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Sources and physiological effects

Dietary sources
The selenium content of food is largely determined by the soils on which the plants and animals thrive. The concentration of selenium in the biosphere is subject to large regional fluctuations – and so the selenium content of crops and livestock varies accordingly. In addition to the geographical origin, the selenium content of the food also depends on the protein content of the food, since selenium is largely contained in the protein fraction. Selenium-rich foods include meat, fish, offal and nuts. Grains also contain selenium, especially in their outer layers. However, selenium is lost when grain is processed into white flour. Most notable the selenium content of the Brazil nut, which provides approx. 70 – 90 µg selenium per nut.
Physiological effects
Cell protector	Component of glutathione peroxidase and thus important function as antioxidant Protection of DNA, membranes and erythrocytes from oxidative damage
Thyroid gland	Cofactor for the formation of active thyroid hormones Influence on basal metabolic rate and cell activities, differentiation and growth
Immune system	Support of humoral and cellular immunity (antibody production, lymphocyte proliferation, cytokine production, interferon synthesis, regulation of cytotoxic T cells and NK cells)
Cancer prevention	Protection of DNA and cells against oxidative damage Anti-carcinogenic effects through growth-inhibiting and cell-death-promoting effect on tumor cells Strengthening of the immune system
Detoxification	Binding of heavy metals and their removal from the body
Liver	Promotion of detoxification function and protection of liver cells

EFSA Health Claims

Health Claims		EFSA Opinion
Selenium	Contributes to the maintenance of normal hair Contributes to the preservation of normal nails Contributes to a normal function of the immune system Contributes to normal thyroid function Helps to protect cells from oxidative stress Contributes to normal sperm formation

Recommended intake

D-A-CH Recommended nutrient intake
	Age	Selenium µg/d
Infants (months)
	0-4	5 - 15
	4-12	7 - 30
Children (years)
	1-4	10 - 40
	4-7	15 - 45
	7-10	20 - 50
	10-13	25 - 60
	13-15	25 - 60
Teenagers/adults (years)		Women	Men
	15-19	30 - 70	30 - 70
	19-25	30 - 70	30 - 70
	25-51	30 - 70	30 - 70
	51-65	30 - 70	30 - 70
	> 65	30 - 70	30 - 70
Pregnancy	30 - 70
Breastfeeding	30 - 70
Increased needs	Vegetarian diet, smoking, sports, heavy metal exposure, autoimmune thyroiditis, inflammation

Recommended intake according to food labelling regulations
(=100 % TB marking on label)		55 µg
Nutrient safety
UL	Long-term daily intake, where no adverse health effects are expected	<400 µg/d (according to NIH)
NOAEL	Maximum intake, with no observed adverse effect	<850 µg/d
Safety	EFSA has looked at the safety of selenium

Status according to Austrian Nutrition Report 2012

Selenium status in children

Fig. 1: Selenium status assessment in school children (7-14 years), by sex

Selenium status in adults

Fig. 2: Selenium status assessment in adults (18 - 64 years), by sex and selenium concentration in plasma (in µmol/L)(n=411)

Selenium status in seniors

Fig. 3: Selenium status assessment in seniors (65 - 80 years)

Detailed information

Critical status in Europe

Selenium is a relatively rare trace element that occurs in different concentrations in the earth's crust. In plants it is mostly found in the form of selenium methionine. The selenium content of food depends strongly on the selenium content in the soil. In large parts of Europe, the soils are extremely poor in selenium, so that vegetable food products have a low content contribute only marginally to the populations intake. The supply of selenium in Germany and Austria does not seem to be sufficiently ensured by the usual diet (1). In addition, the reference values of 30 – 70 µg selenium officially estimated for adults only meet the minimum requirements for demand. Many experts consider these values to be too low to allow an ideal course of all bodily functions or the prevention of diseases. In order to optimally support all selenium-dependent reactions, a daily intake of 100 – 200 µg is required (2).
Official data Austria:

Reference values

parameter	Substrate	reference level	Description
Selenium in the blood	serum	60 - 100 µg/l	Selenium determination in serum only of limited importance, since 65% of selenium is intracellular.
	Whole blood	80 - 130 µg/l	65% of selenium is erythrocytically bound. Hematocrit-correlated whole blood analysis enables the correct interpretation of the supply status. Selenium content in whole blood as a long-term parameter because of the long lifetime of erythrocytes.
Selenium in urine	24-h-urine	5 - 30 µg/l
Interpretation
Low values		Indication of selenium deficiency. Correlated with a reduced activity of selenium-dependent enzymes.
High values		Acute or chronic selenium poisoning. Values in whole blood should not exceed 400 µg/l.
Note on the measurement results
The reference values refer to Central Europe, as the selenium concentration shows strong regional variability.

Nutrigenetics and cancer

Gene/miRNA

Process

Change of activity

Prevention

Nutrient for cancer prevention

VHL

Methylation

reduced

Prevention for colorectal cancer

Selenium

Deficiency symptoms

Impact onf	Symptoms
General health	Tiredness, susceptibility to infections, depression
Thyroid gland	Thyroid hormone conversion disorder (T4 to active T3) Amplification of symptoms of existing hypothyroidism
Immune system	Immundepression Increased allergy tendency
Cardiovascular system	Cardiomyopathie
Musculature	Myopathy, chronic fatigue syndrome

Indications

Effect	Indication	Dosage
Physiological effects at a low intake	For therapy support in oncology	200 - 400 µg/d
	Preventive and accompanying therapeutic for cardiovascular disorders, Diabetes mellitus and diseases of the rheumatic range of forms	100 - 300 µg/d
	Therapeutic support for a weakened immune system	100 - 300 µg/d
	Complementary therapy for autoimmune thyroiditis	200 - 400 µg/d

Administration

General mode of administration
When	Sodium selenite should be taken 1-2 hours after a meal. Selenomethionine/Mustard extract should be taken directly with meals.
Side effects
Chronic overdose can cause neuropathy, hair loss and brittle nails. Acute overdose can cause nausea, diarrhoea and garlicky respiratory odour.
Contraindications
According to the current state of knowledge, no contraindications are known.

Interactions

Drug interactions
Neuroleptics (clozapine)	Increase the need for selenium.
Cytostatics (cisplatin, vinca alkaloids)	Selenium can reduce the nephro-, cardio- and neurotoxicity of cytostatic drugs.
Corticosteroids (e.g. methylprednisolone, dexamethasone, prednisolone)	Selenium can reduce the need for corticoids.
Thyroid therapeutics (L-thyroxine)	Selenium improves the effect of thyroid preparations.
Nutrient interactions
Heavy metals and trace elements	Selenium binds heavy metals.

Description and related substances

Description of the micronutrient

Trace element
Formula: Se
Ion: Se2+

Connections

L-selenomethionine, selenium yeast, selenic acid, sodium selenate, sodium hydrogen selenite, sodium selenite
Organic compounds (e.g. selenomethionine) and inorganic compounds (e.g. selenite, selenate) are readily bioavailable.

References

1) Fuchs, N. Mit Nährstoff heilen: Eine Einführung in die komplexe Orthomolekulare Nährstoff-Therapie, 4. Auflage. Köln: Ralf Reglin Verlag, 2012.
2) Hahn, A. et al. Ernährung: Physiologische Grundlagen, Prävention, Therapie, 3. neu bearbeitete und erweiterte Auflage. Stuttgart: Wissenschaftliche Verlagsgesellschaft Stuttgart, 2016.
3) Drutel, A. et al. 2013. Selenium and the thyroid gland: more good news for clinicians. Clin Endocrinol. 78(2):155-164. doi: 10.1111/cen.12066.
4) Gärtner, R. et al. 2002. Selenium supplementation in patients with autoimmune thyroiditis decreases thyroid peroxidase antibodies concentrations. J Clin Endocrinol Metab. 87(4):1687-1691. doi: 10.1210/jcem.87.4.8421.
5) Aboul-Fadl, T. 2005. Selenium derivates as cancer preventive agents. Curr Med Chem Anticancer Agents. 5(6):637-52. doi: 10.2174/156801105774574676.
6) Reid, M. E. et al. 2006. Selenium supplementation and colorectal adenomas: an analysis of the nutritional prevention of cancer trial. Int J Cancer. 118(7):1777-81. doi: 10.1002/ijc.21529.
7) Lener, M. R. et al. 2013. Can selenium levels act as a marker of colorectal cancer risk? BMC Cancer. 13: 214. doi: 10.1186/1471-2407-13-214.
8) Geoghegan, M. et al. 2006. Selenium in critical illness. Curr Opin Crit Care. 12(2):136-141. doi: 10.1097/01.ccx.0000216581.80051.d6.
9) Ferencik, M., Ebringer, L. 2003. Modulatory effects of selenium and zinc on the immunsystem. Folia Microbiol. 48(3):417-26. doi: 10.1007/BF02931378.
10) Rayman, M. P. 2002. The argument for increasing selenium intake. Proc Nutr Soc. 61(2):203-15. doi: 10.1079/PNS2002153.

References Interactions

Stargrove, M. B. et al. Herb, Nutrient and Drug Interactions: Clinical Implications and Therapeutic Strategies, 1. Auflage. St. Louis, Missouri: Elsevier Health Sciences, 2008.
Gröber, U. Mikronährstoffe: Metabolic Tuning –Prävention –Therapie, 3. Auflage. Stuttgart: WVG Wissenschaftliche Verlagsgesellschaft Stuttgart, 2011.
Gröber, U. Arzneimittel und Mikronährstoffe: Medikationsorientierte Supplementierung, 3. aktualisierte und erweiterte Auflage. Stuttgart: WVG Wissenschaftliche Verlagsgesellschaft Stuttgart, 2014.