Table 2.
Assessment sub‐questions
| Sub‐question | Method | |
|---|---|---|
| sQ1 |
a. What are the clinical effects associated with selenosis (a) in humans? b. What are biomarkers of effect (b) of excess selenium intake in humans? What is their biological relevance? |
Systematic review |
| sQ2 |
a. Is there a causal positive relationship between selenium intake and risk of diseases in humans, with a focus on hypertension, Alzheimer's dementia, amyotrophic lateral sclerosis (ALS), thyroid diseases, prostate cancer, skin cancer, type 2 diabetes mellitus, and overall mortality? b. Is there a causal positive relationship between selenium intake and risk of impaired neuropsychological development in children? c. Is there a positive relationship between selenium intake and excess overall mortality risk in humans? |
Systematic review |
| sQ3 | What is the quantitative relationship between selenium intake and plasma selenium concentrations in humans? | Narrative review and dose–response modelling (if applicable) |
| sQ4 | What is the dose–response relationship between selenium intake and clinical effects of selenosis (a) and/or biomarkers of effect of excess selenium intake in humans? | Systematic review and dose–response modelling (if applicable) |
| sQ5 | What is the dose–response relationship between selenium intake and risk of disease in humans? | Systematic review and dose–response modelling (if applicable) |
| sQ6 | What is the absorption, distribution, metabolism and excretion (ADME) of selenium and specific selenium species from different sources in humans? | Narrative review |
| sQ7 | What are the potential mode(s) of action for the relationships found between selenium intake and adverse health effects? | Narrative review |
| sQ8 |
a. What are the levels of selenium in foods, beverages and food supplements in the EU? b. What is the distribution of daily selenium intake from all dietary sources in EU populations and subgroups thereof? |
Collection of data based on existing EFSA intake estimates and complementary searches in relevant databases and inquiries to competent Authorities of European Countries |
sQ: subquestion.
In the clinical setting, the term selenosis refers to a specific clinical condition resulting from excess selenium exposure, as diagnosed based on accepted signs and symptoms (integumental features in particular). This condition is observed especially in populations living in seleniferous areas. This term can also be more generally used to refer to selenium toxicity and associated features. In the context of the formulation of sQ1 and sQ4, the term selenosis is to be understood in a wide sense.
Biomarker of effect: ‘a measurable biochemical, physiological, behavioural or other alteration within an organism that, depending upon the magnitude, can be recognised as associated with an established or possible health impairment or disease’ (WHO/IPCS, 1993; EFSA Scientific Committee, 2017a). Its biological relevance depends on its relation to the mode of action and the linkage with the adverse effect or the relevant adverse outcome pathway (EFSA Scientific Committee, 2017a).