Changes in Macular Pigment Optical Density and Serum Lutein Concentration in Japanese Subjects Taking Two Different Lutein Supplements

PURPOSE

To investigate macular pigment optical density (MPOD) and serum concentration changes of lutein in Japanese subjects participating in a clinical trial in which two formulations of lutein and zeaxanthin supplements with different physiochemical properties are used.

METHODS

Thirty-six healthy volunteers were recruited into this prospective, randomized, parallel-group, double-masked comparative study at a single institute. Two products were used, FloraGLO® (Kemin Japan) and XanMax® (Katra Phytochem). The lutein particle size and zeaxanthin concentrations differed between the formulations. The subjects consumed one of the two supplements for a duration of up to 6 months. MPOD levels were measured by resonance Raman spectrometry at baseline and once a month until the end of the study. Serum lutein concentration was measured at baseline, month 3, and month 6. The subjects were also tested for contrast sensitivity, glare sensitivity, visual acuity, and in addition had a focal electroretinogram measured.

RESULTS

The mean serum lutein concentrations increased significantly after the first three months, but the mean MPOD levels in either supplement group did not show any statistically significant increase. A detailed analysis, however, revealed three response patterns in both groups for the increase of MPOD levels and serum lutein concentration, i.e. "retinal responders", who had an increase of both MPOD levels and serum lutein concentrations (n = 13), "retinal non-responders", who had only increased serum concentrations and no change in MPOD levels (n = 20), and "retinal and serum non-responders", who had neither MPOD level nor plasma concentration increases (n = 3). The subjects with low MPOD levels at baseline appeared to show increased MPOD levels at the 6 month time point upon lutein supplementation (r = -0.4090, p = 0.0133). Glare sensitivity improved in retinal responders in both supplement groups, while there were no remarkable changes in contrast sensitivity.

CONCLUSIONS

No statistically significant differences could be detected for MPOD levels and serum lutein concentrations between the two investigated lutein supplement formulations. Responses to lutein supplementation regarding MPOD levels and serum lutein concentrations varied between subjects. Subjects with lower MPOD levels at baseline responded well to lutein supplementation. However, since the number of subjects was low, a further study with more subjects is needed to prove that subjects with low MPOD levels will benefit from lutein supplementation.

TRIAL REGISTRATION

UMIN-CTR UMIN000004593.

Association between higher plasma lutein, zeaxanthin, and vitamin C concentrations and longer telomere length: results of the Austrian Stroke Prevention Study

OBJECTIVES

To examine the association between plasma concentrations of antioxidative micronutrients and leukocyte telomere length (LTL) in elderly adults.

DESIGN

Cross-sectional cohort study.

SETTING

Austrian Stroke Prevention Study, a population-based cohort study on brain aging.

PARTICIPANTS

Individuals with a mean age of 66 ± 7 (n = 786; 58% female).

MEASUREMENTS

Concentrations of vitamin C, lutein, zeaxanthin, β-cryptoxanthin, canthaxanthin, lycopene, α- and γ-tocopherol, α- and β-carotene, and retinol in plasma, advanced oxidation protein products as a measure of oxidative stress in serum, and LTL were measured. Vitamins and carotenoids were measured using high-performance liquid chromatography, advanced oxidation protein products using spectrophotometry, and telomere length using quantitative real-time polymerase chain reaction.

RESULTS

Multiple linear regression analyses with adjustment for age and sex demonstrated that higher lutein, zeaxanthin, and vitamin C concentrations were strongly associated with longer telomere length. The associations were independent of body mass index, maximum oxygen uptake, and vascular risk factors and were not mediated by advanced oxidation protein products content.

CONCLUSION

This study provides first evidence that higher lutein, zeaxanthin, and vitamin C concentrations in plasma are associated with longer LTL in normal elderly persons and suggest a protective role of these vitamins in telomere maintenance.

Oxidative stress in rats with hyperhomo-cysteinemia and intervention effect of lutein

AIM

The current study aims to explore the possible molecular mechanism of hyperhomocysteinemia (HHcy) mediated atherosclerosis (AS) and to find an effective intervention method for AS.

MATERIALS AND METHODS

A total of 40 Wistar rats were equalized into four groups: blank control, HHcy, folacin intervention, and lutein intervention groups. HHcy rat models were established. The intervention groups were respectively lavaged with folacin and lutein. Oxidative stress states, the levels of nitric oxide (NO) and endothelin-1 (ET-1), as well as the expression of nuclear factor (NF)-κB p65 and intercellular adhesion molecule (ICAM)-1 were compared.

RESULTS

In the HHcy rats, the activity of serum superoxide dismutase (SOD) and glutathione peroxidase (GPx) significantly decreased, whereas the malondialdehyde content and hydroxyl radical level noticeably increased, indicating that the rats stayed in aggravated oxidative stress states. Lutein intervention inhibited HHcy-induced oxidative stress excitement. In the HHcy rats, the NO level significantly decreased, whereas the ET-1 level significantly increased, indicating that HHcy mediated vascular endothelial dysfunction. Lutein reversed such dysfunction. In the HHcy rats, the mRNA and protein expression of SOD2 and GPX1 in the aortic wall tissue decreased, whereas that of NF-κB p65 and ICAM-1 increased. Lutein significantly upregulated the mRNA and protein expression of SOD2 and GPx1 and downregulated the expression of NF-κB p65 and ICAM-1.

CONCLUSIONS

Oxidative stress and inflammation are the important mechanisms of HHcy-mediated AS. In particular, HHcy-induced aggravated oxidative stress may function as the initial AS-mediating mechanism, upregulating the expression of NF-κB p65 and ICAM-1 and thereby becoming associated with AS. Lutein noticeably intervenes in and inhibits Hcy-mediated oxidative stress excitement and downregulates the expression of inflammation-associated informational molecules.

Lutein + zeaxanthin and omega-3 fatty acids for age-related macular degeneration: the Age-Related Eye Disease Study 2 (AREDS2) randomized clinical trial

IMPORTANCE

Oral supplementation with the Age-Related Eye Disease Study (AREDS) formulation (antioxidant vitamins C and E, beta carotene, and zinc) has been shown to reduce the risk of progression to advanced age-related macular degeneration (AMD). Observational data suggest that increased dietary intake of lutein + zeaxanthin (carotenoids), omega-3 long-chain polyunsaturated fatty acids (docosahexaenoic acid [DHA] + eicosapentaenoic acid [EPA]), or both might further reduce this risk.

OBJECTIVES

To determine whether adding lutein + zeaxanthin, DHA + EPA, or both to the AREDS formulation decreases the risk of developing advanced AMD and to evaluate the effect of eliminating beta carotene, lowering zinc doses, or both in the AREDS formulation.

DESIGN, SETTING, AND PARTICIPANTS

The Age-Related Eye Disease Study 2 (AREDS2), a multicenter, randomized, double-masked, placebo-controlled phase 3 study with a 2 × 2 factorial design, conducted in 2006-2012 and enrolling 4203 participants aged 50 to 85 years at risk for progression to advanced AMD with bilateral large drusen or large drusen in 1 eye and advanced AMD in the fellow eye.

INTERVENTIONS

Participants were randomized to receive lutein (10 mg) + zeaxanthin (2 mg), DHA (350 mg) + EPA (650 mg), lutein + zeaxanthin and DHA + EPA, or placebo. All participants were also asked to take the original AREDS formulation or accept a secondary randomization to 4 variations of the AREDS formulation, including elimination of beta carotene, lowering of zinc dose, or both.

MAIN OUTCOMES AND MEASURES

Development of advanced AMD. The unit of analyses used was by eye.

RESULTS

Median follow-up was 5 years, with 1940 study eyes (1608 participants) progressing to advanced AMD. Kaplan-Meier probabilities of progression to advanced AMD by 5 years were 31% (493 eyes [406 participants]) for placebo, 29% (468 eyes [399 participants]) for lutein + zeaxanthin, 31% (507 eyes [416 participants]) for DHA + EPA, and 30% (472 eyes [387 participants]) for lutein + zeaxanthin and DHA + EPA. Comparison with placebo in the primary analyses demonstrated no statistically significant reduction in progression to advanced AMD (hazard ratio [HR], 0.90 [98.7% CI, 0.76-1.07]; P = .12 for lutein + zeaxanthin; 0.97 [98.7% CI, 0.82-1.16]; P = .70 for DHA + EPA; 0.89 [98.7% CI, 0.75-1.06]; P = .10 for lutein + zeaxanthin and DHA + EPA). There was no apparent effect of beta carotene elimination or lower-dose zinc on progression to advanced AMD. More lung cancers were noted in the beta carotene vs no beta carotene group (23 [2.0%] vs 11 [0.9%], nominal P = .04), mostly in former smokers.

CONCLUSIONS AND RELEVANCE

Addition of lutein + zeaxanthin, DHA + EPA, or both to the AREDS formulation in primary analyses did not further reduce risk of progression to advanced AMD. However, because of potential increased incidence of lung cancer in former smokers, lutein + zeaxanthin could be an appropriate carotenoid substitute in the AREDS formulation.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00345176.

The effect of night vision goggles on the retinocortical bioelectrical activity and its improvement by food supplement

AIM

To investigate the effect of luminance variations, as well as the oral administration of a food supplement, on the visual bioelectric response while using of Night Vision Goggles (NVG).

METHODS

Two trials were performed, both enrolling healthy male aircrew members wearing NVG, and recording Visual Evoked Potentials (VEPs) from scalp electrodes. Both foveal and parafoveal response were evaluated. Latency and amplitude, P100 peak, were measured. In the first set of measurements, VEPs parameters were recorded during unaided photopic conditions and mesopic conditions while using 3rd generation plus NVG (ANVIS 9). In the second set of experiments, after the first basal electrophysiological investigation during mesopic conditions using NVG, patients started a 45 days oral treatment, during which they took 3 tablets per day of a food supplement. The tablets contained a mix of anthocyanosides, procyanidolic oligomers, lutein and vitamins A and E. At the end of this treatment, patients were tested again by pattern-reversal VEP investigation during aided vision condition (wearing NVG) in a mesopic environment.

RESULTS

VEPs parameters, statistically evaluated using a two tailed paired t-test, showed that latency and amplitude were respectively increased (p < 0.001 and p < 0.01 for 15' and 60' minutes of arc) and decreased (p < 0.05) when measured using NVG with respect to unaided basal conditions. Furthermore, the VEP response in NVG aided vision was positively affected by the oral treatment with the food supplement, showing a significant (p < 0.05) decrease of latency and increase of amplitude.

CONCLUSION

The use of NVG impairs the VEP response, and such effect is effectively counteracted by the oral treatment with a food supplement containing a combination of sight improving molecules that might enhance foveal selectivity, central photoreceptors sensitivity and magnocellular fibers effectiveness.

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.

The effect of lutein supplementation on visual fatigue: a psychophysiological analysis

We used psychophysiological technology to examine the effect of an oral supplement, a combination of lutein, zeaxanthin and blackcurrant extract (LUT), on visual fatigue, within the context of a randomized, double-blind, placebo-controlled cross-over trial. The LUT supplement and placebo samples were randomly assigned to thirteen participants, who took the samples for two LUT (and vice versa) for another 2 week. Each participant completed visual proof reading tasks for 2h during each of four testing sessions. Saccade tests were administered before and after the proof reading task, during which the participants moved their eyes back and forth between two targets positioned in the center of two checkerboards. We recorded EEG, EOG, heart rate, and facial muscle potential/performance during the saccade tests. Blood pressure was measured and subjective fatigue and stress scores were collected before and after the proof reading task. We averaged EEG starting at saccade offset in order to analyze eye fixation related potentials (EFRP). Our results suggested that the proof reading task induced visual fatigue. An analysis of EFRP and other psychophysiological data revealed significant differences between the LUT and placebo conditions. These results suggest that supplementation with LUT could help to reduce symptoms of visual fatigue.

Dietary supplements commonly used for prevention

The use of complimentary and alternative medicine is on the rise. This article reviews some of the commonly used herbal supplements and others focusing mainly on disease prevention. A summary table of medical conditions is provided, and when possible, a summary of efficacy and safety is provided to facilitate decision making.

[Lutein and eye health--current state of discussion]

Due to increased life expectancy the number of people with age-related diseases like age-related macular degeneration (AMD) will grow. Currently AMD is incurable and only a few therapeutic strategies are available. Therefore prevention becomes more important. Protective effects related to eye health are discussed for the two carotenoids lutein and zeaxanthin. Meanwhile both substances are offered as food supplements to a great extent. Both carotenoids lutein and zeaxanthin are accumulated in the retina, especially in the macula lutea. They are able to absorb blue light, which damages photoreceptors and pigmentary epithelium. Due to their antioxidative properties they can reduce changes in membrane permeability via quenching reactive oxygen species and free radicals. Research studies suppose lutein and zeaxanthin may contribute to improvement of vision in patients with AMD and other eye diseases. Based on the scientific rationale, these carotenoids may be effective in the prevention of age-related eye diseases. However, this issue has to be examined in a differentiated way.

[Light-absorbing and antiradical properties of a product with lutein and zeaxanthin in vitro and kinetics of carotinoids at single oral administration on rats]

Light-absorbing and antiradical properties of the new product on a basis of lutein and zeaxanthin for correction of eye diseases in model system of initiated oxidation of isopropylbenzene were investigated. It is shown, that the product is the effective light-absorbing agent and inhibitor of free-radical oxidation in vitro. In experiments on animals (rat) the pharmacokinetics of the product was investigated at single oral administration. A simple, specific and sensitive RP-HPLC method for the determination of lutein in rat plasma was developed, which was applied to pharmacokinetic investigation in rats after oral administration of lutein at dose 20 mg/kg. It was established, that the peak plasma levels was achieved to 2 hour and the mean elimination half life was 2,4 hours.

Age related macular degeneration--should your patients be taking additional supplements?

BACKGROUND

The use of over-the-counter complementary medicines and supplements is growing. Patients with age related macular degeneration (AMD) are likely to have heard of, or are possibly already taking, additional supplements that may increase their chances of retaining useful eyesight.

OBJECTIVE

This article looks specifically at evidence regarding the effects of over-the-counter oral supplements such as antioxidants and omega-3 fatty acids on AMD.

DISCUSSION

Diet manipulation and supplementation has a role to play in modifying the risk of disease progression in AMD patients. A combination of vitamins C and E, beta carotene, zinc oxide and cupric oxide has been shown to reduce the rate of visual loss in dry AMD. However, commercially available preparations do not always recommend the correct intake that would match levels found in clinical trials. Other carotenoids such as lutein and zeaxanthin may also be beneficial, intake of these can be increased by altering diet alone. Other useful dietary changes include reducing both animal and vegetable fats and increasing the consumption of fish and nuts.

Lutein presents suppressing but not blocking chemopreventive activity during diethylnitrosamine-induced hepatocarcinogenesis and this involves inhibition of DNA damage

Cancer chemopreventive agents are classified as blocking or suppressing agents if they inhibit initiation or promotion/progression phase of carcinogenesis, respectively. Two experiments were conducted in order to classify lutein as a blocking and/or suppressing agent during rat hepatocarcinogenesis. Inhibitory effects of lutein on hepatic preneoplastic lesions (PNL) and DNA strand breakage induced in Wistar rats by the resistant hepatocyte model of hepatocarcinogenesis (initiation with diethylnitrosamine and promotion with 2-acetylaminofluorene coupled with partial hepatectomy) were investigated when the carotenoid was administered specifically during initiation (experiment 1) or promotion (experiment 2) phase. Animals received by gavage during 2 (experiment 1) or six (experiment 2) consecutive weeks on alternate days 70 mg/kg body weight of lutein. Rats treated with only corn oil during these same periods and submitted to this model were used as controls. Treatment with lutein during initiation did not inhibit nor induced (P>0.05) hepatic preneoplastic lesions and DNA damage. On the other hand, treatment during promotion inhibited (P<0.05) the size of hepatic macroscopic nodules and DNA damage and increased (P<0.05) lutein hepatic levels that reached levels seen in human liver samples. Lutein presented inhibitory actions during promotion but not initiation of hepatocarcinogenesis, being classified as a suppressing agent. This reinforces lutein as a potential agent for liver cancer chemoprevention.

LAST II: Differential temporal responses of macular pigment optical density in patients with atrophic age-related macular degeneration to dietary supplementation with xanthophylls

BACKGROUND

Age-related macular degeneration (ARMD) is the leading cause of vision loss in aging Western societies. The objective of the Lutein Antioxidant Supplementation Trial (LAST) was to determine whether specific dietary interventions increased macular pigment optical density (MPOD) and visual function in patients with atrophic ARMD. The current objective of LAST II is to discern those specific characteristics that increase MPOD, i.e., that might differentiate a responder from a nonresponder.

METHODS

The LAST study was a prospective, 12-month, randomized, double-masked, placebo-controlled trial conducted at an urban midwestern Veterans Administation Hospital from August 1999 to May 2001. Ninety patients with atrophic ARMD entered the study and were assigned randomly to 1 of 3 groups. Patients in group 1 received 10 mg lutein; in group 2, 10 mg lutein in combination with vitamins, minerals, and antioxidants; and in group 3, maltodextrin placebo. Changes in macular MPOD over time were evaluated. Characteristics potentially influencing MPOD included age, weight (body mass index), initial baseline values of macular pigment, and combining xanthophylls with other nutrients.

RESULTS

MPOD increased with supplementation and declined slightly without supplementation (regression slopes not equal to zero in supplemented groups, P < 0.02). The highest increases in MPOD over time occurred in patients with lower baseline values of MPOD. Statistically significant increases in MPOD density were observed in the lutein group for patients with baseline MPOD <or=0.3 optical density units and up to 0.2 optical density units in the lutein plus antioxidant group. Further analysis found that none of the subjects' eyes in the lowest quartile of baseline MPOD were in the lowest quartile for change in MPOD.

CONCLUSION

Noteworthy is the observation that those individuals with lowest MPOD, and in greatest need of supplementation, were also most likely to benefit from either the lutein or the lutein plus antioxidant supplementation. For those individuals who responded to supplementation, their macular pigment optical density had not ceased to increase at 12 months' duration of supplementation. The inference is that if a deficiency in macular pigment optical density is accurately diagnosed, effective interventions should be able to re-establish this prophylactic barrier.

Beneficial long-term effects of combined oral/topical antioxidant treatment with the carotenoids lutein and zeaxanthin on human skin: a double-blind, placebo-controlled study

BACKGROUND

The skin is exposed to numerous environmental assaults that can lead to premature aging. Of these agents, perhaps none is more ubiquitous than the ultraviolet (UV) wavelengths of sunlight. The primary immediate defense against environmental skin damage is the antioxidant capacity of the skin. However, this defense system can be compromised by moderate exposure to UV light. Therefore, bolstering the antioxidant defense system of the skin is a potentially important strategy for reducing environmentally induced skin damage.

AIM OF THE STUDY

This clinical trial was designed to study the efficacy of lutein and zeaxanthin, two potentially important antioxidants found naturally in the skin, upon five skin physiology parameters (surface lipids, hydration, photoprotective activity, skin elasticity and skin lipid peroxidation - malondialdehyde) of human subjects. These xanthophyllic carotenoids were administered either orally, topically, or in combination (both oral and topical routes).

RESULTS

The results obtained indicate that the combined oral and topical administration of lutein and zeaxanthin provides the highest degree of antioxidant protection. However, oral and topical administration of these antioxidants individually also provides significant activity in the skin. In addition, oral administration of lutein may provide better protection than that afforded by topical application of this antioxidant when measured by changes in lipid peroxidation and photoprotective activity in the skin following UV light irradiation.

Lutein supplementation in retinitis pigmentosa: PC-based vision assessment in a randomized double-masked placebo-controlled clinical trial [NCT00029289]

Background

There is no generally accepted medical or surgical treatment to stop the progressive course of retinitis pigmentosa. Previous studies have suggested lutein as a potential treatment with positive effects on macular pigment density. The objective of this study was to examine the effect of lutein supplementation on preservation of visual function in patients with retinitis pigmentosa (RP)

Methods

In a double-masked randomized placebo-controlled phase I/II clinical trial with a cross-over design, 34 adult patients with RP were randomized to two groups. One group, consisted of 16 participants, received lutein supplementation (10 mg/d for 12 wks followed by 30 mg/d) for the first 24 weeks and then placebo for the following 24 weeks, while the other group included 18 participants for whom placebo (24 weeks) was administered prior to lutein. Visual acuity, contrast sensitivity, and central visual field were measured at different illumination levels at baseline and every week using a PC-based test at home.

Results

For visual acuity (VA) at normal illumination level, treatment with lutein reduced logMAR, i.e. improved VA, but this effect was not statistically significant. The changes in normal (100%), low (4%), and very low (0.1%) illumination log CS were not statistically significant (p-values: 0.34, 0.23, and 0.32, respectively). Lutein had a statistically significant effect on visual field (p-value: 0.038) and this effect increased in the model assuming a 6-week delay in effect of lutein. Comparing the development of vision measures against the natural loss expected to occur over the course of 48 weeks, most measures showed reduced decline, and these reductions were significant for normal illumination VA and CS.

Conclusion

These results suggest that lutein supplementation improves visual field and also might improve visual acuity slightly, although these results should be interpreted cautiously. As a combined phase I and II clinical trial, this study demonstrated the efficacy and safety of lutein supplementation.

Treatment of nonexudative (dry) age-related macular degeneration

PURPOSE OF REVIEW

The purpose of this report is to review the recent literature and summarize currently available and potential new treatment options for nonexudative age-related macular degeneration.

RECENT FINDINGS

High-dose vitamin supplementation may have some associated systemic toxicity. It is important to check that the patient is taking beta-carotene and not vitamin A as retinal acetate or palmitate, which have been associated with osteoporosis and hepatotoxicity. High-dose vitamins E and C may be associated with cardiovascular disease. Decreasing inflammation by lowering systemic cardiac C-reactive protein, fibrinogen and cholesterol may be important, especially in light of recent epidemiologic and genetic data. The results of randomized trials of laser treatment for drusen and rheopheresis should be available during 2006. Treatment with these modalities before the results of the trials are evaluated should be avoided.

SUMMARY

The holy grail of therapy for age-related macular degeneration is to avoid the development of choroidal neovascularization. High-dose vitamin supplementation should be used only in those in whom it is indicated and inflammatory parameters including highly sensitive C-reactive protein, fibrinogen and cholesterol should be stabilized because there are data associating these parameters with age-related macular degeneration and also with cardiovascular disease.

Carotenoid actions and their relation to health and disease

Based on extensive epidemiological observation, fruits and vegetables that are a rich source of carotenoids are thought to provide health benefits by decreasing the risk of various diseases, particularly certain cancers and eye diseases. The carotenoids that have been most studied in this regard are beta-carotene, lycopene, lutein and zeaxanthin. In part, the beneficial effects of carotenoids are thought to be due to their role as antioxidants. beta-Carotene may have added benefits due its ability to be converted to vitamin A. Additionally, lutein and zeaxanthin may be protective in eye disease because they absorb damaging blue light that enters the eye. Food sources of these compounds include a variety of fruits and vegetables, although the primary sources of lycopene are tomato and tomato products. Additionally, egg yolk is a highly bioavailable source of lutein and zeaxanthin. These carotenoids are available in supplement form. However, intervention trials with large doses of beta-carotene found an adverse effect on the incidence of lung cancer in smokers and workers exposed to asbestos. Until the efficacy and safety of taking supplements containing these nutrients can be determined, current dietary recommendations of diets high in fruits and vegetables are advised.

Efficiency of a few retinoids and carotenoids in vivo in controlling benzo[a]pyrene-induced forestomach tumour in female Swiss mice

The anticarcinogenic effect of vitamin A2 (dehydroretinol and 3-hydroxyretinol) compounds was studied and compared with that of vitamin A1 (retinoic acid, retinol and retinal) and carotenoids (lutein and beta-carotene) in the benzo[a]pyrene (B(a)P)-induced forestomach tumour model of female Swiss mice in vivo. Tumour growth and gross tumour incidence observed after the administration of B(a)P (eight doses of 1 mg, twice weekly for 4 weeks) and retinoids/carotenoids (2.5 and 4.7 microm per animal per d, 2 weeks before, during and 2 weeks after B(a)P) showed that the groups supplemented with lutein and 3-hydroxyretinol produced the best results in inhibiting tumour growth and had low tumour incidence compared with the control group given B(a)P only (P<0.05). Weights recorded after the different treatments showed that the beta-carotene-supplemented group exhibited maximum weight gain, followed by retinal, retinol, retinoic acid, lutein, dehydroretinol and 3-hydroxyretinol. These results indicate that the anticarcinogenicity of the compounds is not related to the vitamin A biopotencies. Vitamin A2 compounds having half the biopotency of the vitamin A1 compounds were seen to be anticarcinogenic. Again, among the carotenoids, lutein, having 50 % less biopotency, showed more significant results than beta-carotene. Thus it is imperative to conclude that the low animal growth achieved with these compounds has a correlation with the highest suppression of tumour occurrence in the present experiment. Therefore, the daily consumption of foods having high content of lutein and vitamin A2 should be given due importance and weight in further studies.

AMD and micronutrient antioxidants

Age-related maculopathy (ARM) is a common clinical entity. The late-stage manifestations of ARM, which are known as age-related macular degeneration (AMD), have devastating consequences for vision. Various risk factors have been identified in the development of the condition, which are consistent with the premise that oxidative stress plays an important role in its pathogenesis. Thus, the possibility that antioxidant balance can be manipulated through diet or supplementation has created much interest. Associations between diet and nutrition and the clinical features of ARM have been described. Scrutiny of the literature shows consistency in the report of notable reductions in serum micronutrients in wet AMD, however, the evidence for causation is still circumstantial. In this comprehensive review of the clinical literature, we have assessed the evidence for a link between diet and nutrition as risk factors for the development of ARM and AMD. All published case control, population-based, and interventional studies on ARM were examined. Although initial support appeared to be moderate and somewhat contradictory, the evidence that lifetime oxidative stress plays an important role in the development of ARM is now compelling. The positive outcomes in the Age-Related Eye Diseases Study, a major controlled clinical trial, have given hope that modulation of the antioxidant balance through supplementation can help prevent progression of ARM to AMD.