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Clinical Studies
References
Beta Carotene is transformed in the body into vitamin A. It helps the body overcome the problem of thickening and hardening of the artery walls (dissimilated sclerosis) in the circulatory system. It also helps reduce blood cholesterol. Vitamin A is essential for the normal structure and function of epithelial cells, which protect the body from all kinds of environmental contamination.
Vitamin A is a very powerful antioxidant for your heart and circulatory system (only pharmaceutical grade 98% pure natural crystalline Beta Carotene is used in Xtend-Life formulas).
It may also be beneficial in AIDS, cataracts and macular degeneration, leukoplakia, exercise induced asthma, cancer, heart disease and hypertension, Alzheimer's disease, depression, headache and rheumatoid arthritis.
Published Clinical Studiesclin
Nutritional and clinical relevance of lutein in human health.1
Granado F, Olmedilla B, Blanco I.
Servicio de Endocrinologia y Nutricion, Hospital Universitario Puerta de Hierro, Madrid, Spain.
Lutein is one of the most widely found carotenoids distributed in fruits and vegetables frequently consumed. Its presence in human tissues is entirely of dietary origin. Distribution of lutein among tissues is similar to other carotenoids but, along with zeaxanthin, they are found selectively at the centre of the retina, being usually referred to as macular pigments. Lutein has no provitamin A activity in man but it displays biological activities that have attracted great attention in relation to human health. Epidemiological studies have shown inconsistent associations between high intake or serum levels of lutein and lower risk for developing cardiovascular disease, several types of cancer, cataracts and age-related maculopathy. Also, lutein supplementation has provided both null and positive results on different biomarkers of oxidative stress although it is effective in increasing macular pigment concentration and in improving visual function in some, but not all, subjects with different eye pathologies. Overall, data suggest that whereas serum levels of lutein have, at present, no predictive, diagnostic or prognostic value in clinical practice, its determination may be very helpful in assessing compliance and efficacy of intervention as well as potential toxicity. In addition, available evidence suggests that a serum lutein concentration between 0.6 and 1.05 micromol/l seems to be a safe, dietary achievable and desirable target potentially associated with beneficial impact on visual function and, possibly, on the development of other chronic diseases. The use of lutein as a biomarker of exposure in clinical practice may provide some rationale for assessing its relationship with human health as well as its potential use within the context of evidence-based medicine.
Publication Types:
PMID: 14513828 [PubMed - indexed for MEDLINE]
3
Bakery products enriched with phytosterol esters, alpha-tocopherol and beta-carotene decrease plasma LDL-cholesterol and maintain plasma beta-carotene concentrations in normocholesterolemic men and women.
Quilez J, Rafecas M, Brufau G, Garcia-Lorda P, Megias I, Bullo M, Ruiz JA, Salas-Salvado J.
Departament de Tecnologia, Europastry S.A., Barcelona, Spain.
The hypocholesterolemic effects of phytosterols have not been evaluated in bakery products, and the addition of liposoluble antioxidants to the carrier has never been tested. We investigated the effects of consuming croissants and magdalenas (Spanish muffins) enriched with sterol esters, alpha-tocopherol and beta-carotene on plasma lipid and fat-soluble antioxidant concentrations in normocholesterolemic, habitual consumers of bakery products following their usual diet and lifestyle. Using a randomized, double-blind, placebo-controlled design, the control (C) group (n = 29) received two pieces daily (standard croissant and muffin) and the sterol ester (SE) group (n = 28), the same products with sterol esters added (3.2 g/d) for 8 wk. Total and LDL cholesterol (LDL-C) decreased in the SE group by 0.24 mmol/L (P < 0.01) and 0.26 mmol/L (P < 0.005), respectively, whereas these variables did not change in the control group. The total difference in total and LDL-C changes between groups was 0.38 mmol/L (8.9%) and 0.36 mmol/L (14.7%), respectively (P < 0.001). Within-group changes in HDL cholesterol, triacylglycerol or lipoprotein(a) concentrations did not differ. Similarly, within-group changes over time in plasma tocopherol and carotenoid concentrations did not differ between groups. Our findings suggest that bakery products are excellent carriers for phytosterols, and their consumption is associated with a decrease in total and LDL-C concentrations, with no changes in alpha-tocopherol and beta-carotene. The ability of bakery products to include sufficient quantities of beta-carotene to compensate for a potential deficiency, and the fact that their efficacy was not associated with the time of day at which they were consumed, are interesting findings.
Publication Types:
PMID: 14519792 [PubMed - indexed for MEDLINE]
4
Retinoid- and carotenoid-enriched diets influence the ontogenesis of the immune system in mice.
Garcia AL, Ruhl R, Herz U, Koebnick C, Schweigert FJ, Worm M.
Institute of Nutritional Science, University of Potsdam, Potsdam-Rehbrucke, Germany.
Vitamin A (VA) has been identified as an important factor for the development of the immune system, especially during ontogenesis. It has been shown that antibody secretion and proliferation of lymphocyte populations depend on retinoids. In the present study we investigated the influence of a base VA diet and diets enriched with VA, beta-carotene and lycopene, on the ontogenesis of the immune system in mice. We examined the absolute and relative concentrations of splenic B lymphocytes (CD45R/B220), T lymphocytes (CD3+) and their subpopulations (CD4+ and CD8+), and measured serum immunoglobulin G (IgG) concentrations in the offspring of supplemented dams at different ages (1, 3, 5, 7, 14, 21 and 65 days). The experimental diets resulted in higher numbers of T and B lymphocytes after VA and carotenoid enrichment, when compared, at various time-points, with the base diet. Higher values of total serum IgG were found in the beta-carotene-enriched diet group on day 7. On days 7 and 14, the enriched diets induced significant alterations in the percentages and total numbers of splenic lymphocytes in comparison to the base diet. Our results confirm that supplementation with VA and carotenoids affect the immune-cell function during ontogenesis and suggest a possible role of these nutritional factors on the development of the immune system.
PMID: 14511231 [PubMed - indexed for MEDLINE]
Reproducibility and validity of the Diet Quality Index Revised as assessed by use of a food-frequency questionnaire.
Newby PK, Hu FB, Rimm EB, Smith-Warner SA, Feskanich D, Sampson L, Willett WC.
Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111, USA. pknewby@post.harvard.edu
BACKGROUND: The Diet Quality Index Revised (DQI-R) is a dietary assessment instrument based on 10 dietary recommendations reflecting dietary guidelines and policy in the United States. OBJECTIVE: The objective of this study was to assess the reproducibility and validity of the DQI-R as measured by use of food-frequency questionnaires (FFQs). DESIGN: Diet was assessed separately by two FFQs at a 1-y interval and by two 1-wk diet records. DQI-R scores were computed from each method. Venous blood specimens were collected for measurement of dietary biomarkers. Participants (n = 127) were men aged 40-75 y in a validation study of the Health Professionals Follow-up Study. RESULTS: Mean DQI-R scores were 69.5 for FFQ-1, 67.2 for FFQ-2, and 62.0 for the diet records out of a possible score of 100. The reproducibility correlation for the 2 FFQ scores was 0.72. Correlations between scores for each of the 2 FFQs and diet records were 0.66 (FFQ-1) and 0.72 (FFQ-2). DQI-R scores from FFQ-2 were directly correlated with plasma biochemical measurements of alpha-carotene (r = 0.43, P < 0.0005), beta-carotene (r = 0.35, P < 0.005), lutein (r = 0.31, P <0.005), and alpha-tocopherol (r = 0.25, P < 0.05) and were inversely correlated with plasma total cholesterol (r = -0.22, P < 0.05). CONCLUSIONS: These data indicate reasonable reproducibility and validity of the DQI-R as assessed by an FFQ. Future studies are needed to examine whether this index and other instruments of diet quality can reliably predict disease outcomes.
Publication Types:
PMID: 14594780 [PubMed - indexed for MEDLINE]
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