selenium in health and nutrition

Selenium in Health and Disease

Cecilia A. Alamag MS Applied Nutrition

Institute of Human Nutrition and Food, College of Human Ecology, University of the Philippines,

College Los Baños, Laguna

CAALAMAG | Selenium in Health Disease

OUTLINE


I. INTRODUCTIONA. History and Chemical Background B. Sources C. Dietary RequirementsD. Biological Activity, Utilization and ExcretionE. FunctionsF. Laboratory AssessmentG. Deficiency and Toxicity

II. SELENIUM EFFECTS TO HUMAN HEALTHA. CancerB. Cardiometabolic HealthC. ArthritisD. HIVE. Reproductive Health

HISTORY


• integral part of the selenoenzyme cytoplasmic glutathione peroxidase (cGPX)

1817

1957

1973

• discovered by Jöns Jacob Berzelius• named after the Greek Moon

goddess Selene

• essential nutrient for normal growth and reproduction in animals

CHEMICAL BACKGROUND


PERIODIC TABLE OF ELEMENTS


SOURCES


FoodMicrograms

(mcg)Brazil nuts, 1 oz 543Fast food fish sandwich, 1 89Halibut, baked, 1/2 fillet 74Tuna, canned, 3oz 68Oysters, raw, 3oz 56Rice, white, long grain, 1 cup 44Chicken, breast, baked, 3 oz 39Pie crust, 1 38Egg noodles, cooked, 1 cup 38Lobster, 3 oz 36Wheat germ, toasted, 1/4 cup 28Bagel, 1, 4-inch 27Sunflower seeds, 1/4 cup 25Egg, 1 16Bread, whole wheat, 1 slice 10Asparagus, cooked, 1cup 7Milk, 2% fat, 1 cup 6

Content of Selected Foods (Source: Krause’s Food and Nutrition Therapy. 12th ed)

SOURCES


These plants grow in selenium-rich soils

DIETARY REQUIREMENTS


Nutrient Reference Values

Micrograms

EAR 45

RDA 55

RENI 31

UL 400

EAR 70, 60

RDI 60, 50

BIOLOGICAL ACTIVITY & METABOLISM


• Selenomethionine• Plant Source• Supplied with food

BIOAVAILABLE/ ABSORBABLE

• Selenocysteine• Selenomethionine• Selenite

FORMS

BIOLOGICAL ACTIVITY & METABOLISM


ANTAGONIST• Sulfur• Arsenic• Mercury• Guar Gum• Vitamin C

ENHANCER• Protein• Vitamin E• Vitamin A

BODY CONCENTRATION• Red Blood Cells• Liver• Heart• Nails• Tooth Enamel• Renal Cortex• Pituitary Gland• Thyroid Gland• Adrenals• Spleen• Testes & Ovaries

METABOLISM & EXCRETION


FUNCTIONS


Anti-oxidant activity and glutathione synthesis

Hydroperoxides are toxic product of various oxidative processes and potentially harmful oxidizing agent.

FUNCTIONS


Immune Function

• increased production of interferon and other cytokines γ• T cell proliferation• increase in T helper cells

FUNCTIONS


Thyroid activity: deiodinases

deiodinating T4 and T3conversion of T4 to T3

Type I deiodinase

Type II deiodinase

Type III deiodinase

responsible for T4 conversion to T3 in the brain

responsible for deactivating T4 and T3

LABORATORY ASSESSMENT


Typically measured in:• Plasma• Serum• Whole blood• Amniotic fluid• Urine• Hair and toenails

Serum: 50-150 g/LμWhole blood: 60-240 g/LμHair: 0.2-1.4 μg/gramUrine: 15-150 μg/L

Fluorometry

DEFICIENCY AND TOXICITY


Keshan Disease Kashin-Beck Diseasegrowth retardationcataract formationlack of spermatogenesis abnormal placental retentioncardiomyopathymuscle inflammationenhanced skin pallor

Deficiency Toxicitygarlic odor on the breathgastrointestinal disordershair losssloughing of nailsFatigueIrritabilityneurological damageincreased risk of type 2 diabetes

SELENIUM EFFECTS TO HUMAN HEALTH

CANCER


CANCER


induce DNA repair and synthesis in damaged cells

inhibit the proliferation of cancer cells

In 1996, Clark et al. made a double-blind, randomized, placebo-controlled trial involving 1312 patients who have history of squamous cell carcinoma of the skin.

Individuals in the treatment arm were given 200 mg Se/day for a mean of 4.5 years (average daily intake in the U.S. is about 100 mg).

Patients receiving the Se-yeast supplement showed a much lower prevalence of developing and dying from lung, colon or prostate cancer.

CARDIOMETABOLIC HEALTH


oxidative stress from free radicals

heart disease

Selenium is one of a group of antioxidants that may help limit the oxidation of LDL cholesterol and thereby help to prevent coronary artery disease.

CARDIOMETABOLIC HEALTH


In the Flemish Study on Environment Genes and Health Outcomes, higher blood selenium concentrations were associated with lower systolic and diastolic BP levels at baseline and with a lower risk of hypertension over 5.2 years of follow-up among men.

In a cross-sectional study conducted in Finland, a population with low selenium status at the time of the study, serum selenium was also inversely related to systolic BP levels in 722 middle-aged men.

In the HDL-Atherosclerosis Treatment Study (HATS) trial, selenium (100 mg/d) was administered along with vitamin E (800 IU/d), vitamin C (1000 mg/d), and b-carotene (25 mg/d), with no effect on BP levels during three years of follow-up (Brown 2001 as cited by Stranges 2010).

REPRODUCTIVE HEALTH


Testicular tissue contains high concentrations of selenium.

Selenium is essential for testosterone biosynthesis and the formation and normal development of spermatozoa.

Phospholipid hydroperoxide glutathione peroxidase (PHGPx/GPx4) and Selenoprotein P

REPRODUCTIVE HEALTH


The study in 1984 by Bleau et al50 reported an optimal range between 50 and 60 mcg/mL in semen and a positive correlation between sperm count and semen selenium concentration in 125 men from couples being investigated for infertility.

In Scotland, a placebo-controlled randomized control trial (RCT) of 64 men demonstrated that sperm quality and fertility improved after selenium supplementation.

Three small studies, from Poland and the United States, supplementing (200-300 mg/d) with selenite, selenium-enriched yeast, or diets naturally high in selenium reported that, although semen selenium concentrations increased, there were no positive effects on sperm characteristics or activity.

CONCLUSION


As a Nutritionist, would you suggest Selenium Supplementation?

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