[show abstract][hide abstract] ABSTRACT: Increased levels of oxidative stress have been implicated in tissue damage and the development of chronic diseases, and dietary antioxidants may reduce the risk of oxidative tissue damage. As part of a European multicentre project, several studies were undertaken with the aim of testing whether the consumption of foods rich in carotenoids reduces oxidative damage to human tissue components. We describe here the serum response of carotenoids and tocopherols upon supplementation with carotenoids from natural extracts (alpha-carotene+beta-carotene, lutein or lycopene; 15 mg/day) and/or with alpha-tocopherol (100 mg/day) in a multicentre, placebo-controlled intervention study in 400 healthy male and female volunteers, aged 25-45 years, from five European regions (France, Northern Ireland, Republic of Ireland, The Netherlands and Spain). Supplementation with alpha-tocopherol increased serum alpha-tocopherol levels, while producing a marked decrease in serum gamma-tocopherol. Supplementation with alpha- + beta-carotene (carotene-rich palm oil) resulted in 14-fold and 5-fold increases respectively in serum levels of these carotenoids. Supplementation with lutein (from marigold extracts) elevated serum lutein (approx. 5-fold), zeaxanthin (approx. doubled) and ketocarotenoids (although these were not present in the supplement), whereas lycopene supplementation (from tomato paste) resulted in a 2-fold increase in serum lycopene. The isomer distributions of beta-carotene and lycopene in serum remained constant regardless of the isomer composition in the capsules. In Spanish volunteers, additional data showed that the serum response to carotenoid supplementation reached a plateau after 4 weeks, and no significant side effects (except carotenodermia) or changes in biochemical or haematological indices were observed throughout the study. This part of the study describes dose-time responses, isomer distribution, subject variability and side effects during supplementation with the major dietary carotenoids in healthy subjects.
[show abstract][hide abstract] ABSTRACT: High intakes of fruits and vegetables, or high circulating levels of their biomarkers (carotenoids, vitamins C and E), have been associated with a relatively low incidence of cardiovascular disease, cataract and cancer. Exposure to a high fruit and vegetable diet increases antioxidant concentrations in blood and body tissues, and potentially protects against oxidative damage to cells and tissues. This paper describes blood concentrations of carotenoids, tocopherols, ascorbic acid and retinol in well-defined groups of healthy, non-smokers, aged 25-45 years, 175 men and 174 women from five European countries (France, UK (Northern Ireland), Republic of Ireland, The Netherlands and Spain). Analysis was centralised and performed within 18 months. Within-gender, vitamin C showed no significant differences between centres. Females in France, Republic of Ireland and Spain had significantly higher plasma vitamin C concentrations than their male counterparts. Serum retinol and alpha-tocopherol levels were similar between centres, but gamma-tocopherol showed a great variability being the lowest in Spain and France, and the highest in The Netherlands. The provitamin A: non-provitamin A carotenoid ratio was similar among countries, whereas the xanthophylls (lutein, zeaxanthin, beta-cryptoxanthin) to carotenes (alpha-carotene, beta-carotene, lycopene) ratio was double in southern (Spain) compared to the northern areas (Northern Ireland and Republic of Ireland). Serum concentrations of lutein and zeaxanthin were highest in France and Spain; beta-cryptoxanthin was highest in Spain and The Netherlands; trans-lycopene tended to be highest in Irish males and lowest in Spanish males; alpha-carotene and beta-carotene were higher in the French volunteers. Due to the study design, the concentrations of carotenoids and vitamins A, C and E represent physiological ranges achievable by dietary means and may be considered as 'reference values' in serum of healthy, non-smoking middle-aged subjects from five European countries. The results suggest that lutein (and zeaxanthin), beta-cryptoxanthin, total xanthophylls and gamma-tocopherol (and alpha- : gamma-tocopherol) may be important markers related to the healthy or protective effects of the Mediterranean-like diet.
British Journal Of Nutrition 03/2001; 85(2):227-38. · 3.30 Impact Factor
[show abstract][hide abstract] ABSTRACT: Carotenoids are mainly present in vegetables and fruits and display several important biological actions (provitamin A, antioxidant and anticarcinogenic activities and immunomodulation). To assess the intake of carotenoids and their potential health benefits in humans, it is necessary to have reliable information about carotenoid content in food. Saponification is commonly used during analysis of carotenoids in vegetables and fruits to release esterified xanthophylls and to eliminate interfering substances. It is a time-consuming step and involves the use of considerable volumes of solvents in the partition. To reduce the time and costs of the saponification process, we compare the reliability of a “shortcut” (small volumes, vortex 3 min, 20% potassium hydroxide, hexane/methylene chloride extraction) with that of a “standard” protocol (stirring 30 min, 5% potassium hydroxide, petroleum ether/diethyl ether extraction twice plus washings). Accuracy and precision were assessed according to studies of certified reference materials for carotenoid analysis in foods. For lutein, zeaxanthin, α -cryptoxanthin, β -cryptoxanthin, lycopene, α -carotene andβ -carotene, the “shortcut” showed within-day and between-day variability similar to or lower than that of the “standard” protocol, comparable deviation from the assigned values and higher recovery for carotenes, especially for lycopene. Advantages of the “shortcut” include considerably reduced time, higher overall recoveries and lower solvent expenditure, resulting in a reduction in time and total cost of up to 80–90% without loss of accuracy or precision.
Journal of Food Composition and Analysis - J FOOD COMPOS ANAL. 01/2001; 14(5):479-489.
[show abstract][hide abstract] ABSTRACT: Lutein, one of the major carotenoids present in serum, is also widely consumed by most populations. For the purpose of testing the potential health benefits of several carotenoids, lutein was supplied as part of an intervention trial to test whether the consumption of these food constituents reduces oxidative damage to human tissue components. Lutein from a natural source (15 mg/d as mixed ester forms) was supplied for 4 months to eighteen non-smoking, apparently healthy volunteers (nine men, nine women) aged 25-45 years. The serum carotenoid profile was analysed at baseline and monthly thereafter. On average, lutein concentrations increased 5-fold after the first month of supplementation (mean 1.34 (range 0.6-3.34) mumol/l). On reviewing the results, in those volunteers whose lutein levels surpassed 1.05 mumol/l (fourteen of seventeen), we tentatively identified lutein monopalmitate along with another unidentified ester (possibly from a monoketocarotenoid) in serum. Lutein levels returned to baseline values and ester forms were not present 3 months after supplementation was discontinued. Their concentrations did not correlate with, and represented less than 3% of, lutein levels achieved in serum. They were observed before development of, and despite the presence of, carotenodermia. To our knowledge, this is the first time xanthophyll esters have been described in human serum. In view of the fact that xanthophyll esters have not been previously reported in serum and chylomicrons, it seems unlikely that these ester forms would be a reflection of the contents of the capsule. They may indicate a 'ceiling effect' on or saturation of the transport capacity for xanthophylls, and may have been re-esterified in vivo because of the unusual dietary conditions. The determination of the physiological importance of this finding will require further investigation, although neither haematological nor biochemical changes were detected.
British Journal Of Nutrition 12/1998; 80(5):445-9. · 3.30 Impact Factor
[show abstract][hide abstract] ABSTRACT: 1. Patients with insulin-dependent diabetes mellitus are classified among the groups at risk for low vitamin status, and recent studies suggest that some degree of supplementation with antioxidants may be beneficial in helping to prevent certain long-term complications of diabetes mellitus. Our objective was to compare the status of the fat-soluble vitamins and antioxidant-related compounds in patients with well-defined insulin-dependent diabetes mellitus with that of their first-degree relatives, controlling seasonal and analytical variability as factors influencing the interpretation of the data. 2. Fifty-four patients with insulin-dependent diabetes mellitus, 214 non-diabetic, first-degree relatives (controls) and 236 unrelated controls were analysed for retinol, tocopherols (alpha and gamma) and main carotenoids in serum (beta-carotene, alpha-carotene, beta-cryptoxanthin, lutein, zeaxanthin and lycopene) by means of a validated HPLC method. 3. Insulin-dependent diabetes mellitus was associated with lower retinol levels and higher levels of beta-carotene, alpha-carotene and beta-cryptoxanthin than sex-matched, first-degree relatives. alpha-Tocopherol, the alpha-tocopherol/cholesterol ratio, gamma-tocopherol, lutein, zeaxanthin and lycopene showed no differences. Retinol and beta-carotene were the variables most closely associated with diabetes. 4. Patients with insulin-dependent diabetes mellitus showed lower serum retinol status together with higher concentrations of provitamin-A carotenoids. Serum fat-soluble antioxidant levels were greater than or equal to those in controls. According to the serum status observed, individuals with diabetes do not require supplementation with alpha-tocopherol or carotenoids, although the need for retinol supplementation in patients with marginal serum levels should be evaluated.
[show abstract][hide abstract] ABSTRACT: The availability of reliable information on food composition is essential both for the evaluation of diet and for nutritional research to relate diet to health or disease. In this article, we compare the total and individual carotenoid contents and the retinol equivalents in fruits and vegetables reported in several food composition tables and HPLC studies. The impact of the variability in carotenoid intake was evaluated on the basis of Spanish National Consumption Statistics and on the values for a standard diet. We identify, from a user's point of view, errors concerning identification of the items and the terms used to refer to the compounds. Food composition tables overestimate (by 2 to 48%) the retinol equivalent intake, whereas they underestimate (by 30 to 50%) the total carotenoid intake according to HPLC data. We study the effect of these main sources of error, their impact on dietary assessment and on the classification of relevant contributors, and the possible consequences with respect to proper diet in terms of nutritional assessment and epidemiological studies. Given the different dietary habits among populations and the fact that certain items may be over- or underestimated in databases, the use of a single database may be misleading as to the rate of carotenoid consumption and the "true" nutrient intake in a given population, thus weakening the reliability of the study and resulting in erroneous conclusions.
Critical Reviews in Food Science and Nutrition 12/1997; 37(7):621-33. · 4.82 Impact Factor
[show abstract][hide abstract] ABSTRACT: To establish reference ranges for use in clinical and epidemiological studies, we determined concentrations of retinol, alpha-tocopherol, beta-carotene, alpha-carotene, beta-cryptoxanthin, lutein, zeaxanthin, and lycopene in 450 Spanish control subjects and 123 Spanish patients with insulin-dependent diabetes mellitus (IDDM). Results were grouped according to sex, and samples were collected throughout the year. Concentrations of retinol were significantly lower and beta-carotene and alpha-carotene were higher in women than in men, both in controls and IDDM subjects, whereas beta-cryptoxanthin concentrations were higher only in control women. Conditional logistic regression analysis showed that retinol, beta-carotene, and lycopene were the variables associated with diabetes. In comparison with other populations, our controls showed, in general, ordinary concentrations of retinol, comparatively low beta-carotene and high beta-cryptoxanthin concentrations, and a relatively high alpha-tocopherol/ cholesterol ratio.
[show abstract][hide abstract] ABSTRACT: As part of a European project to test if 'the consumption of diets rich in carotenoids reduces oxidative damage to human tissue components', 15 mg/day lutein and 100 mg/day alpha-tocopherol were supplied to ten volunteers. alpha-Tocopherol (alone and combined) provoked an increase in alpha-tocopherol and a decrease in gamma-tocopherol serum levels. Lutein levels increased during the first month (given alone) in all controls but they behaved very differently during the following 3 months. Ketocarotenoids (not supplied) increased whereas anhydroluteins (not supplied) did not change, suggesting that they are formed in vivo.
Cancer Letters 04/1997; 114(1-2):179-81. · 4.26 Impact Factor