Selenium–Fascinating Microelement, Properties and Sources in Food

Abstract

Selenium is a micronutrient that is essential for the proper functioning of all organisms. Studies on the functions of selenium are rapidly developing. This element is a cofactor of many enzymes, for example, glutathione peroxidase or thioredoxin reductase. Insufficient supplementation of this element results in the increased risk of developing many chronic degenerative diseases. Selenium is important for the protection against oxidative stress, demonstrating the highest activity as a free radical scavenger and anti-cancer agent. In food, it is present in organic forms, as exemplified by selenomethionine and selenocysteine. In dietary supplementation, the inorganic forms of selenium (selenite and selenate) are used. Organic compounds are more easily absorbed by human organisms in comparison with inorganic compounds. Currently, selenium is considered an essential trace element of fundamental importance for human health. Extreme selenium deficiencies are widespread among people all over the world. Therefore, it is essential to supplement the deficiency of this micronutrient with selenium-enriched food or yeast cell biomass in the diet.

Selenium, copper, zinc and hypertension: an analysis of the National Health and Nutrition Examination Survey (2011–2016)

“…Also, high sodium intake was not associated with hypertension as expected, presumably because normotensives were consuming high sodium diets compared to hypertensives, who were probably restricting their sodium intake [36]. Studies showed that the total parenteral nutrition patients in hospitals and chronic malnutrition are more likely to develop selenium deficiency which could be replenished by food or supplements rich in selenium, such as mushrooms, garlic, asparagus, eggs and sea-salt [35,37]. Since there are few publications about the metabolism and excretion of selenium, no definitive predictions can be made regarding its physiology and excretion mechanism.…”

“…This finding is comparable with the findings by Mark et al where a group in a nutritionally deprived population was supplemented with dietary selenium and the population developed diastolic but not systolic hypertension [34]. The finding that the increments in selenium values were observed with stable increments in total serum cholesterol over all the quantiles of serum selenium suggests the possibility of selenium accumulation with consumption of high cholesterol containing food, which are also good sources of selenium, such as eggs and meat, causing uniform association with hypertension, in both the serum selenium and serum cholesterol concurrently [35]. Also, the selenium association may be stronger than indicated, since it was found irrespective of using hypertensive medication.…”

A Review of Micronutrients and the Immune System–Working in Harmony to Reduce the Risk of Infection

“…Supplementing the diet with deficient micronutrients has been shown to improve various specific immune functions (Table 2), while supplementation with multiple micronutrients (MMN) may also have significant benefits on immune cells and responses [175][176][177][178]. It should be noted that the source of the micronutrient supplement should be considered (i.e., dietary versus supplements), especially for minerals; organic forms of selenium are more bioavailable than inorganic compounds [179], while the sulfate, gluconate, and fumarate salts of iron have good availability [154], unlike its oxide forms [180]. The bioavailability could potentially have an effect on the efficacy of the supplement.…”

Serum Microelements in Early Pregnancy and their Risk of Large-for-Gestational Age Birth Weight

“…Despite various interventions to enrich the diet with selenium, there are geographical differences in its status in humans. Low levels of Se are recorded in Poland; average values are 70 µg/L, but in some regions of the country, they are as low as 50-55 µg/L [47]. Demand requirements indicate that the Se level should be 70-90 µg/L to ensure adequate glutathione peroxidase (GP-x) activity [34].…”

“…Demand requirements indicate that the Se level should be 70-90 µg/L to ensure adequate glutathione peroxidase (GP-x) activity [34]. Optimal selenium levels are estimated at 60-120 µg/L [47], and all studies showing relationships of lower Se levels with adverse health outcomes are valuable. The effects of Se on human health (including glucose metabolism) show a "U" curve because both the deficiency and excess of Se are harmful.…”