T
twilyth
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This is an excellent article in an excellent publication (Science News).
It catalogs the current controversy about the amount of D we need in our diets (or from sun exposure) and lists the huge number of bodily functions that it is critical for.
Here is just a sampling.
Try to read the whole article if you're at all interested. I guarantee you will be amazed.
The infection fighting ability was discovered inadvertently a century ago when doctors treated tuberculosis patients with rest in the sun. Except no one understood why the cure worked. Now we do.
It catalogs the current controversy about the amount of D we need in our diets (or from sun exposure) and lists the huge number of bodily functions that it is critical for.
Here is just a sampling.
Another study in the United States showed that substantially more people with low vitamin D develop upper respiratory infections than do people with more of the vitamin, and taking up to 2,000 IU a day reduced such infections by two-thirds in one trial. A Dutch research team also reported online in May in Pediatrics that babies with low levels of vitamin D at birth were several times as prone to develop a severe respiratory viral infection in the first year of life as were newborns with ample amounts.
Fighting infection is all well and good, but too much immunity can be a terrible thing. Ask anyone with an autoimmune disease, in which crossed-up immune defenses attack a person’s own tissues. Even milder immune missteps such as asthma and allergy can be difficult to endure.
But taking extra vitamin D doesn’t exacerbate these immune overreactions. If anything it provides an immune gyroscope that moderates them. “Vitamin D makes the immune system smarter, not stronger,” says John Cannell, a forensic psychiatrist at Atascadero State Hospital in California who also studies vitamin D.
Allergy, an immune reaction to innocuous substances, offers an example. When researchers led by Michal Melamed of the Albert Einstein College of Medicine in New York City analyzed vitamin D levels of more than 3,000 children, allergies to peanut, oak and ragweed showed up more often in children with less than 15 nanograms of vitamin D per milli*liter of blood than in kids with at least 30 ng/ml, a level many scientists consider the minimum for good health.
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ON THE MAPScientists who study vitamin D can't help but notice that a host of diseases seem to vary with latitude. Type 1 diabetes, multiple sclerosis and even some cancers appear to be more common in areas that get less sun -- meaning less opportunity for the body to produce vitamin D. The maps above illustrate the apparent link between solar radiation and breast cancer mortality rates.Source, from top: D. M. Harris and V.L.W. Go / /J. of Nutrition 2004; National Cancer Institute
“Vitamin D is seen as essential in immune function,” says Melamed, an epidemiologist and nephrologist. In theory, she says, lacking it early in life disrupts the immune system “and you start having immune reactions to things you should tolerate.”
Asthma, another immune malfunction that can wreak havoc in the lungs, also shows links to low vitamin D levels. In a study conducted at National Jewish Health respiratory hospital in Denver, researchers found that people with asthma who also had low levels of vitamin D had poorer lung function than asthmatics who had higher levels of the vitamin. The results, reported in 2010 in the American Journal of Respiratory and Critical Care Medicine, show that harboring less than 30 ng/ml of vitamin D was associated with higher concentrations of TNF-alpha, an immune protein known to exacerbate inflammation.
A more destructive immune revolt called autoimmunity has a link to vitamin D as plain as a map of the world. Patients with the autoimmune condition type 1 diabetes, or juvenile-onset diabetes, have to receive insulin injections for life because insulin-making cells in the pancreas are killed off by a self-directed onslaught. Cedric Garland, a public health researcher at the University of California, San Diego, has mapped type 1 diabetes around the globe, noting low rates in Barbados, Brazil, Sudan, Algeria and Cuba but a high rate of the disease in Finland, Scotland, Norway, Sweden and New Zealand. In 2008 in Diabetologia, he and colleagues note that the latitude effect follows sun exposure closely.
There are exceptions. Sunny Sardinia has the highest type 1 diabetes rate in the world, apparently because of the population’s genetic profile, and Latvia ranks low. But the overall trend is unmistakable. Many researchers have also noted a latitude trend in multiple sclerosis, a suspected autoimmune disease that is practically unknown in the tropics and most common in Scandinavia.
Because these observations constitute indirect evidence and not causality, some scientists dismiss the latitude theory. But under a microscope, the evidence becomes more direct.
Multiple sclerosis researcher Jorge Correale of the Raúl Carrea Institute for Neurological Research in Buenos Aires has found that patients in the throes of an MS relapse have vitamin D levels lower than do healthy people or patients in remission. MS is marked by inflammation that damages nerve coatings. Vitamin D enhances the development of an inflammation-fighting protein called interleukin-10 and reduces production of two pro-inflammatory proteins in blood from patients, Correale’s team reported in 2009 in Brain.
Try to read the whole article if you're at all interested. I guarantee you will be amazed.
Vitamin D differs from other vitamins in one major way: It is nearly impossible to get enough of it in the diet naturally. Instead, the sun provides it.
After the ultraviolet rays of the sun trigger the synthesis of vitamin D in the skin, the body modifies the vitamin into a steroid hormone. Such hormones are heavy hitters in molecular biology, which probably explains the vitamin’s seemingly broad benefits — ranging from maintaining bone strength to sharpening mental acuity.
Vitamin D triggers a huge range of cell activities by binding to the aptly named vitamin D receptor, a protein docking port found on cells throughout the body. This connection — like a password opening up a new computer screen — instructs the cell to activate or silence certain genes. Gene activity in turn influences which proteins are made or not made by the cell. Since the vitamin D receptor is found on a wide array of cell types, such gene tweaking can influence immune reactions, cell growth, muscle maintenance, calcium absorption, metabolism and other processes.
Sreeram Ramagopalan, a geneticist at Oxford University in England, and his colleagues reported in 2010 in Genome Research that more than 200 genes are awakened or silenced by vitamin D binding to its receptor. Other evidence suggests the number of genes indirectly affected by vitamin D could exceed 2,000.
The infection fighting ability was discovered inadvertently a century ago when doctors treated tuberculosis patients with rest in the sun. Except no one understood why the cure worked. Now we do.