Deficiency diseases

Musculoskeletal and circulatory disorders
  • Selenium deprivation is reported to reduce the activities of the selenium-dependent antioxidant enzymes, leading to a number of functional disorders
  • Vitamin E-deficient animals in the presence of selenium deficiency show dysfunction of skeletal muscles (observed in sheep, cow, horse), cardiac muscles (observed in pig), or smooth muscle (observed in dog, cow), hepatic degradation (observed in rat, pig), increased capillary permeability (observed in chicken), or pancreatic degeneration (observed in chicken)
  • Very low selenium status is a factor in the etiologies of a specific type of juvenile cardiomyopathy (Keshan’s Disease) and a chondrodystrophy (Kaschin-Beck Disease) that were observed in selenium-deficient regions of China
A compromised immune system: Increased susceptibility to diseases
  • Low plasma selenium levels were observed in patients with bacterial and viral infections
  • A clinical study on 53 patients determined that in bacterial infections (septicaemia, pneumonia, erysipelas, and meningitis) the plasma concentrations of selenium, iron and zinc were found to be decreased
  • Selenium deficiency may increase the incidence of viral diseases such as HIV infection, Ebola virus infection and others. Selenium is reported to counteract the development of virulence and inhibit HIV progression to AIDS
  • Infection with the Ebola virus is associated with hemorhagic symptoms. The synthesis of viral selenoproteins is reported to be responsible for these symptoms. One potential viral selenoprotein may contain up to 16 selenium atoms per molecule. The demand for selenium in this synthesis depletes the selenium resources of the human host, leading to severe lipid peroxidation and cell membrane destruction, and contributing to hemorrhagic symptoms
  • In experimental studies, selenium deficiency was found to be associated with a nearly threefold higher likelihood of genital mucosal shedding of HIV-1–infected cells, suggesting that deficiency may increase the infectiousness of women with HIV-1
  • This finding corroborates earlier observations of Ebola outbreaks in selenium-deficient areas of Africa
  • A recent study on mice revealed that Selenium deficiency increases the pathology of the influenza virus infection. Infected Selenium-deficient mice developed much more severe interstitial pneumonitis than did Selenium-adequate mice and showed a weakened immune system response. The authors concluded that these results demonstrate that adequate nutrition is required for protection against viral infection and suggest that nutritional deprivation may be one of many factors that increase the susceptibility of individuals to influenza infection
Impaired thyroid functions
  • Selenium deficiency may also affect thyroid functions, as the active thyroid hormone is synthesized in the presence of the enzyme thioredoxin reductase, of which selenium is an essential constituent
  • Selenium deficiency may aggravate the effects of iodine deficiency on thyroid functions
  • Adequate selenium status is reported to offer protection against some of the neurological effects of iodine deficiency