Lecture 14 minerals deficiencies 2

Consequences of Mineral and Deficiencies Part II Se Selenium Se Overview: Selenium is one of the major mineral antioxidants in animal systems Therefore, all functions that are related to selenium deficiency have to with an impairment in the system’s role to curb the damaging effects of oxidants Selenium Levels in Soil Se Se White Muscle Disease (WMD) • WMD: Selenoprotein W deficient degenerative muscle disease found in all large animals (especially sheep and goats) – most commonly found in newborns or fast growing animals Se Se Deficiency – Keshan Disease Se Se • Causes congestive cardiomyopathy (disease of the myocardium with deterioration in function) • First observed in the Keshan province of China • It was due to low amounts of selenium in the soil •Left ventricle of heart has a thickened, dilated left ventricle with subendocardial fibrosis apparent with amplified whiteness of endocardium Deficiency Continued • Kashin-Beck Disease – Degeneration of articular cartilage between joints (osteoarthritis) – Associated with poor selenium status in areas of northern China, North Korea, and eastern Siberia – Affects children between and 13 years of age – Severe forms may result in joint deformities and dwarfism – There is little evidence that improving selenium nutritional status prevents Kashin-Beck – Other causative factors have been suggested: fungal toxins in grain, iodine deficiency, and contaminated drinking water Se Goiter • Since Selenium is required to convert T4 (inactive) into T3 (active) • A deficiency in Selenium could cause an enlarged thyroid gland in the neck Se Manganese Manganese serves as a cofactor for metalloenzymes, the three most prominent are: Arginase (urea cycle) Pyruvate carboxylase (gluconeogenesis) Mitochondria superoxide dismutase (antioxidant) HUMAN STUDIES Deficiencies of Mn rarely occur in humans Doisy (1972): Human subjects fed a diet containing 0.34 mg/day Mn Slight reddening of the hair Scaly transient dermatitis Hypocholesterolemia Moderate weight loss Friedman et al (1987): Human subjects fed 0.11 mg/day Mn Transient dermatitis in or subjects Hypocholesterolemia ANIMAL STUDIES Multiple species Disorder in lipid and carbohydrate metabolism Impaired growth Impaired skeletal development (neonates) Impaired reproductive function (disturbance in estrous cycle, testicular degeneration) Low viability of young at birth, ataxia in viable young Decrease in egg production, shell quality, hatchability in poultry Impaired embryonic development Shortening of the limbs Enlargement of joints Twisting of limbs -Mn Manganese deficiency in 24 day-old chicks +Mn Swollen joints (After Leach and Harris, 1999) Chromium Deficiency Typical Symptoms A diabetic-like state (hyperglycemia, insulin resistance) Growth impairment Elevated blood lipids Increased aortic plaque formation Decreased fertility and longevity Deficiency (cont.) • Situations – Infants and children malnutrition: diabeticlike disorder of metabolism – Impaired glucose tolerance – Disturbances in lipid and protein metabolism – TPN patients (weight loss) Glucose Tolerance -Cr Blood glucose +Cr Post Absorption (hr) Chromium in Human and Animal Nutrition: A Status Report The essentiality of chromium (Cr) in animal and human nutrition is now well accepted Its well established that Cr potentiates insulin sensitivity Cr deficiency is known to occur in patients on total parenteral nutrition without added Cr Such patients show impaired glucose tolerance, hyperglycemia, relative insulin resistance, peripheral neuropathy, and a metabolic encephalopathy These symptoms are reversed by Cr repletion Cr deficiency is also seen in diabetes mellitus, pregnant and parous (having given birth) women, and the aged population Cr supplementation improves glucose metabolism in glucose intolerant individuals and decreases total/HDL cholesterol ratio Whether Cr supplementation has long-term health benefits is unknown It is still unclear whether Cr deficiency, latent or overt, is a common occurrence in humans on normal diets without added Cr Cr contamination of food by the use of stainless steel processing equipment and eating utensils, and the lack of a clinically feasible test for Cr deficiency continue to impede progress in Cr research Nevertheless, there is considerably clarity as to plasma and urine Cr levels, food and tissue Cr content, and metabolic pathways of Cr metabolism Critical questions still remain regarding the role of Cr in human nutrition