Macular pigment optical density and photophobia light threshold

AbstractLight absorption by macular pigment may attenuate visual discomfort, or photophobia, for targets composed of short-wavelength light. Macular pigment optical density (MPOD) and photophobia light thresholds were measured psychophysically in 10 subjects. The energy necessary to induce photophobia for a short-wavelength target relative to a long-wavelength target was linearly related to MPOD, as well as estimates of peak MPOD and integrated macular pigment. In four subjects who consumed lutein supplements, increases in MPOD corresponded to increases in photophobia light thresholds. Light absorption by macular pigment appears to influence the amount of short-wavelength light necessary to elicit photophobia

Dietary intake and serum concentrations of lutein and zeaxanthin, but not macular pigment optical density, are related in spouses

Lutein and zeaxanthin, 2 carotenoids obtained from the diet, accumulate in the central retina where they are collectively called macular pigment. Although dietary intake of these carotenoids is directly related to tissue concentration, several factors, such as body mass index, appear to indirectly affect macular pigment concentrations. Individuals who consume similar diets and share factors that affect macular pigment, such as married couples, may have similar macular pigment levels. The purpose of this study was to investigate the relatedness of dietary, serum, and retinal concentrations of lutein and zeaxanthin in married couples. Fifty participants, 25 male-female married couples, between 29 and 70 years of age participated in the study. Fruit and vegetable consumption as well as dietary intakes of macronutrients and carotenoids were assessed by a dietary questionnaire. Cholesterol concentrations were measured with reflectance photometry, and serum carotenoid concentrations were determined with high-performance liquid chromatography. Retinal carotenoids, defined as macular pigment optical density (MPOD), were measured by heterochromatic flicker photometry at 4 retinal loci. Dietary intake of lutein and zeaxanthin in the sample was related to serum lutein and zeaxanthin concentrations (P =.01). Both dietary intake (P =.04) and serum concentrations (P =.003) of lutein and zeaxanthin were significantly related to MPOD at 30 \u27 eccentricity. Wives\u27 dietary intake (P =.016) and serum concentrations (P \u3c.001) of lutein and zeaxanthin were linearly related with the husbands\u27. Married couples\u27 MPOD, however, was not related at any retinal locus. Despite similar dietary intakes and serum concentrations of lutein and zeaxanthin, husbands and wives, unexpectedly, did not have similar MPOD. Factors such as lipoprotein concentrations and genes, which are not shared by spouses, appear to influence MPOD more than factors such as diet and body mass index, which are concordant in spouses. (c) 2007 Elsevier Inc. All rights reserved

Air Temperature Affects Biomass and Carotenoid Pigment Accumulation in Kale and Spinach Grown in a Controlled Environment

Crop plants are adversely affected by a variety of environmental factors, with air temperature being one of the most influential. Plants have developed a number of methods in the adaptation to air temperature variations. However, there is limited research to determine what impact air temperature has on the production of secondary plant compounds, such as carotenoid pigments. Kale (Brassica oleracea L.) and spinach (Spinacia oleracea L.) have high concentrations of lutein and ß-carotene carotenoids. The objectives of this study were to determine the effects of different growing air temperatures on plant biomass production and the accumulation of elemental nutrients, lutein, ß-carotene, and chlorophyll pigments in the leaves of kale and spinach. Plants were grown in nutrient solutions in growth chambers at air temperatures of 15, 20, 25, and 30 °C for `Winterbor\u27 kale and 10, 15, 20, and 25 °C for `Melody\u27 spinach. Maximum tissue lutein and ß-carotene concentration occurred at 30 °C for kale and 10 °C for spinach. Highest carotenoid accumulations were 16.1 and 11.2 mg/100 g fresh mass for lutein and 13.0 and 10.9 mg/100 g fresh mass for ß-carotene for the kale and spinach, respectively. Lutein and ß-carotene concentration increased linearly with increasing air temperatures for kale, but the same pigments showed a linear decrease in concentration for increasing air temperatures for spinach. Quantifying the effects of air temperature on carotenoid accumulation in kale and spinach, expressed on a fresh mass basis, is important for growers producing these crops for fresh markets

Irradiance Levels Affect Growth Parameters and Carotenoid Pigments in Kale and Spinach Grown in a Controlled Environment

Carotenoids play critical roles in both light harvesting and energy dissipation for the protection of photosynthetic structures. However, limited research is available on the impact of irradiance on the production of secondary plant compounds, such as carotenoid pigments. Kale (Brassica oleracea L.) and spinach (Spinacia oleracea L.) are two leafy vegetables high in lutein and β-carotene carotenoids. The objectives of this study were to determine the effects of different irradiance levels on tissue biomass, elemental nutrient concentrations, and lutein β-carotene and chlorophyll (chl) pigment accumulation in the leaves of kale and spinach. ‘Winterbor’ kale and ‘Melody’ spinach were grown in nutrient solution culture in growth chambers at average irradiance levels of 125, 200, 335, 460, and 620 μmol m−2 s−1. Highest tissue lutein β-carotene and chls occurred at 335 μmol m−2 s−1 for kale, and 200 μmol m−2 s−1 for spinach. The accumulations of lutein and β-carotene were significantly different among irradiance levels for kale, but were not significantly different for spinach. However, lutein and β-carotene accumulation was significant for spinach when computed on a dry mass basis. Identifying effects of irradiance on carotenoid accumulation in kale and spinach is important information for growers producing these crops for dry capsule supplements and fresh markets

Variability in Elemental Accumulations Among Leafy \u3cem\u3eBrassica oleracea\u3c/em\u3e Cultivars and Selections

The vegetable brassicas are consumed in part for their nutritional values of calcium (Ca), magnesium (Mg), potassium (K), iron (Fe), and zinc (Zn). However, information on the genetic variability of elemental accumulation within kale and collards (Brassica oleracea L. var. acephala DC) is limited. Therefore, 22 kale and collard cultivars and selections suitable for the northeastern United States were field grown under similar fertility regimes over two years and evaluated for elemental accumulation. Leaf tissues were analyzed using inductively coupled argon plasma-atomic emission spectrometry. Significant variability among cultivars and selections was observed for tissue Ca, Mg, K, Fe, and Zn. On average, a two-fold difference in elemental accumulation among the cultivars and selections was measured. Tissue Ca levels ranged from 1.2 (“Crimson Garden”) to 3.1% (“NZ Thousand Head”), tissue Mg ranged from 0.3 (“Crimson Garden”) to 0.6% (“NZ Thousand Head”), tissue K ranged from 2.1 (“NZ Thousand Head”) to 3.5% (30665-96G11), tissue Fe ranged from 53.1 (“Winterbor F1”) to 114.2 mg/kg (“Giant Jersey Kale”), and tissue Zn ranged from 29.1 (“Shetland”) to 71.9 mg/kg (“Redbor F1”). Significant year-to-year variability occurred for Ca, Mg, Fe, and Zn accumulation. Despite these yearly changes, ranking of the cultivars and selections for elemental accumulation, as determined by Spearman\u27s rank correlation coefficient, did not change from year 1 to year 2. Overall, the cultivar with the highest elemental leaf accumulation was “Redbor F1”. Information on genotypic variability for elemental accumulation may be important for producers and consumers looking to select kale and collards with higher nutritional levels of beneficial dietary elements

Spinach Cultigen Variation for Tissue Carotenoid Concentrations Influences Human Serum Carotenoid Levels and Macular Pigment Optical Density Following a 12-Week Dietary Intervention

Increasing intakes of carotenoid-rich plant foods can increase serum carotenoid concentrations and macular pigment optical density (MPOD) in most, but not all, individuals. Research objectives for this study were to (1) characterize tissue lutein (L) and β-carotene (BC) concentrations in carotenoid-rich spinach (Spinacia oleracea L.) cultigens and (2) determine serum carotenoid and MPOD responses in human subjects consuming spinach cultigens differing in tissue L and BC concentrations. Thirteen spinach cultigens were evaluated for carotenoid accumulations over two consecutive growing seasons. ‘Springer\u27 (8.4 and 6.5 mg/100 g of fresh mass for L and BC, respectively) and ‘Spinner\u27 (12.1 and 9.2 mg/100 g of fresh mass for L and BC, respectively) spinach cultigens were selected for a dietary intervention study and represented low- and high-L concentrations. The high-L (‘Spinner\u27) and low-L (‘Springer\u27) spinach treatment groups consisted of 10 subject volunteers ingesting five 50-g spinach servings/week during a 12-week intervention. Average serum L concentrations increased by 22% (P = 0.07) from baseline (0.233 μmol/L) to 12 weeks (0.297 μmol/L) for subjects consuming low-L spinach. Subjects consuming high-L spinach showed increases of 33% (P = 0.04) in serum L from baseline (0.202 μmol/L) to 12 weeks (0.300 μmol/L). Average MPOD did not change for the low-L treatment group; however, subjects in the high-L group demonstrated increases (P = 0.02) in MPOD at the 30‘ eccentricity between baseline (0.343) and 12 weeks (0.374). This study demonstrates that serum carotenoid and MPOD are determined by L concentrations present in the spinach matrix. Results emphasize the role of cultigen selection among vegetable crops in determining phytochemical effects on human health

Variation in Lutein, β-carotene, and Chlorophyll Concentrations among Brassica oleracea Cultigens and Seasons

Green leafy vegetables are important sources of dietary carotenoids, and members of Brassica oleracea L. var. acephala rank highest for reported levels of lutein and β-carotene. Twenty-three leafy B. oleracea cultigens were field grown under similar fertility over two separate years and evaluated for leaf lutein and β-carotene accumulation. Choice of B. oleracea cultigen and year significantly affected carotenoid levels. Lutein concentrations ranged from a high of 13.43 mg per 100 g fresh weight (FW) for B. oleracea var. acephala `Toscano\u27 to a low of 4.84 mg/100 g FW for B. oleracea var. acephala 343-93G1. β-carotene accumulations ranged from a high of 10.00 mg/100 g FW for B. oleracea var. acephala `Toscano\u27 to a low of 3.82 mg/100 g FW for B. oleracea var. acephala 30343-93G1. Carotenoid concentrations were significantly higher in year 2 than in year 1, but rank order among the cultigens for both lutein and ß-carotene did not change between the years. During each year, there were high correlations between leaf carotenoid and chlorophyll pigments. Under similar growing conditions, choice of B. oleracea cultigen will influence carotenoid accumulation, and this may affect the health benefits of consuming these leafy green vegetable crops

The Journal of Nutrition Nutrient Requirements and Optimal Nutrition A 12-Wk Egg Intervention Increases Serum Zeaxanthin and Macular Pigment Optical Density in Women 1

Abstract 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 331mg (EGG 1) or 964 mg (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 ¼ 0.04) and triglycerides (P ¼ 0.02) increased in the PILL group. Serum zeaxanthin, but not serum lutein, increased in both the EGG 1 (P ¼ 0.04) and EGG 2 (P ¼ 0.01) groups. Likewise, MPOD increased in both the EGG 1 (P ¼ 0.001) and EGG 2 (P ¼ 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

Kale Carotenoids Remain Stable while Flavor Compounds Respond to Changes in Sulfur Fertility

Dietary intake of certain carotenoids has been associated with a reduced risk of disease. Kale (Brassica oleracea L. Acephala Group) has the highest levels of carotenoids lutein and β-carotene, and is an excellent source of minerals among the green leafy vegetable crops. However, Brassica vegetables contain glucosinolate (GS) and S-methylcysteine sulfoxide (MCSO). While these sulfur compounds have medicinal value, they are also responsible for the bitter, acrid flavors that are often regarded as objectionable by consumers. Therefore, the objectives of this study were to investigate the influence of increased S fertility levels on (1) elemental accumulation, (2) GS and MCSO production, and (3) the accumulation patterns of carotenoid pigments in the leaves of three kale cultivars. Winterbor, Redbor, and Toscano kale were greenhouse-grown using nutrient solution culture with S treatment concentrations of 4, 8, 16, 32, and 64 mg of S/L. Decreasing S fertility decreased S leaf content, but increased the levels of Mg and Ca accumulation, two important minerals for human health. Levels of GS and MSCO decreased in response to a decreasing S level in nutrient solution. However, accumulation of lutein and β-carotene was unaffected by S treatment. Lowering the S fertility in the production of kale should decrease the levels of negative flavors associated with high levels of GS and MCSO without affecting carotenoid pigment levels. Understanding the combined impact of fertility on flavor compounds and carotenoid pigments may help improve consumer acceptance of phytonutritionally enhanced vegetable crops