Wellness Database

Wellness Database: Vitamin A

Vitamin A is a critical nutrient. It prevents blindness and death in children, improves the immune system, and may prevent cardiovascula disease.

Related: Heart Disease, Children

Related Studies

Vitamin A May Help Reduce Breast Cancer Risk

Summary: In this review, the authors analyzed data from 51 studies examining the relationships between intakes of retinol, vitamin A, vitamin C, and vitamin E on risk of breast cancer, and found that the risk of breast cancer was reduced by 17% in those with the highest vitamin A intake (compared to the lowest, pooled OR=0.83). Furthermore, dietary vitamin A, dietary vitamin E, and total vitamin E intakes all reduced the risk of breast cancer when results from all the studies were pooled, but became nonsignificant when data from the cohort studies was pooled. The authors conclude, "...the total intake of vitamin A and retinol could reduce breast cancer risk."

Reference: "Retinol, vitamins A, C, and E and breast cancer risk: a meta-analysis and meta-regression," Fulan H, Changxing J, et al, Cancer Causes Control, 2011, [Epub ahead of print]. (Address: Department of Epidemiology, Public Health College, Harbin Medical University, 157, Baojian Street, Nangang District, Harbin, Heilongjiang, People's Republic of China).

Vitamin A Critical for Children Under Five

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Summary: In a systematic review and meta-analysis, including results from 43 trials with data from 215,633 children, oral supplementation with vitamin A in children 6 months to 5 years of age, was found to be associated with a 24% reduction in all-cause mortality (rate ratio: 0.76), a 28% reduction in mortality associated with diarrhea (0.72), a reduced incidence of diarrhea (0.85), reduced incidence of measles (0.50), reduced prevalence of vision problems, including night blindness (0.32) and xerophtalmia (0.31). In 3 of the 43 trials, an increased risk of vomiting was found within the first 2 days of supplementation. The authors conclude, "...there is a need for further studies comparing different doses and delivery mechanisms (for example, fortification). Until other sources are available, vitamin A supplements should be given to all children at risk of deficiency, particularly in low and middle income countries."

Reference: "Vitamin A supplements for preventing mortality, illness, and blindness in children aged under 5: systematic review and meta-analysis," Mayo-Wilson E, Imad A, et al, BMJ, 2011 Aug 25; 343: d5094. (Address: Centre for Evidence-Based Intervention, Department of Social Policy and Intervention, University of Oxford, Barnett House, Oxford OX1 2ER, UK).

Vitamin A Prevents Childhood Mortality

Summary: In this Cochrane review, 43 randomized, controlled trials and cluster RCTs (involving a total of 215,633 children) evaluating the effect of synthetic vitamin A supplementation in children ages 6 months to 5 years of age were evaluated and reviewed, and a meta-analysis for all-cause mortality including 17 trials involving 194,795 children (out of which there were 3,536 deaths) was conducted. Children who had received vitamin A supplementation were found to have a 24% observed reduction in the risk of all-cause mortality (RR=0.76). In addition, a 28% reduction in diarrhea mortality (RR=0.72), incidence of diarrhea (RR=0.85), and measles mortality (RR=0.50), were associated with vitamin A supplementation. An increased risk of vomiting was found within the first 48 hours associated with vitamin A supplementation. The authors state, "VAS is effective in reducing all-cause mortality by about 24% compared to no treatment. In our opinion, given the evidence that VAS causes considerable reduction in child mortality, further placebo-controlled trials of VAS in children between 6 months and 5 years of age are not required. There is a need for further studies comparing different doses and delivery mechanisms (for example, fortification)."

Reference: "Vitamin A supplementation for preventing morbidity and mortality in children from 6 months to 5 years of age," Imdad A, Herzer K, et al, Cochrane Database Syst Rev, 2010 Dec 8; 12: CD008524. (Address: Division of Women and Child Health, Aga Khan University Hospital, Stadium Road, PO Box 3500, Karachi, Pakistan, 74800).

Vitamin A Improves Immune System in Anemic

Summary: In a 4-phase study involving children between the ages of 36 to 83 months of age, supplementation with vitamin A was found to significantly increase absolute CD4 and CD8 T-cell counts in children with hypovitaminosis A and anemia. The study involved assessing serum retinol in 631 children, assessing immunological markers in 52 of the vitamin A deficient children, supplementing those 52 children with vitamin A (200,000 IU), and finally, re-assessing serum retinol and immunological markers after 2 months after supplementation. In the study population, 24% were anemic and 2.3% had reduced ferritin levels. After 2 months of supplementation, children with both hypovitaminosis A and anemia were found to have a significant increase in CD4 and CD8 T-cell counts. The authors state, "Vitamin A had an effect on the recruitment of T and B lymphocytes to the circulation of children with hypovitaminosis A and anemia."

Reference: "The Impact of Vitamin A Supplementation on the Immune System of Vitamin A-deficient Children," de Azevedo Paiva A, Rondo PH, et al, Int J Vitamin Nutr Res, 2010; 80(3): 188-96. (Address: Department of Nutrition, Federal University of Teresina, Piaui, Brazil).

Vitamin A May Prevent Cardiovascular Disease

Summary: In a study involving 189 morbidly obese subjects, of which 49% were diagnosed with the metabolic syndrome, levels of beta-carotene were found to be significantly lower as BMI increased, with a significant difference found in patients with versus without the metabolic syndrome, and when metabolic syndrome was diagnosed by NCEP criterion, beta-carotene inadequacy was found to be higher (42.8%), as compared to the whole sample (37.5%). In addition, serum retinol inadequacy was found to be significantly higher (61.3%) in patients with metabolic syndrome, as compared to the whole group (12.7%). The authors conclude, "Considering the vitamin A contribution in antioxidant protection, especially when risk factors for cardiovascular disease are present, it is suggested that great attention be given to morbidly obese. This could aid in prevention and treatment of cardiovascular disease, which affects a significant part of the population."

Reference: "Serum Retinol and Beta-carotene Levels and Risk Factors for Cardiovascular Disease in Morbid Obesity," Villaca Chaves G, Goncalves de Souza G, et al, Int J Vitamin Nutr Res, 2010; 80(3): 159-67. (Address: Departamento de Nutrição Social e Aplicada, Instituto de Nutrição, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Brazil).

Nutrition From Vegetables Benefits Bones

Summary: In a study involving 144 postmenopausal Korean women with osteoporosis and age-matched controls, intake of calcium, plant calcium, potassium, vitamin A, carotene, vitamin B(1), niacin, vitamin E, vitamin C, and vegetables were associated with significantly reduced risk of osteoporosis, after adjusting for potential confounders. Furthermore, intake of vegetables alone, as well as calcium, plant calcium, potassium, and antioxidant vitamins (vitamins C, E, and beta-carotene) abundant in vegetables was significantly associated with BMD. The authors conclude, "Vegetables may be an important source of calcium and may also provide vitamins and minerals that exert additional beneficial effects on the bone."

Reference: "Calcium from plant sources is beneficial to lowering the risk of osteoporosis in postmenopausal Korean women," Park HM, Heo J, Park Y, Nutr Res, 2011 Jan; 31(1): 27-32. (Address: Department of Obstetrics and Gynecology, Yong San Medical Center, College of Medicine, Chung Ang University, Seoul, Korea).

Vitamins Critical To Health In Elderly

Summary: In a longitudinal study involving 78 (44 female, 34 male) free-living, elderly subjects between the ages of 70 and 75 years at baseline, after assessing intake of vitamins, the authors concluded that, "Multivitamin supplementation may be necessary, even in healthy individuals, to ensure an adequate micronutrient intake in the elderly." Data was collected at baseline and after 10 years. At baseline, intake of all vitamins except vitamin B1 were sufficient and exceeded the lowest European RDI. However, 10 years later, the prevalence of vitamin B2 and vitamin A deficiencies rose to 50% and vitamin C deficiency rose from 3% to 6% in men and 2.3% to 4.5% in women. The authors conclude, "...a considerable proportion of our successfully aging elderly were already deficient in, or at high risk of becoming deficient in several essential vitamins. Multivitamin supplementation may be necessary, even in healthy individuals, to ensure an adequate micronutrient intake in the elderly."

Reference: "Ten-year trends in vitamin intake in free-living healthy elderly people: the risk of subclinical malnutrition," Toffanello ED, Inelmen EM, et al, J Nutr Health Aging, 2011; 15(2): 99-103. (Address: E.D. Toffanello, Clinica Geriatrica - Ospedale Giustinianeo (2 piano), via Giustiniani 2, 35128, Padova, Italy. E-mail: .(JavaScript must be enabled to view this email address) ).

Vitamin A Supplementation May Prevent Mortality in Children

Vitamin A and Beta Carotene May Be Beneficial For Obese with Metabolic Syndrome

Over Half of US Adults Take Vitamins Daily

New research published in the Journal of Nutrition found that over half of US adults take a nutritional supplement every single day. Older populations are more likely to be regular consumers with 70% of adults over the age 70 reporting at least one daily supplement.

Dietary supplement use has steadily increased over time since the 1970s; however, no current data exist for the U.S. population. Therefore, the purpose of this analysis was to estimate dietary supplement use using the NHANES 2003–2006, a nationally representative, cross-sectional survey. Dietary supplement use was analyzed for the U.S. population (≥1 y of age) by the DRI age groupings. Supplement use was measured through a questionnaire and was reported by 49% of the U.S. population (44% of males, 53% of females). Multivitamin-multimineral use was the most frequently reported dietary supplement (33%). The majority of people reported taking only 1 dietary supplement and did so on a daily basis. Dietary supplement use was lowest in obese adults and highest among non-Hispanic whites, older adults, and those with more than a high-school education. Between 28 and 30% reported using dietary supplements containing vitamins B-6, B-12, C, A, and E; 18–19% reported using iron, selenium, and chromium; and 26–27% reported using zinc- and magnesium-containing supplements. Botanical supplement use was more common in older than in younger age groups and was lowest in those aged 1–13 y but was reported by ~20% of adults. About one-half of the U.S. population and 70% of adults ≥ 71 y use dietary supplements; one-third use multivitamin-multimineral dietary supplements. Given the widespread use of supplements, data should be included with nutrient intakes from foods to correctly determine total nutrient exposure.

See the report here: http://jn.nutrition.org/content/141/2/261.abstract

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Alpha Lipoic Acid Amino Acids Antioxidants Arginine Calcium Carnitine Carotene Chromium Picolinate Citrulline Coenzyme Q10 DHEA Fat Fiber Fruit and Vegetables Garlic Ginkgo Biloba Glucosamine Vegetarian Diet Green Tea Iron Lutein Lycopene Magnesium Mediterranean Diet Multivitamins Nitric Oxide Nuts Olives Omega 3 Fatty Acids Policosanols Polyphenols Pomegranate Probiotics Pycnogenol Red Yeast Rice Salt Saffron Selenium Soy Theanine Vitamin A Vitamin B Vitamin C Vitamin D Vitamin E Vitamin K White Tea Zinc