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Selenium - Coggle Diagram
Selenium
food sources of selenium
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Se in food chain: from plants which get Se from soil. Se in soil varies by region so availability of Se will vary by region
Different forms of selenium in soil : selonyte form (difficult for plant to absorb, or selenate (easily absorbed by plants )
pH of soil affects absorption of Se: if acidic then will be difficult to absorb (selonyte) and if alkaline then in selenate
organic matter can stop Se being absorbed and high microbial activity will make Se more likely to be absorbed (convert to absorbable form)
. In scotland, Se lower as more granite in siol which has no Se.
biggest sources: organ meats (kidney) and seafood, cereals and grains (if grown in alkaline soil like middle of USA/ canada but UK soil very acidic) [Lancet 2012]
Lowest sources muscle meat, milk and dairy products and fruit and veg [Lancet, 2012]
UK biggest sources of selenium: meat and poultry, bread and cereal (although low typically, high amount eaten), fish, milk and dairy [FSA 2009 Survey]
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2014 UK total diet study: the offal (0.59mg/kg) and fish (0.29 mg/kg) food groups had the highest concentrations of selenium , the remaining food groups were below limit of detection
Elderly and vegetarians/vegans most at risk of low intake Se as eat small amounts or high sources not included in diet
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Se deficiency
Effects of deficiency
increased mortality , viral virulance, poorer immune function, problematic fertility and reproduction, thyroid autoimmune disease, cogntivie decline
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Keshan disease, endemic caridomyopathy (heart enlargement, 50% death rate, arrythmia, mostly affected women)
Keshen disease- notices in keshen region in north east china and led to cardiomyopathy. Seasonal varations occured suggesting additional factor (virus) [yang, 2010}. Improved with 1mg Se supplement in children
[Beck, 2004] effect of Se deficiency on coxsackie virus infection in mice - infected mice with virus and mice with high selenium did not have oxidative stress and lived whereas low selenium had oxidative stress and died (same heart condition seen in keshen region)
effect of se defiency on viruses- Can become very virulent if low se as not enough GPX to reduce oxidative stress so virus casn multiply
Therefore, se deficiency effected viral genome in same way as in mice resulting in the development of heart pathology
What this study shows: Se def. in animal caused mutation of virus to more virulent form causing myocarditis (same as cardiomyopathy seen in china)
Human se def. in china associated with number of viral related conditions: coxsackie virus, Hep B and liver cancer, hantavirus and hemorrhagic fever, COV2 AND COV19 [Sun et al, 2016]
studies show se deficiency affects virulence of these conditions [Rayman, 2022]
selenium status looked in 6 european countries and those alive had higher selenium (COVID 19 mortality annd survival) [Demircan, 2022]- EPIC SAMPLE, biggest sample of covid and se status
ones with lowest selenium levels were the one who died of covid . same seem with funcitonal marker SELENOP
Se status sig. higher in serum samples surviving from Covid patients than non-survivors [Moghaddam 2020]
Selenium
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Se only trace element specified in genetic code: UGA codon in mRNA which specifies insertion of selenocysteine (amino acid with slenium in place of sulphur) to form a selenoprotein as long as there is an adjacent stem-loop structure (SECIS element)
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marker of se status
plasma or serum Se (recent Se status, usually 70-95ug in UK), whole-blood Se (longer term marker), toenail se (very expensive and very accurate), hair (easily contaminated) , functional measures of Se status (concentrations or activities of selenoenzymes like GPX. ALISA measures SELENOP)
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