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Selenium deficiency occurs when an organism lacks the required levels of selenium, a critical nutrient in many species.Deficiency, although relatively rare in healthy well-nourished individuals, [1] can have significant negative results, [2] affecting the health of the heart and the nervous system; contributing to depression, anxiety, and dementia; and interfering with reproduction and gestation.
Selenium deficiency as defined by low (<60% of normal) selenoenzyme activity levels in brain and endocrine tissues only occurs when a low selenium status is linked with an additional stress, such as high exposures to mercury [27] or as a result of increased oxidant stress due to vitamin E deficiency.
Mineral deficiency is a lack of the dietary minerals, the micronutrients that are needed for an organism's proper health. [1] The cause may be a poor diet , impaired uptake of the minerals that are consumed, or a dysfunction in the organism's use of the mineral after it is absorbed.
In fish and other wildlife, selenium is necessary for life but toxic in high doses. For salmon, the optimal selenium concentration is about 1 microgram selenium per gram of whole body weight. Much below that level, young salmon die from deficiency; [144] much above, they die from toxic excess. [143]
It has been proposed by scientists that the evolutionary reason for the female body shape is due in part to this sexual selection.Sex-typical body shapes (a man's muscular physique and a woman's hourglass figure) are an outcome of evolutionary adaptation for reproductive fitness because they convey information about gene quality, health and fertility, which are important elements for mate ...
A deficiency of these essential metals may increase susceptibility to heavy metal poisoning. [76] Selenium is the most toxic of the heavy metals that are essential for mammals. [77] Selenium is normally excreted and only becomes toxic when the intake exceeds the excretory capacity. [78]
Female body shape or female figure is the cumulative product of a woman's bone structure along with the distribution of muscle and fat on the body. Female figures are typically narrower at the waist than at the bust and hips .
Niacin deficiency is a consequence of a diet low in both niacin and the amino acid tryptophan, a precursor for the vitamin. Low plasma tryptophan is a non-specific indicator, meaning it can have other causes. The signs and symptoms of niacin deficiency start to revert within days of oral supplementation with large amounts of the vitamin. [23] [24]