Antioxidant activities of carotenes and xanthophylls

The purpose of this study was to assess the relative antioxidant activities of a range of carotenes and xanthophylls through the extent of their abilities to scavenge the ABTS(.+) radical cation. The results show that the relative abilities of the carotenoids to scavenge the ABTS(.+) radical cation are influenced by the presence of functional groups with increasing polarities, such as carbonyl and hydroxyl groups, in the terminal rings, as well as by the number of conjugated double bonds.

Liquid chromatographic determination of carotenoids in human serum using an engineered C30 and a C18 stationary phase

A C30 stationary phase was specifically engineered for carotenoid separations, and carotenoid measurements using this column are compared with those obtained using a somewhat more conventional C18 column. Both methods were used to contribute measurements for the certification of carotenoids in Standard Reference Material 968b, Fat-Soluble Vitamins and Cholesterol in Human Serum. Analytes were extracted from the serum into hexane. Measurements on the C18 column were made using a gradient of acetonitrile, methanol, and ethyl acetate, which is described in detail elsewhere. Measurements on the C30 column were made using a gradient of water, methanol, and methyl tert.-butyl ether.

Carotenoid and tocopherol concentrations in plasma, peripheral blood mononuclear cells, and red blood cells after long-term beta-carotene supplementation in men

To determine the effects of long-term beta-carotene supplementation on concentrations of carotenoids and tocopherols in plasma and in blood cells, fasting blood was collected from 73 randomly selected physicians from the Boston area who are participating in the Physicians Health Study (PHS). The PHS is a randomized, placebo-controlled, double-blind study. In 1982, 22,071 male physicians were assigned to one of four treatments (325 mg aspirin alone, 50 mg beta-carotene alone, both, or neither) every other day. Plasma, peripheral blood mononuclear cells (PBMCs), and red blood cells (RBCs) from physicians who have participated in the study for approximately 12 y were analyzed for carotenoids and tocopherols. Compared with the placebo group, the supplemented group had higher beta-carotene concentrations in plasma (1.73+/-0.16 compared with 0.54+/-0.06 micromol/L0, RBCs (91.5+/-9.7 compared with 31.2+/-4.2 pmol/g hemoglobin), and PBMCs (61.6+/-10.3 compared with 15.5+/-2.5 pmol/10(7) cells). There were no differences in other carotenoids or tocopherols in plasma, RBCs, and PBMCs between these two groups. The beta-carotene concentrations. Plasma cryptoxanthin correlated with both RBC and PBMC cryptoxanthin concentrations but plasma lycopene correlated only with PBMC lycopene concentrations. These data suggest that plasma may not be the best indicator of carotenoid status. Furthermore, long-term beta-carotene supplementation in men results in higher beta-carotene concentrations in plasma, RBCs and PBMCs without lowering concentrations of other carotenoids or tocopherols.

Destruction of tocopherols, carotenoids, and retinol in human plasma by cigarette smoke

The mechanisms by which exposure to cigarette smoke dramatically increase the incidence and severity of atherosclerosis and the incidence of lung cancer, chronic obstructive airways disease, and emphysema are incompletely understood. Epidemiologic evidence has suggested a modifying role for antioxidant micronutrients, including tocopherols and carotenoids, in these disease processes. It has been suggested that oxidants in cigarette smoke could be involved. We exposed freshly obtained human plasma to the gas phase of cigarette smoke to assess its effects on tocopherols, carotenoids, and retinol. Exposure to cigarette smoke led to the depletion of most of the lipophilic antioxidants in 20 mL human plasma. The order of disappearance was lycopene > alpha-tocopherol > trans-beta-carotene++ > (lutein + zeaxanthin) = cryptoxanthin > gamma-tocopherol = retinol. However, despite a substantial loss of alpha-tocopherol, there was very little peroxidative damage to lipids, and no detectable change in the content of polyunsaturated fatty acid-rich cholesterol esters. We conclude that a wide spectrum of lipophilic micronutrients undergo degradation when exposed to gas-phase cigarette smoke. The relevance of these in vitro findings to possible cigarette smoke-induced depletions of respiratory tract lipophilic antioxidants remains to be clarified.

Dietary intake of specific carotenoids and vitamins A, C, and E, and prevalence of colorectal adenomas

We determined whether intakes of the main dietary carotenoids (alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein plus zeaxanthin, and lycopene) and of vitamins A, C, and E were associated with the prevalence of colorectal adenomas among male and female members of a prepaid health plan in Los Angeles who underwent sigmoidoscopy (n = 488 matched pairs). Participants, ages 50-74 years, completed a 126-item semiquantitative food-frequency questionnaire and a non-dietary questionnaire from 1991 to 1993. In the univariate-matched analysis, alpha-carotene, beta-carotene (with and without supplements), beta-cryptoxanthin, lutein plus zeaxanthin, vitamin A (with and without supplements), and vitamin C (with and without supplements) were associated with a decreased prevalence of colorectal adenomas. After adjustment for intake of calories, saturated fat, folate, fiber, and alcohol, and for current smoking status, body mass index, race, physical activity, and use of nonsteroidal anti-inflammatory drugs, only beta-carotene including supplements was inversely associated with adenomas (odds ratio (OR), 0.6; 95% confidence interval (CI), 0.41.1; trend, P= 0.04; ORs compare highest to lowest quartiles0; vitamin C showed a weaker inverse association (OR, 0.8; 95% CI, 0.5-1.5; trend, P = 0.08); and the remaining compounds were no longer clearly associated with risk. After including beta-carotene with supplements and vitamin C simultaneously in the mutivariate model, the association of beta-carotene with supplements with adenomas was weakened (OR, 0.8; 95% CI, 0.5-1.3; trend P = 0.15), and vitamin C was no longer associated with risk. These data provide only modest support for a protective association of beta-carotene with colorectal adenomatous polyps.

Evaluation of retinol, alpha-tocopherol, and carotenoids in serum of men with cancer of the larynx before and after commercial enteral formula feeding

BACKGROUND

Both epidemiologic and in vitro studies have indicated the inverse correlation between intake and/or blood concentrations of different carotenoids, retinol, and tocoferol with different chronic and degenerative disturbances (cancer, cardiovascular diseases, cataracts, aging). The purpose of this study was to determine the fat-soluble vitamin and carotenoid levels in men with recently diagnosed cancer of the larynx (n = 51) who had undergone total or partial laryngectomy and compare them with those of an age- and sex-matched control group (n = 51). In addition, the effects of commercial enteral formula feeding were assessed in a subgroup of these patients (n = 35).

METHODS

A validated high-performance liquid chromatography method was used to determine the concentrations of six carotenoids (lutein, zeaxanthin, beta-cryptoxanthin, lycopene, alpha-carotene, and beta-carotene), retinol, and alpha-tocopherol in serum. Commercial, rather than blender prepared, enteral formulas were supplied to the patients as the only food source for an average period of 12 days. The statistical analysis was based on nonparametric methods (Mann-Whitney and Wilcoxon).

RESULTS

The levels of all compounds analyzed were significantly lower in men with laryngeal cancer than in the control group. Retinol and tocopherol increased significantly after enteral formula feeding, although they continued to be significantly lower than those of the controls. The carotenoid levels decreased after enteral nutrition.

CONCLUSIONS

The retinol and carotenoid concentrations should be monitored on a routine basis in these patients because of their relationship to this type of cancer. Moreover, it would be of interest to assess the effects of the addition of carotenoids to enteral formulas because they may offer protection from oxidative damage and potentiate the immune system.

Human serum carotenoid concentrations are related to physiologic and lifestyle factors

We examined the concentrations of five carotenoids in the serum and diet of a population-based sample of 400 individuals to determine what physiologic and lifestyle factors were related to serum carotenoid concentrations, how these relationships differed among the carotenoids, and if these relationships reflected differences in carotenoid intake. Lower serum concentrations of alpha-carotene, beta-carotene, beta-cryptoxanthin, and lutein+zeaxanthin generally were associated with male gender, smoking, younger age, lower non-HDL cholesterol, greater ethanol consumption and higher body mass index. Serum lycopene generally was not related to these factors, but lower lycopene levels were associated with older age and lower non-HDL cholesterol. Only the hydrocarbon carotenoids (alpha- and beta-carotene and lycopene) were directly associated with HDL cholesterol. The associations of some factors (gender, age, smoking, and ethanol intake) with serum carotenoids were similar to the associations of these factors with levels in the diet, indicating that serum carotenoids may reflect the influence of these factors on carotenoid intake. Consistent with this notion, correlations between serum and dietary carotenoids did not differ between smokers and nonsmokers. Other factors (HDL and non-HDL cholesterol and body mass index) associated with carotenoids in the serum were not associated with carotenoid intake, indicating that physiologic conditions that affect the absorption, storage, and utilization of carotenoids may influence these associations. These physiologic and behavioral correlates of carotenoids could explain or modify associations of carotenoids with chronic diseases.

beta-Cryptoxanthin selectively increases in human chylomicrons upon ingestion of tangerine concentrate rich in beta-cryptoxanthin esters

beta-Cryptoxanthin is a major source of vitamin A, often second only to beta-carotene, and is present in fruits such as oranges, tangerines, and papayas. Here, we studied the uptake of this carotenoid upon ingestion of tangerine juice concentrate, rich in beta-cryptoxanthin esters. Increasing amounts of free beta-cryptoxanthin were detected in chylomicrons and serum. Peak levels in chylomicrons were reached at t = 6 h, and the concentration returned toward basal levels at t = 9 h. No beta-cryptoxanthin esters were detected in chylomicrons or serum, indicating efficient cleavage in the intestine before the carotenoid is incorporated into lipoproteins by the liver. Other xanthophyll esters, e.g., of zeaxanthin and lutein, were present in low amounts in the tangerine concentrate. As with beta-cryptoxanthin, no esters appeared in serum or chylomicrons, suggesting that the cleavage of carotenoid esters prior to release into the lymphatic circulation occurs generally in human oxocarotenoid biokinetics.

Monitoring of ubiquinol-10, ubiquinone-10, carotenoids, and tocopherols in neonatal plasma microsamples using high-performance liquid chromatography with coulometric electrochemical detection

A method for measuring the lipophilic antioxidants alpha-tocopherol, gamma-tocopherol, ubiquinol-10, ubiquinone-10, beta-cryptoxanthin, and beta-carotene in 5 or 10 microliters neonatal plasma is presented. First lipid extraction together with the internal standards gamma-tocotrienol, ubiquinone-7, ubiquinol-9, ubiquinone-9, and ethyl beta-apo-8'-carotenoate was carried out. Then the components were separated on a RPC2/C18 column. Coulometric electrochemical detection was performed using the reduction-oxidation mode (-0.60 V; -0.15 V; +0.60 V). Detection limits for all components were between 21 and 60 fmol, corresponding to 0.004 and 0.012 mumol/liter plasma; the within-day precision (coefficient of variation) was between 3 and 14% for all measured substances. Reference values are given for healthy newborn children from the second to the sixth day of life. Using the presented HPLC technique it is possible to monitor the concentrations of lipophilic antioxidants in plasma of sick immature newborn children in order to study effects of oxidative stress.

Plasma levels of retinol, retinol-binding protein, all-trans beta-carotene and cryptoxanthin in low birth weight infants

In neonatal medicine, it is thought that retinol is useful for preventing CLD and for fetal development. However, beta-carotene had other vitamin A precursors have not been studied in neonates with CLD or others disorders. Cord blood of neonates including ELBW and VLBW infants was assayed for plasma levels of retinol, RBP, beta-carotene and cryptoxanthin. Plasma beta-carotene levels in ELBW and VLBW were lower than that in term infants, but plasma cryptoxanthin levels in ELBW and VLBW were about the same as in term infants. Plasma retinol and RBP levels showed almost same levels during 23-41 gestational weeks. Maternal smoking reduced plasma beta-carotene but not cryptoxanthin, retinol, or RBP levels. IUGR was associated with increased cryptoxanthin levels in cord blood. Serious neonatal diseases, including CLD and ROP manifested no significant effects on the cord blood vitamin levels. Thus, the occurrence of these diseases at birth could not be predicted by examination of vitamin levels in cord blood.

Distributions of carotenoids and alpha-tocopherol among lipoproteins do not change when human plasma is incubated in vitro

Carotenoids and alpha-tocopherol are dietary, lipophilic antioxidants which may protect plasma lipoproteins from oxidation, a process believed to contribute to atherogenesis. In this study, the quantities and distributions of carotenoids, alpha-tocopherol and major lipids in the plasma and lipoproteins of seven normolipidemic humans were determined. Experiments were also conducted to determine if these antioxidants redistribute among lipoproteins when plasma is incubated in vitro. Virtually all of the total carotenoid in plasma associated with lipoproteins, primarily LDL [73 +/- 10% (mean +/- SD)], as did the more non-polar individual carotenoids, beta-cryptoxanthin (68 +/- 9%); lycopene (79 +/- 9%), and beta-carotene (72 +/- 12%), in patterns which closely resembled the distribution of total cholesterol. Xanthophyll, the most polar carotenoid examined, distributed equally between LDL (44 +/- 11%) and HDL (38 +/- 14%), whereas alpha-tocopherol associated with LDL (43 +/- 12%), HDL (26 +/- 10%), and VLDL (27 +/- 13%). These patterns closely resembled that of phospholipid. Approximately four carotenoid molecules associated with each VLDL and one with each LDL particle, whereas only 25 of every 1000 HDL particles contained carotenoid. Approximately 145 molecules of alpha-tocopherol associated with VLDL, 12 with LDL, and one with each HDL particle. Unlike triglyceride and cholesteryl ester, known to transfer among lipoproteins through the action of cholesteryl ester transfer protein, net transfer of carotenoids and alpha-tocopherol among lipoproteins did not occur.(ABSTRACT TRUNCATED AT 250 WORDS)

Liposoluble vitamins and naturally occurring carotenoids in porphyria cutanea tarda

The authors consider two groups of patients with overt sporadic porphyria cutanea tarda (PCT) from different continents, with the aim of evaluating the possible impairment of the liposoluble antioxidative system, given the possible synergic effect of porphyrins and iron in promoting oxidative cellular damage. Twenty-three Italian outpatients with overt sporadic PCT and 11 outpatients with PCT from Buenos Aires (Argentina) were matched with 60 patients with liver cirrhosis and 52 healthy Italian controls. Serum levels of alpha- and beta-carotene, cryptoxanthin, zeaxanthin, lutein, lycopene, retinol and alpha-tocopherol were detected by a high-performance liquid chromatographic technique devised in our laboratory, which afforded an accurate and simultaneous resolution of all these compounds. The results point to a significant reduction in plasma levels of alpha- and beta-carotene in both the PCT populations with respect not only to controls, but also to the cirrhotic population, which had more severe liver damage. Moreover, other carotenoids with proven antioxidative properties, like cryptoxanthin and lycopene, are greatly reduced in our PCT populations. This confirms the suggested synergic effect of iron and porphyrins in the oxidative intracellular damage with consequent depletion of antioxidative liposoluble molecules.

Changes in serum carotenoids in subjects with colorectal adenomas after 24 mo of beta-carotene supplementation. Australian Polyp Prevention Project Investigators

The effect of beta-carotene supplementation on major serum carotenoid fractions (lutein/zeaxanthin, beta-cryptoxanthin, lycopene, alpha-carotene, and beta-carotene) was investigated in 224 people with colorectal adenomas (139 men, 85 women) recruited for the Australian Polyp Prevention Project (APPP). Each subject was randomly assigned to take either 20 mg beta-carotene/d or placebo over 24 mo. Besides the expected increase in serum concentration of beta-carotene (1073% in men, 839% in women), lycopene (176% in men) and alpha-carotene (211% in men and 166% in women) concentrations were also increased after body mass index, baseline concentration, change in respective carotenoid intake, and other confounding factors were adjusted for. The increase in serum concentrations of these carotenoids after beta-carotene supplementation suggests that beta-carotene may interact biologically with other carotenoids and such interaction would need to be taken into consideration when the protective effect of beta-carotene supplementation for cancer or other diseases is examined.

Plasma carotenoids as biomarkers of vegetable and fruit intake

Higher intakes of vegetables and fruits are associated with a lower risk of certain human cancers. A biomarker of vegetable and fruit intake would be a valuable research tool. A cross-sectional study assessed the association between plasma carotenoid concentrations and intakes of vegetables and fruits. Plasma carotenoids (alpha-carotene, beta-carotene, lutein, beta-cryptoxanthin, and lycopene) were measured in 50 male and 49 female participants, aged 18-37 years, with a wide range of habitual vegetable and fruit intakes. Dietary intakes were assessed via a food frequency questionnaire. Intake of vegetables and fruits and high carotenoid foods were measured. The sum of the plasma carotenoids (excluding lycopene) was highly correlated with intake of total vegetables and fruits (r = 0.59). Of the individual plasma carotenoids, plasma alpha-carotene had the highest correlation with intakes of both total vegetables (r = 0.50) and total fruits (r = 0.58). Intakes of foods with high carotenoid contents were correlated with their corresponding plasma concentrations as follows: high beta-carotene foods (r = 0.41); high lutein foods (r = 0.46); and high lycopene foods (r = 0.11). Multiple regression analyses showed that intake of total vegetables and fruits was the most significant determinant of each plasma carotenoid except lycopene. The utility of combining the plasma carotenoids as biomarkers of vegetable and fruit intake was assessed by a stepwise regression of total vegetable and fruit intake on plasma carotenoids. Significant determinants of intake of total vegetables and fruits were alpha-carotene, beta-cryptoxanthin, lutein, and energy intake (R2 = 0.53).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of micronutrients and antioxidants on lipid peroxidation in human plasma and in cell culture

Plasma levels of triglycerides, retinol, cholesterol, lipid-phase antioxidants (alpha-, gamma-tocopherols, beta-carotene, alpha-carotene, lycopene, beta-cryptoxanthin and lutein/zeaxanthin), and thiobarbituric acid-reactive substances (TBA-RS), as an indicator of lipid peroxidation, were repeatedly determined in nine individuals over a 3-month period. Levels of TBA-RS were positively correlated with plasma triglycerides and gamma-tocopherol, and negatively correlated with plasma carotenoids. These results were consistent with in vitro cell culture studies which showed increased TBA-RS for cells supplemented with linolenic acid and decreased levels when treated with beta-carotene. We conclude that TBA-RS measurements in plasma accurately reflect the level of peroxidizable substrate as modified by the presence of a variety of dietary antioxidants, particularly carotenoids. Although the inter- and intra-individual variabilities for TBA-RS are comparable with the micronutrients and antioxidants measured in this study, high interassay variability and the strong association with the more commonly measured plasma triglycerides suggest the TBA-RS assay to be of limited use in epidemiologic studies. However, this assay does appear to be useful in cell culture studies where experimental conditions can be better controlled. Low ratios of inter- to intra-individual variability in some of the plasma micronutrient and lipid-phase antioxidants measured suggest that multiple samples may be required to characterize individuals in studies evaluating the relation between these plasma constituents and disease incidence.

Retinol, alpha-tocopherol, lutein/zeaxanthin, beta-cryptoxanthin, lycopene, alpha-carotene, trans-beta-carotene, and four retinyl esters in serum determined simultaneously by reversed-phase HPLC with multiwavelength detection

We describe the use of HPLC with multiwavelength detection to measure retinol, alpha-tocopherol, lutein/zeaxanthin, beta-cryptoxanthin, lycopene, alpha-carotene, trans-beta-carotene, beta-carotene, and the linoleate, oleate, palmitate, and stearate esters of retinol in a single 200-microL serum sample. The method is sensitive enough to detect individual retinyl esters in fasting serum from a nonhyperlipidemic population and requires only 12 min for each sample. Serum concentration ranges and means are reported for retinol, alpha-tocopherol, lutein/zeaxanthin, beta-cryptoxanthin, lycopene, alpha-carotene, trans-beta-carotene, and the sum of the retinyl esters from serum analyses of 3480 participants from several different studies.

The relations between cervical cancer and serological markers of nutritional status

We evaluated whether differences in serological nutrient indicators between cases and controls were likely to be due to different usual levels for cases or to altered metabolism due to disease. Blood samples obtained as part of a case-control study of invasive cervical cancer conducted in Latin America were evaluated for case-control differences and for trends with stage of disease. Serum alpha- and beta-carotene, cryptoxanthin, and alpha- and gamma-tocopherol showed no trend with extent of disease, although Stage IV cases had lower alpha- and beta-carotene values than did other cases. A slight trend of decreasing values with stage was observed for serum retinol, lycopene, and lutein. For cholesterol and triglyceride concentrations, an inverse trend was observed with stage of disease, which suggested a clinical effect of the disease on blood lipids. Adjustment for smoking, alcohol intake, or oral contraceptive use did not alter observed relations, nor was there evidence that the altered blood nutrient levels differed by histological type. These data suggest that serum values for some carotenoids from Stage I, II, and III cervical cancer are suitable for etiological studies, but spurious results may be obtained if late-stage cases are included. Evidence of trends with severity of disease for cholesterol and triglycerides, and possibly for retinol, lycopene, and lutein, suggest that special attention be given to disease effects of these nutrients in studies of cervical cancer.

Simultaneous determination of vitamins A and E and carotenoids in plasma by reversed-phase HPLC in elderly and younger subjects

A reversed-phase high-performance liquid-chromatographic method for the simultaneous determination of retinol, alpha-tocopherol, alpha-carotene, beta-carotene, cryptoxanthin, lutein/zeaxanthin, and lycopene is described. This method was applied to plasma measurements in healthy young and elderly subjects. The plasma, deproteinized with ethanol, is extracted twice with n-hexane. After evaporation, the residue is dissolved in 50 microL of tetrahydrofuran and made up to 200 microL with ethanol. Samples (50 microL) are injected onto a 250 x 4.6 mm column of 5-microns-particle Spherisorb ODS1 (Phase Separations) that had been equilibrated with solvent mixture A:B (90:10 by vol) [A = 100 mmol/L ammonium acetate in methanol: acetonitrile (80:20 by vol) and B = 100 mmol/L ammonium acetate in water] at 2 mL/min. The analytes are eluted by running a 12-min linear gradient to 100% A; solvent A is then maintained for 10 min. Intrabatch CVs were 2.3%, 3.3%, 2.8%, 3.6%, 3.6%, and 3.0% for retinol, alpha-tocopherol, lutein/zeaxanthin, cryptoxanthin, lycopene, and beta-carotene, respectively. The corresponding interbatch CVs were 4.9%, 5.8%, 12.3%, 6.5%, 8.0%, and 3.4%.

Serum micronutrients and the subsequent risk of cervical cancer in a population-based nested case-control study

A nested case-control study was conducted in Washington County, MD, to determine whether low serum micronutrients are related to the subsequent risk of cervical cancer. Among the 15,161 women who donated blood for future cancer research during a serum collection campaign in 1974, 18 developed invasive cervical cancer and 32 developed carcinoma in situ during the period January 1975 through May 1990. For each of these 50 cases, two matched controls were selected from the same cohort. The frozen sera of the cases and their matched controls were analyzed for a number of nutrients. The mean serum levels of total carotenoids, alpha-carotene, beta-carotene, cryptoxanthin, and lycopene were lower among cases than they were among controls. When examined by tertiles, the risk of cervical cancer was significantly higher among women in the lower tertiles of total carotenoids (odds ratio 2.7; 95% confidence limit, 1.1-6.4), alpha-carotene (odds ratio, 3.1; 95% confidence limit, 1.3-7.6), and beta-carotene (odds ratio, 3.1; 95% confidence limit, 1.2-8.1) as compared to women in the upper tertiles and the trends were statistically significant. Cryptoxanthin was significantly associated with a lower risk of cervical cancer when examined as a continuous variable. Retinol, lutein, alpha- and gamma-tocopherol, and selenium were not related to cervical cancer risk. Smoking was also strongly associated with cervical cancer. These findings are suggestive of a protective role for total carotenoids, alpha-carotene and beta-carotene in cervical carcinogenesis and possibly for cryptoxanthin and lycopene as well.

Carotenoid content of fruits and vegetables: an evaluation of analytic data

The test of the association between dietary intake of specific carotenoids and disease incidence requires the availability of accurate and current food composition data for individual carotenoids. To generate a carotenoid database, an artificial intelligence system was developed to evaluate data for carotenoid content of food in five general categories, namely, number of samples, analytic method, sample handling, sampling plan, and analytic quality control. Within these categories, criteria have been created to rate analytic data for beta-carotene, alpha-carotene, lutein, lycopene, and beta-cryptoxanthin in fruits and vegetables. These carotenoids are also found in human blood. Following the evaluation of data, acceptable values for each carotenoid in the foods were combined to generate a database of 120 foods. The database includes the food description; median, minimum, and maximum values for the specific carotenoids in each food; the number of acceptable values and their references; and a confidence code, which is an indicator of the reliability of a specific carotenoid value for a food. The carotenoid database can be used to estimate the intake of specific carotenoids in order to examine the association between dietary carotenoids and disease incidence.

The development and application of a carotenoid database for fruits, vegetables, and selected multicomponent foods

A carotenoid database for individual and multicomponent foods has been compiled that contains values for the five most common carotenoids (alpha-carotene, beta-carotene, beta-cryptoxanthin, lycopene, lutein) in 2,458 fruits, vegetables, and multicomponent foods containing fruits and vegetables. The database was used to estimate intakes of specific carotenoids for 19- to 50-year-old women (n = 1,102), using food consumption data obtained from dietary recalls in the US Department of Agriculture Continuing Survey of Food Intake by Individuals, 1986. The major contributors of alpha-carotene were carrots consumed as a single food or as an ingredient in multicomponent foods. Carrots, cantaloupe, and broccoli were the main sources of beta-carotene. Orange juices and blends, oranges, and tangerines were important contributors of beta-cryptoxanthin. Tomatoes and tomato products consumed as single foods or as ingredients in multicomponent foods provided most of the dietary lycopene. Contributors of lutein + zeaxanthin included collard, mustard, or turnip greens; spinach; and broccoli. The per capita consumption of total carotenoids (the sum of the five specific carotenoids) among these women was approximately 6 mg/day.

A nonsaponification method for the determination of carotenoids, retinoids, and tocopherols in solid human tissues

There has been an increasing interest in the measurement of carotenoids, retinoids, and tocopherols in human tissues because some of these micronutrients have been shown to have chemopreventive activity. Since clinical tissue samples obtained for analysis are usually small in quantity, a sensitive analytical procedure that can simultaneously measure all the micronutrients of interest in one small piece of human tissue is necessary. Moreover, some solid tissues, such as skin, are very difficult to homogenize unless they are first saponified in alcoholic KOH, but the saponification often causes substantial destruction of some micronutrients. Thus, a nonsaponification procedure using collagenase to facilitate homogenization was developed. Solid tissues are first incubated in a collagenase solution, homogenized, then incubated in a protease solution, followed by precipitation of tissue proteins and extraction with hexane. Collagenase digestion facilitates homogenization, and protease digestion increases the extractable amounts of the micronutrients from certain tissue samples. In this study, the recovery and precision (coefficient of variation) of the new procedure was determined. In addition, the extracted amounts of seven carotenoids, two retinoids, and two tocopherols from human skin, cervical/ovarian tissue, as well as sarcoma and kidney tumors using the new procedure and a commonly applied saponification procedure were compared.

Essential fatty acids, plasma cholesterol, and fat-soluble vitamins in subjects with age-related maculopathy and matched control subjects

A matched-control study of plasma retinol, alpha-tocopherol, carotenoid, and cholesterol concentrations and the polyunsaturated fatty acid content of plasma and erythrocyte phospholipids was undertaken in 65 elderly patients with age-related maculopathy and 65 control subjects matched for age and sex. Despite the high statistical power of the study and large variations between subjects in the variables under consideration, no significant differences were noted between patients and control subjects. However, several statistically significant differences were noted between male and female subjects independent of their classification with maculopathy or as controls and age: plasma cholesterol, total phospholipids, alpha-tocopherol, and beta-cryptoxanthin concentrations were higher in females than in males. The mean plasma cholesterol concentration for the upper tertile of the whole sample was 7.6 mmol/L. Plasma concentrations of total carotenoids, alpha-carotene, and beta-carotene, but not alpha-tocopherol, were significantly lower in smokers than in non-smokers. The results of this study do not provide any evidence in favor of changing the dietary intake of polyunsaturated fatty acids or fat-soluble vitamins to protect against age-related maculopathy.

Diurnal and seasonal variation of five carotenoids measured in human serum

We studied within-person variation over time in serum concentrations of five carotenoids. In a diurnal study involving 33 subjects, only the 1700 h blood samples demonstrated carotenoid concentrations different from the original 0800 values. Correlations between serum concentrations of the same carotenoids drawn 1 d apart ranged from 0.93 to 0.98. In a seasonal study involving 29 subjects, no systematic trends were observed for serum concentrations of these carotenoids. Correlations between concentrations of the same carotenoids drawn 1 y apart ranged from 0.57 to 0.82. Concentrations of different carotenoids within an individual tended to be correlated with each other. Obtaining one blood sample from subjects is a relatively imprecise way to estimate their usual serum concentrations of carotenoids. If an epidemiological study was to be based on only one determination of serum carotenoids, within-person variability in serum concentrations would attenuate true regression coefficients by 4-13% and would increase the required numbers of study subjects by 19-65%.