Vitamin D - interesting articles

Discussion in 'Synapse' started by Jason, Feb 17, 2010.

  1. Jason

    Jason Developer / Handyman Staff Member

    The thymus, an organ in the chest, plays a dual role in this learning process. It produces the T-cells and also acts as a quality-control centre. “One of the jobs of cells in the thymus is to present every protein in the body to developing T-cells,” Ramagopalan explained in an e-mail. “Any T-cells that recognize a body’s own proteins are ‘auto-reactive’ and have the potential to cause damage if released into the rest of the body. They are normally destroyed if they react to the body’s own proteins.”

    However, “vitamin D appears to be needed for the thymus to appropriately present all proteins in the body and low levels [of vitamin D] allow auto-reactive T-cells to escape” into the bloodstream,” he said.

    The study suggests low levels of vitamin D during this period could get the immune system off to a bad start and increase the risks of MS developing later in life.
  2. Jason

    Jason Developer / Handyman Staff Member

    "About 50 per cent of our vitamin D levels are determined by genetic factors — that was known," Richards said.

    But his new study, considered the largest of its kind, has found variants in three genes are responsible for low vitamin D levels. The genes are involved with the synthesis, breakdown or transport of vitamin D.

    Published in the Lancet, the report by the SUNLIGHT consortium (Study of Underlying Genetic Determinants of Vitamin D and Highly Related Traits) notes that the condition may affect up to half of all healthy adults in the developed world.

    In March, Statistics Canada reported that 10 per cent of Canadians, or about three million people, had inadequate levels of vitamin D in their blood for optimal bone health. A full 1.1 million people were vitamin D-deficient.

    There are no definitive studies on the optimal daily vitamin D dose, but Health Canada currently recommends a daily intake of 200 IU (international units) for those age 50 and under, 400 IU for ages 51-70, and 600 IU for those older than 70.

    Two cups of milk, for example, provide 200 IU of vitamin D.

    snippets from ... [source]
  3. Jason

    Jason Developer / Handyman Staff Member

    Vitamin D Reserve is Higher in Women with Endometriosis


    In recent years, it has also emerged that the function of the vitamin D system is not limited to the regulation of plasma calcium concentration and skeleton mineralization. The vitamin plays an important role in several other physiological systems and, in particular, it has been shown to be an effective modulator of the immune system (Holick, 2004). Various cell types involved in immunologic reactions (monocytes, Langerhans cells, T and B lymphocytes) not only express vitamin D receptor but also possess 1α-hydroxylase, the enzyme that catalyzes the synthesis of the active form of vitamin D (Van Etten et al., 2003; Lehman, 2005). Under experimental conditions, 1,25-dihydroxyvitamin-D3 is strongly immunosuppressive and improves various T-helper-1 triggered diseases including autoimmune encephalomyelitis and autoimmune diabetes in mice and psoriasis in humans. Moreover, it strongly inhibits the function of natural killer cells and promotes T-helper-2 differentiation leading to a T-helper-2 phenotype with augmented production of interleukin(IL)-4, IL-5 and IL-10, and reduced synthesis of interferon-γ (Lehman, 2005). In general, it induces a phenotype that promotes tolerance and suppresses immunity after stimulation with antigen (Van Etten et al., 2003; Lehman, 2005). In line with these findings, epidemiological evidence supports a protective role of vitamin D against some autoimmune diseases that are characterized by a T-helper-1 immunity such as multiple sclerosis, rheumatoid arthritis and type I diabetes mellitus (Holick, 2004; Adorini, 2005).

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