An eye on nutrition: The role of vitamins, essential fatty acids, and antioxidants in age-related macular degeneration, dry eye syndrome, and cataract.

Visual impairment is a global epidemic. In developing countries, nutritional deficiency and cataracts continue to be the leading cause of blindness, whereas age-related macular degeneration (AMD) and cataracts are the leading causes in developed nations. The World Health Organization has instituted VISION 2020: "The Right to Sight" as a global mission to put an end to worldwide blindness. In industrialized societies, patients, physicians, researchers, nutritionists, and biochemists have been looking toward vitamins and nutrients to prevent AMD, cataracts, and dry eye syndrome (DES). Nutrients from the AREDS2 study (lutein, zeaxanthin, vitamin C, vitamin E, zinc, copper, eicosapentanoic acid [EPA], and docosahexanoic acid [DHA]) set forth by the National Institutes of Health remain the most proven nutritional therapy for reducing the rate of advanced AMD. Omega-3 fatty acids, especially DHA, have been found to improve DES in randomized clinical trials. Conflicting results have been seen with regard to multivitamin supplementation on the prevention of cataract.

Healing fats of the skin: the structural and immunologic roles of the omega-6 and omega-3 fatty acids.

Linoleic acid (18:2omega6) and alpha-linolenic acid (18:3omega3) represent the parent fats of the two main classes of polyunsaturated fatty acids: the omega-6 (n-6) and the omega-3 (n-3) fatty acids, respectively. Linoleic acid and alpha-linolenic acid both give rise to other long-chain fatty acid derivatives, including gamma-linolenic acid and arachidonic acid (omega-6 fatty acids) and docosahexaenoic acid and eicosapentaenoic acid (omega-3 fatty acids). These fatty acids are showing promise as safe adjunctive treatments for many skin disorders, including atopic dermatitis, psoriasis, acne vulgaris, systemic lupus erythematosus, nonmelanoma skin cancer, and melanoma. Their roles are diverse and include maintenance of the stratum corneum permeability barrier, maturation and differentiation of the stratum corneum, formation and secretion of lamellar bodies, inhibition of proinflammatory eicosanoids, elevation of the sunburn threshold, inhibition of proinflammatory cytokines (tumor necrosis factor-alpha, interferon-gamma, and interleukin-12), inhibition of lipoxygenase, promotion of wound healing, and promotion of apoptosis in malignant cells, including melanoma. They fulfill these functions independently and through the modulation of peroxisome proliferator-activated receptors and Toll-like receptors.

Cutaneous manifestations of cystic fibrosis.

Cystic fibrosis is an autosomal recessive disease reported in 1 in 2500 live births in Northern American and Northern European Caucasian populations. Classic disease findings include chronic bacterial infection of airways and sinuses, malabsorption of fat, infertility in men, and elevated concentrations of chloride in sweat. Less well-recognized findings associated with cystic fibrosis include cutaneous findings, which can be primary or secondary manifestations of the disease process. Patients demonstrate more atopic and drug hypersensitivity reactions than the general population, but have similar rates of urticaria compared with the general population. In atypical presentations of cystic fibrosis, the nutrient deficiency dermatitis of the disease may aid with diagnosis, and notably can be the presenting sign. Other dermatologic manifestations of cystic fibrosis include early aquagenic skin wrinkling and cutaneous vasculitis, which can be associated with arthralgias. Familiarity with the nutrient deficiency dermatitis of this entity may play a role in the timely diagnosis of the disease, and the other cutaneous findings add to our understanding of the protean nature of its manifestations.