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-Tocopherol Intake and Plasma Concentration of Hispanic and Non-Hispanic White Elders Is Associated with Dietary Intake Pattern1
2 The Jean Mayer U.S. Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, Boston, MA and 3 Center for Organization, Leadership, and Management Research, Boston VA Healthcare System, Boston, MA
* To whom correspondence should be addressed. E-mail: katherine.tucker{at}tufts.edu.
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ABSTRACT |
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 TOP ABSTRACT IntroductionSubjects and MethodsResultsDiscussionLITERATURE CITED |
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-Tocopherol from foods has been associated with protection against several chronic diseases and maintenance of immune function. However, most people do not meet current recommendations for intake. We examined -tocopherol intake and plasma concentration in a representative sample of Puerto Rican and Dominican older adults (n = 447) and in neighborhood-matched non-Hispanic whites (n = 155). A validated food frequency questionnaire was used to assess dietary intake. Mean dietary intakes of -tocopherol were 6 mg in both ethnicities. Only 4.7% of women and 7.9% of men met the estimated average requirement (12 mg/d) for vitamin E from food alone. Top sources of -tocopherol for Hispanics included oils and milk, and for non-Hispanic whites they were ready-to-eat breakfast cereal and sweet baked products. Mean plasma -tocopherol concentrations were 24.5 µmol/L for Hispanics and 25.8 µmol/L for non-Hispanic whites (P > 0.05). Plasma -tocopherol was positively associated with -tocopherol intake (P = 0.003), and significance remained after adjusting covariates and after exclusion of supplement users (P for trend = 0.008). We identified the following 5 dietary patterns by cluster analysis: 1) fruit and breakfast cereal, 2) starchy vegetables, 3) rice, 4) milk and milk products, and 5) sweets. Those following the sweets pattern had the lowest plasma -tocopherol relative to those following the fruit and breakfast cereal or milk patterns (P < 0.05 for all), although they had similar intakes. A large proportion of these elders (>90%) have inadequate intake of -tocopherol, and plasma concentrations were associated with intake patterns.
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Introduction |
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TOPABSTRACTIntroductionSubjects and MethodsResultsDiscussionLITERATURE CITED |
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19 y of 12 mg/d of -tocopherol, and a recommended dietary allowance of 15 mg/d (16). The new recommendations are based only on the -tocopherol form of vitamin E, whereas earlier recommendations included 8 naturally occurring forms of the vitamin. Furthermore, the new recommended intakes of -tocopherol are >50% greater than earlier recommendations.
Our previous studies showed that inadequate -tocopherol intake was highly prevalent in the U.S. population, with only 8–11% of men and 2–8% of women meeting the new EAR for vitamin E from foods alone in the 1994–1996 Continuing Survey of Food Intakes by Individuals (CSFII) (17) and the 2001–2002 NHANES (18). However, there is little information about -tocopherol intake and concentrations in ethnic subgroups, who may have different dietary patterns from the general population. In this study, we examined the dietary intakes and plasma concentrations of -tocopherol in a representative sample of elderly Puerto Ricans and Dominicans living in Massachusetts, along with neighborhood-matched non-Hispanic whites. We compared these intakes with the new EAR, identified major contributors to -tocopherol, and examined the relations among overall dietary patterns, intake, and plasma concentration.
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Subjects and Methods |
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TOPABSTRACTIntroductionSubjects and MethodsResultsDiscussionLITERATURE CITED |
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60 y and 251 neighborhood matched non-Hispanic whites. The Institutional Review Board of Tufts-New England Medical Center, approved the protocol, and subjects gave informed consent before participating.
The current study included 447 Hispanics of Caribbean origin (344 Puerto Ricans and 103 Dominicans), and 155 non-Hispanic whites with plasma and dietary intake data. The remaining Hispanics were not included here, as those participants were from diverse countries with different dietary patterns. There were no significant differences in age, education, energy intake, -tocopherol intake, or -tocopherol plasma concentration between Puerto Ricans and Dominicans, and we combined these 2 groups in our analyses.
Field data collection.
Dietary intakes were assessed with a validated 118-item FFQ, which was specially designed for this population (21). Nutrient profiles were calculated with the Nutrient Data System, version 4.06 (NDS, University of Minnesota). Energy intakes <2.51 MJ/d (600 kcal/d) or >16.74 MJ/d (4,000 kcal/d), or questionnaires with 12 food items blank (n = 46) were considered invalid and excluded from further analysis. We obtained vitamin supplement use information (type, frequency, and dosage) by observing supplement packaging in participants' homes. Supplement intake data were then entered into NDS and added to the dietary intake data to estimate total intake.
Body weight was measured with a balance scale (SECA) with a capacity of 150 kg. Height was measured with a Harpenden pocket stadiometer (Holtain). BMI was calculated as weight (kg) / height (m)2. Duplicate blood pressure measurements were taken by trained field workers. Hypertension was defined as systolic blood pressure 140 mm Hg and/or diastolic blood pressure 90 mm Hg. Subjects were identified as having type 2 diabetes when fasting plasma glucose was >7.0 mmol/L, a random plasma glucose was >11.1 mmol/L, or they reported use of medications for diabetes (insulin or oral medicines) (22). Information on age (y), smoking status (current, former, and never), and current alcohol intake was collected by questionnaire. Alcohol intakes were classified as heavy (>1 drink/d for women and >2 drinks/d for men), moderate (0.1–1 drink/d for women and 0.1–2 drinks/d for men), and nondrinker, based on 13.2 g alcohol/drink.
Fasting blood samples were drawn into tubes containing 0.15% EDTA and centrifuged at 2500 x g for 20 min at 4° to separate plasma. Plasma total cholesterol was measured by enzymatic methods with an automated analyzer (CCX analyzer; Abbott Diagnostics Spectrum) and Abbott enzymatic reagents (23). Plasma -tocopherol concentration was measured by reverse-phase HPLC. Details of the method have been described elsewhere (24,25). Reproducibility and accuracy of the procedures were tested by analyzing representative samples in triplicate from a sample provided by the American Association for Laboratory Accreditation, Washington, DC that contained a known concentration of -tocopherol. Intra- and interbatch CV were 3 and 4.2%, respectively. Plasma -tocopherol concentrations 16 µmol/L [688 µg/dL (0.016 mol/L)] were considered normal (16).
Statistical analysis.
All statistical analyses were completed with SAS 8.1 (SAS Institute). We used the general linear models procedure to compare mean differences across categories, with Duncan's adjustment for multiple comparisons. We used multiple logistic regression to test differences in proportions across categories and to calculate odds ratios (ORs) and 95% CIs. Logarithmic transformations were performed for plasma -tocopherol concentrations to normalize the distribution of data. Foods were ranked, based on the percentage of contribution to -tocopherol intake, separately by ethnic group. The PROC RANK procedure was used to collapse the subjects to 3 groups by their -tocopherol intake tertile. Five dietary patterns were identified previously by cluster analysis, with proportionately greater energy intake from the following: 1) fruit and breakfast cereal, 2) starchy vegetables, 3) rice, 4) whole milk, and 5) sweets (26). We examined the -tocopherol intake, plasma concentration, and prevalence of low plasma -tocopherol across these 5 dietary pattern groups. The sweets pattern was used as reference, because subjects in this pattern had the lowest -tocopherol intake and plasma concentration, relative to other patterns. All regressions were adjusted for age, ethnicity, sex, education, total energy intake, BMI, diabetes, hypertension, smoking, and current alcohol use. We also adjusted -tocopherol concentration for plasma cholesterol.
We found differences (P < 0.05) in total -tocopherol intake and plasma concentration and observed differing relations between intake and plasma concentration in -tocopherol supplement users and nonusers. Ethnicity interacted with supplement use in relation to total -tocopherol intake (P < 0.05). Total -tocopherol intake in non-Hispanic white supplement users was higher than in Hispanic elders. We, therefore, report -tocopherol intake and plasma concentration is stratified by ethnicity and supplement use.
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Results |
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TOPABSTRACTIntroductionSubjects and MethodsResultsDiscussionLITERATURE CITED |
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-tocopherol for Hispanics included oils and salad dressing, milk and milk products, noncitrus fruits, beans/legumes, fish, tomatoes and tomato products, and poultry (Table 2). In contrast, top sources for non-Hispanic white elders included ready-to-eat breakfast cereal, sweet baked products, oils and salad dressing, noncitrus fruits, margarine, and dark green leafy vegetables.
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-tocopherol intake (i.e., -tocopherol from food alone) did not differ significantly between Hispanics and non-Hispanic whites (Table 3). Ninety-four percent of Hispanics and 95% non-Hispanic whites did not meet the EAR (12 mg/d) from diet only. When supplement intake was included, 81 and 65% Hispanics and non-Hispanic whites did not meet the EAR, respectively. Non-Hispanic whites had higher total -tocopherol intake than Hispanics (9.9 vs. 7.5 mg/d, P = 0.008), due to differences in supplement use. However plasma -tocopherol concentrations did not differ significantly between Hispanics and non-Hispanic whites (P = 0.29). When we excluded supplement users, Hispanic elders had greater -tocopherol intakes relative to non-Hispanics (5.8 vs. 5.4 mg/d, P = 0.039).
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-tocopherol intake was positively associated with greater plasma -tocopherol concentration (P for trend = 0.003) (Fig. 1). When we excluded supplement users, the relation between -tocopherol intake and plasma concentration remained significant (P for trend = 0.008). Among nonsupplement users, subjects in the highest and middle intake tertiles were 77 (OR: 0.23, 95% CI: 0.1–0.9) and 61% (OR: 0.39, 95% CI: 0.1–1.1) less likely to have plasma -tocopherol <16 µmol/L, relative to those in the lowest tertile, respectively.
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-tocopherol intakes that did not differ from those of subjects in the sweets dietary pattern group, but they had higher plasma -tocopherol concentrations (P < 0.01) (Table 4). Excluding supplement users, we observed similar difference of plasma -tocopherol concentrations between the fruit and cereals or whole milk pattern groups, and the sweets pattern group (P < 0.05 for both). Subjects in the rice group had the highest -tocopherol intake among all pattern groups, and this was greater than those in the sweets pattern group (P < 0.05). This group's mean plasma -tocopherol concentration was also higher than that of the sweets pattern in the full group (P = 0.02), but it was not significant among nonsupplement users. Only the starchy vegetables pattern group had greater dietary intake (P < 0.05) but similar plasma concentrations, relative to those in the sweets pattern group.
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-tocopherol <16 µmol/L were 4.4, 13.3, 9, 11.4, and 18.1% among the fruit and breakfast cereal, starchy vegetables, rice, milk and milk products, and sweets dietary pattern groups, respectively (Fig. 2). For nonsupplement users, prevalences of plasma -tocopherol <16 µmol/L were 5.6% among the fruit and cereal pattern, relative to >9% among other patterns. Prevalences differed between the fruit and breakfast cereal and sweets pattern groups (P = 0.019 for all subjects and P = 0.045 for nonsupplement users).
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Discussion |
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TOPABSTRACTIntroductionSubjects and MethodsResultsDiscussionLITERATURE CITED |
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-tocopherol concentrations <16 µmol/L.
These findings are consistent with our previous study, where only 8.0% of men and 2.4% of women met the new EAR for vitamin E from foods alone in the 1994–1996 CSFII (17). Similarly, a study from the 1999–2000 NHANES reported adequate intakes of 10 and 4% for men and women, respectively (27). Intake of -tocopherol below 12 mg/d has been shown to relate to risk of hydrogen peroxide–induced hemolysis (16), and there is evidence of association with several major chronic diseases, including Alzheimer's disease, diabetes, and cardiovascular disease (1,5,15).
Although both ethnic groups had low intakes, Hispanics had different dietary -tocopherol sources from non-Hispanic whites. The major source of vitamin E among Hispanics was oils and salad dressing (added to rice, beans, and other foods), which contributed one-third of total dietary -tocopherol intake. Other important -tocopherol sources included milk and milk products, noncitrus fruit, beans/legumes, and fish. In contrast, these neighborhood-matched non-Hispanic whites obtained most of their -tocopherol from ready-to-eat breakfast cereal (12% of total dietary -tocopherol), followed by oils and salad dressing (7%), and noncitrus fruits (6%). The latter ranking is consistent with sources identified in the 1994–1996 CSFII (17). Dietary sources of -tocopherol were limited among Hispanics. The top 3 sources provided 45% of total dietary -tocopherol, relative to 23% in non-Hispanic whites. It is important to note that nut and seed consumption was low in both groups, with median intakes below 0.1 servings/d, and contributing <1% of total -tocopherol intake. Nuts and seeds are rich sources of -tocopherol and have been shown to be associated with lower risk of heart disease (1,28–31) and diabetes (32). We previously showed that greater nut and seed intakes could increase -tocopherol intake when total energy and fat intake were limited (18,33,34).
We observed a significant relation between -tocopherol intake and plasma concentration in this population. This relation remained significant after removal of supplement users. Several epidemiologic studies have observed a positive relation between dietary vitamin E intake and plasma -tocopherol concentration (35–39). However, some found that the association was driven by supplement use and was weaker among nonsupplement users (35,38,39). A study from the NHANES III did not observe a significant association between dietary intakes of vitamin E and plasma -tocopherol concentrations (40). One possible explanation for the inconsistencies between our findings and those of previous epidemiologic studies is that we measured "usual" dietary intake by food frequency questionnaire, whereas some others relied on limited numbers of 24-h recalls. Further, we assessed dietary -tocopherol directly. In other studies, vitamin E intakes included not only -tocopherol, but also other forms of vitamin E, which may have attenuated the association between -tocopherol intake and plasma concentration.
Plasma vitamin E status appeared to be influenced by dietary pattern. Subjects in the fruit and breakfast cereals pattern group were least likely to have low plasma -tocopherol (<16 µmol/L), although their -tocopherol intake was not the highest among the 5 dietary pattern groups. This may be due to breakfast cereal intake. Leonard et al. reported that the bioavailability of vitamin E from fortified breakfast cereal was 
25-fold that from a supplement (41). Combinations of -tocopherol intake with vitamin C could be another reason because vitamin C can effectively regenerate -tocopherol from the -tocopheroxly radical (42). In a recent randomized trial, vitamin C supplements were shown to decrease plasma -tocopherol disappearance rates in smokers (43). Another possible interpretation is that high fruit and vegetable intakes may lower plasma oxidative stress or inflammatory biomarkers (44–47), which could be associated with increased loss of vitamin E in plasma (43,48). In a group of elderly community-dwelling healthy subjects, Anlasik et al. observed that subjects with greater intakes of fruit and vegetables had higher plasma -tocopherol concentrations than those with low fruit and vegetable intakes (49).
Subjects in the milk and milk products dietary pattern group also had relatively high plasma -tocopherol concentrations, despite their lower dietary intakes. These findings are consistent with a study by Hayes et al. (50). They found that vitamin E bioavailability could increase by 100% when it was supplemented via microdispersion in milk, compared with providing the same dose in capsules or orange juice among a sample of healthy adults (n = 48). In another randomized crossover study (n = 8), significantly higher plasma -tocopherol concentrations were observed when subjects consumed whole milk and cereal, relative to cereal with semi-skimmed milk or water (51). Whole milk, rather than low-fat or skim milk, was most commonly consumed by our group of Hispanic elders. The effects of dietary factors on vitamin E bioavailability have been further reviewed by Lodge et al. (52).
Our study has limitations associated with self-reported dietary data. Because vitamin E is in oil, the estimations of oil use and type are important. These Hispanic subjects added a large amount of oil to foods in a fairly consistent manner, and preferred to use corn oil, which allowed a good estimation of intake. Another potential measurement error is underreporting of energy intake, which can result in underestimation of vitamin E intake. We calculated estimated energy requirements based on averages of sex, age, weight, height and physical activity level of each ethnicity and sex group (53). The estimated energy requirements were 8.5, 6.7, 9.0, and 6.8 MJ/d for Hispanic men and women and non-Hispanic white men and women, respectively. These are only slightly higher (1–11% for different ethnicity-sex groups) than means of reported energy intake (7.9, 6.7, 8.0, and 6.6 MJ/d, respectively), suggesting that this is not a large problem in this study. Our study is also limited in that we were not able to distinguish between -tocopherol supplements with 2R-stereoisomers and those with all rac--tocopherol. The current EAR for vitamin E is based on 2R-stereoisomers (16). The effect of this, however, would be to underestimate the prevalence of inadequate -tocopherol intake.
In conclusion, most Hispanic elders in Massachusetts, as well as their neighborhood-matched non-Hispanic white counterparts, had -tocopherol intakes below the recommended adequate intake of 12 mg/d. Fewer than 10% had plasma concentrations below 16 µmol/L. These were associated with their dietary intake patterns. Although subjects in the fruit and breakfast cereal or whole milk patterns did not have the highest -tocopherol dietary intake, relatively higher plasma concentrations were seen in these groups, suggesting that the package of nutrients and foods associated with vitamin E are important and could modify vitamin E status.
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FOOTNOTES |
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4 Abbreviations used: CSFII, Continuing Survey of Food Intakes by Individuals; EAR, estimated average requirement; OR, odds ratio.
Manuscript received 6 June 2006. Initial review completed 27 June 2006. Revision accepted 30 June 2006.
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