Validity of a diet history questionnaire estimating β-carotene,vitamin C and α-tocopherol intakes in Japanese pregnant women

Abstract

We investigated the validity and reproducibility of a self-administered diet history questionnaire (DHQ) that estimates the intakes of β-carotene, vitamin C and α-tocopherol. Ninety-five healthy women with singleton pregnancies in the second trimester were examined at a university hospital in Tokyo. The intakes of β-carotene, vitamin C and α-tocopherol assessed by the DHQ were compared to the corresponding serum concentrations. To assess the reproducibility, 58 pregnant women completed it in two sessions within a 4–5 week interval. We found significantly positive correlations between the energy-adjusted intakes and serum concentrations of β-carotene and vitamin C (r?=?0.254 and r?=?0.323, respectively). However, α-tocopherol intake was not associated with the corresponding serum concentration. The intraclass correlation coefficients of the two-time DHQ were 0.743 (β-carotene), 0.665 (vitamin C) and 0.718 (α-tocopherol). DHQ has acceptable validity and reproducibility for β-carotene and vitamin C intakes in Japanese pregnant women.     

Genome-wide association study identifies three common variants associated with serologic response to vitamin E supplementation in men

Vitamin E inhibits lipid peroxidation in cell membranes, prevents oxidative damage to DNA by scavenging free radicals, and reduces carcinogen production. No study to our knowledge, however, has examined the association between genetic variants and response to long-term vitamin E supplementation. We conducted a genome-wide association study (GWAS) of common variants associated with circulating α-tocopherol concentrations following 3 y of controlled supplementation. The study population included 2112 middle-aged, male smokers in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort who received a trial supplementation of α-tocopherol (50 mg/d) and had fasting serum α-tocopherol concentrations measured after 3 y. Serum concentrations were log-transformed for statistical analysis and general linear models adjusted for age, BMI, serum total cholesterol, and cancer case status. Associations with serum response to α-tocopherol supplementation achieved genome-wide significance for 2 single nucleotide polymorphisms (SNP): rs964184 on 11q23.3 (P = 2.6 × 10(-12)) and rs2108622 on 19pter-p13.11 (P = 2.2 × 10(-7)), and approached genome-wide significance for one SNP, rs7834588 on 8q12.3 (P = 6.2 × 10(-7)). Combined, these SNP explain 3.4% of the residual variance in serum α-tocopherol concentrations during controlled vitamin E supplementation. A GWAS has identified 3 genetic variants at different loci that appear associated with serum concentrations after vitamin E supplementation in men. Identifying genetic variants that influence serum nutrient biochemical status (e.g., α-tocopherol) under supplementation conditions improves our understanding of the biological determinants of these nutritional exposures and their associations with cancer etiology.     

Bioaccessibility of Carotenoids and Tocopherols in Marine Microalgae, Nannochloropsis sp. and Chaetoceros sp

Microalgae can produce various natural products such as pigments, enzymes, unique fatty acids and vitamin that benefit humans. The objective of the study is to study the bioaccessibility of carotenoids (β-carotene and lycopene) and vitamin E (α- and β-tocopherol) of Nannochloropsis oculata and Chaetoceros calcitrans. Analyses were carried out for both the powdered forms of N. oculata and C. calcitrans, and the dried extract forms of N. oculata and C. calcitrans. In vitro digestion method together with RP-HPLC was used to determine the bioaccessibility of carotenoids and vitamin E for both forms of microalgae. Powdered form of N. oculata had the highest bioaccessibility of β-carotene (28.0 ± 0.6 g kg-1), followed by dried extract N. oculata (21.5 ± 1.1 g kg-1), dried extract C. calcitrans (16.9 ± 0.1 g kg-1), and powdered C. calcitrans (15.6 ± 0.1 g kg-1). For lycopene, dried extract of N. oculata had the highest bioaccessibility of lycopene (42.6 ± 1.1 g kg-1), followed by dried extract C. calcitrans (41.9 ± 0.6 g kg-1), powdered C. calcitrans (39.7 ± 0.1 g kg-1) and powdered N. oculata (32.6 ± 0.7 g kg-1). Dried extract C. calcitrans had the highest bioaccessibility of α-tocopherol (72.1 ± 1.2 g kg-1). However, β-tocopherol was not detected in both dried extract and powdered form of C. calcitrans. In conclusion, all samples in their dried extract forms were found to have significantly higher bioaccessibilities than their powdered forms. This may be due to the disruption of the food matrix contributing to a higher bioaccessibility of nutrients shown by the dried extract forms.     

The effect of vitamin E on common cold incidence is modified by age, smoking and residential neighborhood

BACKGROUND: We have previously found a 28% reduction in common cold incidence with 50 mg/day vitamin E supplementation in a subgroup of the Alpha-Tocopherol Beta-Carotene Cancer Prevention (ATBC) Study cohort: older city-dwelling men (> or =65 years) who smoked only 5-14 cigarettes/day. OBJECTIVE: To carry out more detailed analyses to explore the modification of vitamin E effect by age, smoking, and residential neighborhood. METHODS: We examined the effect of vitamin E on common cold risk in subjects consisting of the placebo and vitamin E arms (n = 14,573) of the ATBC Study, which recruited males aged 50-69 years who smoked > or =5 cigarettes/day at the baseline. The ATBC Study was conducted in southwestern Finland in 1985-1993; the active follow-up lasted for 4.7 years (mean). We modeled common cold risk as a function of age-at-follow-up in the vitamin E arm compared with the placebo arm using linear splines in Poisson regression. RESULTS: In participants of 72 years or older at follow-up, the effect of vitamin E diverged. Among those smoking 5-14 cigarettes per day at baseline and living in cities, vitamin E reduced common cold risk (RR = 0.54; 95% CI 0.37-0.80), whereas among those smoking more and living away from cities, vitamin E increased common cold risk (RR = 1.58; 1.23-2.01). CONCLUSIONS: Vitamin E may cause beneficial or harmful effects on health depending on various modifying factors. Accordingly, caution should be maintained in public health recommendations on vitamin E supplementation until its effects are better understood.     

Effects of High Fruit-Vegetable and/or Low-Fat Intervention on Plasma Micronutrient Levels

Objectives: Higher plasma micronutrient levels have been associated with decreased cancer risks. The objective of this study was to determine the relative effects of reduced fat and/or increased fruit-vegetable (FV) intakes on plasma micronutrient levels.

Methods: Healthy, premenopausal women with a family history of breast cancer (n = 122) were randomized across four diet arms for one year in a 2 × 2 factorial design study: control, low-fat, high fruit-vegetable and combination low-fat/high FV diets. Levels of plasma micronutrients were measured in plasma at 0, 3, 6 and 12 months.

Results: The high FV intervention, regardless of fat intake, significantly increased α-carotene, β-carotene and vitamin C levels in plasma. Only the combination high FV, low-fat intervention significantly increased plasma β-cryptoxanthin and zeaxanthin levels over time. Although α-tocopherol was not affected, a potential concern is that the low-fat intervention resulted in significantly decreased both γ-tocopherol dietary intakes and plasma levels, regardless of whether or not FV intakes were concomitantly increased.

Conclusions: Unlike α-tocopherol, γ-tocopherol plasma levels were decreased by a low fat diet, perhaps because γ-tocopherol is not generally added to foods nor widely used in vitamin E supplements. The decreased dietary intakes and plasma levels of γ-tocopherol with a low-fat diet may have implications for health risks since the biological functions of the different tocopherol isomers have been reported to be distinct.     

Vitamin E supplementation may transiently increase tuberculosis risk in males who smoke heavily and have high dietary vitamin C intake

Vitamin E and beta-carotene affect the immune function and might influence the predisposition of man to infections. To examine whether vitamin E or beta-carotene supplementation affects tuberculosis risk, we analysed data of the Alpha-Tocopherol Beta-Carotene Cancer Prevention (ATBC)Study, a randomised controlled trial which examined the effects of vitamin E (50 mg/d) and beta-carotene (20 mg/d) on lung cancer. The trial was conducted in the general community in Finland in 1985-93; the intervention lasted for 6.1 years (median). The ATBC Study cohort consists of 29,023 males aged 50-69 years, smoking at baseline, with no tuberculosis diagnosis prior to randomisation. Vitamin E supplementation had no overall effect on the incidence of tuberculosis (risk ratio (RR) = 1.18; 95% CI 0.87, 1.59) nor had beta-carotene (RR = 1.07; 95% CI 0.80, 1.45). Nevertheless, dietary vitamin C intake significantly modified the vitamin E effect. Among participants who obtained 90 mg/d or more of vitamin Cin foods (n 13,502), vitamin E supplementation increased tuberculosis risk by 72 (95% CI 4, 185)%. This effect was restricted to participants who smoked heavily. Finally, in participants not supplemented with vitamin E, dietary vitamin C had a negative association with tuberculosis risk so that the adjusted risk was 60 (95% CI 16, 81)% lower in the highest intake quartile compared with the lowest. Our finding that vitamin E seemed to transiently increase the risk of tuberculosis in those who smoked heavily and had high dietary vitamin C intake should increase caution towards vitamin E supplementation for improving the immune system.     

Higher baseline serum concentrations of vitamin E are associated with lower total and cause-specific mortality in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study

BACKGROUND: A meta-analysis of 19 trials suggested a small increase in the risk of all-cause mortality with high-dose vitamin E supplementation. Little is known, however, about the relation between mortality and circulating concentrations of vitamin E resulting from dietary intake, low-dose supplementation, or both. OBJECTIVE: We examined whether baseline serum alpha-tocopherol concentrations are associated with total and cause-specific mortality. DESIGN: A prospective cohort study of 29 092 Finnish male smokers aged 50-69 y who participated in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study was carried out. Fasting serum alpha-tocopherol was measured at baseline by using HPLC. Only 10% of participants reported vitamin E supplement use at baseline, and thus serum concentrations of vitamin E mainly reflected dietary intake and other host factors. Risks of total and cause-specific mortality were estimated by using proportional hazards models. RESULTS: During up to 19 y of follow-up, 13 380 deaths (including 4518 and 5776 due to cancer and cardiovascular disease, respectively) were identified. Men in the higher quintiles of serum alpha-tocopherol had significantly lower risks of total and cause-specific mortality than did those in the lowest quintile [relative risk (RR) = 0.82 (95% CI: 0.78, 0.86) for total mortality and 0.79 (0.72, 0.86), 0.81 (0.75, 0.88), and 0.70 (0.63, 0.79) for deaths due to cancer, cardiovascular disease, and other causes, respectively; P for trend for all < 0.0001]. Cubic regression spline analysis of continuous serum alpha-tocopherol values indicated greater risk reductions with increasing concentrations up to approximately 13-14 mg/L, after which no further benefit was noted. CONCLUSION: Higher circulating concentrations of alpha-tocopherol within the normal range are associated with significantly lower total and cause-specific mortality in older male smokers.     

Association between serum alpha-tocopherol and serum androgens and estrogens in older men

There is evidence supporting a role for sex hormones in the etiology of prostate cancer. Supplementation with alpha-tocopherol reduced prostate cancer in the alpha-Tocopherol, beta-Carotene Prevention Study (ATBC Study). The objective of this study was to assess the relation of baseline levels of serum alpha-tocopherol and serum sex hormones in older men. A cross-sectional analysis of serum alpha-tocopherol and sex hormone concentrations was conducted within a subset of the ATBC Study. Serum was collected in the morning after an overnight fast at baseline from 204 men ages 50-69 years participating in the ATBC Study and free of prostate cancer. Hormones were measured by radioimmunoassay, and alpha-tocopherol was measured by high-performance liquid chromatography by standard procedures. Multivariate linear regression was used to evaluate the association of serum alpha-tocopherol with nine androgens and estrogens after controlling for age, body mass index, hormone assay batch, and serum cholesterol. Serum alpha-tocopherol was significantly inversely associated with serum androstenedione, testosterone, sex hormone-binding globulin, and estrone. The difference in hormone concentration per milligram of alpha-tocopherol was 1.8-2.6% for these four hormones. These results indicated that alpha-tocopherol is related to concentrations of several sex hormones in older men and may have implications for the observed protective effect of supplemental vitamin E in relation to prostate cancer in the ATBC Study.     

β-Carotene supplementation decreases placental transcription of LDL receptor-related protein 1 in wild-type mice and stimulates placental β-carotene uptake in marginally vitamin A-deficient mice

The human diet contains β-carotene as the most abundant precursor of vitamin A, an essential nutrient for embryogenesis. Our laboratory previously showed the importance of β-carotene metabolism via β-carotene-15,15'-oxygenase (CMOI) to support mouse embryonic development. However, the mechanisms regulating embryonic acquisition and utilization of β-carotene from the maternal circulation via placenta remain unknown. We used wild-type (WT) and Lrat(-/-)Rbp(-/-) (L(-/-)R(-/-)) mice, the latter being a model of marginal vitamin A deficiency. Pregnant dams, fed a nonpurified diet sufficient in vitamin A throughout life, were i.p. supplemented with β-carotene or vehicle at 13.5 d postcoitum (dpc). Effects of this acute maternal supplementation on retinoid and β-carotene metabolism in maternal (serum, liver) and developing tissues (placenta, yolk sac, embryo) were investigated at 14.5 dpc. We showed that, upon supplementation, placental β-carotene concentrations were greater in L(-/-)R(-/-) than in WT mice. However, the retinoid (retinol and retinyl ester) concentrations remained unchanged in placenta (and in all other tissues analyzed) of both genotypes upon β-carotene administration. We also showed that upon a single i.p. β-carotene supplementation, placental LDL receptor-related protein (Lrp1) mRNA expression was lower in WT mice, and embryonic CmoI mRNA expression was greater in L(-/-)R(-/-) mice. Together, these data suggest a potential role of LRP1 in mediating the uptake of β-carotene across the placenta and that even a marginally impaired maternal vitamin A status may influence uptake and utilization of β-carotene by the placenta and the embryo.     

Tissue distribution of vitamin E metabolites in rats after oral administration of tocopherol or tocotrienol

We previously found that 2,7,8-trimethyl-2(2'-carboxyethyl)-6-hydroxychroman (γCEHC), a metabolite of the vitamin E isoforms γ-tocopherol or γ-tocotrienol, accumulated in the rat small intestine. The aim of this study was to evaluate tissue distribution of vitamin E metabolites. A single dose of α-tocopherol, γ-tocopherol or a tocotrienol mixture containing α- and γ-tocotrienol was orally administered to rats. Total amounts of conjugated and unconjugated metabolites in the tissues were measured by HPLC with an electrochemical detector, and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (trolox) was used as an internal standard. Twenty-four hours later, the vitamin E isoforms were detected in most tissues and in the serum. However, 2,5,7,8-tetramethyl-2(2'-carboxyethyl)-6-hydroxychroman (αCEHC), a metabolite of α-tocopherol or α-tocotrienol, and γCEHC accumulated in the serum and in some tissues including the liver, small intestine and kidney. Administration of α-tocopherol increased the γCEHC concentration in the small intestine, suggesting that α-tocopherol enhances γ-tocopherol catabolism. In contrast, ketoconazole, an inhibitor of cytochrome P450 (CYP)-dependent vitamin E catabolism, markedly decreased the γCEHC concentration. These data indicate that vitamin E metabolite accumulates not only in the liver but also in the small intestine and kidney. We conclude that some dietary vitamin E is catabolized to carboxyethyl-hydroxychroman in the small intestine and is secreted into the circulatory system.     

Effect of Concomitant Consumption of Fish Oil and Vitamin E on T Cell Mediated Function in the Elderly: A Randomized Double-Blind Trial

Objectives: To determine if concomitant consumption of fish oil and vitamin E would modify the vitamin E level needed for improving T cell mediated function in elderly.

Methods: A randomized and double-blind study was conducted using 40 healthy male and female elderly subjects (>65 y) who were randomly assigned to one of 4 groups (n = 10/group). All the subjects received 5 g of fish oil daily containing 1.5 g eicosapentaenoic acid (EPA) and 1 g docosahexaenoic acid (DHA), and a capsule containing different doses of dl-α-tocopherol (0, 100, 200 or 400 mg/day) for 3 mo. Plasma vitamin E and fatty acid levels, and in vivo [delayed-type hypersensitivity skin response (DTH) and T cell sub-population analysis] and ex vivo [mitogen-stimulated peripheral blood mononuclear cells (PBMC) proliferation and interleukin (IL)-2 production] immune functions were determined at baseline and after supplementation.

Results: The control group (fish oil only) did not show a statistically significant change in either DTH or PBMC proliferation. DTH response, however, was significantly increased from baseline in all groups supplemented with fish oil plus vitamin E and a significant positive correlation between DTH response and plasma concentrations of α-tocopherol was observed. PBMC proliferation was only significantly increased in the group supplemented with fish oil plus 200 mg vitamin E. However, the changes caused by fish oil plus vitamin E in either DTH or PBMC proliferation were not significantly different from those observed in control group. Plasma levels of α-tocopherol were significantly increased in all three fish oil plus vitamin E groups and the increase in plasma α-tocopherol level was less profound than that previously reported when vitamin E was given alone.

Conclusions: The immuno-enhancing effect of vitamin E in the elderly is dampened when it is concomitantly consumed with fish oil. This may be due to the smaller increase in plasma concentrations of vitamin E in the presence of fish oil.     

Chemopreventive activity of vitamin E in breast cancer: a focus on γ- and δ-tocopherol

Vitamin E consists of eight different variants: α-, β-, γ-, and δ-tocopherols (saturated phytyl tail) and α-, β-, γ-, and δ-tocotrienols (unsaturated phytyl tail). Cancer prevention studies with vitamin E have primarily utilized the variant α-tocopherol. To no avail, a majority of these studies focused on variant α-tocopherol with inconsistent results. However, γ-tocopherol, and more recently δ-tocopherol, have shown greater ability to reduce inflammation, cell proliferation, and tumor burden. Recent results have shown that γ-enriched mixed tocopherols inhibit the development of mammary hyperplasia and tumorigenesis in animal models. In this review, we discuss the possible differences between the variant forms, molecular targets, and cancer-preventive effects of tocopherols. We recommend that a γ-enriched mixture, γ- and δ-tocopherol, but not α-tocopherol, are promising agents for breast cancer prevention and warrant further investigation.     

Effect of Five-Year Supplementation of Vitamin C on Serum Vitamin C Concentration and Consumption of Vegetables and Fruits in Middle-Aged Japanese: A Randomized Controlled Trial

Objective: This study was aimed at evaluating the effect of long-term vitamin C supplementation on serum and dietary vitamin C and identifying the factors associated with change in serum concentration.

Methods: A total of 439 subjects with atrophic gastritis initially participated in a randomized clinical trial using vitamin C and β-carotene to prevent gastric cancer. We originally randomized the participants into four treatment groups using a 2×2 factorial design, whereby 0 or 15 mg/day β-carotene and 50 or 500 mg/day vitamin C were administered in a double-blind manner. The β-carotene component was terminated early after a mean treatment duration of four months. Before and upon early termination of β-carotene supplementation, 134 subjects dropped out this trial, while 120 and 124 subjects took the vitamin C supplement at either 50 mg or 500 mg daily for five years.

Results: Changes in serum vitamin C were significantly higher in the high-dose group (38.5% increase, 95% CI = 27.0–49.9) than in the low-dose group (13.0% increase, 5.1–20.9) or in the dropout group (3.3% increase, ?2.1–8.6) after five-year supplementation. The serum vitamin C at baseline was negatively associated with changes in serum vitamin C (p < 0.0001), while high-dose (p < 0.0001) and low-dose (p < 0.05) supplementation and female gender (p < 0.001) were positively associated. Dietary intake of vitamin C in the supplementation group was almost identical before and after five-year supplementation of vitamin C (2.31 mg/day decrease, 95% CI = ?15.3–10.7), while a 17.7 mg/day decrease (95% CI = ?44.2–8.86) was observed in the drop-out group.

Conclusion: Five-year vitamin C supplementation induces a remarkable increase in serum vitamin C concentration, and our intervention program appears to have no effect on dietary vitamin C intake.     

复合微量营养素补充剂对北京市成人血和尿营养素水平的影响

目的 探讨复合微量营养素补充剂对健康成人体内营养素水平的影响。方法 选择北京市152名推荐食谱问卷得分低于12分的健康成年人作为研究对象,采用随机数字表法分为安慰剂组和补充剂组,每组76名。两组分别服用安慰剂和复合微量营养素补充剂。8周后检测受试者血浆及尿液中营养素浓度的变化情况。并于研究第56天同时给两组受试者服用复合微量营养素补充剂,观察服药前和服药后2h血浆营养素水平变化。结果 安慰剂组有3例失访,失访率为5.7％。服用复合微量营养素补充剂8周后,补充剂组的血浆α-生育酚[(18.23±0.82)比(14.55±0.73)μmol/L]、β-胡萝卜素[（4.28±0.29）比（2.38±0.24）μmol/L]、维生素C[(42.65±2.11)比(27.49±1.76)μmol/L]、B6[(323.51±15.88)比(69.43±10.47) nmol/L]和B12浓度[(1005.27±23.00)比(796.85±35.57) pmol/L],尿维生素B1[(899.24±70.73)比(174.42±13.38) μg/g·Cr]和B2水平[(3227.68±330.04)比(259.10±33.33)μg/g·Cr],及红细胞叶酸水平[(720.09±21.33)比(633.17±28.75) nmol/L]均明显高于安慰剂组（P均=0.0000）,血浆γ-生育酚浓度明显低于安慰剂组[(2.18±0.13)比(2.87 ±0.26) μmol/L,P=0.0001]。服用复合微量营养素补充剂2h后,补充剂组的血浆维生素C水平明显高于安慰剂组[(54.53±2.43)比(23.02±1.77)mol/L,P=0.0000]。结论 服用复合微量营养素补充剂可改变健康成人体内的营养素水平,但其意义有待进一步研究探讨。     

Re: The influence of vitamin supplements of micronutrient levels in healthy elderly subjects.

Objective: To determine what effects enrichment of human low-density lipoprotein (LDL) with combinations of α-tocopherol and β-carotene would exert on LDL oxidation and attempt to define the nature of the effects.

Methods: Human plasma was pooled and α-tocopherol and β-carotene was added in a four-by-four design resulting in the enrichment of LDL with α-tocopherol and β-carotene in varying concentrations. Enriched and control LDL was oxidized in Cu²⁺ mediated oxidation system and resistance of LDL to oxidation was determined by lag time, thiobarbituric acid reactive substances (TBARS) activity, and rate of oxidation.

Results: Increasing LDL α-tocopherol concentration had a linear relationship with lag time and a negative correlation with rate of oxidation. LDL β-carotene concentration was linearly correlated with the rate of LDL oxidation and β-carotene loss, and exponentially related to TBARS concentration.

Conclusions: These results support earlier findings for the protective effect of α-tocopherol against LDL oxidation, and suggest that β-carotene participates as a prooxidant in the oxidative degradation of LDL under these conditions. Since high levels of α-tocopherol did not mitigate the prooxidative effect of β-carotene, these result indicate that increased LDL β-carotene may cancel the protective qualities of α-tocopherol.     

Vitamin C,Mood and Cognitive Functioning in the Elderly

The present study examined the effects of anti-oxidant vitamin supplementation on mood and cognitive functioning in 205 volunteers (110 females, 95 males; age range: 60–80 years). In this randomised, double-blind, placebo-controlled study, the volunteers received either anti-oxidant supplementation (daily dosage 12mg/d β-carotene, 400 mg/d α-tocopherol and 500mg/d ascorbic acid) or placebo. The volunteers were followed up for 12 months. Vitamin levels were assessed from plasma samples. The primary outcome measures were subjective mood, self-reported cognitive failures, and measures of intelligence. These were measured at 4, 8 and 12 months. There were very few significant differences between the placebo and vitamin groups. Analysis of the effects of changes in vitamin levels on mood and cognition revealed significant effects of changes in vitamin C but not the other anti-oxidants. Increases in vitamin C were associated at 12 months with more positive mood, greater improvements in global assessments of intellectual functioning and a reduction in everyday errors of memory, attention and action. These effects were greatest for those volunteers who had a more negative mood and lower levels of cognitive function at baseline. Overall, results support earlier findings based on examination of dietary intake.     

Association between intake of antioxidants and pancreatic cancer risk: a meta-analysis

We conducted a meta-analysis to systematically evaluate the association between antioxidants intake and pancreatic cancer risk. Relevant articles were retrieved from PUBMED and EMBASE databases and standard meta-analysis methods were applied. Finally a total of 18 studies were included. Comparing the highest with lowest categories, higher dietary intakes of selenium, vitamin C, vitamin E, β-carotene and β-cryptoxanthin were significantly associated with reduced pancreatic cancer risk (for selenium, pooled OR?=?0.47, 95%CI 0.26–0.85; for vitamin C, pooled OR?=?0.68, 95%CI 0.57–0.80; for vitamin E, pooled OR?=?0.70, 95%CI 0.62–0.81; for β-carotene, pooled OR?=?0.74, 95%CI 0.56–0.98; for β-cryptoxanthin, pooled OR?=?0.70, 95%CI 0.56–0.88). Lycopene intake was marginally associated with pancreatic cancer risk (pooled OR?=?0.85, 95%CI 0.73–1.00), while no significant association was observed for α-carotene, lutein and zeaxanthin. In summary, higher dietary intake of selenium, vitamin C, vitamin E, β-carotene and β-cryptoxanthin was inversely associated with pancreatic cancer risk.     

Effects of 6-month multivitamin supplementation on serum concentrations of alpha-tocopherol, beta-carotene, and vitamin C in healthy elderly women

OBJECTIVE: The aim of this study was to evaluate the effect of supplementation with nutritional doses of antioxidant nutrients on the serum concentrations of ascorbic acid, alpha-tocopherol, and beta-carotene in healthy elderly women. METHODS: The study was performed as a randomized placebo-controlled, double-blind trial. Two hundred forty-one free-living, healthy women aged 60 years and older were recruited by newspaper advertisement in Hanover, Germany and its environs. As 21 women dropped out, data of 220 women (aged 60-91 years median 63 years) were included in this evaluation. Subjects were randomly assigned to receive either a multivitamin/mineral or placebo capsule with identical appearance for six months containing 36 mg 36mg vitamin E, 150 mg vitamin C, and 9 mg beta-carotene. Serum concentrations of vitamin C, alpha-tocopherol, and beta-carotene were measured initially and after six months of supplementation. Data were analyzed with the SPSS 10.0 program. RESULTS: Median serum concentrations of alpha-carotene and vitamin E increased significantly in the supplemented group (p=0.000), whereas no significant modifications were observed in the placebo group. Median vitamin C concentration of the supplemented group did not differ from baseline after intervention, but that of the placebo group was significantly decreased after six months (p=0.000). In comparison to estimated desirable serum concentrations of > 30 micromol/L vitamin E, 50 micromol/L vitamin C, and > 0.4 micromol/l beta-carotene at baseline, lower concentrations were found in 21.1%, 6.9%, and 1.0% of all subjects, respectively. After supplementation none of the members of the supplemented group had tocopherol concentrations below 30 micromol/L and only one woman of the supplemented group had a serum beta-carotene concentration below 0.4 micromol/L. The change in serum concentrations of vitamin C and E in the supplemented group depended on the status at baseline. CONCLUSION: A six-month supplementation with physiological doses of antioxidant vitamins improves the blood concentration of these nutrients even in relatively well-nourished elderly women or, as seen for vitamin C, prevents reduction of serum concentrations. Prevalence of suboptimal serum concentrations can be reduced.     

超高效液相色谱-三重四级杆串联质谱法测定血清中维生素A和维生素E

目的 建立一种超高效液相色谱-三重四级杆串联质谱法测定血清中维生素A(视黄醇)和4种具有活性的维生素E(α-生育酚、β-生育酚、γ-生育酚和δ-生育酚)含量的方法.方法 血样经甲醇沉淀蛋白后,用正己烷萃取,吹干后用甲醇复溶,使用C30色谱柱(3 mmx150 mm,2.6 μm)分离,以0.1％甲酸甲醇和0.1％甲酸-...     

Effects of vitamin D3 and calcium supplementation on serum levels of tocopherols, retinol, and specific vitamin D metabolites

γ-Tocopherol (γT) protects against DNA-damaging effects of nitrogen oxides, yet its physiologic regulation in vivo is unknown. Observational studies indicate inverse associations of 25[OH]-vitamin D with γT and leptin. To determine whether vitamin D(3) supplementation alters levels of lipid-soluble micronutrients, serum samples (N = 85 subjects) from a randomized, double-blind, placebo-controlled clinical trial of vitamin D(3) (800 IU) and calcium (2 g), alone and in combination, were analyzed for lipid micronutrients and specific vitamin D metabolites at baseline and after 6 mo of supplementation. Serum 25[OH]-vitamin D(3) levels increased 55% (P < 0.0001) and 48% (P = 0.0005), whereas 25[OH]-vitamin D(2) levels were lower by 48% (P = 0.26) and 21% (P = 0.36) in the vitamin D(3) and vitamin D(3) plus calcium groups, respectively. At baseline, γT levels were inversely associated with 25[OH]D (r = -0.31, P = 0.004). With vitamin D(3) plus calcium treatment, serum α-tocopherol decreased 14% (P = 0.04), whereas similar changes in γT (19% lower, P = 0.14) were observed. No significant effects were observed for D(3) supplementation on leptin or retinol levels. These results are consistent with the hypothesis that vitamin D(3) ± calcium affects serum tocopherol and 25[OH]D(2) levels; however, studies using larger, more homogeneous populations are warranted.