--
Two June research reports show that most patients with rheumatic diseases have levels below the “normal” range of vitamin D, considered in the report to be 48-145 nmol/L. In US measurements, that number is equivalent to 19.2-58 ng/ml. The diseases assessed within the reports were inflammatory joint disease, osteoarthritis, rheumatoid arthritis, myalgia, and osteoporosis. http://www.eurekalert.org/pub_releases/2010-06/elar-vdd061710.php
The research also showed that supplementation of 800-1,000 international units (IU) was not sufficient to normalize vitamin D levels in most patients.
A problem with such studies is that researchers must be in the dark ages not to know that 32 ng/ml is considered the lowest healthful level of vitamin D, and that optimal levels are 50-60. Therefore, when people are below the level of 19, they are not only below deficient, they are severely deficient. In these studies, it is likely that 80% of the people would have been deficient if the appropriate measure of 32 ng/ml had been used, and it is also likely that 100% were suboptimal.
An important fact is this: one minute of full-body sunlight exposure around noon can produce as much as 1,000 IU of vitamin D. This is Nature’s way. It is counterintuitive to suppose that a supplement of only 1,000 IU would be sufficient to achieve optimal levels of vitamin D, if Nature produces vastly more with within 20 minutes. And, in those seasons when vitamin D is not available, many vitamin D scientists now recommend 3,000-5,000 IU daily. Using the miniscule quantities of 400 IU (multivitamin tablet) to 1,000 IU to eliminate the inflammation of diseases like rheumatoid arthritis, unexplained muscle pain and chronic back pain is like trying to attack an elephant with a bb gun.
In all cases in these research papers, the subjects who had the lowest vitamin D levels also had the greatest disease activity, which is not surprising; vitamin D is powerful antiinflammatory hormone, and without it we suffer. More research need to be conducted, using 3,000-5,000 IU daily, or getting people outside with a lot of skin exposure when the sun is direct (without burning of course).
About one year ago I posted a blog that explained a great deal about rheumatoid arthritis and the influence of vitamin D in preventing and reducing the risk of the disease. The following is a repost of that blog, which fits in nicely with what we have just discussed:
Do you suffer from rheumatoid arthritis (RA)? Can vitamin D help?
Both dietary and supplemental vitamin D reduce the risk of RA, which is an autoimmune disease—a disease in which the body’s immune system attacks its own tissue. In a study of 29,000 women, those who ranked in the top third of vitamin D consumption had one-third less risk of RA.[1] It is likely that a greater vitamin D intake would have produced much better results, since it is virtually impossible to ingest sufficient vitamin D from food and multivitamins.
In studies performed on mice, vitamin D was shown to inhibit the progression of rheumatoid arthritis and minimize or prevent symptoms.[2] The same is true in humans. In subjects diagnosed with a form of the disease known as inflammatory arthritis, the lower the vitamin D levels are, the higher is the disease activity.[3] Vitamin D's anti-inflammatory properties and its ability to reduce the autoimmune response are likely responsible for the improvement in RA.[4]
Investigations also find that RA is more common in winter, consistent with the idea that vitamin D is a major factor in reducing the risk.[5] In a report from researchers in Ireland, it was shown that 70% of patients had low vitamin D levels and that 26% were severely deficient.[6] However, in that report, 21 ng/ml was considered as the deficiency level and 10 as the severe deficiency level. A level of 21 is dangerously deficient. The ideal level of vitamin D is 50-60 ng/ml. Using those numbers, it is likely that all of these patients ranged between deficient and severely deficient.
In our health institute/resort, we observed that guests with arthritis often regained full range of motion in their joints from a week to a month after beginning a program. I assumed that our anti-inflammatory vegetarian nutrition was responsible for the positive results. Now I realize that many of the benefits came from sunlight exposure during outdoor exercise.
RA prevention and relief are two more reasons to obtain regular, non-burning sunlight exposure. Remember that sunscreens can prevent 99% of vitamin D production by the skin.
[1] Merlino, L. et al. Vitamin D intake is inversely associated with rheumatoid arthritis: Results from the Iowa Women’s Health Study. Arthritis & Rheumatism 2004;50:72-77.
[2] Cantorna, M. et al. 1,25-Dihydroxycholecalciferol inhibits the progression of arthritis in murine models of human arthritis. J Nutr1998;128:68-72.
[3] Patel, S. et al. Serum vitamin D metabolite levels may be inversely associated with current disease activity in patients with early inflammatory polyarthritis. Arthritis Rheum 2007;56;2143-49.
[4] Cutolo, M. et al. Vitamin D in rheumatoid arthritis. Autoimmune Rev 2007;7:59-64.
[5] Cutolo, M. et al. Circannual vitamin D serum levels and disease activity in rheumatoid arthritis: Northern versus Southern Europe. Clin Exp Rheumatol 2006;24:702-4.
[6] Haroon, M. Report to European Union League Against Rheumatism , June 13, 2008.
Saturday, June 26, 2010
Tuesday, June 22, 2010
Gwyneth Paltrow has “seen the light.”
--
I’m a fan of Gwyneth Paltrow—a talented actress who performs well in any movie genre. She recently performed a great service by posting a “sunlight” article on her newsletter: http://goop.com/?page=newsletter_vn&id=most_recent. In it, she related the fact that her tibia had been fractured, and that on having her vitamin D assessed, she was told that her levels were the lowest her doctors had ever seen. She obviously had a disease called osteomalacia, or adult rickets. They suggested strong vitamin D supplementation and that she spend time in the sunlight. Her statement about sunlight was followed by an exclamation point, suggesting her surprise at such a heretical idea. Gwyneth also included an excellent article by her physician, Frank Lipman, which beautifully puts to rest the notion that after thousands or millions of years under the sunlight, we should avoid any contact with it.
Kudos is due Ms. Paltrow and her physicians, especially Dr. Lipman. When celebrities speak, their fans listen. The Powers of Darkness (POD)—those who would have us avoid the sunlight and have even suggested that we live underground to avoid it[1]—are responsible for the weakened bones of Gwyneth and millions more in the US alone. As stated by Susan Brown, PhD, in a research review in Alternative Medicine Review, “Each year in the United States, more than 1.5 million low-trauma osteoporotic fractures occur, including more than 300,000 hip fractures.”[2]
In spite of the fact that calcium cannot be absorbed without sufficient vitamin D, and that “normal” levels of at least 32 ng/ml are needed to optimize absorption,[3] [4] the POD continue to spew their anti-sun venom.
I recently had the opportunity to work with a woman—who had been away from of the sunlight for years—as she worked as a massage therapist in a large resort hotel. She had experienced a great deal of bone and muscle pain and told me that she had to quit her job; her hands hurt too severely to continue. She also informed me that her bones had begun to shift across her chest as she did massages, and she sometimes had to use crutches to walk. I suggested that she have her vitamin D assessed and she complied. Her D measurement was 6 ng/ml, a level indicative of severe deficiency (we now consider optimal levels to be about 60). After bringing her levels to 45, all of her bone disorders disappeared, and she is now able to resume her career in massage therapy.
Those who read the medical literature are not surprised about Ms. Paltrow’s experience. For instance, one of the most compelling studies on fracture risk and sunlight was done by Dr. Sato and his colleagues in Japan.[5] They studied the effects of sunlight exposure—or the lack thereof—on the bone mass of elderly women who were either exposed to sunlight or were kept inside a care facility. Over twelve months, 129 women were exposed to sunlight every day, and another 129 received no sunlight exposure. The results were startling: in these sedentary women, the sunlight group increased bone mass by an average 3.1%; in the non-sunlight-exposed group, it decreased by 3.3%, a difference of 6.4%. This is important, because high bone mass prevents fractures. The risk of fracture increases two to three times for every 10 percent drop in bone density.[6] In Sato’s study, however, the women who stayed indoors had six-times as many fractures as those who sunbathed outdoors. Also interesting to note is that vitamin D levels in the sunlight-exposed group increased by 400%.
In addition, an investigation in Spain concluded that women who actively participated in sun exposure had one-eleventh the chance of a hip fracture as those who did not![7] Another in Switzerland found that only 4% of hip fracture patients had vitamin D blood levels of 30 ng/ml.[8] In other words, 96% were vitamin D-deficient.
Gwyneth, we appreciate your willingness to help spread the truth about sunlight, one of God’s greatest gifts to the world and the only natural way to obtain vitamin D. We hope that more celebs will speak out against the Powers of Darkness and help us “stop the insanity.”
[1] Dr. Wilma Bergfeld, then-president of the American Academy of Dermatology at Derm Update, the AAD’s 1996 annual media day, Nov. 13, 1996.
[2] Brown, S. Vitamin D and Fracture Reduction: An Evaluation of the Existing Research. Altern Med Rev 2008;13:21-33.
[3] Heaney RP. The vitamin D requirement in health and disease. J Steroid Biochem Mol Biol 2005;97:13-19.
[4] Bischoff-Ferrari HA, Giovannucci E, Willett WC, et al. Estimation of optimal serum concentrations of 25-hydroxyvitamin D for multiple health outcomes. Am J Clin Nutr 2006;84:18-28.
[5] Sato, Y. et al. Amelioration of osteoporosis and hypovitaminosis D by sunlight exposure in stroke patients. Neurology 2003;61:338-42.
[6] Nguyen, T. et al. Prediction of osteoporotic fractures by postural instability and bone density. BMJ 1993;307:1111-15.
[7] Larrosa, M. Vitamin D deficiency and related factors in patients with osteoporotic hip fracture. Med Clin (BARC) 2008;130:6-9.
[8] Bischoff-Ferrari, H. et al. Severe vitamin D deficiency in Swiss hip-fracture patients. Bone 2008;42:597-602.
I’m a fan of Gwyneth Paltrow—a talented actress who performs well in any movie genre. She recently performed a great service by posting a “sunlight” article on her newsletter: http://goop.com/?page=newsletter_vn&id=most_recent. In it, she related the fact that her tibia had been fractured, and that on having her vitamin D assessed, she was told that her levels were the lowest her doctors had ever seen. She obviously had a disease called osteomalacia, or adult rickets. They suggested strong vitamin D supplementation and that she spend time in the sunlight. Her statement about sunlight was followed by an exclamation point, suggesting her surprise at such a heretical idea. Gwyneth also included an excellent article by her physician, Frank Lipman, which beautifully puts to rest the notion that after thousands or millions of years under the sunlight, we should avoid any contact with it.
Kudos is due Ms. Paltrow and her physicians, especially Dr. Lipman. When celebrities speak, their fans listen. The Powers of Darkness (POD)—those who would have us avoid the sunlight and have even suggested that we live underground to avoid it[1]—are responsible for the weakened bones of Gwyneth and millions more in the US alone. As stated by Susan Brown, PhD, in a research review in Alternative Medicine Review, “Each year in the United States, more than 1.5 million low-trauma osteoporotic fractures occur, including more than 300,000 hip fractures.”[2]
In spite of the fact that calcium cannot be absorbed without sufficient vitamin D, and that “normal” levels of at least 32 ng/ml are needed to optimize absorption,[3] [4] the POD continue to spew their anti-sun venom.
I recently had the opportunity to work with a woman—who had been away from of the sunlight for years—as she worked as a massage therapist in a large resort hotel. She had experienced a great deal of bone and muscle pain and told me that she had to quit her job; her hands hurt too severely to continue. She also informed me that her bones had begun to shift across her chest as she did massages, and she sometimes had to use crutches to walk. I suggested that she have her vitamin D assessed and she complied. Her D measurement was 6 ng/ml, a level indicative of severe deficiency (we now consider optimal levels to be about 60). After bringing her levels to 45, all of her bone disorders disappeared, and she is now able to resume her career in massage therapy.
Those who read the medical literature are not surprised about Ms. Paltrow’s experience. For instance, one of the most compelling studies on fracture risk and sunlight was done by Dr. Sato and his colleagues in Japan.[5] They studied the effects of sunlight exposure—or the lack thereof—on the bone mass of elderly women who were either exposed to sunlight or were kept inside a care facility. Over twelve months, 129 women were exposed to sunlight every day, and another 129 received no sunlight exposure. The results were startling: in these sedentary women, the sunlight group increased bone mass by an average 3.1%; in the non-sunlight-exposed group, it decreased by 3.3%, a difference of 6.4%. This is important, because high bone mass prevents fractures. The risk of fracture increases two to three times for every 10 percent drop in bone density.[6] In Sato’s study, however, the women who stayed indoors had six-times as many fractures as those who sunbathed outdoors. Also interesting to note is that vitamin D levels in the sunlight-exposed group increased by 400%.
In addition, an investigation in Spain concluded that women who actively participated in sun exposure had one-eleventh the chance of a hip fracture as those who did not![7] Another in Switzerland found that only 4% of hip fracture patients had vitamin D blood levels of 30 ng/ml.[8] In other words, 96% were vitamin D-deficient.
Gwyneth, we appreciate your willingness to help spread the truth about sunlight, one of God’s greatest gifts to the world and the only natural way to obtain vitamin D. We hope that more celebs will speak out against the Powers of Darkness and help us “stop the insanity.”
[1] Dr. Wilma Bergfeld, then-president of the American Academy of Dermatology at Derm Update, the AAD’s 1996 annual media day, Nov. 13, 1996.
[2] Brown, S. Vitamin D and Fracture Reduction: An Evaluation of the Existing Research. Altern Med Rev 2008;13:21-33.
[3] Heaney RP. The vitamin D requirement in health and disease. J Steroid Biochem Mol Biol 2005;97:13-19.
[4] Bischoff-Ferrari HA, Giovannucci E, Willett WC, et al. Estimation of optimal serum concentrations of 25-hydroxyvitamin D for multiple health outcomes. Am J Clin Nutr 2006;84:18-28.
[5] Sato, Y. et al. Amelioration of osteoporosis and hypovitaminosis D by sunlight exposure in stroke patients. Neurology 2003;61:338-42.
[6] Nguyen, T. et al. Prediction of osteoporotic fractures by postural instability and bone density. BMJ 1993;307:1111-15.
[7] Larrosa, M. Vitamin D deficiency and related factors in patients with osteoporotic hip fracture. Med Clin (BARC) 2008;130:6-9.
[8] Bischoff-Ferrari, H. et al. Severe vitamin D deficiency in Swiss hip-fracture patients. Bone 2008;42:597-602.
Monday, June 21, 2010
Do serum levels of vitamin D correlate to reduced cancer risk or not?
--
The American Journal of Epidemiology just released several studies on vitamin D and cancer that concluded vitamin D levels were not correlated to several cancers; that is, higher levels of vitamin D did not correlate to lowered cancer rates.[1] The key to understanding this finding is that in each case, the levels were measured prior to the diagnoses of cancer. Prediagnostic measurements occur at one point in time and do not measure changes that occur between the measurement and the onset of the disease. If, after the moment of vitamin D measurement, habits of sunlight exposure or diet change, vitamin D levels can fluctuate considerably. I believe that Vitamin D levels at the time of diagnosis are much more indicative of the affects of vitamin D on the risk of disease, and my opinion is that optimal higher vitamin D levels that are maintained for long periods are much more likely to reduce disease risk. Dr. William Grant, in an email today, told me he believed …”serum 25(OH)D levels measured several years ago aren't a good indication of either lifetime 25(OH)D or recent 25(OH)D." 25(OH)D is the measurement labs use to assess serum levels of vitamin D.
A randomized controlled trial (RCT) that maintains similar supplementation amounts for a period of years could give a good indication of whether consistently higher vitamin D levels have a protective affect on cancers. Let’s suppose, for instance, that one group of randomly chosen women received a vitamin D supplement for four years and another group received a placebo during that same time. All of the women would be free of cancer when the study began. Then, at the end of four years, the women would be assessed for the number of cancers in each group, and it could be determined if the supplemented group fared better than the placebo group. This is known as a randomized, placebo-controlled interventional study, and is considered the “gold standard” of research. Obviously, if the vitamin D group fared far better than the placebo group, we could confidently state that consistently higher vitamin D levels over four years correlated strongly with reduced risk of cancer. But wait—we already have such a study. Lappe and colleagues already conducted the study described above and found that the vitamin D group had 60-77% lesser risk of all cancers, compared to the placebo group, after four years.[2] None of the studies published by the American Journal of Epidemiology were RCT’s. This is strong indication that the use of prediagnostic levels of vitamin D may not be of much value.
Also interesting is the fact that the authors of these papers mention that research shows sunlight exposure correlates to a rather impressive risk reduction in most of the cancers studied. There are two outstanding papers, one very recent, which demonstrate that relationship.[3] [4]
Based on what we have just discussed, it is possible that (1) regular sunlight exposure maintains consistently higher levels of vitamin D and results in reductions of cancer similar to those demonstrated in the research conducted by Lappe and colleagues, or (2) sunlight has positive influences of cancer beyond the production of vitamin D. My opinion is that the answer lies in a combination of both. We are beginning to see more research showing that in both cancer and multiple sclerosis, sunlight exposure may have its own anti-cancer benefits. Sunshine is, of course, the most natural way to produce vitamin D. Just be very careful not to sunburn.
[1] http://aje.oxfordjournals.org/papbyrecent.dtl
[2] Lappe, J. et al. Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. Am J Clin Nutr 2007;85:1586–91.
[3] Grant WB. Does solar ultraviolet irradiation affect cancer mortality rates in China? .Asian Pac J Cancer Prev 2007;8(2):236-42.
[4] Chen W, Clements M, Rahman B, Zhang S, Qiao Y, Armstrong BK. Relationship between cancer mortality/incidence and ambient ultraviolet B irradiance in China. Cancer Causes Control.2010 Jun 16. [Epub ahead of print]
The American Journal of Epidemiology just released several studies on vitamin D and cancer that concluded vitamin D levels were not correlated to several cancers; that is, higher levels of vitamin D did not correlate to lowered cancer rates.[1] The key to understanding this finding is that in each case, the levels were measured prior to the diagnoses of cancer. Prediagnostic measurements occur at one point in time and do not measure changes that occur between the measurement and the onset of the disease. If, after the moment of vitamin D measurement, habits of sunlight exposure or diet change, vitamin D levels can fluctuate considerably. I believe that Vitamin D levels at the time of diagnosis are much more indicative of the affects of vitamin D on the risk of disease, and my opinion is that optimal higher vitamin D levels that are maintained for long periods are much more likely to reduce disease risk. Dr. William Grant, in an email today, told me he believed …”serum 25(OH)D levels measured several years ago aren't a good indication of either lifetime 25(OH)D or recent 25(OH)D." 25(OH)D is the measurement labs use to assess serum levels of vitamin D.
A randomized controlled trial (RCT) that maintains similar supplementation amounts for a period of years could give a good indication of whether consistently higher vitamin D levels have a protective affect on cancers. Let’s suppose, for instance, that one group of randomly chosen women received a vitamin D supplement for four years and another group received a placebo during that same time. All of the women would be free of cancer when the study began. Then, at the end of four years, the women would be assessed for the number of cancers in each group, and it could be determined if the supplemented group fared better than the placebo group. This is known as a randomized, placebo-controlled interventional study, and is considered the “gold standard” of research. Obviously, if the vitamin D group fared far better than the placebo group, we could confidently state that consistently higher vitamin D levels over four years correlated strongly with reduced risk of cancer. But wait—we already have such a study. Lappe and colleagues already conducted the study described above and found that the vitamin D group had 60-77% lesser risk of all cancers, compared to the placebo group, after four years.[2] None of the studies published by the American Journal of Epidemiology were RCT’s. This is strong indication that the use of prediagnostic levels of vitamin D may not be of much value.
Also interesting is the fact that the authors of these papers mention that research shows sunlight exposure correlates to a rather impressive risk reduction in most of the cancers studied. There are two outstanding papers, one very recent, which demonstrate that relationship.[3] [4]
Based on what we have just discussed, it is possible that (1) regular sunlight exposure maintains consistently higher levels of vitamin D and results in reductions of cancer similar to those demonstrated in the research conducted by Lappe and colleagues, or (2) sunlight has positive influences of cancer beyond the production of vitamin D. My opinion is that the answer lies in a combination of both. We are beginning to see more research showing that in both cancer and multiple sclerosis, sunlight exposure may have its own anti-cancer benefits. Sunshine is, of course, the most natural way to produce vitamin D. Just be very careful not to sunburn.
[1] http://aje.oxfordjournals.org/papbyrecent.dtl
[2] Lappe, J. et al. Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. Am J Clin Nutr 2007;85:1586–91.
[3] Grant WB. Does solar ultraviolet irradiation affect cancer mortality rates in China? .Asian Pac J Cancer Prev 2007;8(2):236-42.
[4] Chen W, Clements M, Rahman B, Zhang S, Qiao Y, Armstrong BK. Relationship between cancer mortality/incidence and ambient ultraviolet B irradiance in China. Cancer Causes Control.2010 Jun 16. [Epub ahead of print]
Tuesday, June 1, 2010
Air pollution, sunlight, vitamin D and type-two diabetes
Does air pollution cause diabetes, or does pollution cause vitamin D deficiency, which then leads to diabetes?
New research from Germany showed that women who lived in heavily air-polluted areas were at greater risk for type-two diabetes than those who lived in less-polluted areas. Those who lived within 100 meters of busy roadways doubled the diabetes risk. http://www.newswise.com/articles/study-suggests-link-between-air-pollution-and-type-2-diabetes-in-women
The authors assumed that the inhalation of pollutants was responsible for the increased risk of diabetes among those living in heavily-polluted areas, but I suggest another possibility: It is well-known that air pollution filters out sunlight and correlates to profoundly lower vitamin D levels. [1] [2] [3]
But do vitamin D levels have an influence on type-two diabetes? Research shows that Vitamin D levels correlate closely to insulin sensitivity; the higher the vitamin D levels, the more receptive the body is to the action of insulin, which makes carbohydrates easier to metabolize.[4] This same study shows that the higher the vitamin D levels are, the lower are the blood sugar levels. Other research shows that men with the highest vitamin D levels had a 30% reduced risk of type-2 diabetes compared to those with low levels,[5] probably because the beta cells of the pancreas (the insulin producing cells) have vitamin D receptors[6] and function more efficiently when vitamin D levels are higher.[7]
It is highly likely that the reason for the increased risk for diabetes was not the inhalation of air pollutants, but rather the lack of sunlight and subsequent vitamin D deficiency. It is time to leave the pollution and return to the sun.
[1] Mims FM., 3rd Significant reduction of UVB caused by smoke from biomass burning in Brazil. Photochem Photobiol. 1996 Nov;64(5):814–816.
[2] Agarwal, K et al. The impact of atmospheric pollution on vitamin D status of infants and toddlers in Delhi, India. Arch Dis Child 2002;87:111-113
[3] Holick MF. Environmental factors that influence the cutaneous production of vitamin D. Am J Clin Nutr 1995;61:(Suppl):638S-645S.
[4] Chiu K. et al. Hypovitaminosis D is associated with insulin resistance and beta cell dysfunction. Am J Clin Nutr 2004;79:820-25.
[5] Mattila, C. Serum 25-hydroxyvitamin D concentration and subsequent risk of type-2 diabetes. Diabetes Care 2007;30:2569-70.
[6] Brown, A. et al. Vitamin D. American J of Physiol 1999;277(2 Pt 2):F157-75.
[7] Norman, A. et al. Vitamin D deficiency inhibits pancreatic secretion of insulin. Science 1980;209:823-25.
New research from Germany showed that women who lived in heavily air-polluted areas were at greater risk for type-two diabetes than those who lived in less-polluted areas. Those who lived within 100 meters of busy roadways doubled the diabetes risk. http://www.newswise.com/articles/study-suggests-link-between-air-pollution-and-type-2-diabetes-in-women
The authors assumed that the inhalation of pollutants was responsible for the increased risk of diabetes among those living in heavily-polluted areas, but I suggest another possibility: It is well-known that air pollution filters out sunlight and correlates to profoundly lower vitamin D levels. [1] [2] [3]
But do vitamin D levels have an influence on type-two diabetes? Research shows that Vitamin D levels correlate closely to insulin sensitivity; the higher the vitamin D levels, the more receptive the body is to the action of insulin, which makes carbohydrates easier to metabolize.[4] This same study shows that the higher the vitamin D levels are, the lower are the blood sugar levels. Other research shows that men with the highest vitamin D levels had a 30% reduced risk of type-2 diabetes compared to those with low levels,[5] probably because the beta cells of the pancreas (the insulin producing cells) have vitamin D receptors[6] and function more efficiently when vitamin D levels are higher.[7]
It is highly likely that the reason for the increased risk for diabetes was not the inhalation of air pollutants, but rather the lack of sunlight and subsequent vitamin D deficiency. It is time to leave the pollution and return to the sun.
[1] Mims FM., 3rd Significant reduction of UVB caused by smoke from biomass burning in Brazil. Photochem Photobiol. 1996 Nov;64(5):814–816.
[2] Agarwal, K et al. The impact of atmospheric pollution on vitamin D status of infants and toddlers in Delhi, India. Arch Dis Child 2002;87:111-113
[3] Holick MF. Environmental factors that influence the cutaneous production of vitamin D. Am J Clin Nutr 1995;61:(Suppl):638S-645S.
[4] Chiu K. et al. Hypovitaminosis D is associated with insulin resistance and beta cell dysfunction. Am J Clin Nutr 2004;79:820-25.
[5] Mattila, C. Serum 25-hydroxyvitamin D concentration and subsequent risk of type-2 diabetes. Diabetes Care 2007;30:2569-70.
[6] Brown, A. et al. Vitamin D. American J of Physiol 1999;277(2 Pt 2):F157-75.
[7] Norman, A. et al. Vitamin D deficiency inhibits pancreatic secretion of insulin. Science 1980;209:823-25.
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