Category: Vitamin D

Calcium supplements with vitamin D against colon cancer?

Admin

February 18, 2006

A large study attempted to show whether or not calcium and vitamin D prevent colon cancer. It was a strange study, using low doses over a short period.

There are probably those who believe that the latest study on calcium and vitamin D shows that neither is good for anything. But we should hesitate before going to that extreme. One can also believe that the study was not suited to draw this conclusion. Or, as it is stated in a leading editorial in “The New England Journal of Medicine:” the conclusion should be interpreted in light of the study was complicated and in light of the probability that the doses of calcium and vitamin D were too low.

The debate regards the insidious and widespread cancers of the colon and rectum. Half of a group of 36,282 American women between the ages of 50 and 79 took part in a seven year study where they received daily supplements of 1,000 mg calcium and 400 units vitamin D to see if reduced their risk of these diseases. The supplements given are the same as two normal calcium and vitamin D vitamin tablets, which many take to strengthen their bones. After the seven years the researchers assessed the number of women who developed colon and rectum cancer. The result was disheartening: Whether the women received supplements or placebo had not effect on the risk.

There was a single positive find buried in the data. The women who had the least vitamin D in their blood during the study had with statistical certainty the greatest probability of developing colon cancer. This could indicate that vitamin D has a positive effect. There was also a tendency, but only a tendency, that these women had the greatest benefit from the supplements.

Quite a lot of things contribute to that this conclusion be taken with a grain of salt. This is partially due to that the study was very complex.

Possibly the most important objection is that it “only” lasted seven years. It is believed that colon cancer takes 10-20 years to develop before it is diagnosed. It the supplements prevent a new cancer from forming it is clear that for this reason no effects will be found as early as after seven years. This has been considered: Participants in the study will be monitored further for the next five years.

Strong objections
If the goal was to show a difference within the seven year period, those responsible should have at least ended the study by examining the intestines of all of the participants in order to find early cancer stages, or polyps. This did not occur. There was neither the money nor the resources necessary to do over 35,000 intestinal examinations. It was only possible to establish that the number of independently undertaken intestinal exams and the number of discovered cancers in the two groups were about the same. But maybe nothing more can be expected.

One confusing detail is that the study participants were allowed to continue taking the supplements that they had taken before the study along with the supplements that they received as a part of the study. On average they received 1,100 mg calcium and 350 units vitamin D, both close to the recommended dosages, before the study began. Many of them therefore must have received very large doses of calcium, over 2,000 mg, per day. Is it reasonable to guess that this is the reason for the slightly increased frequency of self-reported kidney stones? 2.4% of those who received supplements and 2.1% of those who received placebo, got kidney stones during the seven years.

Also, the average age was relatively low (62), which reduced the risk of cancer, and therefore weakened the study. It was further weakened by the fact that more than one out of four participants did not finish the study. Whether this dropout rate is because calcium pills can cause constipation is not considered in the article.

Just as important, the dose of vitamin D, as referred to in the editorial, may have been too low. Recently it has been estimated that about 1,000 units daily is necessary for most people in order to achieve any supposed cancer preventing effect. This amount of vitamin D (or more accurately 25-(OH)-vitamin D) is necessary to achieve a serum concentration of over 30 nano-grams per litre (75 nanomols per millilitre). Nevertheless, only a minority of the study participants received this amount.

What can be concluded from this? The editorial gives some suggestions for new studies. Much indicates that vitamin D, and maybe calcium, prevents cancer. But we still lack sufficient knowledge.

By: Vitality Council

References:
1. Wactawski-Wende J et al. Calcium plus vitamin D supplementation and the risk of colorectal cancer. N Engl J Med 2006;354:684-96.
2. Forman M C et al. Calcium plus vitamin D3 supplementation and colorectal cancer in women. N Engl J Med 2006;354:752-4.
3. Garland C F et al. The role of vitamin D in cancer prevention. Am J Publ Health 2006;96:9-18.

Vitamin D Prevents Cancer

Admin

December 30, 2005

A new and much discussed analysis, has shown that nearly every other cancer case can be prevented by D vitamin, if everyone is getting the suffient dosage, which almost no one is.

It has now been proven that the frequency of cancer can be reduced dramatically by increasing the population’s vitamin D intake.

This is the claim of the American researcher Cedric Garland, who is a professor of epidemiology at the University of Southern California, San Diego. He is behind the largest analysis of vitamin D research and cancer to date. 63 studies from 1962-2004 were analysed.

As a whole they strongly indicate that if the population’s intake of vitamin D is set up to 1,000 units per day, the frequency of colon cancer would be halved while the number of breast cancers and ovarian cancers would be reduced by a third. The 1,000 units of vitamin D (25 micrograms) would be, with certainty, without side effects. This is the same as five times the normally recommended dose, which only few receive.

Garland, who has studied vitamin D for 25 years, is very certain of his results. In a statement given to the BBC and The Independent he declared that there is now such an overwhelming amount of indications from the best observational studies, that governmental action is warranted.

It is worth noticing that these internationally respected media concerns both came with detailed reports, which also were followed by a leading editorial in The Independent. The study itself was published in the February 2006 issue of the American Journal of Public Health. The results were also published beforehand online in an extensive statement on the university’s (UCSD) official homepage.

Garlands interest for vitamin D was awakened when he noticed in the 1980’s that the risk of colon cancer and breast cancer in the northern United States was double that of the risk in the Southern states. He and others started a 12 year study, which lead to a hypothesis that the reason behind this phenomenon is sunlight’s ability to create vitamin D in the skin. This theory has subsequently been tested in many ways. It also fits with the increased cancer frequency in cities, when air pollution containing sulphur dioxide blocks the vitamin D producing short ultraviolet solar radiation.

This also fits with the diet and cancer studies on workers in Chicago and with the low frequency of breast cancer in Japan, where though there is little sunlight, the diet is largely fish based. Fatty fish are just about the only regular source of vitamin D outside of the summer months in Japan, Chicago, and Northern Europe. Additionally, the theory fits well with the fact that the many people, who for genetic reasons utilize vitamin D poorly, are strongly overrepresented among those who suffer cancers of the colon, breast, prostate, and more.

More and more indications
The faithful subscribers to this newsletter may remember our accounts of the studies of the last year which have shown that women with low vitamin D status have much more frequently lumps in their breasts than others. This is a relationship which fits with a higher risk of cancer.

They may also remember that an American (as well as a large Norwegian) study showed that the possibility of beating many cancer forms is best when the cancer is found during the summer, when vitamin D status is highest.

This indicates that the vitamin not only prevents cancer, but also inhibits cancer growth. Concordantly with Garland’s claim, African Americans have a lower chance of recovery form breast cancer than Anglo Saxon individuals. This may be due to a reduced vitamin D status brought on by the reduced ability to absorb vitamin D which comes with dark skin colour.

These results and others are strengthen by animal studies where it has been proven that vitamin D promotes cell death in abnormal cells in the process called apoptosis and has a general dampening effect on cell growth. This last principle is utilized by psoriasis salves, which contain a vitamin D – like substance which inhibits the overwhelming growth and lack of cell maturation which characterises this skin disease.

The optimal daily vitamin D dose, especially during the winter months between October and May, is according to Garland about 1,000 units (or 25 micrograms) per day. This recommendation is based on a study from October 2005. The 1,000 units lead to a concentration of the vitamin D precursor 25-OH-vitamin D of about 80 nmol/l (nanomol per litre), which Garland found to lead to the lowest risk of colon cancer.

Much also indicates that Garland is correct that vitamin D supplements could save thousands of lives. If this is the case, than any media claim that we get superfluous vitamins is contrary to public health.

By: Vitality Council

References:
1. Garland CF et al. The Role of Vitamin D in Cancer Prevention. Am J Public Health. 2006;96(2):9-18. 2005 Dec 27; [Epub ahead of print].
2. Gorham ED et al. Vitamin D and prevention of colorectal cancer. J Steroid Biochem Mol Biol. 2005 Oct;97(1-2):179-94. Epub 2005 Oct 19.
3. Garland CF et al. Serum 25-hydroxyvitamin D and colon cancer: eight-year prospective study. Lancet. 1989 Nov 18;2(8673):1176-8.
4. Jeremy Laurance, Health Editor. Revealed: the pill that prevents cancer. The Independent 28.12.05.

New Theory on the origin of the flu

Claus Hancke

November 15, 2005

A recent theory claims that one does not catch the flu from contagious people, but by the activation of a dormant virus activated by vitamin D deficiency.

Serious medical journals do not often engage themselves with what private individuals think. In the latest issue of “The British Medical Journal” an exception is made on the journal’s last page, which is written regularly by the pretty named but anonymous female doctor, “Minerva.” Minerva has given her readers interesting scientific news, great and small, every week for decades.

This time she has pointed out a “blog” (an internet forum) with a gripping story on the virtues of vitamin D and why the flu sets in during the winter. She relates that the blog’s author is a member of “The vitamin D council,” a non-profit organisation which wishes to combat vitamin D deficiency.

Minerva recounts that he may be just another person who has hopped aboard the flu bandwagon. But could he possibly have found something important?

The blog is written by the Californian Dr. John Cannell. He explains, including many citations, first and foremost his theory about how the flu arises. The theory states that the flu is not so much the result of contagion, but more the activation of a dormant virus which we already have in our bodies. This virus can be activated and cause the flu when we are weakened by vitamin D deficiency during the winter. It is similar to the mechanisms behind cold sores, where the virus is dormant but can be activated causing a break out.

Does this sound like nonsense? In 2003, a department in the United State’s Center for Disease Control (CDC) disclosed that they had been unable to find any English language documentation for the flu being able to be infectious from person to person.

The recently dead epidemiologist, Edward Hope-Simpson discovered that when the elderly get shingles, it is caused by the same virus which causes chickenpox as a child. It becomes dormant in the body but can cause shingles when one is weakened by age.

Hope-Simpson became interested in the well known, but quite strange, fact that the flu only arises when the sun weakens during the winter. In the tropics, one gets the flu during the rainy season. He found that influenza outbreaks with exactly the same virus occurred year after year at almost exactly the same time in two far separated places, Prague and his English home town, Cirencester. With the help of old church records he found that, despite our faster daily lives, flu epidemics arise at the same time of year as they have for the last 400 years. This is true even in isolated towns; in such places the flu comes at the same time as in big cities.

Therefore, Hope-Simpson believed that flu epidemics are not cause by infection, but by a weakened state caused by the absence of sunlight. Canning now adds that vitamin D has a meaningful effect on the immune system and that the Japanese, as far back as 1945, found that it can protect rats against the flu. The well known vitamin D deficiency during the winter could be the reason for the weakened state that Hope-Simpson postulated.

Canning proposes that we should stock up on capsules of 50,000 units vitamin D in the event of a bird flu pandemic. He does not know if this will do any good, but says that it might save your life.

In any event, as Minerva also believes, his blog (as Minerva also believes) gives us something to think about.

By: Vitality Council

References:
1. www.knowledgeofhealth.com/report.asp?story=Why%20Flu%20Epidemics%20Occur%20in%20Winter
2. Minerva. British Medical Journal 2005;331:1152.

www.knowledgeofhealth.com/report.asp
bmj.bmjjournals.com
www.iom.dk

Vitamin D as a Universal Remedy

Admin

September 13, 2005

Vitamin D, which most people lack in the winter and many lack in the summer, has an increasing number of roles to play. A deficiency in Vitamin D increases the risk of multiple sclerosis, several types of cancer, skin diseases, and even increased blood pressure.

Vitamin D plays an important role in the public consciousness, but even a bigger role in the minds of those who develop new medicine. Substances which are related to vitamin D are central to the treatment of many serious diseases. This is shown by a comprehensive and very well documented summary from the American pharmaceutical giant Eli-Lily.

In this summary the status and possibility of vitamin D treatment for (among others) prostate cancer, enlarged prostate, breast cancer, rheumatoid arthritis, psoriasis, leukaemia, multiple sclerosis, type I diabetes, skin cancer, hypertension, and of course osteoporosis is examined.

Here are some examples:

Multiple sclerosis (MS) is a so called autoimmune disease, which means that it is a disease where the body’s immune system turns against parts of the body itself, in this case nerve tissue. In animal models of this disease it is possible to avoid outbreaks with the help of calcitriol. Calcitriol is the active version of the vitamin and is created as needed by the body so long as the vitamin D deposits are sufficient. MS is most common in temperate countries, where the sun in relatively low in the sky and vitamin D deficiency is common.

Rheumatoid arthritis is also an autoimmune disease, but with this disease the joints are attacked by the immune system. People with small vitamin D depots more often suffer from rheumatoid arthritis and the risk is higher in temperate countries than in subtropical climes. In animals it is possible to avoid worsening of symptoms if calcitriol is given early enough.

Psoriasis is already treated with salves which contain the vitamin D containing substance calcipotirol (Daivonex), which helps at least 70% of sufferers. Sunlight also helps. Like vitamin D, calcipotirol has the ability to help cells become mature and specialized without growing uncontrolled.

Death rates from prostate cancer are lowest in sunny countries, and the risk of getting this disease is highest in men who have small vitamin D deposits. In a study prostate cancer growth was inhibited in six out of seven patients with the help of calcitriol tablets (0.5-2.5 microgram per day). This is also explained by the vitamin’s effects on the cells. Because normal prostate cell growth is also slowed, researchers also see a possibility of using such treatment for enlarged prostate.

Breast cancer and colon cancer are more common in people who do no get much sun. Both the growth and the spread of breast cancer are reduced by calcitriol in animal studies. Regarding colon cancer, increased growth has been seen in animals that were artificially given vitamin D deficiency. This cancer inhibiting property is predicted to play an important role in future treatment.

Finally, hypertension should be considered. Lack of sunlight and vitamin D in the blood are believed to contribute to high blood pressure. High blood pressure is quickly caused (in mice) by avoiding vitamin D.

All of the above illnesses have the common factor that they can be provoked by lack of sunlight, the most important source of vitamin D. They are also counteracted by vitamin D and vitamin D like substances.

One could wish that it would be possible to treat and prevent these illnesses with the active form of vitamin D, calcitriol. But this is a risky method which can lead to increase calcium levels in the blood and kidney stones. Therefore we must be content with getting vitamin D the natural way, which is to say from sunlight or by eating fatty fish, and then let the organism create calcitriol as needed.

Unfortunately at our latitudes the fours summer months from May to August are the only months where there is enough sun that we create vitamin D in the skin. Those who do not come out in the sun or are covered in clothing, do not create near enough. This makes it necessary to take vitamin D in pill form.

The task is to get enough vitamin D. This is not possible during the dark months without vitamin supplements or eating a lot of fatty fish. Deficiency creates a larger problem than many are aware.

By: Vitality Council

Reference:
Nagpal S et al. Noncalcemic actions of vitamin D receptor ligands. Endocrine Reviews 2005;26:662-87.

edrv.endojournals.org
www.iom.dk

Vitamin D Together With NSAID Medicine Fights Prostate Cancer

Claus Hancke

September 3, 2005

A world-famous Vitamin-D researcher has initiated a study with a very simple treatment of cancer of the prostate. If expectations are met, then it could result in a revolution in the treatment of the most frequent form of cancer in men.

Among men over 60 at least every other have cancer in the prostate, usually without knowing it. It has been discovered many years ago by investigating men who died for some other reason. Cancer in the prostate is typically a disease that you do not die from – but with! Nevertheless, it is the most frequent cause of cancer among men after lung cancer.

It is therefore difficult to deny that there is an obvious need for an effective treatment, but the treatment has been at a standstill for many years. Only now something is about to happen. More and more, the disease has been associated with the extremely widespread lack of vitamin D. Vitamin D has a normalizing and growth-inhibiting effect in many tissues.

Faith in vitamin D has now become so great that one of the world’s leading vitamin D researchers, Professor David Feldman from Stanford University, has launched a clinical study. It targets men with prostate cancer who have relapsed during usual treatment.

Feldman will give them a combination of active vitamin D (calcitriol, see below) and regular arthritis pills (ibumetin or naproxen), both in moderate doses. To avoid side effects of calcitriol, it is given only once a week, but the exact dose is not stated.

Several years of laboratory studies have preceded this. Here, it has recently been shown that calcitriol reduces the growth of prostate cancer by 25%. The same result is obtained by treatment with traditional anti-rheumatic drugs (NSAID preparations, e.g. ibumetin and naproxen).

But most convincingly, when vitamin D and anti-rheumatic drugs are combined, growth slows down by as much as 70%, even if you are content with tolerable doses of each. Both agents counteract the formation of the so-called prostaglandins, which cause the cancer cells to grow and – in another context – cause arthritic pain, etc. If they are combined, the effect is enhanced.

This, as well as the announcement of the new trial, can be seen in, among other things, of a new press release from Stanford University. If the trial fulfills expectations, it will not only have enormous significance for the treatment. It will also be a sleight-of-hand tip for healthy men to get more vitamin D – perhaps a lot more – so they can make enough calcitriol themselves (calcitriol is only available by prescription).

Feldman is not just anyone when it comes to vitamin D. Together with two others, he is behind the book “Vitamin D” (Academic Press), which is a standard work for researchers with 1,800 pages. The newly revised edition costs DKK 3,445, so it is unlikely to be a bestseller. Feldman has been researching vitamin D for many years and has more than 200 scientific articles behind him.

Vitamin D is not a vitamin, but a hormone. It is formed in the skin by sun exposure, but must be converted in the liver and kidneys to become the active calcitriol. It is by now accepted by everyone that the elderly in particular cannot possibly get enough vitamin D if they do not receive supplements or eat plenty of oily fish. This is because, with age, the skin largely loses the ability to form the vitamin. In the dark half-year, the sun is also so low in the sky (in our northern latitudes) that neither young nor old form anything of importance, whether they get sun or not.

There are less than five micrograms of vitamin D in a typical Danish daily diet, but officially it is now recommended that adults get twice as much, nursing home residents four times as much. It is not difficult to find researchers who believe that this too is too little. The upper limit of risk-free intake is estimated at 50 micrograms per day.

By: Vitality Council

Reference:
Moreno J, Krishnan AV, Feldman D. Molecular mechanisms mediating the anti-proliferative effects of Vitamin D in prostate cancer. J Steroid Biochem Mol Biol. 2004 Nov;92(4):317-25

Vitamin D Helps Against Lung Cancer

Admin

May 2, 2005

Vitamin D looks more and more like a sharp weapon against cancer. An American study points towards high Vitamin D status being a great advantage, if you have lung cancer.

The belief that vitamin D counteracts cancer is strongly growing. It is based, among other things, on the known normalizing effect of the vitamin on cells and tissues, but also that the frequency of, for example, breast, prostate and colon cancer is considerably higher in countries low in sun such as Denmark, where the sun low in the sky from September to May, so low that No vitamin D is formed in the skin. In addition, the Danish diet completely lacks vitamin D, except fatty fish.

By: Vitality Council

References:
1. American Association for Cancer Research. Press Release 18 April 2005.
2. Trump DL et al. Anti-tumor activity of calcitriol: pre-clinical and clinical studies. J Steroid Biochem Mol Biol. 2004 May;89-90(1-5):519-26.
3. Nakagawa K et al. 22-oxa-1{alpha},25-dihydroxyvitamin D3 inhibits metastasis and angiogenesis in lung cancer. Carcinogenesis. 2005 Feb 17;[Epub ahead of print].

www.aacr.org
www.sciencedirect.com
carcin.oupjournals.org
www.iom.dk

Breast Cancer may be Caused by Vitamin D Deficiency

Claus Hancke

October 19, 2004

Women who do not utilize vitamin D well enough will often get breast cancer and fibrocystic breasts are a sign of calcium and vitamin D deficiency.

Much suggests that vitamin D prevents breast cancer. If so, sunlight, which is the overall dominant source of vitamin D, can significantly prevent breast cancer.

The theory is now supported by a new English study that has shown that women who utilize vitamin D badly have doubled the risk of getting breast cancer.

Researchers from St. George’s Hospital in London compared tissue from approx. 400 women with breast cancer with tissue from an equal number of healthy women. In doing so, they discovered that women with aberrant receptors for vitamin D appeared twice as often in breast cancer statistics as others.

It is known that vitamin D exerts a normalizing effect on the cells in e.g. breast tissue. When the vitamin activates a receptor, a regulatory and growth-reducing effect is triggered inside the cell. Experiments have further shown that breast tissue can activate vitamin D so that it chemically matches the receptors. Previously, it was thought that this only happened in the kidneys.

The connection between vitamin D and breast cancer is supported by a new Canadian study of more than 500 40-60-year-old women. Mammograms showed that women with low vitamin D status have four times as many small nodules in their breasts as those who are better supplied with the vitamin.

Both a high intake of vitamin D and plenty of calcium in the diet were statistically very reliably associated with a tendency to nodules. It is already known that lumpy breasts are a pronounced risk factor for breast cancer.

The scientific interest in vitamin D as a remedy against cancer is increasing rapidly. In November, a three-day conference will be held in Maryland, supported by the American Institute of Health (NIH), with numerous presentations from the USA, Canada, France, England, Germany, Belgium, Austria and others. on this subject alone.

The interest was initially stimulated by the fact that the frequency of, among other things, cancer of the colon, prostate and breast is significantly less in sunny countries than in e.g. Denmark, where the sun is so low from October to May that the skin does not produce vitamin D.

Among researchers, strong voices have advocated for several years that the intake of vitamin D should be raised from the 10 micrograms per day recommended for the elderly (younger people are recommended half), to 25 micrograms per day or even more. The 25 micrograms correspond to the content in 10 ml of cod liver oil. Normal Danish diet contains only a few micrograms.

By: Vitality Council

 

References:
1. Guy M, Lowe LC, Bretherton-Watt D et al. Vitamin D receptor gene polymorphisms and breast cancer risk. Clin Cancer Res. 2004 Aug 15;10(16):5472-81.
2. Bérubé S et al. Vitamin D, calcium, and mammographic breast densities. Cancer Epidemiology, Biomarkers & Prevention. 2004;13(9):1466-72.

clincancerres.aacrjournals.org
www.cbcrp.org/research/PagePeriodical.asp
www.iom.dk

Vitamin D, Research references

Admin

January 1999

1. Anonymous. Vitamin D supplementation in the elderly Lancet 1: 306-307, 1987.
2. Chapuy MC, Chapuy P, Mennier PJ. Calcium and vitamin D supplements. Effects on calcium metabolism in elderly people. Am J Clin Nutr 46: 324-328, 1987.
3. Chapuy MC, Arlot ME, Duboeuf F et al. Vitamin D3 and calcium to prevent hip fractures in elderly women. N Engl J Med 327: 1637-1642, 1992.
4. Crombie IK. Distribution of malignant melanoma on the body surface. Br J Cancer 43: 842-849, 1981.
5. Gaby SK, Singh VN. Vitamin intake and health: A scientific review. New York: Marcel Dekker. p 59-70, 1990.
6. Garland CF, Garland FC. Do sunlight and vitamin D reduce the likelihood of colon cancer? Int J Epidemiol 9: 227-231, 1980.
7. Garland C, Shekelle RB, Barrett-Connor E et al. Dietary vitamin D and calcium and risk of colorectal cancer. Lancet 1: 307-309, 1985.
8. Garland CF, Comstock GW, Garland FC et al. Serum 25-hydroxy vitamin D and colon cancer. Lancet 2: 1176-1178, 1989.
9. Garland FC, Garland CF, Gorham ED et al. Geographic variation in breast cancer mortality in the United States. A hypothesis involving exposure to sular radiation. Arch Environ Health 45: 261-267, 1990.
10. Garland CF, Gorham ED, Young JF. Geographic variation in breast cancer mortality in the United States: A hypothesis involving exposure to solar radiation. Prevent Med 19: 614-622, 1990.
11. Haug S, Muller F, Aukrust P, et al. Subnormal serum concentrations of 1,25-vitamin D in human immunodeficiency virus infection: Correlation with degree of immune deficiency and survival. J Infect Dis 169:889-92, 1994.
12. Koh HK, Kligler BE, Lew RA. Sunlight and cutaneous malignant melanoma. Evidence for and against causation. Photochem Photobiol.19: 614-622, 1990.
13. Kroger H, Penttila I, Alhava E. Low serum vitamin D metabolites in women with rheumatoid arthritis. Scand J Rheumatol 22: 172-7, 1993.
14. Lips P, van Ginkel FC, Jongen MJ et al. Determinants of Vitamin D status in pahents with hip fracture and in elderly control subject. Am J Clin Nutr 46: 1005-1010, 1987.
15. MacLaughlin J, Holick MF. Aging decreases the capacity of human skill to produce vitamin D3. J Clin Invest; 76: 1536-1538, 1985.
16. McAlindon T, Felson D, Zhang Y, et al. Relation of dietary intake and serum levels of vitamin D to progression of osteoarthritis of the knee among participants in the Framingham study. Ann Intern Med 125; 5: 353-9, 1996.
17. Norman AW. Vitamin D. In: Present knowledge in nutrition.7th edn.Washington DC: International Life Sciences Press. p 120-129, 1996.
18. Omdahl JL, Garry PJ, Hunsaker LA et al. Nutritional status in a healthy elderly population: Vitamin D Nutritional status in a healthy elderly population: Vitamin D. Am J Clin Nutr 36: 1225-1233, 1982.
19. Parfitt AM, Gallagher JC, Heaney RP et al. Vitamin D and bone health in the elderly. Am J Clin Nutr 36: 1014-1031, 1982.
20. Reed A et al. 25-hydroxy vitamin D therapy in children with active juvenile rheumatoid arthritis: Short-term effects on serum osteocalcin levels and bone mineral density. J Pediatr 119; (4): 657-60, 1991.
21. Sowers MR, Wallace RB, Lemke JH. The association of intakes of vitamin D and calcium with blood pressure among women. Am J Clin Nutr 42: 135-142, 1985.
22. Sowers MF, Wallace RB, Hollis BW et al. Relationship between 1,25-dihydroxy vitamin D and blood pressure in our geographically defined population. Am J Clin Nutr 48: 1053-1056, 1988.
23. Vagero R, Ringback G, Kiveranta H. Vagero Melanoma and other tumors of the skin among office, other outdoor/indoor workers in Sweden. Br J Cancer 53: 507-512, 1986.
24. Webb AR, Holick MF. Influence of season and latitude on cutaneous synthesis of vitamin D3. Ann Rev Nutr 8: 375-399, 1988.
25. Wiedmann KH, Brattig NW, Diao GD et al. Serum inhibiting factors (SIF) are of prognostic value in acute viral hepatitis. Lancet i: 307-309, 1985.

 

Sources
Joseph E. Pizzorno Jr., Michael T. Murrey & Melvyn R. Werbach.