Life Extension Magazine

Life Extension Magazine September 2005

Abstracts

Zeaxanthin

Macular pigment density is reduced in obese subjects.

PURPOSE: Because of the potential protective function of lutein (L) and zeaxanthin (Z) within the retina and lens, a better understanding of factors influencing tissue deposition is needed. The largest fractions of L and Z are stored in adipose tissue. Thus, higher body fat content and body mass index (BMI) may be expected to influence the quantities of L and Z in the retina (measured as macular pigment optical density, MPOD). METHODS: Six hundred eighty subjects were tested. Information on MPOD, body mass index (BMI), body fat percentage (n = 400, using bioelectric impedance), dietary intake (n = 280, using a food frequency questionnaire), and serum carotenoid content (n = 280, using reversed phase high-performance liquid chromatography) was obtained. RESULTS: There was an inverse relationship between MPOD and BMI (n = 680, r = -0.12, P < 0.0008) and between MPOD and body fat percentage (n = 400, r = -0.12, P < 0.01). These relationships were largely driven by data from the subjects with higher BMI (more than 29, 21% less MP) and higher body fat percentage (more than 27%, 16% less MP). Dietary carotenoid intake and serum carotenoid levels were also lower in subjects with higher BMI (n = 280). CONCLUSIONS: Obese subjects tend to have lower retinal L and Z. This reduction may be due to decreased dietary intake of L and Z and/or competition between retina and adipose tissue for uptake of L and Z.

Invest Ophthalmol Vis Sci. 2002 Jan;43(1):47-50

Fruits and vegetables that are sources for lutein and zeaxanthin: the macular pigment in human eyes.

BACKGROUND: It has been suggested that eating green leafy vegetables, which are rich in lutein and zeaxanthin, may decrease the risk for age related macular degeneration. The goal of this study was to analyse various fruits and vegetables to establish which ones contain lutein and/or zeaxanthin and can serve as possible dietary supplements for these carotenoids. METHODS: Homogenates of 33 fruits and vegetables, two fruit juices, and egg yolk were used for extraction of the carotenoids with hexane. Measurement of the different carotenoids and their isomers was carried out by high performance liquid chromatography using a single column with an isocratic run, and a diode array detector. RESULTS: Egg yolk and maize (corn) contained the highest mole percentage (% of total) of lutein and zeaxanthin (more than 85% of the total carotenoids). Maize was the vegetable with the highest quantity of lutein (60% of total) and orange pepper was the vegetable with the highest amount of zeaxanthin (37% of total). Substantial amounts of lutein and zeaxanthin (30-50%) were also present in kiwi fruit, grapes, spinach, orange juice, zucchini (or vegetable marrow), and different kinds of squash. The results show that there are fruits and vegetables of various colours with a relatively high content of lutein and zeaxanthin. CONCLUSIONS: Most of the dark green leafy vegetables, previously recommended for a higher intake of lutein and zeaxanthin, have 15-47% of lutein, but a very low content (0-3%) of zeaxanthin. Our study shows that fruits and vegetables of various colours can be consumed to increase dietary intake of lutein and zeaxanthin.

Br J Ophthalmol. 1998 Aug;82(8):907-10

Carotenoid analyses of selected raw and cooked foods associated with a lower risk for cancer.

We examined the carotenoid content of selected foods consistently found to be associated with a lower risk for various epithelial cancers in epidemiologic studies. Both raw and cooked samples of green, leafy vegetables and yellow or orange vegetables were quantitatively examined by high-performance liquid chromatography for individual carotenoid content. The results indicated that fresh, green, leafy vegetables were moderately high in beta carotene (0.5-14.6 mg/100 g) and very high in oxygenated carotenoids or xanthophylls, primarily lutein and its stereoisomers (2.3-63.0 mg/100g) [corrected]. The fresh, yellow or orange vegetables examined were very high in beta carotene (16.0-120.5 mg/100 g) [corrected] but had no detectable nonhydrocarbon carotenoids. Cooking differentially reduced the lutein content compared with the beta carotene content in green, leafy vegetables. These analyses suggest that consumption of carotenoids in addition to beta carotene may be associated with a lower risk for cancer.

J Natl Cancer Inst. 1990 Feb 21;82(4):282-5

Kinetics of gastro-intestinal transit and carotenoid absorption and disposal in ileostomy volunteers fed spinach meals.

BACKGROUND: Reports of low carotenoid absorption from food sources has undermined their postulated ‘protective’ role as one of the active agents in diets rich in vegetable matter. AIM OF THE STUDY: This study quantified beta-carotene and lutein absorption from a representative green vegetable with different degrees of processing, using both mass balance and metabolic modelling of triglyceride-rich lipoprotein plasma fraction (TRL) response. METHODS: Whole or chopped-leaf cooked spinach was fed to volunteers (n = 7, paired) with vegetable oil (40 g) in yoghurt. Blood and ileal effluent samples were collected for up to 24 h. Effluent and TRL samples were analysed for lutein and beta-carotene by HPLC. A digesta transit model was used to describe meal transit and a single compartment model used to predict percentage absorption from the plasma TRL response. RESULTS: Mass balance showed 25% of lutein and beta-carotene were absorbed from chopped spinach, compared with 25% beta-carotene and 40 % lutein from whole-leaf spinach. Increased lutein absorption correlated to slower gastrointestinal (GI) transit for the whole-leaf meal. An area under the curve (AUC) response for the TRL fraction, found in 50% of cases, was not confined to those with the greatest percentage absorption. Absorption by mass balance and TRL AUC indicate a half-life of newly absorbed carotenoid around 11 min CONCLUSION: GI residence time appears to have an effect on the absorption of lutein but not beta-carotene. Rapid clearance is probably the main reason for absence of measurable plasma concentration excursions. Lack of plasma response cannot be interpreted as lack of carotenoid absorption without knowledge of the absorption and disposal kinetics.

Eur J Nutr. 2004 Feb;43(1):15-22. Epub 2004 Jan 6

Comparison of serum carotenoid responses between women consuming vegetable juice and women consuming raw or cooked vegetables.

The objective of this study was to examine serum concentrations of alpha-carotene, beta-carotene, lutein, lycopene, and beta-cryptoxanthin due to consumption of vegetable juice versus raw or cooked vegetables. Subjects included female breast cancer patients who had undergone surgical resection and who were enrolled in a feasibility study for a trial examining the influence of diet on breast cancer recurrence. A high-vegetable, low-fat diet was the focus of the intervention, and some of the subjects were specifically encouraged to consume vegetable juice. At 12 months, blood samples were collected and analyzed for carotenoid concentrations via high-performance liquid chromatography methodology. Matched analysis and paired t test were conducted on two groups: those who consumed vegetable juice (the juice group) and those who consumed raw or cooked vegetables (no juice group). Serum concentrations of alpha-carotene and lutein were significantly higher in the vegetable juice group than in the raw or cooked vegetable group (P < 0.05 and P = 0.05, respectively). Paired t test analysis did not demonstrate a significant difference in serum values of beta-carotene, lycopene, and beta-cryptoxanthin between subjects consuming juice and those not consuming any juice. These results suggest that alpha-carotene and lutein appear to be more bioavailable in the juice form than in raw or cooked vegetables. Therefore, the food form consumed may contribute to the variability in serum carotenoid response to vegetable and fruit interventions in clinical studies.

Cancer Epidemiol Biomarkers Prev. 1999 Mar;8(3):227-31

Storage stability of lutein during ripening of cheddar cheese.

Lutein (3,3’-dihydroxy-alpha-carotene) has been identified as a dietary factor that can delay the onset of age-related macular degeneration (AMD). However, available food sources of lutein contain only modest amounts of the carotenoid. Food fortification with lutein extract has been identified as a low-budget approach to prevent the onset or progression of AMD. The objectives of this study were to 1) incorporate various amounts of lutein into Cheddar cheese; 2) examine the color, pH, microbiological, and sensory characteristics of the Cheddar cheese during storage; and 3) analyze the stability of lutein during the cheese maturation process. Lutein extracted from corn was added to Cheddar cheese in quantities of 1, 3, and 6 mg per serving size. Measurements of the lutein stability were carried out by HPLC using a YMC C30 carotenoid column. Microbiological analyses of cheese samples included aerobic plate count, coliform, and yeast/mold counts. The color attributes a* and b* were significantly different between the treatment and control groups; however, no significant difference was observed in L* value and pH. Significant differences among 1, 3, and 6 mg lutein-enriched cheeses were observed in the aerobic plate count and yeast/mold compared with the control. Cheese samples contained no detectable levels of coliforms (< 10 cfu/g). The HPLC data showed quantitative recovery of lutein during the storage period, and no lutein degradation products were identified. These results indicate that lutein, a functional additive with purported ability to prevent or reduce the onset of AMD, can be incorporated into cheese adding value to this product.

J Dairy Sci. 2005 May; 88(5):1661-70

Amount of fat in the diet affects bioavailability of lutein esters but not of alpha-carotene, beta-carotene, and vitamin E in humans.

BACKGROUND: Fat-soluble vitamin E and carotenoids are regarded as being protective against chronic diseases. Little is known about the effect of dietary fat on the bioavailability of these compounds. OBJECTIVE: The objective of this study was to assess the effect of the amount of dietary fat on plasma concentrations of vitamin E and carotenoids after supplementation with these compounds. DESIGN: During two 7-d periods, 4 groups of 14-15 volunteers received daily, with a low-fat hot meal, 1 of 4 different supplements: vitamin E (50 mg), alpha- plus beta-carotene (8 mg), lutein esters (8 mg lutein), or placebo. The supplements were provided in a low- or high-fat spread supplied in random sequence during either of the 2 experimental periods. RESULTS: As anticipated, plasma concentrations of vitamin E, alpha- and beta-carotene, and lutein were significantly higher in the supplemented groups than in the placebo group. The amount of dietary fat consumed with the hot meal (3 or 36 g) did not affect the increases in plasma concentrations of vitamin E (20% increase with the low-fat spread and 23% increase with the high-fat spread) or alpha- and beta-carotene (315% and 139% with the low-fat spread and 226% and 108% with the high-fat spread). The plasma lutein response was higher when lutein esters were consumed with the high-fat spread (207% increase) than with the low-fat spread (88% increase). CONCLUSION: Optimal uptake of vitamin E and alpha- and beta-carotene requires a limited amount of fat whereas the amount of fat required for optimal intestinal uptake of lutein esters is higher.

Am J Clin Nutr. 2000 May;71(5):1187-93

Modulation of multidrug resistance and apoptosis of cancer cells by selected carotenoids.

The multidrug resistance (MDR) proteins that belong to the ATP-binding casette superfamily are present in a majority of human tumors and are an important final cause of therapeutic failure. Therefore, compounds which inhibit the function of the MDR-efflux proteins may improve the cytotoxic action of anticancer chemotherapy. The effects of carotenoids were studied on the activity of the MDR-1 gene-encoded efflux pump system. The carotenoids, isolated from paprika and other vegetables, were tested on the rhodamine 123 accumulation of human MDR-1 gene-transfected L1210 mouse lymphoma cells and human breast cancer cells MDA-MB-231 (HTB-26). Capsanthin and capsorubin enhanced the rhodamine 123 accumulation 30-fold relative to nontreated lymphoma cells. Lycopene, lutein, antheraxanthin and violaxanthin had moderate effects, while alfa- and beta-carotene had no effect on the reversal of MDR in the tumor cells. Apoptosis was induced in human MDR1 transfected mouse lymphoma cells and human breast cancer MDA-MB-231 (HTB-26) cell lines in the presence of lycopene, zeaxanthin and capsanthin. The data suggest the potential of carotenoids as possible resistance modifiers in cancer chemotherapy.

In Vivo. 2004 Mar-Apr;18(2):237-44

Correlates of serum lutein + zeaxanthin: findings from the Third National Health and Nutrition Examination Survey.

The determinants of blood levels of carotenoids were previously investigated in small or select samples. The relations of serum lutein + zeaxanthin to possible diet, lifestyle, and physiological determinants in 7059 participants of the Third National Health and Nutrition Examination Survey (1988-1994), > or = 40 y old, were examined. In a fully adjusted, multiple linear regression model, lower serum lutein + zeaxanthin was significantly associated with smoking, heavy drinking, being white, female, or not being physically active, having lower dietary lutein + zeaxanthin, higher fat-free mass, a higher percentage of fat mass, a higher waist-hip ratio, lower serum cholesterol, a higher white blood cell count, and high levels of C-reactive protein (P < 0.05). The model explained 24% of the variation present in serum lutein + zeaxanthin for the current sample. The correlation between dietary and serum lutein + zeaxanthin was 0.17 and increased to 0.18 after adjusting for the effects of given covariates. Each 10% increase in dietary lutein + zeaxanthin was associated with a 1% increase in serum conditional on other terms in the model. Many factors that influence the level of serum lutein + zeaxanthin remain unknown.

J Nutr. 2004 Sep;134(9):2387-94