Vitamin Information Center

Over the past few years the sun has gotten a bad rap. Too much sunshine can put you at risk for skin cancer. And an overdose of sun can also lead to nasty sunburns, or even heatstroke.

But the sun isn’t always bad for the body. Scientists have known for years that the sun is a great source of vitamin D. This vitamin naturally boosts the immune system, your body’s defense against disease. Now mushrooms bathed in ultraviolet (UV) light — like that from the sun — can help you get some of this valuable vitamin.

Each year there are more and more studies released that suggest if you want to be healthy, vitamin D is where it’s at. Vitamin D strengthens your heart and bones, and can prevent asthma and some forms of cancer and diabetes.

Some foods, like fish and eggs, are naturally brimming with the vitamin. And others, like milk and some cereals, are fortified with vitamin D. But you would need to consume a lot of milk and cereal to get your daily dose of vitamin D. Sunlight still reigns king as the best source for vitamin D.

Recently scientists have shown that specially treated mushrooms could give people a vitamin D boost. U.S. Department of Agriculture researchers in California treated portabella mushrooms to suntanning sessions of up to 18 minutes. The mushrooms didn’t develop a bronze glow or complain of heat stroke though. Instead each mushroom produced nearly 4 micrograms of vitamin D per gram of tissue. When white mushrooms were given similar sun treatments, these fungi boasted extra vitamin D, too. Now both kinds of vitamin-infused ‘shrooms are on the market. So if you like mushrooms, you could munch your way to a higher daily dose of Vitamin D.

Depending on a person’s age, people should get between 5 and 15 micrograms (or 200 to 600 international units) of vitamin D each day. Without these amounts, people are prone to get diseases like rickets, which causes distorted, soft bones. These numbers, though, are really just a minimum. Now some scientists suggest it’s better to get as much as five times the recommended vitamin D dose each day.

Having more foods with Vitamin D is a good thing, since there are also several factors that make it hard to get enough of the vitamin from just the sun.

One factor influencing elderly people’s vitamin D intake is that they often spend less time outdoors. Therefore, they need more vitamin D in their diet. And if you spend a lot of your time indoors, playing video games or on the computer, you may need extra vitamin D from your food, too.

Skin color and weight also help determine a person’s vitamin D needs. Darker skin filters out more of the sun’s UV light, so people with darker skin need more sun exposure to make necessary amounts of vitamin D. For unknown reasons, heavier people also need a greater amount of UV light to enable vitamin D production.

And latitude — how far north or south you live — can play a major role in the sun’s ability to help you get adequate vitamin D amounts. As you get farther away from the equator, the amount of UV-filtering atmosphere increases. This means that at higher, more northern latitudes, people get less UV rays. So, if you live in a state like Alaska, most of the year you can’t get enough sun to trigger the vitamin’s production by your skin.

Eating foods enriched with vitamin D or taking a daily vitamin may not be as satisfying as breaking out your bathing suit and lying in the sun. But the right foods and supplements can help keep you healthy until summer’s rays are here again.

High intake of Vitamin D can reduce chronic pain in women, a new study has suggested. A team of researchers from the Institute of Child Health in London found that women suffering from chronic pain may benefit from an extra daily dose of vitamin D, which comes from sunshine and fortified milk.

Called the “sunshine vitamin” because of its exceptional quality of being produced by the body by just basking in the warm sun, low levels of the vitamin D may contribute to women’s chronic pain that can cause complications such as sleep disorders, loss of appetite and depressiondefine or other serious disorders.

The British researchers reached their findings after studying 7,000 women and men aged 45 in England, Scotland and Wales. In their study the researchers found that chronic widespread pain is linked to low levels of the vitamin D in women, but surprisingly not in men.

Lead researcher Dr Elina Hyppnen of the Institute of Child Health in London and colleagues found that all women, irrespective of whether they were smokers, non-drinkers, overweight or underweight, reported higher rates of chronic pain due to vitamin D deficiency. However, vitamin D levels appeared to make no difference to the number of male participants who reported pain symptoms.

The researchers, who reported their findings in the latest edition of the ‘Annals of Rheumatic Diseases’ journal, found that women with vitamin D levels between 75 and 99 nanomoles of 25-hydroxy-vitaminD (25(OH)D) per liter of blood, a level believed necessary for good bone health, had the lowest rates (8%) of chronic pain, while women with vitamin D levels of less than 25 mmol/liter had the highest rates (14.4%) of this type of pain.

As the deficiency of vitamin D only affects women, the researchers believe female hormonesdefine may have some role to play in women’s chronic pain.

Though the latest research suggested that vitamin D levels could play a role in some cases of chronic pain in women, but lead researcher Hyppnen thinks the follow-up studies are needed to confirm the findings.

Still she thinks, “If I had chronic pain I would certainly check I was getting enough vitamin D.”

But, Kate MacIver of the Pain Research Institute at Liverpool University cautioned that high intake of Vitamin D supplements to prevent or treat chronic pain could result in Vitamin D toxicity and high blood calcium levels.

Technically a hormone, Vitamin D is produced within the body when the skin is exposed to the ultraviolet B (UVB) rays in the sunlight. Known as sunshine vitamin, it is also found in oily fish, egg yolks and margarine.

The basic function of vitamin D is to regulate the levels of calcium and phosphorous in the blood, thus helping to build strong bones and healthy teeth. It’s also believed to strengthen the immune systemdefine and possibly prevent some forms of cancerdefine, including prostate, breast and especially colondefine cancer.

Deficiency of Vitamin D can occur due to inadequate dietary intake of preformed vitamin D, malabsorption of vitamin D, or too little exposure to sunlight. The deficiency can lead to problems such as liver or kidney disorders or hereditary disorders. In adults, vitamin D deficiency can lead to osteoporosis, as well as rickets in children and osteoporosis in pregnant and post menopausal women.

As little as 30 minutes of early morning or late afternoon sunlight on the face, hands and arms two or three times a week can supply the entire Vitamin D one needs. In addition, many experts recommend 400-600 IU a day for people over the age of 50 and 800 IU for those over the age of 70. For younger adults, 200-400 IU a day is probably sufficient.

DEAR DR. DONOHUE: I am a 76-year-old female. Until December 2005, I thought I was in fairly decent health. That’s when I suffered a fractured hip. I didn’t fall, just sort of slipped down. I have recovered and feel great, and I exercise. Last April, my doctor prescribed 50,000 IU vitamin D once a week. I have been taking it ever since. I get lots of sun. I also take 600 mg of calcium with 200 IU vitamin D twice a day. And I take one multivitamin a day, a Centrum Silver. My doctor wants me to consider taking Fosamax. What’s going on? I worry about getting too much vitamin D. How does a person know how much is too much?

— T.W.

Most adults get too little vitamin D. The official recommendation for daily vitamin D intake is 200 IU for those from 19 to 50, 400 IU for those between 51 and 70, and 600 IU for those 71 and older. Many experts believe these recommendations are insufficient and that the daily dose should be 800 IU to 1,000 IU. Vitamin D enhances calcium absorption and plays a critical role, therefore, in keeping bones strong and in preventing fractures. There are hints that vitamin D prevents osteoarthritis, lessens the risk of prostate cancer and helps prevent diabetes and heart disease. Time will tell if all this is true. The stuff about bones is true.

We get vitamin D when sunlight strikes the skin. It turns a substance in the skin known as a “provitamin” into vitamin D. Ten minutes of sunlight on the face and arms, three times a week to daily, is all the sunlight needed for this conversion. Older people’s skin is not so efficient in making the vitamin, and those living in northern latitudes can’t depend on sunlight conversion in the winter months.

From your weekly 50,000 IU tablet, you get about 7,000 IU of the vitamin daily. Centrum Silver has 500 IU. You get another 400 IU with your daily calcium tablets. So your daily intake is around 8,000 IU. Too much vitamin D can be a problem. It can damage the kidneys and can actually draw calcium from the bones. The upper daily limit is set at 10,000 IU. You haven’t crossed the border, but you’re in its neighborhood. The 50,000 IU tablet can correct a vitamin D deficiency in six to eight weeks. I’d say you’ve made that correction. Ask your doctor about stopping this high-dose vitamin therapy. If there is a question about the adequacy of your body store of vitamin D, a blood test can determine if it is too low, too high or just right.

DEAR DR. DONOHUE: Our 21-year-old daughter has been diagnosed with peripheral neuropathy. Her finger turned a shade of blue. She went to the emergency room and got the diagnosis there. What kind of doctor should we consult to determine if this is her condition?

— V.C.

Your family doesn’t have a history of having peripheral neuropathy, right? So let’s remove all the genetic causes of it from consideration.

Twenty-one is young to come down with it. It’s more of an older person’s illness. People with diabetes and a few other diseases also are targets for it, but your daughter is in otherwise good health.

A blue finger isn’t a usual sign. Your daughter should see a neurologist or a vascular specialist to confirm this diagnosis, which appears a bit strange to me.

Readers may write to Dr. Donohue or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com.

To help keep tired players from putting their controllers down, Japanese game peripheral maker Cybergadget has released a new line of vitamin supplements aimed at gamers.

“Game Sapuri” promises to keep gamers at their best, and is available in two flavors: Blue Berry, which aims to keep players refreshed after epic play sessions, and DHA, which boosts concentration while playing. Packs sell for 880 yen (about $9), and includes enough for 15 days of use (you take two a day).

Since Metal Gear Solid 3: Snake Eater included Japan’s favorite energy bar CalorieMate, one must wonder if  the upcoming Metal Gear Solid 4: Guns of the Patriots could see Snake take his daily dose of vitamins.

A new study appears to explain how humans, along with other higher primates, guinea pigs and fruit bats, get by with what some have called an �inborn metabolic error�: an inability to produce vitamin C from glucose.

Unlike the more than 4,000 other species of mammals who manufacture vitamin C, and lots of it, the red blood cells of the handful of vitamin C-defective species are specially equipped to suck up the vitamin�s oxidized form, so-called L-dehydroascorbic acid (DHA), the researchers report in the March21st issue of Cell, a publication of Cell Press. Once inside the blood cells, that DHA–which is immediately transformed back into ascorbic acid (a.k.a. vitamin C)–can be efficiently carried through the bloodstream to the rest of the body, the researchers suggest.

�Evolution is amazing. Even though people talk about this as an �inborn error��a metabolic defect that all humans have�there is also this incredible manner in which we�ve responded to the defect, using some of the body�s most plentiful cells,� said Naomi Taylor of Université Montpellier I and II in France, noting that the body harbors billions of red blood cells. �[Through evolution], we�ve created this system that takes out the oxidized form of vitamin C and transports the essential, antioxidant form.�

Meanwhile, the red cells of other mammals apparently take up very little, if any, DHA, which might explain why they need to produce so much more vitamin C than we need to get from our diets, Taylor said. The recommended daily dose of vitamin C for humans is just one mg/kg, while goats, for example, produce the vitamin at a striking rate of 200 mg/kg each day.

In essence, the red cells of animals that can�t make vitamin C recycle what little they�ve got. Earlier studies had described the recycling process, Taylor said. �Our contribution to the whole story is to show that this process of recycling exists specifically in mammals that don�t make vitamin C.�

Scientists knew that the protein called Glut1, found in the membranes of cells throughout the body, is the primary transporter of glucose. They also knew that Glut1 can transport DHA too, thanks to the structural similarities between the two molecules. In biochemical assays, it appeared that the glucose transporter would move glucose and DHA interchangeably.

But, in the new study, Taylor�s group made a surprising discovery: The Glut1 on human red blood cells strongly favors DHA over glucose. In fact, the human blood cells are known to carry more Glut1 than any other cell type, harboring more than 200,000 molecules on the surface of every cell. Nevertheless, the researchers found, as red blood cells develop in the bone marrow, their transport of glucose declines even as Glut1 numbers skyrocket.

The key to the glucose transporters switch to DHA, they show, is the presence of another membrane protein called stomatin. (Accordingly, in patients with a rare genetic disorder of red cell membrane permeability wherein stomatin is only present at low levels, DHA transport is decreased by 50% while glucose uptake is significantly increased, they report.)

Then, another surprise: The researchers found that the red cells of mice, a species that can produce vitamin C, don�t carry Glut1 on their red blood cells at all. They carry Glut4 instead. They suspected that the differences in human red blood cells might be linked to our inability to synthesize the reduced form of DHA, vitamin C, from glucose. In fact, they confirmed Glut1 expression on human, guinea pig and fruit bat red blood cells, but not on any other mammalian red cells tested, including rabbit, rat, cat, dog and chinchilla. Next, they took a closer look at primates. Primates belonging to the Haplorrhini suborder (including prosimian tarsiers, new world monkeys, old world monkeys, humans and apes) have lost the ability to synthesize vitamin C, whereas primates in the Strepsirrhini suborder (including lemurs) are reportedly able to produce this vitamin, Taylor explained.

Notably, they detected Glut1 on all tested red blood cells of primates within the higher primate group, including long-tailed macaques, rhesus monkeys, baboons and magot monkeys. In marked contrast, Glut1 was not detected on lemur red blood cells. Moreover, they report, although DHA uptake in human and magot red cells was similar, the level of transport in cells from three different lemur species was less than 10% of that detected in higher primates.

�Red blood cell-specific Glut1 expression and DHA transport are specific traits of the few vitamin C-deficient mammalian species, encompassing only higher primates, guinea pigs and fruit bats,� the researchers concluded. �Indeed, the red cells of adult mice do not harbor Glut1 and do not transport DHA. Rather, Glut4 is expressed on their cells. Thus, the concomitant induction of Glut1 and stomatin during red blood cell differentiation constitutes a compensatory mechanism in mammals that are unable to synthesize the essential ascorbic acid metabolite,� otherwise known as vitamin C.

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The researchers include Amelie Montel-Hagen, Institut de Genetique Moleculaire de Montpellier, CNRS, Universite´ Montpellier I and II, Montpellier, France; Sandrina Kinet, Institut de Genetique Moleculaire de Montpellier, CNRS, Universite´ Montpellier I and II, Montpellier, France; Nicolas Manel, Institut de Genetique Moleculaire de Montpellier, CNRS, Universite´ Montpellier I and II, Montpellier, France; Cedric Mongellaz, Institut de Genetique Moleculaire de Montpellier, CNRS, Universite´ Montpellier I and II, Montpellier, France; Rainer Prohaska, Max F. Perutz Laboratories, Department of Medical Biochemistry, Medical University of Vienna, Vienna, Austria; Jean-Luc Battini, Institut de Genetique Moleculaire de Montpellier, CNRS, Universite´ Montpellier I and II, Montpellier, France; Jean Delaunay, Hematologie, Hopital de Bicetre, APHP, INSERM U779, Faculte´ de Medecine Paris-Sud, Le Kremlin-Bicetre, France; Marc Sitbon, Institut de Genetique Moleculaire de Montpellier, CNRS, Universite´ Montpellier I and II, Montpellier, France; and Naomi Taylor, Institut de Genetique Moleculaire de Montpellier, CNRS, Universite´ Montpellier I and II, Montpellier, France.