Beta-carotene and human health: A review of current research

β-Carotene-production methods, biosynthesis from Phaffia rhodozyma, factors affecting its production during fermentation, pharmacological properties: A review

β-Carotene is the most treasured provitamin A carotenoid molecule exhibiting antioxidant and coloring properties and significant applications in the food, pharmaceutical, and nutraceutical industries. β-Carotene has many biological functions within the human body; however, it is not synthesized within the human body, so its requirements are fulfilled through food and pharmaceuticals. Its manufacturing via chemical synthesis or extraction from plants offers low yields with excessive manufacturing expenses, which attracted the researchers toward microbial production of β-carotene. This alternative provides higher yield and low expenses and thus is more economical. Phaffia rhodozyma is a basidiomycetous yeast that is utilized to prevent cardiovascular diseases and cancer and to enhance immunity and antiaging in people. This paper reviews the methods of production of β-carotene, biosynthesis of β-carotene fromP. rhodozyma, factors affecting β-carotene production during fermentation, and pharmacological properties of β-carotene.

Changes in stability and in vitro digestion of egg-protein stabilized emulsions and β-carotene gels in the presence of sodium tripolyphosphate

BACKGROUND

Egg proteins are effective emulsifiers and gelators in food systems. However, the physicochemical stability and control release properties of egg-protein stabilized emulsions and gels need to be further improved. The potential of sodium tripolyphosphate (St) to improve the functionality of egg proteins was evaluated.

RESULTS

The emulsions with St had smaller particle sizes and higher zeta potential, leading to better physical stability. Furthermore, the oxidation stability increased with increasing St contents, possibly due to its metal chelating capacity and the improved emulsifying activity of whole-egg dispersions. Phosphate had a positive impact on the chemical stability of β-carotene in whole-egg liquids and gels, decreasing the degradation during thermal treatment. The gel made with St was firm and broke down slowly, leading to a low rate of digestion and β-carotene release in simulated gastric fluid.

CONCLUSION

This study shows that St is useful to improve the egg proteins stabilized emulsions and gels, which is applicable in the development of emulsion-based food grade gel products. © 2021 Society of Chemical Industry.

Role of Zucchini and Its Distinctive Components in the Modulation of Degenerative Processes: Genotoxicity, Anti-Genotoxicity, Cytotoxicity and Apoptotic Effects

Zucchini (Cucurbita pepo subsp. pepo) is a seasonal vegetable with high nutritional and medical values. Many useful properties of this fruit are attributed to bioactive compounds. Zucchini fruits ("Yellow" and "Light Green" varieties) and four distinctive components (lutein, β-carotene, zeaxanthin and dehydroascorbic acid) were selected. Firstly, the lutein, β-carotene, zeaxanthin and dehydroascorbic acid contents were determined in these fruits. Then, in order to evaluate the safety and suitability of their use, different assays were carried out: (i) genotoxicity and anti-genotoxicity tests to determine the safety and DNA-protection against hydrogen peroxide; (ii) cytotoxicity; and (iii) DNA fragmentation and Annexin V/PI (Propidium Iodide) assays to evaluate the pro-apoptotic effect. Results showed that: (i) all the substances were non-genotoxic; (ii) all the substances were anti-genotoxic except the highest concentration of lutein; (iii) "Yellow" zucchini epicarp and mesocarp exhibited the highest cytotoxic activity (IC50 > 0.1 mg/mL and 0.2 mg/mL, respectively); and (iv) "Light Green" zucchini skin induced internucleosomal DNA fragmentation, β-carotene being the possible molecule responsible for its pro-apoptotic activity. To sum up, zucchini fruit could play a positive role in human health and nutrition due to this fruit and its components were safe, able to inhibit significantly the H₂O₂-induced damage and exhibit anti-proliferative and pro-apoptotic activities toward HL60 (human promyelocytic leukemia cells) tumor cells. The information generated from this research should be considered when selecting potential accessions for breeding program purposes.

Design of microemulsion system suitable for the oral delivery of poorly aqueous soluble beta-carotene

Beta-carotene is a potent antioxidant for maintaining human health. However, its oral absorption is low due to poor aqueous solubility of less than 1 μg/ml. A microemulsion delivery system was designed to solubilize beta-carotene toward enhancing its oral bioavailability. From seven pseudoternary diagrams constructed, three systems were selected with large microemulsion areas suitable for oral administration and dilution in the predominately aqueous gastrointestinal fluids. Conductivity and rheology characterization were conducted along four dilution lines within the selected systems. Three pseudoternary-phase diagrams were selected with large microemulsion regions, >60% of the total phase diagram area, which provide microemulsions with higher drug-loading capacity. A phenomenon was observed by which both propylene glycol and Capmul MCM EP stabilize the microstructure of the microemulsions has been proposed based on the characterization studies. An optimal bicontinuous microemulsion formulation was selected comprising 12% orange oil, 24% Capmul MCM, 18% Tween 20, 6% Labrasol, 20% propylene glycol and 20% water, with a high beta-carotene loading capacity of 140.8 μg/ml and droplet size of 117.4 nm. In conclusion, the developed novel microemulsion formulation allows solubilizing beta-carotene and is a promising basis for further development as a functional beverage.

Genotypic variability of carotenoids in traditional tomato cultivars

Traditional varieties constitute a wide source of genetic variation that can be used per se or to obtain new cultivars with high consumer appeal and nutritional value. This work focuses on the carotenoid and chlorophyll profiles and contents of 53 traditional tomato cultivars, paying particular attention to compounds with recognized health-promoting properties. The study includes fruits with different shapes (oblate, slightly flattened, rounded, heart-shaped, long oblong and pyriform), colors (yellow, pink and red) and sizes (very small to very large). In addition, black colored tomato fruits with yellow, pink or red background color were studied. The highest concentrations of lycopene, β-carotene, phytoene and phytofluene were found in pink and red tomatoes, while the highest concentrations of lutein, violaxanthin, neoxanthin and chlorophylls were found in fruits with a dark coloration, regardless of their background coloration. Finally, the highest concentrations of the studied compounds as a whole (except β-carotene) were found in red- and pink-black varieties. Findings will hopefully contribute to recovering many tomato traditional varieties for use, directly in the field or as donor parents for breeding programs, to increase the nutraceutical properties of commercial varieties.

Thermal degradation of β-carotene studied by ion mobility atmospheric solid analysis probe mass spectrometry: full product pattern and selective ionization enhancement

Atmospheric solid analysis probe mass spectrometry has the capability of capturing full product patterns simultaneously including both volatile and semi-volatile compounds produced at elevated temperatures. Real-time low-energy collision-induced fragmentation combined with ion mobility separations enables rapid identification of the chemical structures of products. We present here for the first time the recognition of full product patterns resulting from the thermal degradation of β-carotene at temperatures up to 600 °C. Solvent vapor-induced ionization enhancement is observed, which reveals parallel thermal dissociation processes that lead to even- and odd-numbered mass products. The drift-time distributions of high mass products, along with β-carotene, were monitored with temperature, showing multiple conformations that are associated with the presence of two β-rings. Products of masses 346/347, however, show a single conformation distribution, which indicates the separation of two β-rings resulting from the direct bond scission at the polyene hydrocarbon chain. The thermal degradation pathways are evaluated and discussed.

Blue-Green Algae Inhibit the Development of Atherosclerotic Lesions in Apolipoprotein E Knockout Mice

Hyperlipidemia and inflammation contribute to the development of atherosclerotic lesions. Our objective was to determine antiatherogenic effect of edible blue-green algae (BGA) species, that is, Nostoc commune var. sphaeroides Kützing (NO) and Spirulina platensis (SP), in apolipoprotein E knockout (ApoE(-/-)) mice, a well-established mouse model of atherosclerosis. Male ApoE(-/-) mice were fed a high-fat/high-cholesterol (HF/HC, 15% fat and 0.2% cholesterol by wt) control diet or a HF/HC diet supplemented with 5% (w/w) of NO or SP powder for 12 weeks. Plasma total cholesterol (TC) and triglycerides (TG) were measured, and livers were analyzed for histology and gene expression. Morphometric analysis for lesions and immunohistochemical analysis for CD68 were conducted in the aorta and the aortic root. NO supplementation significantly decreased plasma TC and TG, and liver TC, compared to control and SP groups. In the livers of NO-fed mice, less lipid droplets were present with a concomitant decrease in fatty acid synthase protein levels than the other groups. There was a significant increase in hepatic low-density lipoprotein receptor protein levels in SP-supplemented mice than in control and NO groups. Quantification of aortic lesions by en face analysis demonstrated that both NO and SP decreased aortic lesion development to a similar degree compared with control. While lesions in the aortic root were not significantly different between groups, the CD68-stained area in the aortic root was significantly lowered in BGA-fed mice than controls. In conclusion, both NO and SP supplementation decreased the development of atherosclerotic lesions, suggesting that they may be used as a natural product for atheroprotection.

Lipid-soluble nutrient status of healthy Omani school children before and after intervention with oily fish meal or re-esterified triacylglycerol fish oil

OBJECTIVES

Over the past two decades, the Omani diet has changed considerably to resemble a high calorie and a low nutrient density Western diet. We investigated the fat soluble nutrient status of children before and after intervention with fish diet or fish oil.

METHODS

Children ages 9 and 10 y (n = 314) were recruited from three randomly selected schools. The schools were assigned to a fish, fish oil, or control group and the children were given a lightly grilled oily fish, a re-esterified triacylglycerol fish oil capsule, or no fish for 12 wk.

RESULTS

Plasma vitamin A, beta carotene, vitamin E concentrations, and vitamin E/total lipid ratio at baseline were 2.7 ± 0.85 μmol/L, 0.68 ± 0.48 μmol/L, 21.1 ± 4.8 μmol/L, and 5.0 ± 0.81 μmol/mmol, respectively, and none of the children were deficient. They were severely deficient (<27.5 nmol/L; 10.5% boys and 28.5% girls), deficient (27.5-44.9 nmol/L; 47.6% boys and 49.4% girls) or insufficient (50-74.9 nmol/L; 34.6% boys and 21.5% girls) in vitamin D; only 7.3% boys and 0.6% girls had optimal status (≥75 nmol/L). Parathyroid hormone (5.0 ± 1.7 versus 5.8 ± 2.1 pmol/L; P < 0.0001) and alkaline phosphatase (225.2 ± 66.6 versus 247.8 ± 73.7 U/L; P < 0.01) levels were lower in boys. Postintervention, the fish oil (54.1 ± 17.5 nmol/L; P < 0.001) and fish (49.2 ± 17.4 nmol/L; P < 0.05) groups had elevated levels of vitamin D compared with the controls (42.3 ± 17.5 nmol/L).

CONCLUSIONS

Vitamin D deficiency is prevalent in Omani school children, but it can be mitigated with omega-3 fatty acid supplementation. Vitamin D plays a crucial role in skeletal and extraskeletal systems. Hence, there is a need for a child-focused program of food fortification and outdoor activities to alleviate the problem.

Colour and viscosity of egg yolk after addition of beetroot to feed for laying hens

The colour and viscosity of egg yolk are among major indicators assessed by consumers and food technology. This study attempts to evaluate the colour and viscosity of yolk in laying hens’ eggs after the addition of dried beetroot (Beta vulgaris L. ssp. esculenta var. rubra) at the amount of 1% and 2% per feeding dose (in July and August 2012). The experiment was performed on 24 hens that were divided into three groups of 8 laying hens. The preparatory phase lasted one week (standard diet), followed by four weeks during which experimental layers received a diet enriched with beetroot. Then, all layers were fed a mixture without beetroot for the following four weeks. Eggs were collected during the whole period of 8 weeks. In total, 30 eggs from each group were subjected to analysis. The colour of eggs was determined using spectrophotometry, by the Colour-guide sphere spex portable colorimeter. The results showed a significant (P < 0.05) increase in value L* of yolk colour in experimental groups whereas values a* and b* (indicators of the international colorimetric scale CIELAB) did not vary significantly. Similarly, specific purity C*ab did not show a significant difference (P < 0.05) between the control and experimental groups. The egg yolk viscosity was lower in experimental groups compared to the control group but the difference was not significant. The addition of dried beetroot at the amount of 1 and 2% per feeding dose had no effect on colour and viscosity. This paper supported the null hypothesis that the addition of dried beetroot to the feeding dose at the amount of 1% and 2% has no effect on the colour and viscosity of egg yolk.

Optimisation of the formulation of β-carotene loaded nanostructured lipid carriers prepared by solvent diffusion method

In this study, the optimised β-carotene loaded nanostructured lipid carriers (NLC) were prepared using the solvent diffusion method. Response surface methodology (RSM) was employed in conjunction with a central composite design (CCD) to evaluate the effect of the preparation variables on particle size and β-carotene stability to optimise the NLC formulation. Quadratic polynomial was the best fitted mathematical model for the experimental results. The statistical evaluations revealed that the lipid phase concentration and the surfactant concentration had significant effect on particle size of NLC. In addition, the influence of the liquid lipid to total lipid ratio and temperature on β-carotene degradation was more important. The optimum formulations with minimum particle size (8-15 nm) and low β-carotene degradation (0-3%) were derived from the fitted models and were experimentally examined which demonstrated a reasonable agreement between experimental and predicted values. Transition electron microscopy (TEM) observations exhibited spherical morphology of β-carotene loaded NLC.

Anti-inflammatory activity of lycopene isolated from Chlorella marina on type II collagen induced arthritis in Sprague Dawley rats

The role of commercially available lycopene (all-trans) from tomato in controlling arthritis has been reported. Even though many reports are available that the cis form of lycopene is more biologically active, no report seems to be available on lycopene (cis and trans) isolated from an easily available and culturable sources. In the present study, the anti-arthritic effect of lycopene (cis and trans) from the algae Chlorella marina (AL) has been compared with lycopene (all-trans) from tomato (TL) and indomethacin (Indo). Arthritis (CIA) was developed in male Sprague dawley rats by collagen and the following parameters were studied. The activities of inflammatory marker enzymes like cyclooxygenase (COX), lipoxygenase (LOX) and myeloperoxidase (MPO) were found to be decreased on treatment with AL when compared to TL and Indo. Changes in Erythrocyte sedimentation rate (ESR), white blood cell (WBC) count, red blood cells (RBC) count, hemoglobin (Hb), C-reactive protein (CRP), rheumatoid factor (RF), and ceruloplasmin levels observed in the blood of arthritic animals were brought back to normal by AL when compared to TL and Indo. Histopathology of paw and joint tissues showed marked reduction in edema on supplementation of AL. Thus these results indicate the potential beneficiary effect of algal lycopene on collagen induced arthritis in rats when compared to TL and even to the commonly used anti-inflammatory drug indomethacin. Therefore lycopene from C. marina would be recommended as a better natural source with increased activity and without side effects in the treatment of anti-inflammatory diseases.

Quantifying the influence of thermal process parameters on in vitro β-carotene bioaccessibility: a case study on carrots

This study describes a detailed and systematic investigation on the effect of thermal processing in terms of temperature and time (kinetic study) on β-carotene in vitro bioaccessibility in carrots. β-Carotene in vitro bioaccessibility increased with increasing processing temperature and time until steady-state conditions were reached after prolonged heating. The bioaccessibility values in steady-state conditions were temperature dependent. The experimental bioaccessibility data could adequately be modeled with a fractional conversion model. For the first time, modeling of processing-induced bioaccessibility changes is reported in literature. The results of the present kinetic study were used to estimate the impact of industrially relevant thermal processes on β-carotene bioaccessibility in carrots by simulation. It was shown that, to achieve a high β-carotene bioaccessibility, processing of carrots is essential (i.e., on the one hand, intense thermal processing or, on the other hand, mild thermal processing combined with intense mechanical processing).

The BioCassava plus program: biofortification of cassava for sub-Saharan Africa

More than 250 million Africans rely on the starchy root crop cassava (Manihot esculenta) as their staple source of calories. A typical cassava-based diet, however, provides less than 30% of the minimum daily requirement for protein and only 10%-20% of that for iron, zinc, and vitamin A. The BioCassava Plus (BC+) program has employed modern biotechnologies intended to improve the health of Africans through the development and delivery of genetically engineered cassava with increased nutrient (zinc, iron, protein, and vitamin A) levels. Additional traits addressed by BioCassava Plus include increased shelf life, reductions in toxic cyanogenic glycosides to safe levels, and resistance to viral disease. The program also provides incentives for the adoption of biofortified cassava. Proof of concept was achieved for each of the target traits. Results from field trials in Puerto Rico, the first confined field trials in Nigeria to use genetically engineered organisms, and ex ante impact analyses support the efficacy of using transgenic strategies for the biofortification of cassava.

Influence of drying by convective air dryer or power ultrasound on the vitamin C and β-carotene content of carrots

Convective air drying and power ultrasound effects on vitamin C and β-carotene contents in carrots were studied. For convective air drying, a central composite face-centered design fitting temperature between 40 and 65 °C and air flow rate between 2 and 6 × 10(-1) m/s were used; previously, carrots were blanched. Likewise, ultrasound drying was performed on both unblanched and blanched carrots at 20, 40, and 60 °C for 120, 90, and 75 min, respectively. Blanching had a sharp effect on vitamin C and β-carotene degradation (80-92% retentions, respectively), and convective air drying led to further losses (32-50% and 73-90% retentions, respectively). According to the response surface model, a combination of 40 °C and 6 × 10(-1) m/s will maximize vitamin C retention in dried carrots, whereas 40 °C and 3.3 × 10(-1) m/s will ensure the highest β-carotene content. Ultrasound drying caused higher vitamin C and β-carotene retention (82-92% and 96-98%, respectively) than convective air drying. Blanched carrots dehydrated by ultrasound showed retentions of 55% and 88% of vitamin C and β-carotene, respectively. Ultrasound drying at 20 °C for 120 min caused the maximum vitamin C and β-carotene contents. Therefore, power ultrasound may be considered a valuable tool to obtain high nutritive dehydrated carrots.

Beta-carotene isomerization kinetics during thermal treatments of carrot puree

The effect of thermal processing on the stability of beta-carotene in carrot puree was investigated in a broad temperature range (80-150 degrees C). Heat induced changes in the stability of beta-carotene resulting in the conversion into its cis-isomers until an equilibrium state was reached after prolonged heating. By using nonlinear one-step regression analysis, the overall isomerization of all-trans-beta-carotene and the formation of individual cis-isomers could be modeled with a fractional conversion model. The Arrhenius equation was used to describe the temperature dependence of the reaction rate constants. As indicated by the low activation energies for all compounds (11 kJ mol(-1)), the isomerization rate constants showed little sensitivity toward the treatment temperature. The temperature dependence of the equilibrium concentration values after prolonged heating (C(f)) varied for the different compounds, but in all cases, a linear relation between the C(f) values and the treatment temperature could be noted. Although isomerization was observed as a result of thermal processing, it could be concluded that during industrially relevant heating processes, the retention of all-trans-beta-carotene in plain carrot puree was relatively high, which is most likely due to the presence of the protecting food matrix.

Concentrações de vitamina A no leite humano e características socioeconômicas e nutricionais maternas: resultados de estudos brasileiros

OBJETIVOS: agregar e discutir os resultados de estudos realizados no Brasil que avaliaram a concentração de vitamina A no leite materno. FONTES DOS DADOS: foram pesquisadas as bases LILACS, Banco de Teses da Capes, SciELO (Scientific Electronic Library), e Plataforma Lattes -seção de produção científica. As palavras-chaves utilizadas foram: gestantes, lactante, concentração de vitamina A no leite humano, Brasil. As buscas foram realizadas em 2006 e atualizadas em março de 2008. Foram incluídos todos os estudos localizados. SÍNTESE DOS DADOS: foram localizados 14 estudos, publicados entre 1988 e 2008, heterogêneos quanto ao tamanho da amostra, fase do leite, período do dia da coleta e método de determinação das concentrações de vitamina A. Foram descritas concentrações médias de vitamina A no leite humano entre 0,62 e 4,50 µmol/L. CONCLUSÕES: não houve consenso sobre a relação entre concentração de vitamina A no leite humano e vitamina A dietética, estado nutricional materno, características obstétricas e demográficas e duração da gestação. Sugere-se que estudos futuros utilizem, amostras de leite maduro, coletadas aleatoriamente ao longo dos diferentes períodos do dia, e a utilização do high performance liquid chromatography - HPLC - como método de determinação de vitamina A.

Beta-carotene isomer composition of sub- and supercritical carbon dioxide extracts. Antioxidant activity measurement

In the present work sub- and supercritical extraction conditions using carbon dioxide were studied in order to obtain extracts with different compositions from the green microalgae Dunaliella salina. Different compositions of beta-carotene isomers were identified in the extracts by using HPLC-DAD. Also, antioxidant activity of the extracts was measured using a TEAC assay. An experimental design was applied considering two factors, extraction pressure and temperature, in a wide range of values, trying to maximize the extraction yield. Higher yields were obtained at high pressures and low temperatures, that is, at higher CO2 densities. Attempts were made to correlate the antioxidant activity of the extracts with their chemical composition by means of principal component analysis. A certain relationship was found between their antioxidant activity and the isomeric composition of beta-carotenes. As a result, an original equation is proposed to predict the antioxidant activity of extracts from D. salina in terms of the ratio 9-cis-beta-carotene/all-trans-beta-carotene, the concentration of alpha-carotene, and, especially, the concentration of 9-cis-beta-carotene.

Moult speed constrains the expression of a carotenoid-based sexual ornament

We investigated the effect of moult speed on the expression of a sexually selected, carotenoid-based feather ornament in the rock sparrow (Petronia petronia). We experimentally accelerated the moult speed of a group of birds by exposing them to a rapidly decreasing photoperiod and compared the area and the spectral characteristics of their ornaments with those of control birds. Birds with accelerated moulting rate showed a smaller yellow patch with lower yellow reflectance compared to their slow-moulting counterparts. Considering that the time available for moulting is usually constrained between the end of the breeding season and migration or wintering, carotenoid feather ornaments, whose expression is mediated by moult speed, may convey long term information about an individual's condition, potentially encompassing the previous breeding season. Furthermore, the observed trade-off between moult speed and ornament expression may represent a previously unrecognized selective advantage for early breeding birds.

Investigation of the vitamins A and E and β-carotene content in milk from UK organic and conventional dairy farms

During a 12-month longitudinal study, bulk-tank milk was collected from organic (n=17) and conventional (n=19) dairy farms in the UK. Milk samples were analysed for vitamin A (retinol), vitamin E (α-tocopherol) and β-carotene content. The farming system type, herd production level and nutritional factors affecting the milk fat vitamin content were investigated by use of mixed model analyses. Conventionally produced milk fat had a higher mean content of vitamin A than organically produced milk fat, although there were no significant differences in the vitamin E or β-carotene contents between the two types of milk fat. Apart from farming system, other key factors that affected milk fat vitamin content were season, herd yield and concentrate feeding level. Milk vitamin content increased in the summer months and in association with increased concentrate feeding, whilst higher-yielding herds had a lower milk vitamin E and β-carotene content. Thus, conventional dairy farms in the UK produced milk with a higher vitamin A content, possibly owing to increased vitamin A supplementation in concentrate feeds. However, knowledge of the effects of season, access to fresh grazing or specific silage types and herd production level may also be used by all producers and processors to enhance the vitamin content in milk.

Potential of NIR-FT-Raman spectroscopy in natural carotenoid analysis

This paper demonstrates the special advantages of FT-Raman spectroscopy for in situ studies of several carotenoids that occur ubiquitously in the plant kingdom. Spectra obtained from various tissues of a range of plant species indicate that the wavenumber location of C=C stretching vibrations is mainly influenced both by the length as well as by the terminal substituents of the polyene chain of carotenoids and by their interaction with other plant constituents. The obtained results show also the usefulness of Raman spectroscopy in the investigation of cis-trans isomerization of carotenoids during processing. Additionally, 2-D Raman mappings present a unique possibility to evaluate the individual distribution of carotenoids in the intact plant tissue; in this context different 7-, 8-, and 9-double bond conjugated carotenoids can be analyzed independently in the same sample. Furthermore, the use of Raman spectroscopy for in situ detection of unstable substances such as epoxycarotenoids is discussed.

Carotenoid and retinoid metabolism: insights from isotope studies

Use of isotopes as tracers has had an important role in elucidating key features of vitamin A and retinoid metabolism in animal models and humans. Their use has shown that beta-carotene absorption is variable, and that the appearance of beta-carotene and its metabolites in the blood by time since dosing follows characteristic patterns. Retinol formed from beta-carotene shows a different pattern, as does lutein. In this article, we summarize and discuss insights and some surprises into the absorption and metabolism of vitamin A, beta-carotene, and lutein that were gained with the use of isotope tracers in humans, rats, and cells as models.

Anticancer and health protective properties of citrus fruit components

Accumulated evidence from experimental and epidemiological studies indicates that there is a low risk of degenerative diseases, cardiovascular disease, hypertension, cataract, stroke and, in particular, cancers in people with a high intake of fruit and vegetables. This protective effect is assumed to be associated mainly with the antioxidant activities of either individual or interacting bioactive components present in the fruits and vegetables, and with other biochemical and physical characteristics of the identified and unknown bioactive components. The implicated bioactive components present in citrus fruits include vitamin C, beta-carotene, flavonoids, limonoids, folic acid, and dietary fibre. A high intake of citrus fruits may reduce the risk of degenerative diseases.

Dietary carotenoids contribute to normal human skin color and UV photosensitivity

The aim of the current study was to determine whether dietary carotenoids influence skin pigmentation and UV photosensitivity in a healthy unsupplemented panel (n = 22) of Caucasian (skin Type II) subjects. Skin spectrophotometric and tristimulus (L*a*b*) CR200 chromameter readings were made at various body sites to objectively measure skin carotenoid levels and skin color, respectively. The minimal erythemal dose (MED) was also measured to determine the intrinsic UV photosensitivity of the skin. We found that tristimulus b* values (but not L* and a* values) were consistently and closely correlated with skin carotenoid levels at a number of body sites including the back (r = 0.85, P < 0.00001), forehead (r = 0.85, P < 0.00001), inner forearm (r = 0.75, P < 0.0001) and palm of the hand (r = 0.78, P < 0.0001). Skin carotenoid levels and MED were also correlated in these subjects (r = 0.66, P < 0.001), as were tristimulus b* values and MED (r = 0.71, P < 0.0002). From these observations, we conclude that carotenoids from a normal, unsupplemented diet accumulate in the skin and confer a measurable photoprotective benefit (at least in lightly pigmented Caucasian skin), that is directly linked to their concentration in the tissue. Carotenoids also appear to contribute measurably and significantly to normal human skin color, in particular the appearance of "yellowness" as defined objectively by CR200 tristimulus b* values. On the basis of these findings we believe that objective measurements of skin color, in particular tristimulus b* values, may be a potentially useful means of monitoring dietary carotenoid status and assessing UV photosensitivity in Caucasian populations.

Serum carotenoid depletion follows first-order kinetics in healthy adult women fed naturally low carotenoid diets

Dietary intakes of carotenoids are highly variable in human populations as are serum carotenoid concentrations. However, there are few controlled data relating carotenoid intake to concentration. Most of the data that are available are from measurements of the absorption and decay of large pharmacologic doses of carotenoids, and are therefore of unknown physiologic relevance. Our objective was to determine the half-life (t(1/2)) of the most abundant carotenoids in blood serum from healthy adult women living under controlled conditions. As part of two carotenoid isotopic studies, we measured serum concentrations of beta-carotene, alpha-carotene, lutein, zeaxanthin, beta-cryptoxanthin and lycopene in 19 healthy young adult women that were fed controlled low carotenoid diets for approximately 10 wk. All other nutrients (vitamins A, E and C) were provided at 100-150% of the 1989 U.S. recommended dietary allowance levels. Exercise and activities were controlled throughout the studies to simulate usual activity patterns. Carotenoid concentrations were measured by reversed-phase HPLC. Serum carotenoid concentration decreases during depletion followed first-order kinetics. The half-lives determined in decreasing order were as follows: lutein (76 d) > alpha-carotene (45 d) = beta-cryptoxanthin (39 d) = zeaxanthin (38 d) = beta-carotene (37 d) > lycopene (26 d). Half-lives were unrelated to physical or demographic characteristics such as body mass, body fat, racial background or age in these relatively homogeneous groups. Carotenoids decreased by similar first-order mechanisms, although the rates differed for individual carotenoids.

Suplementação de vitaminas na prevenção de câncer

Este trabalho constitui uma revisão de dados epidemiológicos sobre a relação entre o consumo de vitaminas e prevenção de câncer. Estudos observacionais evidenciam uma associação inversa consistente entre a ingestão de frutas e hortaliças e risco de câncer, e um efeito protetor das vitaminas C, E e dos carotenóides contra certos tipos de câncer. Resultados de estudos de intervenção, na prevenção primária de câncer, são contraditórios, sendo que em dois desses estudos o beta-caroteno, suplementado em doses consideradas farmacológicas, isolado ou associado à vitamina E ou à vitamina A, mostrou-se deletério para tabagistas. Ao contrário, a ingestão de doses mais fisiológicas de antioxidantes parece ser mais eficaz, sendo que a ação sinérgica dessas substâncias na quimioprevenção de câncer já foi demonstrada tanto em modelo in vivo de carcinogênese quanto em estudo epidemiológico de intervenção. Como estratégia de prevenção de câncer preconiza-se o consumo de dietas ricas em frutas e hortaliças, que aportem cerca de 150 mg de vitamina C, 30 mg de vitamina E e 4 mg de carotenóides. A ingestão de quantidades mais elevadas, na forma de suplementos, não está recomendada.

Variability of the conversion of beta-carotene to vitamin A in women measured by using a double-tracer study design

BACKGROUND

Blood beta-carotene and vitamin A responses to oral beta-carotene are variable in humans. Some individuals are characterized as responders and others as low- or nonresponders. A better understanding of the conditions that produce the variability is important to help design public health programs that ensure vitamin A sufficiency.

OBJECTIVE

Our objective was to assess variability in absorption and conversion of beta-carotene to vitamin A in vivo in humans by using a novel double-tracer ¿hexadeuterated (D(6)) beta-carotene and D(6) retinyl acetate approach.

DESIGN

Eleven healthy women were housed at the US Department of Agriculture Western Human Nutrition Research Center metabolic unit for 44 d, where they consumed diets adequate in vitamins and minerals except for carotenoids. After an adaptation period, the women were given 30 micromol D(6) retinyl acetate orally, followed 1 wk later with 37 micromol D(6) beta-carotene (approximately equimolar doses). Time-dependent plasma concentration curves were determined for D(6) retinol, D(6) beta-carotene, and trideuterated (D(3)) retinol (derived from D(6) beta-carotene).

RESULTS

Mean (+/-SE) absorption of D(6) beta-carotene was 3.3 +/- 1.3% for all subjects. The mean conversion ratio was 0.81 +/- 0.34 mol D(3) retinol to 1 mol D(6) beta-carotene for all subjects. However, only 6 of the 11 subjects had plasma D(6) beta-carotene and D(3) retinol concentrations that we could measure. The mean absorption of D(6) beta-carotene in these 6 subjects was 6.1 +/- 0.02% and their conversion ratio was 1.47 +/- 0.49 mol D(3) retinol to 1 mol D(6) beta-carotene. The remaining 5 subjects were low responders with </=0.01% absorption and a mean conversion ratio of 0.014 +/- 0.004 mol D(3) retinol to 1 mol D(6) beta-carotene.

CONCLUSION

Variable absorption and conversion of beta-carotene to vitamin A both contribute to the variable response to consumption of beta-carotene. Our double-tracer approach is adaptable for identifying efficient converters of carotenoid to retinoid.

Dietary lutein stimulates immune response in the canine

The possible immuno-modulatory action of dietary lutein in dogs is not known. Female Beagle dogs (17-18-month old; 11.4+/-0.4kg body weight) were supplemented daily with 0, 5, 10 or 20mg lutein for 12 weeks. Delayed-type hypersensitivity (DTH) response to saline, phytohemagglutinin (PHA) and a polyvalent vaccine was assessed on Weeks 0, 6 and 12. Blood was sampled on Weeks 0, 2, 4, 8 and 12 to assess (1) lymphocyte proliferative response to PHA, concanavalin A (Con A), and pokeweed mitogen (PWM), (2) changes in peripheral blood mononuclear cell (PBMC) populations, (3) interleukin-2 (IL-2) production and (4) IgG and IgM production. After the completion of 12-week study, we continued to collect the blood weekly up to 17 weeks to evaluate the changes in immunoglobulin production upon first and second antigenic challenges on Weeks 13 and 15. Plasma lutein+zeaxanthin was undetectable in unsupplemented dogs but concentrations increased (P<0.05) rapidly on Week 2 in lutein-supplemented dogs. Thereafter, concentrations generally continued to increase in dose-dependent manner, albeit at a much slower rate. Dogs fed lutein had heightened DTH response to PHA and vaccine by Week 6. Dietary lutein increased (P<0.05) lymphocyte proliferative response to all three mitogens and increased the percentages of cells expressing CD5, CD4, CD8 and major histocompatibility complex class II (MHC II) molecules. The production of IgG increased (P<0.05) in lutein-fed dogs after the second antigenic challenge. Lutein did not influence the expression of CD21 lymphocyte marker, plasma IgM or IL-2 production. Therefore, dietary lutein stimulated both cell-mediated and humoral immune responses in the domestic canine.

Nicotinamide (vitamin B3) as an effective antioxidant against oxidative damage in rat brain mitochondria

Nicotinamide (vitamin B3) an endogenous metabolite, showed significant inhibition of oxidative damage induced by reactive oxygen species (ROS) generated by ascorbate-Fe2+ and photosensitization systems in rat brain mitochondria. It protected against both protein oxidation and lipid peroxidation, at millimolar concentrations. Inhibition was more pronounced against oxidation of proteins than peroxidation of lipids. Chemically related endogenous compounds, tryptophan and isonicotinic acid, showed comparable inhibitory properties. The protective effect observed, at biologically relevant concentrations, with nicotinamide was more than that of the endogenous antioxidants ascorbic acid and alpha-tocopherol. Hence our studies suggest that nicotinamide (vitamin B3) can be considered as a potent antioxidant capable of protecting the cellular membranes in brain, which is highly susceptible to prooxidants, against oxidative damage induced by ROS.

Ascorbate is depleted by smoking and repleted by moderate supplementation: a study in male smokers and nonsmokers with matched dietary antioxidant intakes

BACKGROUND

Lack of reliable dietary data has hampered the ability to effectively distinguish between effects of smoking and diet on plasma antioxidant status. As confirmed by analyses of comprehensive food-frequency questionnaires, the total dietary intakes of fruit and vegetables and of dietary antioxidants were not significantly different between the study groups in the present study, thereby enabling isolation of the effect of smoking.

OBJECTIVE

Our objective was to investigate the effect of smoking on plasma antioxidant status by measuring ascorbic acid, alpha-tocopherol, gamma-tocopherol, beta-carotene, and lycopene, and subsequently, to test the effect of a 3-mo dietary supplementation with a moderate-dose vitamin cocktail.

DESIGN

In a double-blind, placebo-controlled design, the effect of a vitamin cocktail containing 272 mg vitamin C, 31 mg all-rac-alpha-tocopheryl acetate, and 400 microg folic acid on plasma antioxidants was determined in a population of smokers (n = 37) and nonsmokers (n = 38). The population was selected for a low intake of fruit and vegetables and recruited from the San Francisco Bay area.

RESULTS

Only ascorbic acid was significantly depleted by smoking per se (P < 0.01). After the 3-mo supplementation period, ascorbic acid was efficiently repleted in smokers (P < 0.001). Plasma alpha-tocopherol and the ratio of alpha- to gamma-tocopherol increased significantly in both supplemented groups (P < 0.05).

CONCLUSIONS

Our data suggest that previous reports of lower concentrations of plasma vitamin E and carotenoids in smokers than in nonsmokers may primarily have been caused by differences in dietary habits between study groups. Plasma ascorbic acid was depleted by smoking and repleted by moderate supplementation.