Judy D. Ribaya-Mercado

Lutein and Zeaxanthin and Their Potential Roles in Disease Prevention

Lutein and zeaxanthin are xanthophyll carotenoids found particularly in dark-green leafy vegetables and in egg yolks. They are widely distributed in tissues and are the principal carotenoids in the eye lens and macular region of the retina. Epidemiologic studies indicating an inverse relationship between xanthophyll intake or status and both cataract and age-related macular degeneration suggest these compounds can play a protective role in the eye. Some observational studies have also shown these xanthophylls may help reduce the risk of certain types of cancer, particularly those of the breast and lung. Emerging studies suggest as well a potential contribution of lutein and zeaxanthin to the prevention of heart disease and stroke. Even as the evidence for a role of lutein and zeaxanthin in disease prevention continues to evolve, particularly from human studies directed to their bioavailability, metabolism, and dose-response relationships with intermediary biomarkers and clinical outcomes, it is worth noting that recommendations to consume foods rich in xanthophylls are consistent with current dietary guidelines.

Safety and Tolerability of Esterified Phytosterols Administered in Reduced-Fat Spread and Salad Dressing to Healthy Adult Men and Women

Objective/Design: The safety and tolerability of three levels of plant sterol-esters administered in reduced-fat spread and salad dressing vs. control products were evaluated in this randomized, double-blind, four-arm parallel study. Methods: Eighty-four free-living men and women consumed reduced-fat spread and salad dressing providing 0.0 g/day (n = 21), 3.0 g/day (n = 21), 6.0 g/day (n = 19) or 9.0 g/day (n = 23) of phytosterols as esters for an eight-week treatment period. Results: Side effects did not differ among the groups during the study, and there were no study product-related serious adverse events. There were no changes in clinical laboratory values in response to phytosterol intake. Blood concentrations of all fat-soluble vitamins remained within normal reference ranges, and there were no differences in serum vitamin responses among the four groups. Alpha- and trans-β-carotene levels were reduced in the 9.0 g/day group vs. control (p < 0.05), but all carotenoid values remained within normal ranges throughout the study. All groups receiving phytosterols had significant increases in serum campesterol vs. control (p < 0.001), but β-sitosterol responses did not differ from control. Total, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol responses did not differ significantly among the groups. The total:HDL cholesterol response in the 9.0 g/day group was significantly different from the control group response (−9.6% vs. 2.6%, p < 0.05). A median increase of 7.8% in serum triglycerides was observed in the control group, which differed significantly from the response in the 3.0 g/day arm (−13.3%, p < 0.05). Discussion: The results of this study indicate that phytosterol esters are well tolerated and show no evidence of adverse effects at a daily intake of up to 9.0 g of phytosterols for eight weeks.

Effect of beta-carotene supplementation on the human sunburn reaction.

Abstract Beta‐carotene, a quencher of excited species such as singlet oxygen and free radicals, has been reported to protect against cutaneous photodamage, including sunburn acutely and photocarcinogenesis chronically. The present double blind placebo‐controlled study examines the ef‐tect of beta‐carotene supplementation on the human sunburn response and specifically on the induction of sunburn cells at the time of peak reaction intensity (24 h) after a single solar simulated light exposure 3 times the individually determined minimal erythema dose (MED). Administered orally either as a single 120 mg dose to dietarily restricted subjects or for 23 d as a daily 90 mg supplement to subjects on standard diets, beta‐carotene increased plasma and skin levels of beta‐carotene compared to both pretreatment levels and placebo‐treated controls, but provided no clinically or histologically detectable protection against a 3 MED sunburn reaction. Thus, these data suggest that oral beta‐carotene supplementation is unlikely to modify the severity of cutaneous photodamage in normal individuals to a clinically meaningful degree.

EFFECTS OF CONSUMING FOODS CONTAINING OAT BETA-GLUCAN ON BLOOD PRESSURE, CARBOHYDRATE METABOLISM AND BIOMARKERS OF OXIDATIVE STRESS IN MEN AND WOMEN WITH ELEVATED BLOOD PRESSURE

Objective:To assess the effects of consuming foods containing oat β-glucan on blood pressure, carbohydrate homeostasis and biomarkers of oxidative stress.Design:A randomized, double-blind, controlled clinical trial.Setting:The trial was conducted at two clinics.Subjects and interventions:Ninety-seven men and women with resting systolic blood pressure 130–179 mm Hg and/or diastolic blood pressure 85–109 mm Hg were randomly assigned to consume foods containing oat β-glucan or control foods for 12 weeks. Resting blood pressures, insulin and glucose values before and after standard breakfast meals, and four biomarkers of oxidative stress were measured before and at the end of the treatment period.Results:Changes from baseline to week 12 in mean peak insulin and incremental area under the insulin curve differed significantly between groups (P=0.037 and 0.034, respectively), with the β-glucan group showing declines and the control group remaining essentially unchanged. Blood pressure responses were not significantly different between groups overall. However, in subjects with body mass index above the median (31.5 kg/m2), both systolic (8.3 mm Hg, P=0.008) and diastolic (3.9 mm Hg, P=0.018) blood pressures were lowered in the β-glucan group compared to controls. No significant differences in biomarkers of oxidative stress were observed between treatments.Conclusions:The results of the present trial suggest beneficial effects of foods containing β-glucan from oats on carbohydrate metabolism, and on blood pressure in obese subjects.Sponsorship:Funding for this study was provided by the Quaker Oats Company.

Influence of Dietary Fat on β‐Carotene Absorption and Bioconversion into Vitamin A

Dietary fat facilitates the utilization of carotenoids and, based on serum beta-carotene or retinol responses following ingestion of meals containing carotene and fat sources, it has been reported that the amount of fat required in a meal may be minimal (approximately 3-5 g). However, the dietary fat requirement for optimal carotene utilization in humans cannot be fully ascertained without longer-term dose-response studies that measure the changes in vitamin A body stores in response to varying levels of dietary fat. In humans, vitamin A body stores can be determined by use of stable isotope-dilution methods. Animal studies have shown that although the level of dietary fat has no effect on serum vitamin A concentrations of animals fed beta-carotene, higher liver vitamin A concentrations were found in those that ingested higher fat levels. Other factors that might influence the relationship of fat intake and beta-carotene utilization include the type of fat ingested, physicochemical properties of the carotenoid source, amount of carotene ingested, whether fat and beta-carotene sources are provided in the same meal, the presence of helminthic infections, age, and vitamin A status.

Effect of beta-carotene supplementation on the concentrations and distribution of carotenoids, vitamin E, vitamin A, and cholesterol in plasma lipoprotein and non-lipoprotein fractions in healthy older women.

OBJECTIVE We studied the effect of beta-carotene supplementation on the concentrations and distribution in plasma lipoprotein and non-lipoprotein fractions of carotenoids, alpha-tocopherol, retinol, and cholesterol. METHODS Ten women ingested either 90 mg of beta-carotene or placebo daily for 3 weeks while residing in their homes and eating their usual meals. Carotenoids (beta-carotene, lycopene, lutein/zeaxanthin), retinol, alpha-tocopherol, and cholesterol were measured in plasma lipoprotein and non-lipoprotein fractions before and after treatment. RESULTS In the beta-carotene-supplemented group, total plasma beta-carotene increased 14-fold from 0.48 +/- 0.13 to 6.83 +/- 2.12 mumol/L (p = 0.04). Although the greatest increase in beta-carotene was in low-density-lipoproteins (LDL), the magnitude of increase was similar in LDL, high-density-lipoproteins (HDL), and very-low-density-lipoproteins (VLDL). Thus, the relative distribution of beta-carotene in lipoproteins was unchanged: approximately 71% was in LDL, approximately 15% in HDL and approximately 12% in VLDL, before and after beta-carotene supplementation. There were no changes in amounts and distribution in lipoproteins of the other carotenoids, alpha-tocopherol, and cholesterol. There was no change in the amount of retinol in lipoprotein-deficient plasma. There were no changes in total plasma triglycerides. Significant positive correlations were found between LDL- or VLDL-cholesterol and alpha-tocopherol in LDL or VLDL, respectively; between LDL- or VLDL-cholesterol and lutein/zeaxanthin in LDL or VLDL, respectively; and between HDL-cholesterol and beta-carotene in HDL. CONCLUSIONS beta-Carotene supplementation (90 mg/day for 3 weeks) in healthy older women results in an enrichment of all plasma lipoprotein fractions with beta-carotene, but does not alter the relative distribution of beta-carotene in lipoproteins. beta-Carotene supplementation has no effect on the amounts and relative distribution of lycopene, lutein/zeaxanthin, and alpha-tocopherol in lipoproteins, or of retinol in the non-lipoprotein fraction of plasma. Short-term beta-carotene supplementation has no effect on the concentrations of plasma total triglycerides, total cholesterol, HDL-, LDL-, and VLDL-cholesterol.

Acute effects of dietary glycemic index on antioxidant capacity in a nutrient-controlled feeding study.

Oxidative stress, caused by an imbalance between antioxidant capacity and reactive oxygen species, may be an early event in a metabolic cascade elicited by a high glycemic index (GI) diet, ultimately increasing the risk for cardiovascular disease and diabetes. We conducted a feeding study to evaluate the acute effects of low‐GI compared with high‐GI diets on oxidative stress and cardiovascular disease risk factors. The crossover study comprised two 10‐day in‐patient admissions to a clinical research center. For the admissions, 12 overweight or obese (BMI: 27–45 kg/m2) male subjects aged 18–35 years consumed low‐GI or high‐GI diets controlled for potentially confounding nutrients. On day 7, after an overnight fast and then during a 5‐h postprandial period, we assessed total antioxidant capacity (total and perchloric acid (PCA) protein‐precipitated plasma oxygen radical absorbance capacity (ORAC) assay) and oxidative stress status (urinary F2α‐isoprostanes (F2IP)). On day 10, we measured cardiovascular disease risk factors. Under fasting conditions, total antioxidant capacity was significantly higher during the low‐GI vs. high‐GI diet based on total ORAC (11,736 ± 668 vs. 10,381 ± 612 µmol Trolox equivalents/l, P = 0.002) and PCA‐ORAC (1,276 ± 96 vs. 1,210 ± 96 µmol Trolox equivalents/l, P = 0.02). Area under the postprandial response curve also differed significantly between the two diets for total ORAC and PCA‐ORAC. No diet effects were observed for the other variables. Enhancement in plasma total antioxidant capacity occurs within 1 week on a low‐GI diet, before changes in other risk factors, raising the possibility that this phenomenon may mediate, at least in part, the previously reported effects of GI on health.

Physical activity, energy requirements, and adequacy of dietary intakes of older persons in a rural Filipino community

BackgroundAging is a process associated with physiological changes such as in body composition, energy expenditure and physical activity. Data on energy and nutrient intake adequacy among elderly is important for disease prevention, health maintenance and program development.MethodsThis descriptive cross-sectional study was designed to determine the energy requirements and adequacy of energy and nutrient intakes of older persons living in private households in a rural Filipino community. Study participants were generally-healthy, ambulatory, and community living elderly aged 60–100 y (n = 98), 88 of whom provided dietary information in three nonconsecutive 24-hour food-recall interviews.ResultsThere was a decrease in both physical activity and food intake with increasing years. Based on total energy expenditure and controlling for age, gender and socio-economic status, the average energy requirement for near-old (≥ 60 to < 65 y) males was 2074 kcal/d, with lower requirements, 1919 and 1699 kcal/d for the young-old (≥ 65 to < 75 y) and the old-old (≥ 75 y), respectively. Among females, the average energy requirements for the 3 age categories were 1712, 1662, and 1398 kcal/d, respectively. Actual energy intakes, however, were only ~65% adequate for all subjects as compared to energy expenditure. Protein, fat, and micronutrients (vitamins A and C, thiamin, riboflavin, iron and calcium) intakes were only ~24–51% of the recommended daily intake. Among this population, there was a weight decrease of 100 g (p = 0.012) and a BMI decrease of 0.04 kg/m2 (p = 0.003) for every 1% decrease in total caloric intake as percentage of the total energy expenditure requirements.ConclusionThese community living elderly suffer from lack of both macronutrient intake as compared with energy requirements, and micronutrient intake as compared with the standard dietary recommendations. Their energy intakes are ~65% of the amounts required based on their total energy expenditure. Though their intakes decrease with increasing age, so do their energy expenditure, making their relative insufficiency of food intake stable with age.

Influence of carotene-rich vegetable meals on the prevalence of anaemia and iron deficiency in Filipino schoolchildren

Objective:To determine the effects of eating carotene-rich green and yellow vegetables on the prevalence of anaemia, iron deficiency and iron-deficiency anaemia in schoolchildren.Subjects and methods:Schoolchildren (n=104), aged 9–12 years, received standardized meals containing 4.2 mg of provitamin A carotenoids/day (mainly β-carotene) from yellow and green leafy vegetables and at least 7 g dietary fat/day. The meals were provided three times/day, 5 days/week, for 9 weeks at school. Before and after the dietary intervention, total-body vitamin A pool size was assessed by using the deuterated-retinol-dilution method; serum retinol and β-carotene concentrations were measured by high-performance liquid chromatography; and whole blood haemoglobin (Hb) and zinc protoporphyrin (ZnPP) concentrations were measured by using a photometer and a hematofluorometer, respectively.Results:After 9 weeks, the mean total-body vitamin A pool size increased twofold (95% confidence interval (CI): −0.11, −0.07 μmol retinol; P<0.001), and serum β-carotene concentration increased fivefold (95% CI: −0.97, −0.79 μmol/l; P<0.001). Blood Hb (95% CI: −1.02, −0.52 g per 100 ml; P<0.001) and ZnPP increased (95% CI: −11.82, −4.57 μmol/mol haem; P<0.001). The prevalence of anaemia (Hb<11.5 g per 100 ml) decreased from 12.5 to 1.9% (P<0.001). There were no significant changes in the prevalence of iron deficiency or iron-deficiency anaemia.Conclusions:Ingestion of carotene-rich yellow and green leafy vegetables improves the total-body vitamin A pool size and Hb concentration, and decreases anaemia rates in Filipino schoolchildren, with no effect on iron deficiency or iron-deficiency anaemia rates.

Relationships of body mass index with serum carotenoids, tocopherols and retinol at steady-state and in response to a carotenoid-rich vegetable diet intervention in Filipino schoolchildren

In marginally nourished children, information is scarce regarding the circulating concentrations of carotenoids and tocopherols, and physiological factors influencing their circulating levels. We determined the serum concentrations of carotenoids, tocopherols and retinol at steady state and in response to a 9-week vegetable diet intervention in 9-12-year-old girls (n=54) and boys (n=65) in rural Philippines. We determined cross-sectional relationships of BMI (body mass index) with serum micronutrient levels, and whether BMI is a determinant of serum carotenoid responses to the ingestion of carotenoid-rich vegetables. We measured dietary nutrient intakes and assessed inflammation by measurement of serum C-reactive protein levels. The children had low serum concentrations of carotenoids, tocopherols and retinol as compared with published values for similar-aged children in the U.S.A. The low serum retinol levels can be ascribed to inadequate diets and were not the result of confounding due to inflammation. Significant inverse correlations of BMI and serum all-trans-beta-carotene, 13-cis-beta-carotene, alpha-carotene, lutein, zeaxanthin and alpha-tocopherol (but not beta-cryptoxanthin, lycopene and retinol) were observed among girls at baseline. The dietary intervention markedly enhanced the serum concentrations of all carotenoids. Changes in serum all-trans-beta-carotene and alpha-carotene (but not changes in lutein, zeaxanthin and beta-cryptoxanthin) in response to the dietary intervention were inversely associated with BMI in girls and boys. Thus, in Filipino school-aged children, BMI is inversely related to the steady-state serum concentrations of certain carotenoids and vitamin E, but not vitamin A, and is a determinant of serum beta- and alpha-carotene responses, but not xanthophyll responses, to the ingestion of carotenoid-rich vegetable meals.