All posts by william-davis

Another in a series of data extrapolations that attempt to predict long-term cancer risk from medical radiation exposure was published in the July 13, 2009 Archives of Internal Medicine, viewable here.

Over the years, I've fussed about the radiation dose used by some centers for CT heart scans. (Note: I'm talking about CT heart scans, not CT coronary angiograms, an entirely different test with different radiation exposure.) In the "old" days, when electron-beam devices (EBT) were the best on the block, the old single-slice CT scanners (the predecessor of the current 64-slice MDCT scanners) exposed patients to ungodly quantities of radiation, while the EBT devices required very small quantities (0.5 mSv or about the equivalent of 4 standard chest x-rays or one mammogram).

But CT technology has advanced considerably. While EBT has been phased out (although it was an exceptional technology, GE acquired the small California manufacturer, then promptly scrapped the operation; you can guess why), multi-detector CT (MDCT) technology has improved in speed, image quality, and radiation exposure.

While it has improved, radiation exposure still remains an issue. The authors of the study applied the scanning protocols used at three hospitals and those in several CT heart scan studies, then calculated radiation exposure. They found a more than ten-fold range of exposure, from 0.8 mSv to 10.5 mSv. (All scanners were MDCT, none EBT.)

That's precisely what I've been worrying about: In the rapid rush to develop new devices, radiation exposure has often been a neglected issue. While some scan centers do an excellent job and take steps to minimize exposure, others barely lift a finger and consequently expose their patients to unnecessary radiation.

However, it's not as bad as it sounds. For one, the study included 16-slice MDCT scanners, a scanner type that I warned people to not use because of radiation. On the current most popular 64-slice devices, much lower radiation exposure is possible, on the order of 0.8-1.2 mSv routinely--if the center takes the effort.

This study, while eye-opening, will achieve some good: CT heart scans are here to stay. But the day-to-day practice of heart scanning should be:

1) standardized
2) conducted with radiation exposure as low as possible, preferably <0.8 mSv

To read more about this issue, below I've reprinted a 2007 full Track Your Plaque Special Report, CT Heart Scans and Radiation: The Real Story.

CT heart scans and radiation: The real story

“My personal opinion is that many patients today who are receiving multiple CT scans may well be getting at least comparable doses to subjects that have now developed malignancies from x-ray radiation received in the 1930s and '40s. And, similar to those days when the doses were unknown, the dose that patients receive today over a course of years of multiple CT scans is also completely unknown . . .

“I recommend that all healthcare providers become familiar with the concept that 1

Low HDL makes Dr. Friedewald a liar

17. March 2007 William Davis (5)

There's a $22 billion industry based on treating LDL cholesterol, a fictitious number.

LDL cholesterol is calculated from the following equation:

LDL cholesterol = Total cholesterol - HDL cholesterol - triglycerides/5

So when your doctor tells you that your LDL cholesterol is X, 99% of the time it has been calculated. This is based on the empiric calculation developed by Dr. Friedwald in the 1960s. Back then, it was a reasonable solution, just like bacon and eggs was a reasonable breakfast and a '62 Rambler was a reasonable automobile.

One of the problems with Dr. Friedewald's calculation is that the lower HDL cholesterol, the less accurate LDL cholesterol becomes. If it were just a few points, so what? But what if it were commonly 50 to 100 mg/dl inaccurate? In other words, your doctor tells you that your LDL is 120 mg/dl, but the real number is somewhere between 170 and 220 mg/dl. Does this happen?

You bet it does. In my experience, it is an everyday event. In fact, I'm actually surprised when the Friedewald calculated LDL closely approximates true LDL--it's the exception.

Dr. Friedewald would likely have explained that, when applied to a large population of, say, 10,000 people, calculated LDL is a good representation of true LDL. However, just like saying that the average weight for an American woman is 176 lbs (that's true, by the way), does that mean if you weigh 125 lbs that you are "off" by 41 lbs? No, but it shows how you cannot apply the statistical observations made in large populations to a single individual.

The lower HDL goes, the more inaccurate LDL becomes. This would be acceptable if most HDLs still permitted reasonable estimation of LDL--but it does not. LDL begins to become significantly inaccurate with HDL below 60 mg/dl.

How to get around this antiquated formula? In order of most accurate to least accurate:

--LDL particle number (NMR)--the most accurate by far.

--Apoprotein B--available in most laboratories.

--"Direct" LDL

--Non-HDL--i.e., the calculation of total cholesterol minus HDL. But it's still a calculated with built-in flaws.

--LDL by Friedewald calculation.

My personal view: you need to get an NMR if you want to know what your LDL truly is. A month of Lipitor costs around $80-120. A basic NMR costs less than $90. It's a relative bargain.

Menopause unleashes lipoprotein(a)

16. March 2007 William Davis (0)

Faye was clearly frustrated.

At age 52, she was having chest pains every day. A CT heart scan showed a score of zero. A CT coronary angiogram showed no plaque whatsoever.

"Everything went downhill when my menopause started. I gained weight, I started to have chest pains, my blood pressure went up, my cholesterol shot up."

She saw three physicians, none of whom shed much light on the situation. They ran through the predictable sequence of (horse, not human) estrogens, anti-depressants, suggestions for psychological counseling.

But we checked Faye for lipoprotein(a), which she proved to have at a high level of 182 nmol/l. This explained a lot.

A curious and predictable set of phenomenon occur to females with Lp(a) proceeding through the menopause. As estrogen recedes:

--Lp(a) levels rise dramatically.

--Blood pressure goes up, sometimes creating severe hypertension by mid- to late-50s.

--Chest pain can develop, presumably due to "endothelial dysfunction" or "microvascular angina", both representing abnormal coronary artery constriction facilitated by worsening expression of Lp(a).

All too often, these phenomena get dismissed as simply part of the menopausal package, when they are, in fact, important facets of this very important genetic pattern that confers high risk for heart disease.

If any of this rings familiar for you or a loved one, think Lp(a). Though Faye hadn't yet developed any measurable coronary plaque by her CT heart scan score, it was likely on its way, given the surge in Lp(a) expression as menopause unfolded--unless its recognized and appropriate preventive action taken.

Vitamin D must be oil-based

15. March 2007 William Davis (0)

I've talked about this before, but I need to periodically remind everybody:
Vitamin D must be an oil-based capsule, a gel-cap, not a tablet.

Lisa is one of early success stories: a heart scan score of 447 in her early 40's, modest reduction of CT heart scan score three years ago.

However, Lisa had a difficult time locating oil-based vitamin D. There has, in fact, been a national run on vitamin D and I'm told that even manufacturers are scrambling to keep up with the booming demand. So, she bought tablets instead and was taking 3000 units per day.

She came in for a routine check. Lisa's 25-OH-vitamin D3: 17 ng/ml, signifying severe deficiency, the same as if she were taking nothing at all. (Recall that we aim for 50 ng/ml.)

In other words, vitamin D tablets do not work. It is shameful. I see numerous women taking calcium tablets with D--the vitamin D does not work. I've actually seen blood levels of zero on these preparations.

You may have to look, but if you want to enjoy the extraordinary benefits of vitamin D replacement, it must be an oil-based capsule. Carlson's and Vitamin Shoppe have excellent prepartions. They raise blood levels substantially and consistently, and they're inexpensive. We pay $5.99 for a bottle of 120 capsules.

Vitamin D for $200?

13. March 2007 William Davis (2)

What if vitamin D cost $200 rather than $2?

In other words, what if cholecalciferol, or vitamin D3, was a patent-protectable agent that would sell for an extravagant price, just like a drug?

Vitamin D would be the hot topic. There would be TV ads run during Oprah, slick magazine two-page spreads with experts touting its outsized benefits, insurance companies would battle over how much your copay should be.

The manufacturer would host large fancy symposia to educate physicians on how wonderful vitamin D is for treatment of numerous conditions, complete with dinner, a show, and gifts. They would hire expert speakers to speak, scientists to have articles ghost-written, give out knick knacks with the brand label inscribed--just like Lipitor, Actos, Vytorin, ReoPro, Plavix . . .

After all, what other "drug" substantially increases bone density (up to 20% in adult females), enhances insulin responses 30% (equivalent to the TZD drugs, Actos and Avandia), and slashes colon cancer risk?

But it's not a drug. That is both vitamin D's strength and its weakness. It's a strong point because it's natural, phenomenally helpful across a variety of conditions, and inexpensive. It is also a weakness because, at $2 a month, no one is raking in the $12 billion annually that Pfizer makes for Lipitor that allows it to fund an enormous marketing campaign.

Vitamin D is a "discovery" of huge importance for health, including making reductions of CT heart scan scores far more likely for more people. And it comes without a prescription.

What's up with garlic?

13. March 2007 William Davis (0)

Fanatic Cook has posted an excellent summary on the recent negative attention cast on garlic preparations, at least for LDL cholesterol reduction.

Go to http://fanaticcook.blogspot.com to view.

I think Fanatic Cook is right--despite the lack of LDL reducing effects, it doesn't necessarily mean no benefit whatsoever. Anti-coagulation and anti-inflammatory effects, in particular, are well proven.

I do think, however, that it argues more in favor of sticking to whole cloves, rather than supplements. The benefits are also likely small. I would view garlic as a soft advantage for your plaque control program. You can do fine without it. You might do slightly better with it.

Drop the pretense

12. March 2007 William Davis (1)

Most hospitals maintain the "Saint _____" in their names, despite many having little or nothing to do with the church.

Out of 15 hospitals in my area, 13 are named after saints.

In my view, a more honest name would be something like "ABC Medical Enterprises, Inc." The profit motive, aggressive marketing tactics, and high CEO salaries would make better sense then. The trend to convert practicing physicians from professionals acting on behalf of patient welfare into paid employees would also be clearer.

Imagine Walmart were to change its name to "St. Mary's Emporium" Would it modify your perception of their business? I think it would. It would cause many people to believe that maybe their work was, at least in part, charitable and being done for the public welfare. But Walmart makes such pretense--they are in business for profit, just like all businesses.

It's time for the pretense to be dropped. Hospitals are cut-throat profit-seeking operations, operating under the guise of charitable, tax-free institutions. It's the farthest thing from the truth.

John Cannell on Vitamin D

11. March 2007 William Davis (2)

You can always count on Dr. John Cannell for unique perspectives on vitamin D. I reprint here his unfailingly entertaining and informative Vitamin D Newsletter on whether vitamin D replacement enhances physical performance.

The whole vitamin D "discovery" sometimes worries me. Vitamin D has proven to be an unbelievable, remarkable, dramatic boon to health, including facilitation in dropping CT heart scan scores. Yet the answer was always right in front of us. It worries me that you and I might have the answer to important questions right within our grasp all along--but don't know it. What if the same were true, say, for cancer? That is, a profound answer is right there, but our eyes just pass right over it.

Anyway, we should all keep our eyes open and perhaps you and I will continue to identify the most powerful tools available that return control over heart disease to us and take it away from the perverse, procedural hospital formula that still reigns.

If you haven't done so already, be sure to visit Dr. Cannell's website, www.vitamindcouncil.com.

The Vitamin D Newsletter
March, 2007

Peak Athletic Performance and Vitamin D

"No way doc." I had just finished telling my patient about the benefits of vitamin D, telling him he should take 4,000 IU per day, using all the techniques I had learned in 30 years of medical practice to convince someone proper treatment is important. But, he knew the U.S. government said he only needed 200 IU per day, not 4,000. He also knew the official Upper Limit was 2,000 IU a day. "What are you trying to do doc, kill me?" I told him his 25(OH)-vitamin D blood test was low, only 13 ng/ml. He had read about that too, in a medical textbook, where it said normal levels are between 10 and 40 ng/ml. "I'm fine doc;" adding "Are you in the vitamin business?" I explained I was not; that the government used outdated values; that recent studies indicate ideal 25(OH)D levels are about 50 ng/ml; and that they indicated that he needed about 4,000 IU per day to get his level up to 50. "No thanks doc, I'm fine."

So I tried a different tact. I brought him copies of recent press articles. "Look," I said, "look at these." Science News called vitamin D the Antibiotic Vitamin. The Independent in England says vitamin D explains why people die from influenza in the winter, and not the summer. U.S. News and World Report says almost everyone needs more. Newsweek says it prevents cancer and helps fight infection. In four different recent reports, United Press International says that: it reduces falls in the elderly, many pregnant women are deficient , it reduces stress fractures, and that it helps heals wounds.

He glanced at the articles, showing a little interest in stress fractures. Then he told me what he was really thinking. "Look doc, all this stuff may be important to old guys like you. I'm 22. All I care about are girls and sports. When I get older, maybe I'll think about it. I'm too young to worry about it. I'm in great condition." I couldn't argue. He was in good health and a very good basketball player, playing several hours every day, always on indoor courts.

What could I do to open his eyes? As an African American, his risk of early death was very high, although the risk for blacks doesn't start to dramatically increase until their 40's and 50's. Like all young people, he saw himself as forever young. The U.S. government was no help, relying on a ten-year-old report from the Institute of Medicine that is full of misinformation.

I tired to tell him that the 200 IU per day the U.S. government recommends for 20-year-olds is to prevent bone disease, not to treat low vitamin D levels like his. I pointed out the U.S. government's official current Upper Limit of 2,000 IU/day is the same for a 300 pound adult as it is for a 25 pound toddler. That is, the government says it's safe for a one-year-old, 25-pound, child to take 2,000 IU per day but it's not safe for a 30-year old, 300-pound, adult to take 2,000 and one IU a day. I mean, whoever thought up these Upper Limits must have left their thinking caps at home. Nevertheless, nothing worked. My vitamin D deficient patient was not interested in taking any vitamin D.

What are young men interested in? I remembered that he had told me: "Sex and sports." Two years ago I had researched the medical literature looking for any evidence vitamin D enhanced sexual performance. Absolutely nothing. That would have been nice. Can you imagine the interest?

Then I remembered that several readers had written to ask me if vitamin D could possibly improve their athletic performance? They told me that after taking 2,000 to 5,000 IU per day for several months, they seemed just a little faster, a little stronger, maybe had a little better balance and timing. A pianist had written to tell me she even played a better piano, her fingers moved over the keys more effortlessly! Was vitamin D responsible for these subtle changes or was it a placebo effect? That is, did readers just think their athletic performance improved because they knew vitamin D was a steroid hormone precursor (hormone, from the Greek, meaning "to set in motion")?

The active form of vitamin D is a steroid (actually a seco-steroid) in the same way that testosterone is a steroid and vitamin D is a hormone in the same way that growth hormone is a hormone. Steroid hormones are substances made from cholesterol, which circulate in the body, and work at distant sites by "setting in motion" genetic protein transcription. That is, both vitamin D and testosterone regulate your genome, the stuff of life. While testosterone is a sex steroid hormone, vitamin D is a pleomorphic (multiple function) steroid hormone.

All of a sudden, it didn't seem so silly. Certainly steroids can improve athletic performance although they can be quite dangerous. In addition, few people are deficient in growth hormone or testosterone, so when athletes take sex steroids or growth hormone they are cheating, or doping. The case with vitamin D is quite different because natural vitamin D levels are about 50 ng/ml and, since almost no one has such levels, extra vitamin D is not doping, it's just good treatment. I decided to exhaustively research the medical literature on vitamin D and athletic performance. It took me over a year.

To my surprise, I discovered that there are five totally independent bodies of research that all converge on an inescapable conclusion: vitamin D will improve athletic performance in vitamin D deficient people (and that includes most people). Even more interesting is who published this literature, and when. Are you old enough to remember when the Germans and Russians won every Olympics in the 60's and 70's? Well, it turns out that the most convincing evidence that vitamin D improves athletic performance was published in old German and Russian medical literature.

With the help of my wife and mother-in-law, both of whom are Russian, and with the help of Marc Sorenson, whose book Solar Power is a must read, I finally was able to look at translations of much of the old Russian and German literature. When one combines that old literature with the modern English language literature on neuromuscular performance, the conclusion is inescapable. The readers who wrote me are right.

If you are vitamin D deficient, the medical literature indicates that the right amount of vitamin D will make you faster, stronger, improve your balance and timing, etc. How much it will improve your athletic ability depends on how deficient you are to begin with. How good an athlete you will be depends on your innate ability, training, and dedication. However, peak athletic performance also depends upon the neuromuscular cells in your body and brain having unfettered access to the steroid hormone, activated vitamin D. In addition, how much activated vitamin D is available to your brain, muscle, and nerves depends on having ideal levels of vitamin D in your blood - about 50 ng/ml, to be precise.

Why would I write about such a frivolous topic like peak athletic performance when cancer patients all across this land are dying vitamin D deficient? Like many vitamin D advocates, I have been disappointed that the medical profession and the public don't seem to care about vitamin D. Maybe people, like my young basketball player, will care if it makes better athletes. So, Hey! You jocks! Listen up! I'm talking speed, balance, choice reaction time, muscle mass, muscle strength, squats, reps, etc. Important stuff. Here's the Vitamin D Council's first ever sports quiz.

1. Vitamin D-producing UVB radiation improves athletic performance and may have been widely practiced by German and Russian Olympic athletes in the 1960's and 70's.

True. I found tantalizing evidence the Russians and especially the Germans were on to this during the 60's and 70's when those two nations took turns placing number one and number two in the Olympics every year?

For example, in 1938, Russian researchers reported that a course of ultraviolet irradiations improved speed in the 100-meter dash in college students compared to matched controls, both groups undergoing daily training. Average 100-meter dash times decreased from 13.51 seconds to 13.28 seconds in the non-irradiated controls, but from 13.63 seconds to 12.62 seconds in the irradiated students. Here we see training improved times but training and irradiation improved times much more. Obviously, irradiation or vitamin D would not render the same magnitude of improvements in world-class sprinters, but they would be happy with a few milliseconds.

Gorkin Z, Gorkin MJ, Teslenko NE. [The effect of ultraviolet irradiation upon training for 100m sprint.] The Journal of Physiology of the USSR [Fiziol, z. (RSSR)] 1938; 25: 695-701. (In Russian)

If you want to know what early German thinking was on this, read this summation of the German literature:

"It is a well-known fact that physical performance can be increased through ultra-violet irradiation. In 1927, a heated argument arose after the decision by the German Swimmers' Association to use the sunlamp as an artificial aid, constituting an athletic unfairness, doping, so to speak. In 1926, Rancken had already reported the improving effect of sunlamp irradiation on muscle work with the hand-dynamo-graph. Heib observed an improvement in swimming times after repeated irradiations. In thorough experiments, Backmund showed that a substantial increase in muscle activity happens after radiation of larger portions of the body with an artificial sunlamp; that this performance increase is not caused through local - direct or indirect - effects on the musculature, but through a general effect. This general effect, triggered by ultra-violet irradiation, is caused by a systemic effect on the nervous system." (p. 17)

Parade GW, Otto H. Die beeinflussung der leistungsfahigkeit durch Hohensonnenbestrahlung. Zeitschrift fur Klinische Medizin (Z Klin Med),1940;137:17-21 [In German]

In 1945, two Americans measured the cardiovascular fitness and muscular endurance of 11 male Illinois subjects undergoing training in an indoor physical education class, comparing them to 10 matched controls. Both groups underwent similar physical training. Treatment consisted of ultraviolet irradiation, given in the nude, up to two minutes per session, three times per week, for ten weeks in the late fall and winter. After ten weeks, the treatment group had a 19% standard score gain in cardiovascular fitness compare to a 2% improvement in the control students. To regular readers of this newsletter, it should come as no surprise that the un-irradiated control group reported twice as many viral respiratory infections as the treatment group.

Allen R, Cureton T. Effects of Ultraviolet Radiation on Physical Fitness. Arch Phys Med 1945: 10: 641-44.

In 1952, the German sports medicine researcher, Spellerberg, reported on the effects of wholesale irradiation of athletes studying and training at the Sports College of Cologne - including many elite athletes - with a "central sun lamp." He irradiated the athletes in their bathing suits, on both sides of their bodies, for up to ten minutes, twice a week, for 6 weeks. He reported a "convincing effect" on athletic performance and a 50% reduction in sports injuries. Results were particularly impressive for swimmers, soccer, handball, hockey, and tennis players, as well as for boxers and most track and field athletes. He reported that irradiation leading to burns, further irradiation of athletes having achieved peak performance, and irradiation within 24 hours of competition, all impaired athletic performance. Their results were so convincing, the Sports College of Cologne officially notified the "national German and International Olympic committee." (p. 570)

Spellerberg AE. [Increase of athletic effectiveness by systematic ultraviolet irradiation.] Strahlentherapie 1952; 88: 567-70. [In German]

In 1952, Ronge exposed 120 German schoolchildren to UV lights installed in classrooms and compared them to 120 un-irradiated control children. Over a two-year period - excluding summer vacations - he tested both groups with a series of six cardiovascular fitness tests using a bike ergometer. Un-irradiated children showed a distinct seasonality in fitness, with the highest values right after summer break and the lowest values in the spring. Treated children showed no seasonal differences in physical performance. Differences in work performance between the irradiated and un-irradiated children were most conspicuous in the spring with 56% difference between the two groups. In a final experiment, he gave 30 children in the control classrooms 6.25 mg (250,000 IU) of vitamin D as a single dose in February and found their performance had "increased considerably," one month later but did not report the actual numbers. He concluded that vitamin D, either as a supplement or induced via UV irradiation, improved physical performance.

Ronge HE. [Increase of physical effectiveness by systematic ultraviolet irradiation.] Strahlentherapie 1952; 88: 563-6. [In German]

In 1954, another researcher, at the Max-Planck Institute for Industrial Physiology in Dortmund, Germany, administered three different wavelengths of UV light over 8 weeks to university students. He found that ultraviolet light in the vitamin D-producing UVB range was consistently effective in reducing resting pulse, lowering the basal metabolic rate, and increasing athletic performance. UVA had no effect; interestingly, artificial UVC irradiation (the atmosphere normally completely filters out UVC radiation and thus it's not naturally present on earth) also gave some positive results.

Lehmann G. [Significance of certain wave lengths for increased efficacy of ultraviolet irradiation.] Strahlentherapie. 1954 Nov;95(3):447-53. [In German]

In 1956, Hettinger and Seidel irradiated seven subjects in two different experiments: athletic performance on bike-ergometers and forearm muscle strength. They found that UV radiation induced a significant improvement in both muscle strength and athletic performance.

Hettinger T, Seidl E. [Ultraviolet irradiation and trainability of musculature.] Internationale Zeitschrift für angewandte Physiologie, einschliesslich Arbeitsphysiologie 1956; 16: 177-83. [In German]

Another German researcher, at the Institute for Medical Physics and Biophysics at the University of Gottiingen, studied reaction times (the time needed to recognize a light and switch it off) during October and November in a series of controlled experiments on 16 children and an unspecified number of adults. He first controlled for practice effects (getting better by practicing) and then administered nine full-body UV radiation treatments over three weeks to the two treatment groups, using placebo radiation in the two control groups. UV radiation improved choice reaction time by 25% in children and 20% in adults while reaction time worsened in controls. The improvements in the irradiated groups peaked at the end of the three weeks of UV treatments and reverted to baseline levels three weeks later. In the two control groups, he found distinctly improved reaction times in the sunnier months.

Sigmund R. [Effect of ultraviolet rays on reaction time in man.] Strahlentherapie. 1956; 101: 623-9. [In German]

The next study threw me because it was very well conducted, meticulously designed, and completely negative. In 1963, Berven reported on the effects of ultraviolet irradiation and vitamin D supplementation in a group of 30 Stockholm schoolchildren, aged 10 -11, comparing them to appropriate controls. He found no seasonality of fitness in the control group and no effect from either irradiation or two different vitamin D supplementation protocols (1500 IU of cholecalciferol daily for two months and a single dose of 400,000 IU of ergocalciferol) on performance on a bike ergometer.

Berven H. The physical working capacity of healthy children; seasonal variations and effect of ultraviolet irradiation and vitamin-D supply. Acta paediatrica. Supplementum 1963; 148: 1-22.

However, two things were not right and got me thinking. One, Berven found no seasonality of physical fitness and was the only author who found no such seasonal variations in athletic performance. Second, he found no effect from irradiation, again, the only author. Then I realized he was working with Swedish children in the late 1950's. Supplementation of children with high doses of vitamin D - often as cod liver oil - was routine in Scandinavia in the past, particularly in children. For example, in neighboring Finland, the official recommended daily dose of vitamin D for children - including infants - was 4,000 IU per day until 1964, when authorities reduced it to 2,000 IU/day. (That's right, you read that correctly, 4,000 IU per day for infants, which is too much by the way.)

In 1975, Finnish authorities reduced it to 1,000 IU per day, and, in 1992, to 400 IU per day. I emailed Professor Elina Hypponen who confirmed that the Swedish recommendations were similar to the Finnish ones. Therefore, it seems highly unlikely that many of Berven's Swedish children, studied in 1958 and 1959, all from "families with a good standard of living," were vitamin D deficient. Therefore, this study showed that vitamin D will not improve athletic ability in vitamin D replete people. That's very important because it indicates more is not necessarily better. More is only better if you are not taking enough.

Hypponen E, et al. Intake of vitamin D and risk of type 1 diabetes: a birth-cohort study. Lancet. 2001 Nov 3;358(9292):1500-3.

In the 1960's, three American researchers conducted experiments with university students. Rosentswieg studied the effects of a single six-minute dose of UV light on each side of the trunk in 23 college women, recording changes in various tests of muscle strength at one and five hours. He found a trend towards significance after five hours in white but not African American students. In 1968, Cheatum found that a six-minute administration of UV light, on each side of the trunk, increased the speed of 15 college women in the 30-yard dash. In 1969, Rosentswieg found a six-minute dose of UV light, on each side of the trunk, finding improved performance on a bicycle ergometer in college women. However, unlike the Germans and Russians, I could find no evidence that any of these American findings interested any American professionals involved in the care or train

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