Wednesday, December 02, 2009
Here is an article that I came across that I want to share:
by Catherine Ebeling, RN BSN
November 29, 2009
The Importance of Vitamin D in Diet and Sunlight
Vitamin D is one of most promising of anything in nutrition that can potentially have a major effect on fighting colds and flu, as well as other contagious diseases. More research is being done on this amazing vitamin, which is actually a hormone. Vitamin D is not a cure-all, but its correlation between human levels of this and immunity is significant. Vitamin D affects many aspects of our health-from its ability to help us fight disease, to dampening the fires of autoimmune disease, and improving our moods.
Vitamin D's effect on the immune system is incredibly important. That may explain why sun exposure in sanitariums cured tuberculosis 100 years ago.
What is it about vitamin D and its ability to help fight infection?
Vitamin D is a unique vitamin for three reasons:
Its the only known precursor of a potent steroid hormone, calcitriol, or activated vitamin D. Most other vitamins are antioxidants or co-factors in enzyme reactions. Activated vitamin D, among other actions, turns protein production on and off, as needed by your body. Vitamin D can actually regulate genetic expression in many areas of the body.
Unfortunately, vitamin D does not exist in appreciable quantities in normal diets-especially today's highly processed diets. If you really tried you could get several thousand units a day, if you ate sardines for breakfast, herring for lunch and wild-caught salmon for dinner. But the only people who ever regularly consume that much fish are people, like the Inuit, who live at the extremes of latitude. Foods like milk that Americans depend on for their vitamin D contains no naturally-occurring vitamin D-it is added, but only a miniscule amount of 100-200mg per serving.
The vitamin D system really has it real origins in the skin-not the digestive tract. Up until the last ten to twenty years, when dermatologists and the medical community began warning us about the dangers of sunlight, we humans made adequate amounts of vitamin D by exposing our naked skin to the sunlight. Unfortunately, many people live and work and spend most of their time inside of buildings and do not get out in the sun. We simply cannot get adequate amounts of vitamin D from our diet, so we either need to be in the sun more or get vitamin D from dietary supplements.
The third way vitamin D is different from other vitamins is the dramatic difference between natural vitamin D intake of our ancestors and today. Today, most humans only make about a thousand units of vitamin D a day from sun exposure; many people, such as the elderly or African Americans, make much less than that.
How much did humans naturally make in the past? A single, twenty-minute, full body exposure to summer sun will trigger the delivery of 20,000 units of vitamin D into the circulation of most people within 48 hours. Twenty thousand units, that's the single most important fact about vitamin D. Compare that to the 100 units you get from a glass of milk, or the several hundred daily units the U.S. government recommend as "Adequate Intake."
Continued from Newsletter
naked in sub-equatorial Africa, where the sun shines directly overhead much of the year and where our species must have obtained tens of thousands of units of vitamin D every day, in spite of the skin developing heavy melanin concentrations for protecting the deeper layers of the skin. When humans migrated to more temperate areas of the world, skin got lighter to allow for more rapid vitamin D production.
In the last three hundred years, humans made the transition to working indoors. Just in the last hundred years, we began to travel inside enclosed vehicles. These last few decades, we began to slather on sunscreen and totally avoid the sun. Obviously, all these changes have drastically lowered vitamin D blood levels in modern humans. The inescapable conclusion is that vitamin D levels today are not only low, but they are extremely low.
In studies done on prisoners-who get very little sun exposure, it was found that all had vitamin D blood levels that tested in the extremely low range. Supplements of 2,000 IU. were given to replace some of the missing vitamin D. The question is would the vitamin D supplementation prevent the prisoners from catching the flu?
In the last several years, dozens of medical studies have called attention to a worldwide vitamin D deficiency, especially among African Americans and the elderly--the two groups most likely to die from influenza. Cancer, heart disease, stroke, autoimmune disease, depression, chronic pain, depression, gum disease, diabetes, hypertension, and a number of other diseases, as well as contagious diseases such as colds and flu, have recently been associated with vitamin D deficiency. Is a lack of vitamin D the reason that everyone catches the flu in the fall and winter?
Think of this:
Although the influenza virus exists in the population year-round, influenza is considered a wintertime illness
Children with vitamin D deficient rickets are much more likely to suffer from respiratory infections. In particular, people who had a history of asthma or some form of chronic obstructive pulmonary disease (COPD) are even more likely to show a vitamin D deficiency. Asthma patients with the lowest vitamin D levels had five times the risk for respiratory infection, and vitamin D-deficient COPD patients had twice the risk.
The elderly in most countries of the world are much more likely to die in the winter than the summer but most of that mortality rate, although often related to cardiac or pulmonary conditions, is, in fact, due to influenza.
Could vitamin D levels explain these mysteries that account for hundreds of thousands of deaths every year? Studies have found the influenza virus is present in the population year-around, so why is it considered a wintertime illness? The common cold actually got its name because it is much more common in cold weather.
Because of our exposure to sunlight in the summer, vitamin D blood levels are at their highest then, but reach their lowest levels during the flu and cold season in the winter. Interesting connection...
Consider this possibility: Influenza and colds could be a symptom of vitamin D deficiency in the same way that an unusual form of pneumonia (pneumocystis carinii) is a symptom of AIDS.
How does Vitamin D work in the immune system?
Briefly, there are two primary systems that exist in the body to fight infections; the innate or immediate system, and the acquired or adaptive immune system that makes antibodies to pathogens it is exposed to. Recent evidence indicates seasonal impairments of the antimicrobial peptide (AMPs) systems are crucial to impaired innate immunity. These impairments are caused by seasonal fluctuations in vitamin D levels. The evidence that vitamin D has profound effects on the body's innate immunity is rapidly growing.
Unlike adaptive immunity, innate immunity is that branch of the body's defense that responds rapidly to infections before the body has ever encountered that antigen. Of the body's effectors that respond to pathogens, the best studied are the antimicrobial peptides (AMPs).
Epithelial tissues and white blood cells produce these AMPs and they exhibit rapid and broad-spectrum antimicrobial activity against bacteria, fungi, and viruses. Antimicrobial peptides protect the epithelial surfaces by creating a hostile antimicrobial environment.
The crucial role of vitamin D in the innate immune system was discovered only very recently. Both epithelial cells and macrophages increase expression of the antimicrobial compound that reacts to the microbes, an expression that is dependent upon the presence of vitamin D.
The presence of vitamin D also appears to suppress the pro-inflammatory cytokines. Thus, vitamin D appears to both enhance capacity to produce natural antibiotics and at the same time dampen certain destructive parts of the immune response, especially those responsible acute inflammation, which is what happens when influenza becomes deadly.
Because humans obtain most vitamin D from sun exposure and not from diet, a varying percentage of the population is vitamin D deficient, at any time, during any season, at any latitude, although the percentage is higher in the winter, in the aged, in the obese, in the sun-deprived, in the dark-skinned, and in populations that live closer to the poles.
Seasonal variation of vitamin D levels can even occur around the equator and widespread vitamin D deficiency can happen anywhere on earth, due to sun avoidance, rainy seasons, and air pollution.
HOW MUCH VITAMIN D IS ENOUGH, AND CAN YOU GET TOO MUCH?
Most experts agree that it's time to raise the vitamin D intakes that are now recommended: 200 IU a day if you're 50 or under, 400 IU if you're 51 to 70, and 600 IU if you're over 70. These small amounts would do little to help immune function.
There was no evidence at all for the current recommendations. The current recommendations are based on some very outdated research. It was known that 400 IU--the amount in a teaspoon of cod liver oil--would cure rickets in a child. Then they made the mistake of applying the same amount to adults.
Also shaky is the highest level of vitamin D that's safe to take on a daily basis (the Tolerable Upper Intake Level), which is 2,000 IU. That level was based on a 1984 study of six patients in India, and the researchers never measured the patients' blood levels. It's horrific data that shouldn't be used."
Researchers from Boston University School of Medicine have found that previtamin D3 production varies depending on several factors including skin type and weather conditions. The study appears in the March 2008 issue of the Journal of Bone and Mineral Research.
Excessive exposure to sunlight does not result in Vitamin D intoxification because previtamin D3 and vitamin D3 are photolyzed to several photoproducts. During the winter at latitudes above 35 degrees, there is minimal if any previtamin D3 production in the skin. Increased skin pigmentation, application of a sunscreen, aging and clothing have a dramatic effect on previtamin D3 production in the skin.
In one study, fifteen healthy adults aged 20-53 received exposure three times per week from a commercial tanning bed that emitted five percent of its UV energy in the UVB range to most of their body while in a bathing suit. D levels were determined weekly for a total of seven weeks.
Exposure to tanning bed irradiation revealed: 1 percent production of previtamin D after one minute, and a linear increase to 10 percent at 10 minutes. After one week of three times a week exposure, there was a 50 percent increase in D levels that continued to increase over a period of five weeks to 150 percent above baseline levels. The blood levels of Vitamin D plateaued after five weeks and were sustained out to seven weeks.
Vitamin D deficiency is common in both children and adults worldwide," said Michael Holick, PhD, MD, director of the General Clinical Research Center and professor of medicine, physiology and biophysics at BUSM and senior author of this study. "Exposure to lamps that emit UVB radiation is (actually) an excellent source for producing vitamin D3 in the skin and is efficacious in patients with fat malabsortion syndromes."
According to researchers, most experts now agree that a minimum of 1000 IU of vitamin D3 per day is necessary to maintain circulating concentrations of Vitamin D.
But because some people need more than others, she adds, "we'd have to recommend 3,000 to 4,000 IU a day to get those blood levels in 98 percent of the population." Those intakes appear to be safe.
The bottom line: researchers are convinced that we should be getting as much vitamin D as lifeguards, not office workers.
"A light-skinned person out in the sun in a bathing suit, with no sunscreen, can make 20,000 to 30,000 IU in 30 minutes," explains Harvard's Edward Giovannucci, though a person with darker skin or less skin exposed would make much less.
"Perhaps unknowingly, most of us have been deficient compared to conditions under which our cavemen ancestors evolved," he adds. "Estimates are that most humans evolved with vitamin D levels at ten or more times the levels most of have now.
Why take vitamin D? Until recently, blood levels of vitamin D that are typical in a Boston winter (about 40 nanomoles per liter) were considered "normal." However, early humans had vitamin D levels closer to 130 nanomoles per liter because they were exposed to the sun's ultraviolet rays all day, Taking 1,000 IU of vitamin D a day (with no sun exposure) would bring those Boston blood levels up to about 80 nanomoles per liter. Taking 4,000 IU would bring them to 100 nanomoles per liter.
Where's the D?
Your skin makes vitamin D when it's exposed to the sun's ultraviolet rays (unless you're wearing sunscreen). But north of the line running roughly between Los Angeles and Atlanta, the UV light is too weak to make vitamin D from late fall through early spring.
It's easier to get vitamin D from a supplement or fortified food than to worry about whether you're getting enough sun, especially in the winter or northern latitudes. There are some foods that contain higher amounts of vitamin D, such as: organic, grass-fed beef liver,
grass-fed dairy butter rich in vitamin D and vitamin A, raw milk grass-fed cheese, egg yolks, sardines, mackerel, salmon, herring, cod liver oils, shrimp, chicken liver, oysters and fortified foods such as orange juice, milk and infant formula.
It's difficult to get your daily recommended amount from foods containing vitamin D And most multivitamins only contain 400 IU of vitamin D, so most people will need an additional supplement."
The recommended dosages for cod liver oil provide about 500 IU vitamin D for children, 1000-5000 IU vitamin D for adults and up to 9000 IU for those taking large amounts of cod liver oil to deal with stress and disease.
95% of the population needs about 5,000IU a day is generally required to bring vitamin D levels up to the appropriate levels, according to some physicians. You will get some vitamin D from the foods you eat, but certainly nowhere near the amounts you need. If you take a vitamin D supplement, look for vitamin D3, (also called cholecalciferol vitamin D; a hormone synthesized in the skin from the sun, or obtained from the diet.
By: J. J. Cannel, Epidemic Influenza And Vitamin D, Medical News Today, September 15, 2006
Eades, Michael, M.D., Vitamin D and Influenza, May 18, 2009,
Orthopaedics; Public Health, Feb 21, 2008.
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