Vitamin D: The Real Facts,Truths, and Sources of The Sun Vitamin

When you research, read, and watch the news as much as I do, you can see the new nutrient and supplement trends coming a mile away. Sometimes they’re valid, other times they aren’t. I can say for certain to buckle up and hop on the D-train because it’s here to stay. In fact, this isn’t a newly found miracle baby; this is an age old savior that we’ve been neglecting.

What is Vitamin D?

Vitamin D is a fat soluble steroid hormone (and if we weren’t playing fast and loose with the terminology, it technically isn’t a vitamin at all). The main job of vitamin D is to maintain normal blood levels of calcium and phosphorus. Note that’s the main job. It’s said that over 200 genes are affected by vitamin D. It doesn’t matter where you turn, its uses are everywhere. Bone, heart, insulin, depression, pain, happiness, cancer, fibromyalgia, thyroid… you name it, vitamin D plays a role.

Michael F. Holick, a leading researcher on the importance of vitamin D, has said that “Vitamin D deficiency is the disease of neglect.”

And he couldn’t be more right.

The cure for rickets — a widespread epidemic in the children of the softening of the bones — was found by sticking children on the roof of a building. Can you sit there and take that in for a moment? An illness that was making the limbs of children turn into mush was cured by the sun.

You may wonder what this has to do with you, but bones should be your pride and joy. Not to mention the fact that recent studies show an alarming rate of newborns and mothers are becoming more and more deficient. Are past problems coming back to bite us in our vitamin-deficient rears?

Beyond just bones, being too low in vitamin D can lead to a decrease in thyroid function. Although not directly involved in synthesis or secretion, a deficiency can produce increases in the levels of parathyroid hormone.

On the wellbeing side, an increased occurrence of depression and a decrease in mental focus have been found time and time again. There are also links that have shown women who supplement with vitamin D may lose fat easier than those who don’t.

Currently, the desired levels are 30 to 75 ng/mL-nmol/L, and anything less is seen as deficient, though higher doesn’t necessary mean you’re at a toxic level. The concern is for consistent levels above the 200 range.

The bottom-out number should really be 30; however, we’re seeing study after study show that levels are constantly hitting below this all around the world, and the aftereffect is becoming an epidemic.

ng/mL	nmol/L	Status
<>	<>	These levels suggest severe illness, usually seen in rickets or sick infants.
<>	<>	While not directly or instantly crippling, these levels overtime may contribute to illness both acute and chronic.
≥ 30	≥ 75	Seen by some to be the desired range and achieving of optimal health.
Consistently > 200	Consistently > 500	Could be toxic and lead to hypercalcemia and hyperphosphatemia.

Serum 25-hydroxyvitamin D [25(OH)D] concentrations and health

How Do You Get It?

Vitamin D is the “sun vitamin,” meaning that you should receive 80 to 100% of your intake from the sun. When ultraviolet (UV) rays hit the skin, they’re absorbed and converted, setting into motion your body’s process of creating vitamin D. In truth, this should be the end all for receiving your daily intake.

However, things just aren’t that simple.

What About Food Intake?

Vitamin D can be found in small amounts in certain fishes, fortified milks, and egg yolks.

The problem is that the intake would have to consist of very high levels and multiple times daily to give you the effects you need. It also would depend on the quality of your food. With fish, for instance, it’s been shown that farmed salmon (fish raised in tiny boxes eating crappy fish food) held at least 25% less vitamin D than wild-caught salmon.(1)

Take-home point being, if you think that the Wal-Mart fish nutrients are doing something for you, think again. What they eat is what you eat. As well, the fortified milk and cereal claims of vitamin D can be off by as much as 80% of what the label says.

Here’s a chart that gives you a general rundown of food sources for vitamin D:

Food	IU per serving	Percent DV
Cod liver oil, 1 tablespoon	1,360	340
Salmon, cooked, 3.5 ounces	360	90
Mackerel, cooked, 3.5 ounces	345	90
Tuna fish, canned in oil, 3 ounces	200	50
Sardines, canned in oil, drained, 1.75 ounces	250	70
Milk, nonfat, reduced fat, and whole, vitamin D-fortified, 1 cup	98	25
Margarine, fortified, 1 tablespoon	60	15
Ready-to-eat cereal, fortified with 10% of the DV for vitamin D, 0.75-1 cup (more heavily fortified cereals might provide more of the DV)	40	10
Egg, 1 whole (vitamin D is found in yolk)	20	6
Liver, beef, cooked, 3.5 ounces	15	4
Cheese, Swiss, 1 ounce	12	4

Selected food sources of vitamin D (2,3)

Differences in Vitamin D

Vitamin D comes in two main forms: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). There’s a D1, D3, and D5, but in short, their importance and our control of them isn’t the main topic here.

Vitamin D2 is made by the UV irradiation of ergosterol in yeast, and vitamin D3 is made by the irradiation of 7-dehydrocholesterol from lanolin and the chemical conversion of cholesterol.

It’s suggested that D3 is far superior to D2 at raising levels in the body and holding them higher for extended periods of time.(4,5) Because of this, if you’re going the supplement route for your intake of vitamin D, D3 is the winner of the group.

The overall goal of vitamin D is to raise serum levels in the body and do so as best as possible. To date, both D2 and D3 supplements at prescription-grade levels have shown to do this. D2, however, has been shown to be toxic at higher levels. (It should be noted that you can’t achieve toxic levels of D in the body with just the sun.)

How Long is Too Long in the Sun?

This is the tricky part and most often misunderstood. Obviously, there’s plenty of data to back up that being in the sun too long without protection can lead to skin cancers. The flipside is that being in the sun too little might lead to cancer as well.

You may think that applying some sunscreen will get you the best of both worlds, but sadly sunscreen has been shown to block upwards to 95% of vitamin D uptake from the sun.(6)

What are you to do?

A good solution is to spend fifteen minutes in the sun and then apply your sunscreen. It’s suggested that fifteen minutes a day can be enough. However, for a lot, that isn’t the case. And unless you’re living below 42 degrees North latitude (a line approximately between the northern border of California and Boston), in the wintertime you aren’t going to get it at all.(7)

Studies also show that if you’re African America or Hispanic then you need near double what Caucasians need.(8,9)

The Do’s and Don’ts of Vitamin D

If you find yourself stuck inside, above the magic line, or of darker skin, then you might need to look at better options of getting vitamin D.

1. Don’t be obese: Obesity blocks vitamin D intake by as much as 55%.

2. Don’t be scared of the sun: We’re a culture of extremes and look at where it’s got us. You need some sun, so don’t be afraid of it. Just call it quits before you burn like a lobster.

3. Do eat cod liver oil: Cod liver oil in supplement form is a really simple and easy way to get in lots of D3 during those months when you may not be able to.

4. Don’t be scared of the tanning bed: If you’ve ever known a friend with an iguana or turtle, then you know that in order to survive they need those ultraviolet exposures. Well, so do you!

Exposure to tanning beds resulted in a 100% increase in blood concentrations of vitamin D.(10) The problem is, just as with the sun, people take things too far. It’s a great way to get what you need in the winter months, but the same “don’t overdo it” rules apply.

5. Do get tested: In general, you should be getting a full vitamin and mineral testing every six months. Is it time for a checkup?

6. Do hit the numbers: While 400 IU is the recommend dosage, there’s nothing wrong with getting 1,000 IU, especially from D3, and namely during the “off season.”

7. Do take this seriously: I’m not usually one for dramatics, but there are so many low level health problems that can lead to higher level problems, and issues from a vitamin D deficiency can be really simple to solve.

Take it seriously; get in your sun, get in your oils, and take advantage of the problems you can fix every chance you get.

—

References

1. An evaluation of the vitamin D3 content in fish: Is the vitamin D content adequate to satisfy the dietary requirement for vitamin D?

2. Nutrition Coordinating Center. Nutrition Data System for Research (NDS-R). Version 4.06/34. Minneapolis: University of Minnesota, 2003.

3. U.S. Department of Agriculture, Agricultural Research Service. USDA Nutrient Database for Standard Reference, Release 16. Nutrient Data Laboratory Home Page, 2003.

4. Houghton LA, Vieth R. The case against ergocalciferol (vitamin D2) as a vitamin supplement. Am J Clin Nutr 2006;84:694-7.

5. Nesby-O’Dell S, Scanlon KS, Cogswell ME, Gillespie C, Hollis BW, Looker AC, et al. Hypovitaminosis D prevalence and determinants among African-American and white women of reproductive age: third National Health and Nutrition Examination Survey, 1988-1994. Am J Clin Nutr 2002;76:187-92.

6. http://www.ajcn.org/cgi/reprint/80/6/1678S.pdf

7. Cranney C, Horsely T, O’Donnell S, Weiler H, Ooi D, Atkinson S, et al. Effectiveness and safety of vitamin D. Evidence Report/Technology Assessment No. 158 prepared by the University of Ottawa Evidence-based Practice Center under Contract No. 290-02.0021. AHRQ Publication No. 07-E013. Rockville, MD: Agency for Healthcare Research and Quality, 2007.

8. Nesby-O’Dell S, Scanlon KS, Cogswell ME, Gillespie C, Hollis BW, Looker AC, et al. Hypovitaminosis D prevalence and determinants among African-American and white women of reproductive age: third National Health and Nutrition Examination Survey, 1988-1994. Am J Clin Nutr 2002;76:187-92.

9. Yetley EA. Assessing vitamin D status of the U.S. population. Am J Clin Nutr. In press.

10. Holick, M. F. (2004). Vitamin D: importance in the prevention of cancers, type 1 diabetes, heart disease, and osteoporosis. American Journal of Clinical Nutrition, 79, 362-371.

Source: http://avidityfitness.net/2008/10/13/vitamin-d-the-real-factstruths-and-sources-of-the-sun-vitamin/

Top 10 Ways to Stay Energized

Even if you're a hyper-organized, task-oriented worker with an expansive mind and endless ambition, you won't get a lot done if your mind and body are demanding you curl up and doze off. Luckily, you can overcome a late night of net surfing, a rough morning, or just the post-lunch stupor without becoming an over-wired mess. We've put together 10 of the best ways to jumpstart your brain and get back into a productive groove, and all of them are tricks you can put to work this Monday. Photo by neps.

10. Make your own energy products.

If you're going to resort to a brick of grains and protein to give you short-term "power" or "energy," you may as well have it be cheap—and tastier than those foil-wrapped roofing tiles. Same goes for re-hydrating drinks, which can be easily mixed at home. Foodie extraordinaire Alton Brown has recipes for three different home-baked bars, as does About.com's Sports Medicine section. Of course, there's always the free stuff flowing from the tap for true replenishment.

9. Listen to brain-stretching music.

Among other tips offered up by software programmer Brad Isaac for beating "brain drain," the exhaustion that comes from sustained concentration, is working a little Mozart or Bach into your playlist. There's no overly hook-y melody to pull your mind away, and the harmony of so many instruments together relaxes your mind. Strings and brass not your thing? Try the non-intrusive, up-tempo ambient of Groove Salad.

8. Deal with job burnout.

Even if you're generally happy with your job, the people you work with, and the work you're doing, small annoyances and responsibilities can build up over time, until a dark, angry cloud hangs over you seven and a half hours per day. Seriously—feeling overwhelmed by your tasks was the second most frequent response in our poll on energy zappers. The Simple Dollar blog recommends scheduling an immediate vacation to take care of piling-up home stuff and set your mind free. Web Worker Daily suggests finding a new project. However you handle burnout, keeping an even head about your job gives you a lot more energy to spend on stuff that's a lot more fun.

7. Schedule around your energy peaks.

Writer and speaker Michelle Dunn describes herself as "very organized," but there are times of the day she just can't be productive. So when she's about to hit a lull—like right after lunch—she schedules errands and tackles non-thinking tasks, and otherwise schedules around her energy. Of course, not everybody can just run off to Target whenever they're feeling blah, so 43 Folders honcho Merlin Mann explains subtle ways to work inside your schedule.

6. Get outside—even if it's cloudy.

Even if you live in one of those areas with perma-gray skies for two-thirds of the year, getting outside every day can give you a vitamin D boost and the resulting mood and energy improvements. The National Institutes of Health recommends getting 10 to 15 minutes of sun each day, and a layer of sunscreen if you're getting more. Even better, you get away from the screens, voicemails, and low-level humming of the office.

5. Crank out some morning exercises.

You know those mornings where you have to get right up and do something with a deadline? The groans about coffee and sleep fall away, and you usually get it done. Give yourself a now-now-now pushup cycle right after your breakfast, and you might just shake off your sluggish self-doubt and get moving. If you're looking to get more out of your morning time, personal trainer Dan Boyle offers a two and a half minute core routine that'll definitely leave you aware that you're awake. Photo by whyld.

4. Eat the right nutrition mix.

Sugar and bread give you a quick jolt of energy, but ultimately result in an insulin-powered crash later in the day. Too much meat doesn't give you enough of the quick-firing stuff. Balancing out your lunch, instead of just eating leftover pasta, can have a big impact on your day, according to the Harvard School of Public Health Nutrition Source. As Lifehacker guest editor (and current io9 editor) Annalee Newitz puts it:

Remember, carbs come in fruits and veggies as well as grains. And you can get protein from meat, dairy, fish, eggs and beans (like soy or pinto). The perfect lunch might be veggies with fish (mmm, nicoise salad, anyone?), and the best snack an apple with a little cheese.

It's also not a bad idea to keep the heavy meals for morning to ensure better sleeping patterns.

3. Put your senses to work.

If you're stuck at work after a rough night, chances are you'll be staring at a hypnotizing screen or look-alike paperwork and finding it hard to stay awake. WikiHow suggests a multi-sensory assault on your tired self. Try scenting yourself awake with some essential oils of (or just strong scent of) peppermint or rosemary, or target the alertness-sparking stress points like your earlobes and the skin between your thumb and forefinger. Keep yourself a little chilly, and try to move around a bit—it's your best shot at not having the boss notice you haven't said a word since 9AM. Photo by cote.

2. Switch from venti to smaller caffeine doses.

Slamming half a carafe of coffee to get alert and productive is kind of like pounding a six-pack to get social and funny—you're going to miss your mark, in often painful ways. Research suggests that small, frequent doses of caffeine—like tea breaks, caffeinated mints, and even chocolate—do a better job of keeping your brain from feeling fatigued than jitter-inducing java. Of course, if you've got the willpower and patience, you could also just drink half-cups of coffee more frequently. Photo by ToOb.

1. Master the power nap.

Taking a nap isn't calling it quits on getting energized—it's just running a quick defrag on your neural drive and rebooting. We've covered the ins and outs of napping pretty thoroughly here, but if you need a quick take-away, try the Boston Globe's comprehensive cheat sheet. If shut-eye alone can't bring you back, try a coffee-charged caffeine nap.

Source: LifeHacker

Receptor gene linked to melanoma risk

A variation of the gene responsible for metabolising vitamin D appears to increase the risk of melanoma, a serious and sometimes fatal skin cancer, Italian researchers report.

The authors believe that the altered form of the receptor is less able to bind to vitamin D, a vitamin that can be produced in sun-exposed skin. Prior research has suggested that this binding helps protect against melanoma.

Variants in the vitamin D receptor gene have been hypothesised to affect the risk of melanoma, but findings from prior studies have been conflicting.

The current investigation represents the first combined analysis performed using published data, according to a report in an upcoming issue of the American Cancer Society's journal Cancer.

Data from six studies, which included a total of 2152 patients with melanoma and 2410 subjects without the cancer, were included in the analysis.

Vitamin receptors

Together, the studies examined the impact of five vitamin D receptor gene variations, or "variants," designated TaqI, FokI, BsmI, EcoRV, and Cdx2, on the risk of melanoma.

Patients with the BsmI variant had a 30% increased risk of melanoma, report Dr Simone Mocellin and Dr Donato Nitti, from the University of Padua. This would account for close to 10% of melanoma cases.

The FokI variant did not affect the risk of melanoma and the impact of the other three variants was less clear.

The authors conclude that although the effects of the BsmI variant are not fully known, "these findings indirectly support the hypothesis that sun exposure may have an anti-melanoma effect through activation of the vitamin D system."

But they add that additional research is needed, calling for a larger study to "test whether any vitamin D receptor is independently associated with melanoma risk."

Boosting vitamin D

Professor Bruce Armstrong of the University of Sydney, who was not part of the study, says there is a growing body of evidence supporting the link between low levels of vitamin D and melanoma.

"There are some interesting links out there," says Armstrong. "We know that people who have less active receptors seem to be at higher risk [of developing melanomas]."

"That suggests vitamin D is quite important in preventing melanoma in the first place."

Armstrong says that people with a less effective BsmI gene would benefit from an increased amount of the vitamin D.

But he says there is debate over how to increase vitamin D levels, with countries such as the United States advocating the use of oral supplements.

"In Australia we've tended to accept the view that a small amount of direct UV (ultraviolet light) is beneficial," says Armstrong.

But he warns that this should be done in moderation.

"You don't need large amounts ... and should only be in the sun when the UV index is below 3," Armstrong says.

Source: abc.net

Skin cancer fears may increase risk of bone thinning disease

British people may not be not getting enough sunlight to generate sufficient levels of vitamin D, as they are worried about the possibility of skin cancer, according to a poll by the National Osteoporosis Society. The poll found that awareness of the importance of wearing sunscreen is high, with 74 per cent of people believing you should always apply sunscreen when going out in the sun in the UK.

However, a small amount of regular exposure to the sun is important as sunlight is one of the best natural sources of vitamin D, which is important for strong bones and reduces the risk of the bone thinning disease osteoporosis.

We all need a bit of sunshine in our lives, but it's important to remember that the amount of sun needed to make enough vitamin D is always less than the amounts that cause reddening of the skin or sunburn. - Caroline Cerny, health campaigns manager, Cancer Research UK

Professor Roger Francis, chair of the National Osteoporosis Society's Medical Board, commented: "High profile skin cancer campaigns have made people far more aware of the dangers of overexposure to the sun.

"However, an unanticipated side-effect may be that people now feel that they shouldn't spend any time in the sun at all. Potentially, this could result in a lack of vitamin D and increased risk of osteoporosis."

The professor noted that too much sun causes skin cancer and ageing and advised against spending lengthy periods in the sun.

"However, we feel that people should be able to get out and enjoy some summer sunshine over the next couple of months," he claimed, adding: "We can use the summer months to build up our levels of vitamin D so that we have enough stored to last us through winter."

Cancer Research UK's health campaigns manager, Caroline Cerny, said that by enjoying the sun sensibly, it is possible for everyone to make enough vitamin D while not increasing their risk of skin cancer.

"The amount of time in the sun required to make enough vitamin D changes from person to person and depends on things like skin type, time of day, time of year, and where you are in the world," she noted.

Ms Cerny advised: "We all need a bit of sunshine in our lives, but it's important to remember that the amount of sun needed to make enough vitamin D is always less than the amounts that cause reddening of the skin or sunburn."

Simple ways to get enough sunshine without increasing the risk of overexposure include hanging the washing outside to dry or watering the garden while your face and arms are bare.

However, people who are fair-skinned, have lots of moles and freckles, or who have a family history of skin cancer should take particular care and everyone should avoid the strong sunshine in the middle of the day.

News provided by Adfero in collaboration with Cancer Research UK. Please note that all copy is © Adfero Ltd and does not reflect the views or opinions of Cancer Research UK unless explicitly stated.

Vitamin D and Breast Cancer Risk

Moderate exposure to sunlight promotes good health

Who says vitamin D is just for kids? Certainly not Dr. Northrup! Research is now revealing a far greater role for vitamin D—including the prevention of breast, ovarian, prostate, and colorectal cancer.¹

In fact, Dr. Northrup says that suboptimal levels of vitamin D may be one of the reasons why breast cancer incidence is higher in northern latitudes than near the equator. Research has shown that women who have blood levels of vitamin D above 52 ng/ml have half the risk of breast cancer as those with lower levels. Most women have to take 1,000 IU of vitamin D per day (either from sunlight, eating fish, or supplementation) to get this level.² Adequate vitamin D would also prevent scores of women from getting the brittle bones associated with aging.

It’s even estimated that additional exposure to vitamin D would save more than 23,000 American lives per year due to the reduction in cancer mortality.³

“Though today we’re taught to be afraid of the sun, all of us, including children, need regular sunlight to be healthy,” Dr. Northrup explains. “Our inner wisdom knows this, and that’s why despite all the propaganda about the dangers of sun exposure, millions of people still flock to the beach. The sun just feels too good to be all that bad!”

In addition to increasing serotonin levels in our blood and helping to balance melatonin, the sun’s UV rays enable our bodies to manufacture vitamin D in the fat layer under the skin.⁴ Exposure to outdoor sunlight is a much more reliable predictor of vitamin D levels in your blood than your dietary intake.

The body can make enough vitamin D from sun exposure to last the entire year! The more body area that’s exposed the better. Full-body exposure to sunlight on clear days at equatorial latitudes can easily provide the equivalent of 4,000 to 20,000 IU in less than 30 minutes in those with lightly pigmented skin. Those with darker pigmentation need more.

The key is moderation and avoidance of sunburn. Early morning or late afternoon sun is the safest. Avoid midday sun whenever possible. When I sunbathe, I always stop before getting any sign of a burn.

Need more vitamin D in your life? Here are a few tips from Dr. Northrup:

• Take your vitamin D supplement.
  (minimum of 1,000 IU per day)
  
• Get additional vitamin D by eating fish.
  Wild sockeye salmon, silver salmon, and albacore tuna contain anywhere from 300-700 IUs of vitamin D per 3.5 oz. serving, depending on the supplier. Consider eating these types of fish regularly.
  
• Consider a series of short visits to the tanning booth if you live in the North.
  (Don't get red!)
  
• Take a sunbath when you can.
  I'd recommend using sunscreen on your face. The rest of your body can absorb the UV light and make the vitamin D.

References

1. Holick MF. 2004. Vitamin D: importance in the prevention of cancers, type 1 diabetes, heart disease, and osteoporosis. Am J Clin Nutr, 79:362-71.
2. Garland CF, Mohr SB, Gorham ED, Grant WB, Garland FC. Evidence of need for increased vitamin D fortification of food based on pooled analysis of studies of serum 25-hydroxyvitamin D and breast cancer. Proc Amer Assoc Cancer Res 2006;47:[Abstract 4008]
3. Northrup, Christiane, M.D., 2005. Mother-Daughter Wisdom: Creating a Legacy of Physical and Emotional Health, Bantam: New York. p. 217.
4. Ibid., 216.

Sunny outlook for vitamin D lab testing

Testing for vitamin D levels once was uncommon. But as more and more studies raise awareness about vitamin D deficiencies, testing for the vital vitamin is skyrocketing.

Tests ordered for vitamin D grew by about 80 percent between May 2007 and May 2008, according to Richard Reitz, a medical director with Quest Diagnostics of Madison, N.J., one of the country's largest diagnostic labs. Another top lab -- Burlington, N.C.-based Lab Corporation of America -- saw a 90 percent leap in D test requests between 2007 and 2008, says Eric Lindblom, a company executive. Neither firm would release the actual numbers.

The testing hoopla is due to emerging research that links vitamin D deficiency with some infectious diseases, cancers, cardiovascular disease and autoimmune disorders, says Patsy Brannon, professor of nutritional sciences at Cornell University.

Other research indicates that many Americans are deficient in vitamin D, says Catherine Gordon, director of the bone health program at Children's Hospital Boston.

Supplements and D-rich foods, such as fortified milk, may be recommended for patients with low D levels, Gordon says. Sunshine's UV rays also activate one form of vitamin D in the body.

The Institute of Medicine recommends 200 IUs a day for children and 400 IUs daily for adults, though some experts recommend more.

Gannett News Service

Review of vitamin D guidelines urged

A flurry of research indicating that vitamin D may have a dizzying array of health benefits has reignited an intense debate over whether federal guidelines for the "sunshine vitamin" are outdated, leaving millions unnecessarily vulnerable to cancer, heart disease, diabetes and other ailments.

The studies have produced evidence that low levels of vitamin D make men more likely to have heart attacks, breast and colon cancer victims less likely to survive, kidney disease victims more likely to die, and children more likely to develop diabetes. Two other studies suggested that higher vitamin D levels reduce the risk of dying prematurely from any cause.

In response to these and earlier findings, several medical societies are considering new recommendations for a minimum daily vitamin D intake, the American Medical Association recently called for the government to update its guidelines, and federal officials are planning to launch that effort.

But many leading experts caution that it remains premature for people to start taking large doses of vitamin D. While the new research is provocative, experts argue that the benefits remain far from proven. Vitamin D can be toxic at high doses, and some studies suggest it could increase the risk for some health problems, experts say.

"The data are intriguing and serve as, no pun intended, food for further fruitful research," said Mary Frances Picciano, at the Office of Dietary Supplements of the National Institutes of Health. "But beyond that, the data are just not solid enough to make any new recommendations. We have to be cautious."

The clash is the latest in a long, often unusually bitter debate. Some skeptics question whether funding by the tanning, milk and vitamin industries is biasing some advocates. Frustrated proponents accuse skeptics of clinging to outdated medical dogma.

Reinhold Vieth, a professor of nutritional sciences and pathobiology at the University of Toronto, is one of a small but vocal cadre of researchers pushing doctors and patients to stop waiting for new official guidelines. Physicians should routinely test their patients for vitamin D deficiencies, and more people - especially African Americans - should take supplements and increase their exposure to the sun, they say.

"The bottom line is we now recognize that vitamin D is important for health for both children and adults and may help prevent many serious chronic diseases," said Michael Holick, a professor of medicine, physiology and biophysics at Boston University.

Scientists have long known that vitamin D is a vital nutrient the skin produces when hit by ultraviolet light from sunlight and other sources. The amount of vitamin D produced varies, depending on where the person lives, skin pigment, age and other factors. African Americans and other dark-skinned people, and anyone living in northern latitudes, make far less than other groups.

With people spending more time indoors surfing the Web, watching television, working at desk jobs, and covering up and using sunblock when they do venture outdoors, the amount of vitamin D that people create in their bodies has been falling. Milk and a few other foods are fortified with vitamin D, and it occurs naturally in others, such as fatty fish, but most people get very little through their diets.

Studies have found that deficiencies may be common, with perhaps half of adults and children having what some consider inadequate levels. Federal guidelines call for people to get 200 to 600 international units a day, depending on age and other factors. But those recommendations were last updated in 1997 and were aimed primarily at preventing bone diseases, such as rickets in children and osteoporosis in the elderly.

Since then, studies have indicated that vitamin D offers a plethora of health benefits, possibly protecting against heart disease, many forms of cancer, immune system disorders such as multiple sclerosis and rheumatoid arthritis, infectious diseases such as tuberculosis and the flu, and perhaps mental illnesses including schizophrenia and depression.

The Canadian Cancer Society upped its recommendation to 1,000 units a day last year. Some believe Americans should routinely consume at least 2,000 international units a day.

But others have reservations. Dermatologists worry that encouraging people to get unprotected sun exposure or use tanning salons may increase the rate of skin cancer.

"We're in the middle of a skin cancer epidemic," said C. William Hanke, president of the American Academy of Dermatology. "Tanning is risky and dangerous behavior. Ultraviolet light is classified as a carcinogen. We need to protect our skin."

This article appeared on page A - 5 of the San Francisco Chronicle