The role of carotenoids in human health

Whole grain cereals: functional components and health benefits

Cereal-based food products have been the basis of the human diet since ancient times. Dietary guidelines all over the world are recommending the inclusion of whole grains because of the increasing evidence that whole grains and whole-grain-based products have the ability to enhance health beyond the simple provision of energy and nutrients. In this review we will examine the main chemical components present in whole grains that may have health enhancing properties (dietary fiber, inulin, beta-glucan, resistant starch, carotenoids, phenolics, tocotrienols, and tocopherols) and the role that whole grains may play in disease prevention (cardiovascular diseases and strokes, hypertension, metabolic syndrome, type 2 diabetes mellitus, obesity, as well as different forms of cancer). The knowledge derived from the functional properties of the different chemical components present in whole grains will aid in the formulation and development of new food products with health enhancing characteristics.

Carotenoids in nature: insights from plants and beyond

Carotenoids are natural isoprenoid pigments that provide leaves, fruits, vegetables and flowers with distinctive yellow, orange and some reddish colours as well as several aromas in plants. Their bright colours serve as attractants for pollination and seed dispersal. Carotenoids comprise a large family of C40 polyenes and are synthesised by all photosynthetic organisms, aphids, some bacteria and fungi alike. In animals carotenoid derivatives promote health, improve sexual behaviour and are essential for reproduction. As such, carotenoids are commercially important in agriculture, food, health and the cosmetic industries. In plants, carotenoids are essential components required for photosynthesis, photoprotection and the production of carotenoid-derived phytohormones, including ABA and strigolactone. The carotenoid biosynthetic pathway has been extensively studied in a range of organisms providing an almost complete pathway for carotenogenesis. A new wave in carotenoid biology has revealed implications for epigenetic and metabolic feedback control of carotenogenesis. Developmental and environmental signals can regulate carotenoid gene expression thereby affecting carotenoid accumulation. This review highlights mechanisms controlling (1) the first committed step in phytoene biosynthesis, (2) flux through the branch to synthesis of α- and β-carotenes and (3) metabolic feedback signalling within and between the carotenoid, MEP and ABA pathways.

Effects of tomato- and soy-rich diets on the IGF-I hormonal network: a crossover study of postmenopausal women at high risk for breast cancer

To determine whether dietary modifications with tomato products and/or a soy supplement affected circulating levels of insulin-like growth factor (IGF)-1 and other markers of cell signaling in postmenopausal women at risk for developing breast cancer. Eligible and consented postmenopausal women at high risk for developing breast cancer were enrolled in a 26-week, two-arm (tomato and soy, 10 weeks each) longitudinal dietary intervention study in which each woman served as her own control. Changes in biochemical endpoints including IGF-I, IGF-binding protein (IGFBP)-3, estradiol, sex hormone-binding globulin (SHBG), C-peptide, and insulin were measured for each intervention arm. Carotenoid and isoflavone levels were measured to assess adherence. Significant increases in carotenoid and isoflavone levels during the tomato and soy study arms, respectively, suggested that women were adherent to both arms of the intervention. The tomato-rich diet had little effect on cell-signaling biomarkers previously associated with breast cancer risk. However, results of the soy intervention showed that concentrations of IGF-I and IGFBP-3 increased by 21.6 and 154.7 μmol/L, respectively (P = 0.001 for both) and SHBG decreased by 5.4 μmol/L (P < 0.001) after consumption of the soy protein supplement. Increased soy protein intake may lead to small, but significant, increases in IGF-I and IGFBP-3. Soy consumption also led to a significant decrease in SHBG, which has been hypothesized to promote, rather than prevent, cancer growth. Previous epidemiologic studies, however, have confirmed protective effect of soy on breast cancer. Additional investigation about the effect of soy on breast cancer risk and its mechanism of action is warranted.

Deposition of carotenoids in egg yolk by short-term supplement of coloured carrot (Daucus carota) varieties as forage material for egg-laying hens

BACKGROUND

Supplying egg-laying hens with different forage materials may influence egg production and quality. The aim of this study was to examine the short-term effects of standard feed plus 70 g day(-1) per hen of three coloured carrot varieties (orange, yellow and purple) as forage material in comparison with a standard feed control on egg production, egg yolk colour and deposition of carotenoids in the yolk.

RESULTS

Carrot supplementation reduced feed intakes significantly, but not on a dry matter basis. Orange carrot treatment significantly reduced egg mass production, whereas yellow and purple carrot treatments did not differ from the control. Egg and yolk weights of all carrot-supplemented treatments were significantly lower than those of the control, but yolk percentages were similar. Yolk redness increased significantly in the order control < yellow < orange < purple. A similar trend was seen for yolk yellowness, but yellow and orange carrots reached the same level. Yolk colour and carotenoid contents correlated positively and significantly. In particular, purple carrot treatment increased the yolk content of lutein (>1.5-fold) and beta-carotene (>100-fold) compared with the control.

CONCLUSION

Supplementing the feed of egg-laying hens with coloured carrots efficiently increased yolk colour parameters and carotenoid contents, which gives opportunities for improved nutritional value of eggs from forage material-supplemented hens.

Effects of lutein and zeaxanthin on aspects of eye health

Lutein and zeaxanthin are members of the oxygenated carotenoids found particularly in egg yolks and dark-green leafy vegetables. A great deal of research has focused on their beneficial roles in eye health. The present article summarises the current literature related to the bioactivity of these carotenoids, emphasising their effects and possible mechanisms of action in relation to human eye health. Available evidence demonstrates that lutein and zeaxanthin are widely distributed in a number of body tissues and are uniquely concentrated in the retina and lens, indicating that each has a possible specific function in these two vital ocular tissues. Most of epidemiological studies and clinical trials support the notion that lutein and zeaxanthin have a potential role in the prevention and treatment of certain eye diseases such as age-related macular degeneration, cataract and retinitis pigmentosa. The biological mechanisms for the protective effects of these carotenoids may include powerful blue-light filtering activities and antioxidant properties. Although most studies point towards significant health benefits from lutein and zeaxanthin, further large-scale randomised supplementation trials are needed to define their effects on ocular function in health and disease.

Determination of toxic perilla ketone, secondary plant metabolites and antioxidative capacity in five Perilla frutescens L. varieties

Perilla frutescens L. is a traditional Asian crop with multiple uses. Several varieties exist but only little data is available about the content of the toxic perilla ketone and secondary plant metabolites of those genotypes. To estimate the nutritional value of this new vegetable more information about those components is necessary. We investigated five genotypes of P. frutescens L. to determine their content of PK, phenolics, carotenoids and AC. AC was examined using ABTS-decolorization assay and lipid peroxidation assay. Carotenoids were identified and quantified by HPLC analysis, phenolics were quantified by means of Folin-Ciocalteu and PK was identified by GC/MS. Two genotypes were found to contain PK, a potent lung toxin, and are therefore not suitable for consumption. The phenolic content and corresponding antioxidative capacity of all genotypes is considerably high compared to other vegetables. All genotypes moreover contain notably high concentrations of carotenoids with contents up to fivefold higher than in other carotenoid rich vegetables. The results indicate that there are several genotypes which are not suitable for consumption due to their content of PK. However PK free genotypes are rich sources of natural antioxidants, and may therefore be considered as a novel vegetable with health promoting properties.

Site-specific concentrations of carotenoids in adipose tissue: relations with dietary and serum carotenoid concentrations in healthy adults

BACKGROUND

Dietary carotenoids are related to a decreased risk of certain diseases. Serum and adipose tissue carotenoid concentrations are used as biomarkers of intake.

OBJECTIVES

The objectives of this study were to evaluate site-specific concentrations of carotenoids in adipose tissue and to examine relations between carotenoid concentrations in the diet, serum, and adipose tissue.

DESIGN

Healthy adults (12 women and 13 men) participated in this cross-sectional study. Dietary carotenoids over the past year were assessed with a food-frequency questionnaire. Serum and adipose tissue biopsy samples were collected from the abdomen, buttock, and inner thigh for the measurement of carotenoids by HPLC.

RESULTS

Many adipose carotenoids were inversely related to percentage body fat, although lycopene was the only carotenoid inversely correlated with all 3 sites. Most of the carotenoids were significantly higher in the abdominal adipose tissue than in the thigh (P < 0.05). Concentrations of alpha-carotene, beta-carotene, 5-cis-lycopene, and total carotenoids were significantly higher in the buttocks than in the thigh (P < 0.05). Concentrations of alpha-carotene, cis-lycopene, and lutein (with or without zeaxanthin) were significantly higher in the abdomen than in the buttocks (P < 0.05). Dietary intake was significantly correlated with serum concentrations of alpha-carotene, beta-carotene, beta-cryptoxanthin, and total carotenoids. Carotenoid intake was significantly correlated with adipose tissue concentrations of alpha-carotene, beta-carotene, beta-cryptoxanthin, cis-lycopene, and total carotenoids (P < 0.05) but varied by site. Of all the adipose tissue sites evaluated, the abdomen showed the strongest correlation with long-term dietary carotenoid intakes and with serum (indicator of short-term intake) for most carotenoids.

CONCLUSIONS

Body fat may influence the tissue distribution of carotenoids. Abdominal adipose tissue carotenoid concentrations may be a useful indicator of carotenoid status.

Associations between lutein, zeaxanthin, and age-related macular degeneration: an overview

Age-related macular degeneration, the leading cause of blindness in the elderly, is a degenerative condition of the macula characterized by death or dysfunction of the photoreceptors. With the aging population growing, the incidence of age-related macular degeneration is expected to increase. This raises concern about the future of visual dysfunction related falls and the resulting injuries in the elderly population. Lutein and zeaxanthin are macular pigments that may play a role in reducing the development and progression of age-related macular degeneration. Evidence is accumulating on the consumption of lutein and zeaxanthin (in whole food or supplemental form), the resulting concentrations in the serum, and tissue distribution throughout the body, particularly in the retina. Lutein and zeaxanthin intake increases serum concentrations which in turn increases macular pigment density. Existing literature focuses on factors affecting macular pigment density, functions of lutein and zeaxanthin as blue-light filters and antioxidants, and risk factors associated with age-related macular degeneration. Few studies have focused on the impact of dietary lutein and zeaxanthin on retinal function and the potential to preserve vision and prevent further degeneration. This presents an opportunity for further research to determine an effective dose that delays the progression of age-related macular degeneration.

Antioxidant capacity and antimutagenic activity of natural oleoresin from greenhouse grown tomatoes (Lycopersicon esculentum)

Natural oleoresins rich in lycopene were obtained from two varieties of tomato (Zedona and Gironda) and their nutraceutical potential (antioxidant and antimutagenic capacity) was evaluated. Both oleoresins had a high content of lycopene, 58.33+/-1.67 mg/g (Zedona) and 63.97+/-0.80 mg/g (Gironda). The antioxidant activity (AA) of the oleoresins by beta-carotene method were 56.4-74.5% (Zedona) and 51-72.8% (Gironda), while when using the free radical stable 2,2-diphenyl-picryl-hydrazyl (DPPH) method, the antiradical activity (ARA) was determined to be 18.2-32.7% (Zedona) and 16.6-26.7% (Gironda) for the concentrations tested that of 200-400 microM equivalents of lycopene. The antimutagenic activity of the oleoresins was tested against aflatoxin B1 (AFB1) using the microsuspension assay, both varieties had a very high antimutagenic potential against AFB1 (60-66%).These results suggest the NCRT can be taken advantage to obtaining rich oleoresin in lycopene with a nutraceutical value.

Time- and media-dependent secondary carotenoid accumulation in Haematococcus pluvialis

The green microalgae Haematococcus pluvialis synthesizes secondary carotenoids after exposure to environmental stress, a process that is used for the biotechnological production of astaxanthin (Ax). This study reports, for the first time, the medium-dependent changes in the carotenoid pattern throughout the cultivation process as well as the exact composition of carotenoids and their fatty acid mono- and diesters using LC-MS. Secondary carotenoid formation started immediately upon exposure to nutrient depletion and high light conditions. Ax and its corresponding mono- and diesters were detected simultaneously. After 15 days of cultivation, no significant changes were detected in carotenoid composition; however, the ratio between carotenoid mono- and diesters still varied. Main carotenoids were identified as Ax linolenate and Ax oleate, but also five adonirubin and one lutein monoester were detected. The influence of three different autotroph media was studied on carotenoid content, which reached a maximum 16.1 mg/g dry weight. The results indicate that media composition has an influence on the ratio of Ax mono- to diester but not on the qualitative composition of secondary carotenoids in H. pluvialis. Beside the pathway via echinenone, canthaxanthin and adonirubin the results indicate that Ax biosynthesis takes place via another route: from beta-carotene via beta-cryptoxanthin, zeaxanthin and adonixanthin.

Carotenoids in raw and parboiled brown and milled rice

Color measurements on flour of five raw rice cultivars with different degrees of milling (DOM) showed that red and brown pigments are concentrated in the outer rice layers, i.e. bran and outer endosperm (DOM < 15%). Extinction measurements (lambda 450 nm) of rice extracts showed that yellow pigments are virtually absent in the middle and core endosperm (DOM > 15%). The relation between the extinction values and the yellow color parameter (b*) showed that both are representative for the yellow pigment content of flour from rice with DOM lower than 9%. Determinations of the carotenoid levels in raw brown rice samples indicated that carotenoid levels in raw brown rice are lower than in common nonrice cereals. The major brown rice carotenoids are beta-carotene and lutein (both ca. 100 ng/g), while zeaxanthin levels are lower (ca. 30 ng/g). Regression analyses indicated that yellowness, extinction values, and quantitative carotenoid data are related. b*-Values and contents of total carotenoids (r = 0.70), beta-carotene (r = 0.84), lutein (r = 0.78), and zeaxanthin (r = 0.83) were linearly related. However, extinction values (lambda 450 nm) and contents of total carotenoids (r = 0.92), beta-carotene (r = 0.91), lutein (r = 0.89), and zeaxanthin (r = 0.84) showed the best correlations. The three-step hydrothermal treatment parboiling reduces carotenoid contents of brown rice to trace levels. Consequently, pigments do not contribute to the final color of milled parboiled rice.

Dietary terpenoids and prostate cancer chemoprevention

Cancer chemoprevention by phytochemicals may be one of the most feasible approaches for cancer control. Phytochemicals obtained from vegetables, fruits, spices, teas, herbs and medicinal plants, such as terpenoids and other phenolic compounds, have been proven to suppress experimental carcinogenesis in various organs in pre-clinical models. Recent studies have indicated that mechanisms underlying chemopreventive potential may be a combination of antioxidant, anti-inflammatory, immune-enhancing, and hormone modulation effects, with modification of drug metabolizing enzymes, influence on cell cycle and cell differentiation, induction of apoptosis, suppression of proliferation and angiogenesis playing roles in the initiation and secondary modification stages of neoplastic development. Specific features of prostate cancer, such as high prevalence and long latency period provides ample opportunities for chemopreventive agents to work at various stages of disease progression. Finally, suitable populations with appropriate risk factors, including the presence of pre-malignant lesions and genetic predispositions, need to be well characterized for future chemopreventive interventions. Here we review naturally occurring dietary terpenoids as useful agents for prostate cancer chemoprevention with reference to their classes and sources.

Long-term strict raw food diet is associated with favourable plasma beta-carotene and low plasma lycopene concentrations in Germans

Dietary carotenoids are associated with a reduced risk of chronic diseases. Raw food diets are predominantly plant-based diets that are practised with the intention of preventing chronic diseases by virtue of their high content of beneficial nutritive substances such as carotenoids. However, the benefit of a long-term adherence to these diets is controversial since little is known about their adequacy. Therefore, we investigated vitamin A and carotenoid status and related food sources in raw food diet adherents in Germany. Dietary vitamin A, carotenoid intake, plasma retinol and plasma carotenoids were determined in 198 (ninety-two male and 106 female) strict raw food diet adherents in a cross-sectional study. Raw food diet adherents consumed on average 95 weight% of their total food intake as raw food (approximately 1800 g/d), mainly fruits. Raw food diet adherents had an intake of 1301 retinol activity equivalents/d and 16.7 mg/d carotenoids. Plasma vitamin A status was normal in 82% of the subjects (> or = 1.05 micromol/l) and 63% had beta-carotene concentrations associated with chronic disease prevention (> or = 0.88 micromol/l). In 77% of subjects the lycopene status was below the reference values for average healthy populations (< 0.45 micromol/l). Fat contained in fruits, vegetables and nuts and oil consumption was a significant dietary determinant of plasma carotenoid concentrations (beta-carotene r 0.284; P < 0.05; lycopene r 0.168; P = 0.024). Long-term raw food diet adherents showed normal vitamin A status and achieve favourable plasma beta-carotene concentrations as recommended for chronic disease prevention, but showed low plasma lycopene levels. Plasma carotenoids in raw food adherents are predicted mainly by fat intake.

Effects of carotenoids from lucerne, marigold and tomato on egg yolk pigmentation and carotenoid composition

1. The effects of various sources of natural carotenoids (Px alfalfa concentrate, tomato powder and marigold extract) as feed additives in quail diets on egg yolk pigmentation and carotenoid composition were investigated. 2. Adult Japanese quail were fed one of 5 different diets for 23 d: three diets each contained Px alfalfa concentrate (PX) or tomato powder (TP) or marigold extract (MG), one diet contained marigold extract and tomato powder (MG + TP) and a control diet (wheat/barley based) was low in carotenoid. All products were added at a rate of 2%, apart from marigold extract which was added at a rate of 0.2%. 3. Visual assessment of yolk colour (Roche colour fan) showed a stabilised yolk colour of 1.6, 7.7, 8.5, 8.8 and 10.6 for the control, PX, TP, MG and MG + TP treatments, respectively. 4. The total carotenoid concentration of the egg yolks were 2.2, 22.4, 4.1, 39.0 and 37.7 microg/g for the experimental groups fed the following diets: control, PX, TP, MG and MG + TP, respectively. Deposition of retinol, alpha-tocopherol and gamma-tocopherol in the egg yolk was unaffected by treatments. 5. Lutein was shown to be the major carotenoid in the egg yolk, comprising 1.65, 17.97, 2.03, 31.14 and 28.57 microg/g in control, PX, TP, MG and MG + TP, respectively. Inclusion of TP in the quail diet resulted in lycopene transfer to the egg. 6. It was concluded that, in comparison with the control group, there was an increase in the yolk concentrations of lutein, zeaxanthin, lycopene and beta-carotene in eggs produced by female quail fed diets supplemented with natural carotenoids.

Supplementation of the maternal diet with tomato powder and marigold extract: effects on the antioxidant system of the developing quail

The effects of natural dietary carotenoid supplementation of the maternal diet (tomato powder and marigold extract) on transfer to the egg yolk and on the development of the antioxidant system of the young quail liver in early postnatal life were investigated. Sixty Japanese quail (Coturnix coturnix japonica) were allocated to four treatment groups, each with three replicates consisting of four females and one male each. The quail were fed on one of four different diets for 23 d, each of them based on a low carotenoid, wheat/barley-based control diet. Tomato powder and marigold extract were added at rates of 20 and 2 g/kg to treatments 2 and 3, respectively. Marigold extract and tomato powder were also used in combination in treatment 4 at 2 g marigold + 20 g tomato powder/kg of diet. At 20 weeks of age, 60 eggs from each treatment were collected and placed in an incubator. After hatching, d-old quail from each group were reared (under standard commercial conditions) up to 14 d of age. They were fed on a low-carotenoid commercial diet. After hatch, at 1, 7 and 14 d, the livers of five young quail from each treatment were assessed for total carotenoid concentration and carotenoid profile. Results indicated that lycopene is transferred from the feed to the egg yolk and further to the liver of the developing embryo. Elevated carotenoid concentration in the egg yolk and correspondingly in the liver of newly hatched quail remains significant during first week posthatch. Lutein and lycopene did not affect vitamin E concentration in the egg yolk or liver of the newly hatched quail. A combination of increased concentrations of lycopene and lutein in the egg yolk results in elevated concentrations of coenzyme Q in the liver of the newly hatched quail.

Critical assessment of various techniques for the extraction of carotenoids and co-enzyme Q10 from the Thraustochytrid strain ONC-T18

A variety of techniques for extracting carotenoids from the marine Thraustochytrium sp. ONC-T18 was compared. Specifically, the organic solvents acetone, ethyl acetate, and petroleum ether were tested, along with direct and indirect ultrasonic assisted extraction (probe vs bath) methods. Techniques that used petroleum ether/acetone/water (15:75:10, v/v/v) with 3 h of agitation, or 5 min in an ultrasonic bath, produced the highest extraction yields of total carotenoids (29-30.5 microg g-1). Concentrations up to 11.5 microg g-1 of canthaxanthin and 17.5 microg g-1 of beta;-carotene were detected in extracts stored for 6 weeks. Astaxanthin and echinenone were also detected as minor compounds. Extracts with and without antioxidants showed similar carotenoid concentration profiles. However, total carotenoid concentrations were approximately 8% higher when antioxidants were used. Finally, an easy-to-perform and inexpensive method to detect co-enzymes in ONC-T18 was also developed using silica gel TLC plates. Five percent methanol in toluene as a mobile phase consistently eluted co-enzyme Q10 standards and could separate the co-enzyme fractions present in ONC-T18.

A 12-wk egg intervention increases serum zeaxanthin and macular pigment optical density in women

Two carotenoids found in egg yolk, lutein and zeaxanthin, accumulate in the macular retina where they may reduce photostress. Increases in serum lutein and zeaxanthin were observed in previous egg interventions, but no study measured macular carotenoids. The objective of this project was to determine whether increased consumption of eggs would increase retinal lutein and zeaxanthin, or macular pigment. Twenty-four females, between 24 and 59 y, were assigned to a pill treatment (PILL) or 1 of 2 egg treatments for 12 wk. Individuals in the PILL treatment consumed 1 sugar-filled capsule/d. Individuals in the egg treatments consumed 6 eggs/wk, containing either 331 microg (EGG 1) or 964 microg (EGG 2) of lutein and zeaxanthin/yolk. Serum cholesterol, serum carotenoids, and macular pigment OD (MPOD) were measured at baseline and after 4, 8, and 12 wk of intervention. Serum cholesterol concentrations did not change in either egg treatment group, but total cholesterol (P = 0.04) and triglycerides (P = 0.02) increased in the PILL group. Serum zeaxanthin, but not serum lutein, increased in both the EGG 1 (P = 0.04) and EGG 2 (P = 0.01) groups. Likewise, MPOD increased in both the EGG 1 (P = 0.001) and EGG 2 (P = 0.049) groups. Although the aggregate concentration of carotenoid in 1 egg yolk may be modest relative to other sources, such as spinach, their bioavailability to the retina appears to be high. Increasing egg consumption to 6 eggs/wk may be an effective method to increase MPOD.

Sucrose deficiency delays lycopene accumulation in tomato fruit pericarp discs

Tomato (Solanum lycopersicum) fruit ripening is characterized by a massive accumulation of carotenoids (mainly lycopene) as chloroplasts change to chromoplasts. To address the question of the role of sugars in controlling carotenoid accumulation, fruit pericarp discs (mature green fruits) were cultured in vitro in the presence of various sucrose concentrations. A significant difference in soluble sugar content was achieved depending on external sucrose availability. Sucrose limitation delayed and reduced lycopene and phytoene accumulation, with no significant effect on other carotenoids. Chlorophyll degradation and starch catabolism were not affected by variations of sucrose availability. The reduction of lycopene synthesis observed in sucrose-limited conditions was mediated through metabolic changes illustrated by reduced hexose accumulation levels. In addition, variations of sucrose availability modulated PSY1 gene expression. Taken together our results suggest that the modulation of carotenoid accumulation by sucrose availability occurs at the metabolic level and involves the differential regulation of genes involved in carotenoid biosynthesis.

Risk assessment for the carotenoids lutein and lycopene

Lutein and lycopene, two prevalent carotenoids in the human diet have become increasingly popular ingredients in dietary supplements. A large body of human and animal research suggests that oral forms of these carotenoids may provide benefits in the areas of eye, prostate, skin and cardiovascular health. The increased awareness and use of these ingredients in dietary supplements warrants a comprehensive review of their safety. Systematic evaluation of the research designs and data provide a basis for risk assessment and the usual tolerable Upper Level of Intake (UL) derived from it if the newer methods described as the Observed Safe Level (OSL) or Highest Observed Intake (HOI) are utilized. The OSL risk assessment method indicates that the evidence of safety is strong at intakes up to 20mg/d for lutein, and 75 mg/d for lycopene, and these levels are identified as the respective OSL. Although much higher levels have been tested without adverse effects and may be safe, the data for intakes above these levels are not sufficient for a confident conclusion of long-term safety.

The influence of different electrical conductivity values in a simplified recirculating soilless system on inner and outer fruit quality characteristics of tomato

Irrigation with saline water affects tomato fruit quality. While total fruit yield decreases with salinity, inner quality characterized by taste and health-promoting compounds can be improved. For a detailed description of this relationship, the influence of three different salt levels [electrical conductivity (EC) 3, 6.5, and 10] in hydroponically grown tomatoes was investigated. Rising salinity levels in the nutrient solution significantly increased vitamin C, lycopene, and beta-carotene in fresh fruits up to 35%. The phenol concentration was tendentiously enhanced, and the antioxidative capacity of phenols and carotenoids increased on a fresh weight basis. Additionally, the higher EC values caused an increase of total soluble solids and organic acids, parameters determining the taste of tomatoes. Total fruit yield, single fruit weight, and firmness significantly decreased with rising EC levels. Regression analyses revealed significant correlations between the EC level and the dependent variables single fruit weight, total soluble solids, titrable acids, lycopene, and antioxidative capacities of carotenoids and phenols, whereas vitamin C and phenols correlated best with truss number, and beta-carotene correlated best with temperature. Only pressure firmness showed no correlation with any of the measured parameters. As all desirable characteristics in the freshly produced tomato increased when exposed to salinity, salinity itself constitutes an alternative method of quality improvement. Moreover, it can compensate for the loss of yield by the higher inner quality due to changing demands by the market and the consumer. This investigation is to our knowledge the first comprehensive overview regarding parameters of outer quality (yield and firmness), taste (total soluble solids and acids), nutritional value (vitamin C, carotenoids, and phenolics), as well as antioxidative capacity in tomatoes grown under saline conditions.

Microbial Isoprenoid Production: An Example of Green Chemistry through Metabolic Engineering

Saving energy, cost efficiency, producing less waste, improving the biodegradability of products, potential for producing novel and complex molecules with improved properties, and reducing the dependency on fossil fuels as raw materials are the main advantages of using biotechnological processes to produce chemicals. Such processes are often referred to as green chemistry or white biotechnology. Metabolic engineering, which permits the rational design of cell factories using directed genetic modifications, is an indispensable strategy for expanding green chemistry. In this chapter, the benefits of using metabolic engineering approaches for the development of green chemistry are illustrated by the recent advances in microbial production of isoprenoids, a diverse and important group of natural compounds with numerous existing and potential commercial applications. Accumulated knowledge on the metabolic pathways leading to the synthesis of the principal precursors of isoprenoids is reviewed, and recent investigations into isoprenoid production using engineered cell factories are described.

The monoterpene terpinolene from the oil of Pinus mugo L. in concert with alpha-tocopherol and beta-carotene effectively prevents oxidation of LDL

Antioxidants from several nutrients, e.g. vitamin E, beta-carotene, or flavonoids, inhibit the oxidative modification of low-density lipoproteins. This protective effect could possibly retard atherogenesis and in consequence avoid coronary heart diseases. Some studies have shown a positive effect of those antioxidants on cardiovascular disease. Another class of naturally occurring antioxidants are terpenoids, which are found in essential oils. The essential oil of Pinus mugo and the contained monoterpene terpinolene effectively prevent low-density lipoprotein (LDL)-oxidation. In order to test the mechanism by which terpinolene protects LDL from oxidation, LDL from human blood plasma enriched in terpinolene was isolated. In this preparation not only the lipid part of LDL is protected against copper-induced oxidation--as proven by following the formation of conjugated dienes, but also the oxidation of the protein part is inhibited, since loss of tryptophan fluorescence is strongly delayed. This inhibition is due to a retarded oxidation of intrinsic carotenoids of LDL, and not, as in the case of some flavonoids, attributable to a protection of intrinsic alpha-tocopherol. These results are in agreement with our previous results, which showed the same effects for a monoterpene from lemon oil, i.e. gamma-terpinene.

Changes in USDA food composition data for 43 garden crops, 1950 to 1999

OBJECTIVES

To evaluate possible changes in USDA nutrient content data for 43 garden crops between 1950 and 1999 and consider their potential causes.

METHODS

We compare USDA nutrient content data published in 1950 and 1999 for 13 nutrients and water in 43 garden crops, mostly vegetables. After adjusting for differences in moisture content, we calculate ratios of nutrient contents, R (1999/1950), for each food and nutrient. To evaluate the foods as a group, we calculate median and geometric mean R-values for the 13 nutrients and water. To evaluate R-values for individual foods and nutrients, with hypothetical confidence intervals, we use USDA's standard errors (SEs) of the 1999 values, from which we generate 2 estimates for the SEs of the 1950 values.

RESULTS

As a group, the 43 foods show apparent, statistically reliable declines (R < 1) for 6 nutrients (protein, Ca, P, Fe, riboflavin and ascorbic acid), but no statistically reliable changes for 7 other nutrients. Declines in the medians range from 6% for protein to 38% for riboflavin. When evaluated for individual foods and nutrients, R-values are usually not distinguishable from 1 with current data. Depending on whether we use low or high estimates of the 1950 SEs, respectively 33% or 20% of the apparent R-values differ reliably from 1. Significantly, about 28% of these R-values exceed 1.

CONCLUSIONS

We suggest that any real declines are generally most easily explained by changes in cultivated varieties between 1950 and 1999, in which there may be trade-offs between yield and nutrient content.

Determination of beta-carotene and lutein available from green leafy vegetables by an in vitro digestion and colonic fermentation method

Green leafy vegetables (Spinacea oleracea, Cnidoscolus aconitifolius, and Solanum americanum) contain a high amount of beta-carotene (27-52 mg/100 g of dry sample) and lutein (140-193 mg/100 g of dry sample). The amount of beta-carotene and lutein released from the food matrix by the action of digestive enzymes ranged from 22 to 67% and from 27 to 77%, respectively. There was a significant correlation between the enzymatic release of carotenoids (lutein + beta-carotene) and the content of Klason lignin, nonstarch polysaccharides, and resistant protein. The carotenoids released by the in vitro colonic fermentation ranged from 2 to 11%, and part of them (0.251-4.03 mg/100 g of original dry sample) remained intact in the fermentation media and could be potentially absorbed in the colon. A significant part of carotenoids seems to be unavailable in the intestinal tract (16% in S. oleracea to 58% in C. aconitifolius).

Carotenoid absorption from salad and salsa by humans is enhanced by the addition of avocado or avocado oil

Dietary lipids are hypothesized to be an important factor for carotenoid bioavailability. However, most carotenoid-rich fruits and vegetables are low in lipids. The objective of this study was to assess whether the addition of avocado fruit as a lipid source enhances carotenoid absorption in humans. Healthy subjects (n = 11/study) were recruited for 2 crossover, postprandial studies. The effect of avocado addition (150 g) to salsa on lycopene and beta-carotene absorption was examined in Study 1, and the absorption of lutein, alpha-carotene, and beta-carotene from salad in Study 2. Furthermore, the effects of avocado dose (75 vs. 150 g containing 12 vs. 24 g lipid, respectively) and of lipid source (avocado fruit vs. avocado oil) on carotenoid absorption were examined in Study 2. Intact carotenoids were quantified in the plasma triacylglycerol-rich lipoprotein (TRL) fraction during the 9.5 h after consumption of the test meal and expressed as baseline-corrected area under the concentration-vs.-time curve (AUC). The addition of avocado to salsa enhanced lycopene and beta-carotene absorption (P < 0.003), resulting in 4.4 and 2.6 times the mean AUC after intake of avocado-free salsa, respectively. In Study 2, supplementing 150 g avocado or 24 g avocado oil to salad similarly enhanced alpha-carotene, beta-carotene, and lutein absorption (P < 0.01), resulting in 7.2, 15.3, and 5.1 times the mean AUC after intake of avocado-free salad, respectively (150 g avocado). Neither the avocado dose nor the lipid source affected carotenoid absorption. In conclusion, adding avocado fruit can significantly enhance carotenoid absorption from salad and salsa, which is attributed primarily to the lipids present in avocado.

Terpenoids as Plant Antioxidants

Plant antioxidants are composed of a broad variety of different substances like ascorbic acid and tocopherols, polyphenolic compounds, or terpenoids. They perform several important functions in plants and humans (e.g., carotenoids function as accessory pigments for light harvesting and provide photoprotection and pigmentation in plants). Monoterpenes and diterpenes, which are the main components of essential oils, act as allelopathic agents, attractants in plant-plant or plant-pathogen/herbivore interactions or repellants. For humans, carotenoids play an important role for health, carotenoids with provitamin A activity are important for vision; other carotenoids influence the human immune function and gap-junctional communication (GJC). Additionally, their antioxidative capacity is believed to be responsible for the health promoting properties of fruits and vegetables. Three main ways of antioxidant action of carotenoids have been detected until now (i.e., quenching of singlet oxygen, hydrogen transfer, or electron transfer). These mechanisms and investigation of antioxidant activity in vitro are discussed in detail. The monoterpenes limonene and perillyl alcohol may be promising substances in cancer therapy. Several investigations have studied the antioxidant activity of monoterpenes and diterpenes or essential oils in vitro. Results as well as the action of a newly discovered, very effective antioxidant (i.e., gamma-terpinene) are discussed. An important point when assessing the antioxidant activity of plant antioxidants is to consider their interaction with other antioxidants. Especially combinations of hydrophilic and lipophilic antioxidants may exert synergistic effects, as has been shown for rutin in combination with gamma-terpinene, lutein, or lycopene.

The role of antioxidants in the Mediterranean diets: focus on cancer

The incidence of certain cancers in the Mediterranean area is lower than in other areas of the world (e.g. in northern Europe and the USA). As nutrition and dietary factors comprise one of the three major factors for human carcinogenesis, the hypothesis was formulated that the dietary profile of the Mediterranean diet, rich in antioxidants, might exert preventive actions. Alas, the vast majority of experiments to prove this hypothesis have been obtained in vitro, and most of the necessary information on the absorption, distribution and metabolism of oligonutrients is currently lacking. Yet, even though the exact role of antioxidants in the Mediterranean diet is yet to be fully established, data from observational studies are strong enough to reinforce the notion that a diet low in saturated fat and alcohol and rich in plant food and whole grain, such as the traditional Mediterranean diet, is associated with lower risk of cancer and should be actively promoted.

Single-Dose Pharmacokinetic Study of Lycopene Delivered in a Well-Defined Food-Based Lycopene Delivery System (Tomato Paste-Oil Mixture) in Healthy Adult Male Subjects

This report details the findings of a single-dose Phase I pharmacokinetic and toxicity study of a food-based formulation of lycopene in healthy adult male subjects. Five dosing groups (n = 5 per group) were sequentially treated with increasing doses of lycopene ranging from 10 to 120 mg. Blood samples were collected for a total of 28 days (672 h) after administration of single doses of lycopene. The mean time (tmax) to reach maximum total lycopene concentration (Cmax) ranged from 15.6 to 32.6 h. The Cmax for total lycopene ranged between 4.03 and 11.27 μg/dl (0.075–0.210 μm). Mean AUC0–96 and elimination half-life for total lycopene ranged from 214 to 655 μg h/dl (3.986–12.201 μmol h/l) and 28.1 and 61.6 h, respectively. The changes observed in lycopene exposure parameters (e.g., Cmax and AUC0–96) were not proportional to increments in dose, with larger increases observed at the lowest end of the dosing range (10–30 mg). Chylomicron lycopene was measured during the first 12 h with the differences observed among the dosing groups not reaching statistical significance. These findings may reflect a process of absorption that is saturable at very low dosing levels or may be explained by the large interindividual variability in attained lycopene concentrations that were observed within each dosing group. Pharmacokinetic parameters for trans- and cis-lycopene isomers were calculated and are reported here. The formulation was well tolerated with minimal side effects, which were mainly of gastrointestinal nature and of very low grade.

The science behind lutein

In humans, as in plants, the xanthophyll lutein is believed to function in two important ways: first as a filter of high energy blue light, and second as an antioxidant that quenches and scavenges photo induced reactive oxygen species (ROS). Evidence suggests that lutein consumption is inversely related to eye diseases such as age-related macular degeneration (AMD) and cataracts. This is supported by the finding that lutein (and a stereo isomer, zeaxanthin) are deposited in the lens and the macula lutea, an area of the retina responsible for central and high acuity vision. Human intervention studies show that lutein supplementation results in increased macular pigment and improved vision in patients with AMD and other ocular diseases. Lutein may also serve to protect skin from UV-induced damage and may help reduce the risk of cardiovascular disease. Crystalline lutein is readily absorbed from foods and from dietary supplements whereas, to enter the bloodstream, lutein esters require prior de-esterification by intestinal enzymes. Unlike the hydrocarbon carotenoids which are mainly found in the LDL fraction, xanthophylls like lutein and zeaxanthin are incorporated into both HDL and LDL. Today, lutein can be obtained from the diet in several different ways, including via supplements, and most recently in functional foods. Animal toxicology studies have been performed to established lutein's safety as a nutrient. These studies have contributed to the classification of purified crystalline lutein as generally recognized as safe (GRAS). The achievement of GRAS status for purified crystalline lutein allows for the addition of this form into several food and beverage applications. This achievement speaks directly to the quality and safety of purified lutein.

Measurements of the major isoforms of vitamins A and E and carotenoids in the blood of people with spinal-cord injuries

We used reversed-phase HPLC with diode array detection to simultaneously measure the major isoforms of vitamins A, E, and the carotenoids in serum from 55 healthy people with spinal cord injuries. Typically, the method measured retinol (vitamin A), alpha-tocopherol (vitamin E) and beta-carotene, alpha-carotene, lutein, lycopene, and cryptoxanthin (carotenoids). gamma-Tocopherol (vitamin E), 25-hydroxycalciferol (vitamin D), and the carotenoid zeaxanthin could also be measured when they were present in high concentrations. Healthy people with spinal cord injuries were more likely than similar people without injuries to have low concentrations of alpha-tocopherol, and to a lesser extent retinol and beta-carotene.