the same dietician in the two interviews. regression was the method applied to estimate the determi- Response rate in the ®rst and second interview were nants of serum a-tocopherol concentration. The indepen- respectively 68.9% and 61.9% of the initial sample. House- dent variables considered for the analyses were: gender, hold measures were used to estimate portion sizes. The age (y), vitamin E intake (mg/d), alcohol consumption (g/ dieticians were in charge of conversion of food portion size d), BMI (Kg/m2) and total energy intake (Kcal/d). The into grams and milliliters, and of food codi®cation. dependent variable was the serum a-tocopherol concentration standardized by serum total lipid concentration. Anthropometric measures Assumptions of linear regression models were tested by Bathroom scales which were calibrated every day were pair-wise scatter plots, quantile-normal plots of the resi- used to estimate subjects weights their heights were deter- duals, residuals versus predicted plots and partial leverage mined using non-extensible wall measures. plots. Log transformation of the dependent variable was Laboratory analyses necessary in order to ful®l the assumption of homoscedas- Blood samples were obtained in standardized conditions by ticity of the residuals. Once the ®nal model was ®tted, vacuum extraction from 12 h fasted individuals. Blood was in¯uential analysis was performed by examination of high centrifuged at 3000 rpm and 8C for 15 min, and serum leverage, DFITS, DEBeta data points and Cook's distance. was frozen at 7 80C in the health centers of extraction. Serum a-tocopherol was measured by high performance Results liquid chromatography (HPLC) with a UV detector (280 nm). The mobile phase was methanol: water (95:5), Serum concentration of a-tocopherol and characteristics of 2 mL/min. (Lehman & Martin, 1982). the sample by tertiles of vitamin E intake are shown in The range of coef®cients of variation (CV) was 5±5.5% Table 1. No statistical differences were found between in the sample replicated analysis. categories of vitamin E intake for any of the studied In order to avoid misclassi®cation of vitamin E nutri- variables from unadjusted analyses. tional status, the plasma a-tocopherol concentration was Mean energy intake was 7.9 kJ (1905 kcal), median was adjusted by serum lipid concentration (total cholesterol and 7.6 kJ (1818 kcal), 25th percentile was 6.8 kJ (1639 kcal) triglycerides) (Willett et al, 1983a). and 75th percentile was 8.6 kJ (2062 kcal). Table 2 shows serum concentration of a-tocopherol and characteristics of Food composition table the sample by tertiles of alcohol consumption. The propor- The food composition database used to estimate nutrient tion of men increased with increasing levels of alcohol intake was the ReÂpertoire GeÂneÂral des Aliments (Feinberg consumption. Serum concentration of a-tocopherol and Determinants of the nutritional status of vitamin E P GascoÂn-Vila et al 725 Table 1 Serum a-tocopherol concentration and characteristics of the 143 participants by tertiles of vitamin E intake

Tertiles of vitamin E intake (mg/d)

Low Medium High Pa (4.73±8.24) (8.25±9.28) (9.29±17.89)

Gender (% of males)a 34.8 57.4 44.0 0.2 Mean s.d. Mean s.d. Mean s.d.

Age (y) 44.3 12.8 46.9 19.9 48.5 15.3 0.5 Body Mass Index (BMI) 26.4 4.7 25.3 3.2 25.7 3.6 0.6 Energy-adjusted vitamin 9.9 8.0 9.5 13.0 11.1 9.6 0.2 E intake (mg/d) Standardized serum a-tocopherol (mmol/L)a 32.4 8.1 31.4 5.8 32.1 8.2 0.7 aP Kruskall±Wallis test.

Table 2 Serum a-tocopherol concentration and characteristics of the 143 participants by tertiles of alcohol consumption

Tertiles of alcohol consumption (g/d)

Low Medium High Pa (0.00±3.83) (3.84±10.20) (10.21±81.37)

Gender (% of males)a 29.2 34.0 72.9 0.0003 Mean s.d. Mean s.d. Mean s.d.

Age (y) 43.0 17.7 48.4 15.1 48.5 15.6 0.2 Body Mass Index (BMI) 25.4 4.2 25.9 4.3 26.0 3.0 0.002 Energy-adjusted vitamin 9.0 1.8 9.1 2.3 8.6 1.7 0.8 E intake (mg/d) Standardized serum a-tocopherol (mmol/L)a 30.3 7.7 30.9 8.2 30.6 5.3 0.3 aP Kruskall±Wallis test.

Table 3 Serum a-tocopherol concentration and characteristics of the 143 participants by tertiles of Body Mass Index (BMI)

Tertiles of Body Mass Index (BMI)

Low Medium High Pa (18.3±24.0) (24.1±26.8) (26.9±40.2)

Gender (% of males) 32.6 58.3 44.9 0.1 Mean s.d. Mean s.d. Mean s.d.

Age (y) 36.2 13.7 49.9 15.7 53.2 14.2 0.0001 Energy-adjusted alcohol consumption (g/d)a 7.0 7.0 11.9 9.9 11.5 12.7 0.009 Energy-adjusted vitamin 9.1 2.0 9.0 1.9 8.6 1.9 0.5 E intake (mg/d) Standardized serum a-tocopherol (mmol/L)a 30.1 5.7 32.2 5.9 33.4 9.3 0.1 aP Kruskall±Wallis test. characteristics of the sample by tertiles of BMI are shown residuals. However, for better interpretation of the estima- in Table 3. Age increased with increasing tertiles of BMI tors of the b-parameters, we used the untransformed regres- (P < 0.05). Alcohol consumption was higher in the second sion coef®cients, which are unbiased despite and third tertile of BMI than in the ®rst tertile group heteroscedasticity (Hamilton, 1992). The regression coef®- (P < 0.05). The Pearson correlation coef®cient between the logarithm of vitamin E intake and the logarithm of Table 4 Pearson correlation coef®cient between the logarithm of serum serum a-tocopherol was 0.15, between the logarithm of a-tocopherol (micromol/L) and the logarithm of the independent variables BMI and the logarithm of serum a-tocopherol it was 0.17, considered for the analyses: vitamin E intake (mg/d), alcohol consumption and for the logarithm of alcohol consumption and the (g/day), BMI (Kg/m2), total energy intake (kcal/d), age (y) and gender. logarithm of serum a-tocopherol it was 0.14 (Table 4). In Signi®cance level (P) multivariate analyses, vitamin E intake was signi®cantly Serum a-tocopherol associated with serum a-tocopherol concentration, after adjusting for age, gender, BMI, alcohol consumption and Pearson correlation coef®cient P energy intake. Vitamin E intake 0.15 0.03 BMI also in¯uenced serum a-tocopherol concentration, BMI 0.17 0.04 whereas no association was observed between alcohol Alcohol consumption 0.14 0.01 intake and serum a-tocopherol (Table 5). In our ®nal Age 0.16 0.06 linear regression model, we used the logarithm of serum Energy intake 0.02 0.5 Gender 7 0.07 0.42 a-tocopherol in order to have homoscedasticity of the Determinants of the nutritional status of vitamin E P GascoÂn-Vila et al 726 Table 5 Predictors of serum a-tocopherol concentrationa in multivariate 1983b; Ascherio et al, 1992). The lower associations analyses b-coef®cient, standard error, con®dence interval and signi®cance between intake of vitamin E and serum a-tocopherol level found in our study could be due to the fact that less than Independent b-coef®cient (s.e.) 95% CI for b P 10% of our study population took vitamin E supplements variable (Serra-Majem et al, 1996). In this study, vitamin E supple- ment intake was taken into account in the estimation of Energy intake 0.0002 (0.0001) (0.00002, 0.0003) 0.03 Alcohol 0.002 (0.002) ( 0.0020, 0.0003) 0.40 total vitamin E intake. A further reduction in the observed consumption association could be caused by differences in the dietary Age 0.003 (0.001) ( 0.0002, 0.0056) 0.07 assessment method used to estimate intake. We used a Sex 0.094 (0.055) ( 0.0140, 0.2029) 0.09 replicated 24 h recall method and the other studies used BMI 0.010 (0.005) (0.0003, 0.0197) 0.04 Vitamin E intake 0.018 (0.009) (0.0001, 0.0351) 0.049 food frequency questionnaires (FFQ). The 24 h recall Intercept 2.387 (0.3169) (1.7600, 3.0140) < 0.001 method provides high answer rates, it can be used in low literacy population groups, its reproductibility is high, and R2 0.1056. its cost is relatively low (Block, 1982). However, the high Adjusted R2 0.0655. aSerum a-tocopherol concentration was transformed to the logarithm day-to-day ¯uctuation of individual nutrient intake (Bal- logh et al, 1971; Beaton et al, 1979) in the diet assessment when using daily methods may lead to misclassi®cation of cients for vitamin E intake, BMI and energy intake in the the subject's long term dietary intake (Witschi, 1990). untransformed model were 0.66, 0.34 and 0.004 respec- In order to account for seasonal variation of dietary tively. intake, we collected the data during two different periods: winter and summer. To avoid attenuation of the true associations we further adjusted for within-person varia- Discussion bility (Beaton, 1979). We found that for each one unit In this cross-sectional study we found that intake of vitamin increase in BMI, serum a-tocopherol increased by E was positively associated with serum a-tocopherol con- 0.34 micromol/l, after adjusting for gender, age, vitamin centration. For each one mg increase in vitamin E intake, E intake, alcohol intake and energy intake. The adipose serum a-tocopherol concentration increased, on average, tissue is the most important pool of a-tocopherol in the 0.66 micromol/L, after adjusting for age, gender, BMI, human body (Bieri, 1972; Hunter, 1990), and Quetelet's alcohol consumption and energy intake. Index (weight/height2) is a good estimator of adiposity in We used serum a-tocopherol concentration as an indi- epidemiologic studies (Criqui et al, 1982; Willett, 1990). cator of vitamin E nutritional status. a-tocopherol is the However, the bioavailability of vitamin E in the adipose most abundant and biologically active form of vitamin E tissue is not well known, nor are the mechanisms which (Tietz, 1986). Serum and plasma a-tocopherol are the most regulate the release of alpha-tocopherol from the adipocyte frequently used biomarkers of vitamin E nutritional status into the plasma (Farrel and Bieri, 1975). Adipose tissue because they are technically easiest to obtain and process, concentration of vitamin E in well-nourished populations and because they are more suitable for large population increases with intake of supplements of vitamin E (Bieri, studies (Gibson, 1990). 1972). Our study population had vitamin E intakes above Concentration of plasma a-tocopherol varies according the recommended dietary allowances (Gutteridge & Hali- to method of analysis and serum lipid concentration well, 1994). The Pearson correlation coef®cient between (Gibson, 1990). High performance liquid chromatography the logarithm of the BMI and the logarithm of the serum a- (HPLC) is the method of choice to analyze serum vitamin E tocopherol concentration was 0.17 (Table 4). concentration (Behrens et al, 1986). This method is rela- Some authors have observed a correlation coef®cient tively simple, and rapid, it requires only small volumes of between a-tocopherol concentration in adipose tissue and serum/plasma, and it allows different tocopherols to be plasma a-tocopherol levels of 0.34 (Kaardinal et al, 1995). differentiated (Bieri, 1984; Bieri et al, 1985; Behrens et al, Lifestyle factors other than diet could modify the nutri- 1986). tional status of vitamin E (Stryker et al, 1988). For The very strong correlation between vitamin E plasma example, oxidative stress by alcohol consumption could concentration and serum lipid concentration is due to the reduce serum concentration of a-tocopherol (Knutse et al, fact that a-tocopherol is transported in blood as part of a 1993). Alcohol consumption could induce lipid peroxida- lipoprotein complex (Gibson, 1990). Plasma a-tocopherol tion (Clot et al, 1994). Intake of vitamin E has an important concentration standardized by total lipids is established as a role in counteracting the oxidative stress caused by alcohol biochemical marker of the nutritional status of vitamin E consumption (Nordmann, 1994). (Willett et al, 1983a). However, as in previous studies (Stryker et al, 1988; The regression coef®cient for the logarithm of vitamin E Comstock et al, 1988), we did not ®nd an association intake in the multivariate model was 0.018 (Table 5), which between alcohol intake and serum a-tocopherol concentra- was lower than that observed in previous studies (Willett et tion in the linear regression model. Low intakes of alcohol al, 1983b; Ascherio et al, 1992). have not been related to depletion of antioxidant vitamins In our study the Pearson correlation coef®cient between in the human body (Clot et al, 1994), but plasma concen- the logarithm of energy-adjusted vitamin E intake and the tration of a-tocopherol is lower in alcoholics than in people logarithm of the standardized serum a-tocopherol was 0.15 with low intakes of alcohol (Lecomte et al, 1994). Epide- (Table 4). Previous studies have observed correlations from miological and experimental studies have shown that the 0.12±0.65 (Willett et al, 1983a; Willett et al, 1983b; oxidative stress by alcohol consumption depends on the Stryker et al, 1988; Knekt et al, 1988; Ascherio et al, amount and frequency of ethanol intake (Lecomte et al, 1992). 1994; Clot et al, 1994; Azzalis et al, 1995). In our study; In these studies the highest associations were found in alcohol intake was low compared to other regions in Spain individuals who took vitamin E supplements (Willett et al, (Aranceta et al, 1990). Concentration of serum tocopherol Determinants of the nutritional status of vitamin E P GascoÂn-Vila et al 727 varies according to age (Gibson, 1990; Serra-Majem et al, Windgard DL (1982): Adjustment for obesity in studies of cardiovas- 1996). The crude association between age and serum cular disease. Am. J. Epidemiol. 116, 685±691. Diplock AT (1991): Antioxidant nutrients and disease prevention: an vitamin E may be largely due to its association with overview. Am. J. Clin. Nutr. 53, 189S, 193S. plasma lipids. In this study, the effect of age as a predictor Farran A, Boatella J, Serra-Majem L, Ribas L, Rafecas M & Codony R of serum a-tocopherol disappeared after standardization of (1994): Criterios generales de elaboracioÂn y utilizacioÂn de tablas y serum a-tocopherol by serum cholesterol and triglyceride sistemas de datos de composicioÂn de alimentos. Rev. de San. e Hig. concentrations. Pub. 68, 427±441. Farrell PM & Bieri JG (1975): Megavitamin E supplementation in man. Am. J. Clin. Nutr. 28, 1381±1386. Feinberg M, Favier JC & Ireland Riper J (1991): ReÂpertoire GeÂneÂral Des Conclusion Aliments. Ciqual-Lavoisier, Paris, ®rst edition. Gey KF (1989): Inverse correlation of vitamin E and ischemic heart Serum a-tocopherol concentration, used as an indicator of disease. Int. J. Vit. Nutr. Res. 30 (suppl), 224±231. the nutritional status of vitamin E, seems to be determined Gibson RS (1990): Assessment of the status of vitamins A, D, and E. by vitamin E intake and BMI in this non-smoking popula- In: Principles of Nutritional Assessment, (1st edn), ed. RS Gibson, pp tion group. 377±412. Oxford University Press, New York. Grant A & DeHoog S (1985): Nutritional Assessment and Support (3rd edn). Grant-Dehoog: Seattle. AcknowledgementsÐThe authors wish to acknowledge Dr. Francesc Gutteridge MC & Haliwell B (1994): Antioxidants in Nutrition, Health and MaciaÁ for their helpful assistance in the laboratory analysis of vitamin E Disease (1st edn), p 67. Oxford University Press: London. and to Miss Marta Olmos, Mr. Jordi EspunÄas and Mrs. Neus GalõÂ for their Hamilton LC (1992): Regression with Graphics (1st edn). Belmont Dux- assistance in the ®eld work of the biochemical analysis. This study was bury Press: California. supported by a research agreement between the Department of Health of Hunter D (1990): Biochemical indicators of dietary intake. In Nutritional the Autonomous Government of Catalonia and the Bosch Gimpera Epidemiology (1st edn). ed. WC Willett, pp 143±216. Oxford: Oxford Foundation of the University of Barcelona (contract 2415/95). Pablo University Press. Kardinaal AF, Van Veer P, Brants HA, Van den Berg H, Schoonhoven J & GascoÂn Vila received a fellowship for Research Personel Training from Hermus RJ (1995): Relations between antioxidant vitamins in adipose the Spanish Ministry of Education and Culture Ministry. tissue, plasma, and diet. An. J. Epidemiol. 141 (5), 440±450. Kayden HJ, Hatam LJ & Traber MG (1983): The measurement of nanograms of tocopherol from needle aspiration biopsies of adipose References tissue: normal and abetalipoproteinemic subjects. J. Lipid Res. 24, 652± 656. Ames BN (1983): Dietary carcinogens and anticarcinogens. Oxygen Knetk P, Maatela J, Aaran RK, Nikkari T, Hakama M, Hakulinen T, Peto radicals and degenerative diseases. Science 221, 1256±1264. R, Saxen E & Teppo L (1988): Serum vitamin E and risk of cancer Aranceta J, PeÂrez C & Eguileor Y (1990): Encuesta Nutricional del Pais among Finnish men during a 10-year follow-up. Am. J. Epidemiol. 127, Vasco. Vitoria: Gobierno Vasco. 28±41. Ascherio A, Stampfer MJ, Colditz GA, Rimm EB, Litin L & Willett WC Knutse SF, Ringstad J, Nilssen OR & Thomassen Y (1993): A Com- (1992): Correlations of vitamin A and E intakes with the plasma parative study of serum selenium and vitamin E levels in a population concentrations of carotenoids and tocopherols among American men of male risk drinkers and abstainers. Biol. Trace Elem. Res. 36 (1), 65± and women. J. Nutr. 122, 1792±1801. 71. Ashwell M (1993): Diet and Heart Disease (1st edn). A Round Table of Kushi LH, Folsom AR, Prineas RJ, Mink PJ, Wu Y & Bostick RM factors. British Nutrition Foundation: London. (1996): Dietary antioxidant vitamins and death from coronary Azzalis LA, Junqueira VB, Simon K, Giavarotti L,Silva MA, Kogake M, heart disease in postmenopausal women. N. Engl. J. Med. 334, 1156± Simizu K, Barros SB, Fraga C & Porta EA (1995): Prooxidant and 1162. antioxidant hepatic factors in rats chronically fed in ethanol regimen Lecomte E, Herberth B, Pirrollet P, Chancerelle Y, Aruand J, Musse N, treated with an acute dose of lindane. Free Rad. Biol. Med. 19(2), 147± Paille F, Siest G & Artur Y (1994): Effect of alcohol consumption on 159. blood antioxidant nutrients and oxidative stress indicators. Am. J. Clin. Balogh M, Kahn HA & Medalie JH (1971): Random repeated 24-hour Nutr. 60 (2), 255±261. dietary recalls. Am. J. Clin. Nutr. 24, 304±310. Lehman J & Martin HL (1982): Improved direct determination of alpha- Beaton GH, Milner J, Corey P, McGuire V, Cousins M, Stewart E, de and gamma-tochopherols in plasma and platelets by liquid chromato- Ramos M, Hewitt D, Gransbsch PV, Kassim N & Little JA (1979): graphy, with ¯uorescence detection. Clin. Chem. 28, 1784±1787. Sources in variance in 24-hour dietary recall data: implications for Nordmann R (1994): Alcohol and antioxidant systems. Alcohol-alcohol. nutrition study design and interpretation. Am. J. Clin. Nutr. 32, 2546± 29 (5), 513±522. 2259. Rimm EB, Stampfer MJ, Ascherio A, Giovannucci E, Colditz GA & Behrens WA, Thompson JN & Medere R (1986): Alpha- and Gamma- Willett W (1993): Vitamin E consumption and the risk of coronary heart Tocopherol concentrations in human serum. J. Am. Coll. Nutr. 5, 91±96. disease in men. N. Engl. J. Med. 328, 1450±1456. Bellizzi MC, Franklin MF, Duthie GG & James WPT (1994): Vitamin E Serra-Majem L, Ribas L, Garcia-Closas R, Ramon J, Salvador G, Farran and coronary heart disease: the European paradox. Eur. J. Clin. Nutr. A, Serra J, Sabater G, Jover L, GascoÂn P, Tresserras R, SaltoÂ E, ChacoÂn 48, 822±831. P, Pastor MC, Pvchal A, Lloveras G, Taberner JL & Salleras L (1996): Bieri JG (1972): Kinetics of tissue of alpha-tocopherol depletion and AvaluacioÂ de l'Estat Nutricional de la PoblacioÂ Catalana (1992±93). repletion. Ann. N. Y. Acad. Sci. 203, 181±191. Department de Sanitat i Seguretat Social. Generalitat de Catalynya: Bieri JG (1984): Vitamin E.: In Present Knowledge in Nutrition (5th edn), Barcelona. pp 226±240. The Nutrition Foundation Inc: Washington. Stahelin HB, Gey KF, Eichholzer M, Ludin E, Bernasconi F, Thurneysen J Bieri JG, Tolliver TJ & Catignani GL (1985): Simultaneous determination & Brubacher G (1991): Plasma antioxidant vitamins and subsequent of alpha-tocopherol and retinol in plasma or red cells by high pressure cancer mortality in the 12-year follow-up of the Prospective Basel liquid chromatography. J. Liq. Chrom. 8, 473±484. Study. Am. J.Epidemiol. 133 (8), 766±775. Block GH (1982): A review of validations of dietary assessment methods. Stampfer MJ, Hennekens CH, Manson JE, Colditz GA, Rosner B & Willett Am. J. Epidemiol. 115, 492±505. WC (1993): Vitamin E consumption and the risk of coronary heart Buiatti E, MunÄoz N, Kato I, Vivas J, Muggli R, Clummer M, Benz M, disease in women. N. Engl. J. Med. 328, 1444±1449. Fraceschi S & Oliver W (1996): Determinants of plasma anti-oxidant Stryker S, Kaplan L,Stein A, Stampfer MJ, Sober W & Willett WC (1988): vitamin levels in a population at high risk for stomach cancer. Int. J. The relation of diet, cigarette smoking, and alcohol consumption to Cancer 65(3), 317±322. plasma beta-carotene and alpha-tocopherol levels. Am. J. Epidemiol. Clot P, Tabone M, Arico S & Albano E (1994): Monitoring oxidative 127, 283±296. damage in patients with liver cirrhosis and different daily alcohol Tietz NW (1986): Textbook of Clinical Chemistry. (1st edn) W.B. intake. Gut 35(11), 1637±1643. Saunders Company: Philadelphia. Comstock GW, Menkes MS, Schober SE, Vuilleumier JP & Helsing KJ Traber MG & Kayden HJ (1987): Tocopherol distribution and intra- (1988): Serum levels of retinol, beta-carotene, and alpha-tocopherol in cellular localization in human adipose tissue. Am. J. Clin. Nutr. 46, older adults. Am. J. Epidemiol. 127, 114±123. 488±495. Criqui M, Klauber H, Barret-Connor E, Holdbrook MJ, SuaÂrez L & Willett WC, Stampfer MJ, Underwood BA, Taylor J & Hennekens CH Determinants of the nutritional status of vitamin E P GascoÂn-Vila et al 728 (1983a): Vitamins A, E, and Carotene: effects of supplementation on Willett WC & Stampfer MJ (1986): Total energy intake: Implications for their plasma levels. Am. J. Clin. Nutr. 38, 559±566. epidemiologic analyses. Am. J. Epidemiol. 124, 17±27. Willett WC, Stampfer MJ, Underwood BA, Hennekens CH, Speizer FE & Willett WC (1990): Anthropometric measures and body composition. In: Rosner B (1983b): Validation of dietary questionnaire with plasma Nutritional Epidemiology (1st edn), ed. WC Willett, pp 143±216, 217± carotenoid and alpha-tochopherol levels. Am. J. Clin. Nutr. 38, 631± 244. Oxford University Press: Oxford. 639. Witschi JC (1990): Short-term dietary recall and recording methods. In: Willett WC (1986): Selenium, vitamin E, ®ber and the incidence of human Nutritional Epidemiology (1st edn) ed. WC Willett, pp 52±68. Oxford cancer: an epidemiological perspective. Avance. Experim. Med. Biol. University Press: Oxford. 206, 27±34.