Vitamin D acts in the body as both a vitamin and a hormone, exerting a powerful influence on maintaining bone density and preventing vital steps in the development of breast, prostate and colon cancers (and possibly other cancers). There is also evidence to suggest that more optimal vitamin D levels can reduce the risk of multiple sclerosis through it effects on immune system function.

Throughout younger adult life supplementation with vitamin D of 400 IU from a high potency multi-vitamin and mineral, combined with the vitamin D intake most people acquire from fortified dairy products and fish, is usually adequate to maintain blood levels of vitamin D in a range that is associated with healthy bone development, and the prevention of breast, prostate and colon cancers, and multiple sclerosis, according to available studies. However, by age 45-50 the enzyme in the kidney (alpha-hydroxylase) that converts vitamin D into its most active form (1,25 dihydroxy vitamin D, also known as calcitriol) becomes less active. This results in decreased synthesis of calcitriol and thus, tissues that rely on the health promoting influences of calcitriol are left to feel the effects of a calcitriol insufficiency state. Studies strongly suggest that the age-related decline in synthesis of calcitriol within the kidneys is a major contributing factor to the development of osteoporosis in women and men over 50 years of age, and the age-related increase in risk of breast, prostate and colon cancers that is common in North America and many industrialized countries. However, studies also indicate that individuals over the age 45 can compensate for the decline in calcitriol synthesis by raising their blood levels of the less potent form of vitamin, known as 25-hydroxy vitamin D.

Abundant evidence exists to show that adults who maintain blood levels of 25-hydroxy vitamin D in the range of 85-120 nmol/L (nanomoles per liter) have a significantly lower risk of developing osteoporosis, breast cancer, ovarian cancer, prostate cancer, colon cancer and multiple sclerosis. Studies also show that to ensure that your blood levels of 25-hydroxy vitamin D are within this protective range, it is important for you to increase your vitamin D supplementation to 800-1,000 IU per day, after the age of 45. Up until age 45 the 400 IU of vitamin D per day I have recommended you ingest from a high potency multiple vitamin and mineral is adequate to meet your vitamin D needs in most cases. However, after age 45, I am strongly advising you to add an additional daily supplement that contains 400-600 IU of vitamin D in a formulation that also provides an additional 500-700 mg of calcium (If the product also contains some additional magnesium, zinc and other bone support nutrients, that is perfectly acceptable). To appreciate the importance of providing your body with additional vitamin D after the age of 45, let’s examine the often under appreciated evidence that illustrates the vital role vitamin D plays in anti-aging and disease prevention throughout our lifetime.

As I stated earlier vitamin D acts in the body as both a vitamin and a hormone. Its most well known function in the body is its role in enhancing the absorption of calcium and supporting bone development and bone density. In fact, since the Middle Ages, cod liver oil, a rich source of vitamin D, has been used to prevent and treat rickets. Rickets is a disease of infancy and childhood caused by a vitamin D deficiency, whereby there is insufficient bone ossification (lack of conversion of fibrous bone or cartilage into hard, mature bone via the deposition of calcium and other minerals). This results in bones that become bent and distorted via the pulling action of muscles and an inability to bear the weight of gravity as the child grows. In 1930, Vitamin D was isolated and shown to be the fat-soluble compound in cod liver oil that was effective against rickets.

However, its not just infants and young children who require vitamin D for bone development and bone strength. Vitamin D is required at all stages in life to increase bone mineral density in our younger years and to prevent the loss of calcium form bone after the age of 50. Both the increased deposition of calcium into our bones that occurs at an optimal rate up to age 24, and the prevention of calcium being leached from our bones after age 50, are essential aspects in the prevention of osteoporosis. Thus, your lifetime vitamin D nutritional status is a key factor in the risk of developing osteoporosis. Unfortunately, it has been a much overlooked and under appreciated nutrient in this regard, as well as in regards to its ability to prevent certain cancers and possibly multiple sclerosis.

With respect to optimizing bone mineral density and strengthening our bones against the development of osteoporosis and rickets, here are a few of the functions provided by vitamin D that pertain to its ability to maintain the integrity of our bones and other hard tissues of the body (teeth and nails):

1. Vitamin D in the bloodstream stimulates the intestinal absorption of calcium and phosphorous by its effects on stimulating the synthesis of calcium-binding protein in intestinal cells. It is calcium-binding protein that facilitates the absorption of calcium from the intestinal tract into the bloodstream. Thus, insufficient vitamin D blood levels results in a decrease in calcium-binding protein synthesis within intestinal cells and a marked reduction in the absorption of calcium (and phosphorous) from the intestinal tract into the bloodstream. And this results in insufficient amounts of available calcium (and phosphorous) for deposition into our bones, creating bones that show sub-optimal bone mineral density and setting the stage for the development of osteoporosis and related bone fractures. 
2. Vitamin D regulates the metabolism of calcium and phosphorous, which is vital for many functions including neuromuscular function, and mineralization of bone, nails and teeth.
3. Vitamin D acts directly on bone aiding bone formation and in times of need, it stimulates the release of calcium from bone to help maintain blood calcium within the normal range; a function it shares with parathyroid hormone.

The fact of the matter is that insufficient vitamin D during our lifetime results in sub-optimal bone density and an increased risk of osteoporosis. Unfortunately, vitamin D insufficiency is wide spread in North America, especially in the more northern regions, where sunlight intensity is very limited between October and May. In the July 2002 edition of the American Journal of Clinical Nutrition, Dr. Michael Holick from Boston University Medical Center provided an important editorial reviewing the evidence related to Vitamin D status and its influence on bone health, immune function, and risk of colon, breast, ovarian and prostate cancer. He cites a recent report by Nesby-O’Dell, which provides irrefutable evidence that Vitamin D deficiency is a major unrecognized epidemic in adult women of childbearing age (15-49) in the U.S., and suggests it is likely that Vitamin D deficiency is equally prevalent among males of the same age. Older individuals have also been shown to be at very high risk for vitamin D due to poor intake of vitamin D containing foods, reduced sun-light exposure and reduced conversion of 25-hydroxy vitamin D into calcitriol. Calcitriol is twice as potent as 25-hydroxy vitamin D in regards to its vitamin D effects on our bones and other tissues. Vitamin D deficiency is considered to correlate with a blood level of 25-hydroxyvitamin D below 20 nmol/L. Optimal levels of vitamin D are considered to be in the range of 85-120 nmol/L. It is this range of vitamin D status that is most strongly associated with a reduced risk of osteoporosis, many cancers and multiple sclerosis. Unfortunately, a great number of adults fall into the range above the deficiency threshold and below the optimal range of vitamin D blood levels, which would be defined as a blood level of 21-79 nmol/LL. This middle ground I refer to as vitamin D insufficiency. To make matters worse many drugs inhibit the action or absorption of vitamin D, which further contributes to the widespread state of vitamin D insufficiency that is prevalent in our society.

It is well known that cortisone or predisone therapy (glucocorticoids) interfere with the metabolism of Vitamin D and are associated with increased risk of osteoporosis. Barbituates and anticonvulsants also cause increased breakdown (degradation) of Vitamin D and its metabolites and thereby increase osteoporosis risk. Other drugs that reduce Vitamin D nutritional status include: 

1. Allopurinol
2. Bile Acid Sequestrants (eg. Cholestyramine and colestipol)
3. Cimetidine and other H-2 Antagonists
4. Oral Contraceptives
5. Heparin
6. Hydroxychloroquine
7. Indapamide
8. Isoniazid
9. Mineral oil
10. Neomycin
11. Thiazide Diuretics
12. Rifampin – may reduce blood vitamin D levels by 70%
13. Orlistat – reduces blood levels of Vitamin D

Your Bones Need More Vitamin D Support After 45

As I have mentioned, after the age of 45-50 the body is less able to convert 25-hydroxy vitamin D into calcitriol, due to a decline in the activity of the kidney enzyme known as alpha-hydroxylase. Unfortunately, 25-hydroxy vitamin D is only half as potent as calcitriol in regards to its vitamin D effects on the body. However, if blood levels of 25-hydroxy vitamin D can be raised into the range of 85-120 nmol/L this amount of 25-hydroxy vitamin D can compensate for the drop off in calcitriol levels, which is an inevitable part of the aging process. Studies show that by supplementing your diet with 800-1,000 IU of vitamin D per day after the age of 45, your blood levels of 25-hydroxy vitamin D will reach the ideal range of 85-120 nmol/L and you will in turn, reduce your risk of osteoporotic fractures to a very significant degree. Lets look at several studies that clearly illustrate this point.

In a large study of 3,720 elderly women living in nursing homes, those receiving 1,200 mg of calcium and 800 IU of vitamin D supplementation each day showed a 43% reduction in hip fractures over a 3-year period compared to those not taking these supplements (M. Chapuay, 1994). Another study showed that supplementation of postmenopausal women with 700 IU of vitamin D daily can reduce the annual rate of hip fractures from 1.3% to 0.5%, which is nearly a 60% reduction (B. Dawson-Hughes, 1995). Another study combining the supplementation of 500 mg of calcium and 700 IU of vitamin D revealed a significant reduced hip fracture rate in men and women taking this combination, compared to the placebo group, in a 3-year follow-up study (B. Dawson-Hughes, 1997). There is now ample evidence to suggest that after the age of 45 it is extremely prudent to increase your vitamin D supplementation to reach a total daily value of 800-1,000 IU, in order to significantly reduce your risk of osteoporosis. This advice is meant for both men and women as osteoporosis now affects one in four women over the age of fifty and one in eight men over the age of 65. However, the benefits of increased vitamin D supplementation doesn’t end with the prevention of osteoporosis, but also has important implications for the prevention of breast, ovarian, prostate and colon cancer, as we shall explore next.

Vitamin D receptors exist on intestinal cells and bone for regulating calcium absorption and bone metabolism as I have discussed. However, vitamin D receptors are also present in a wide variety of other tissues and organs, including the brain, pancreas, skin, gonads, prostate, stomach, colon, breast, kidney, connective tissue, parathyroid gland, mononuclear cells, and activated T and B-lymphocytes. Recent studies indicate that tissues expressing Vitamin D receptors are able to convert 25-hydroxyvitamin D, which they extract from the bloodsteam, into calcitriol for their own internal use. As I have stated the calcitriol form of Vitamin D is the most potent form of vitamin D, and this is not only with respect to bone support, but studies also illustrate that calcitriol exerts a number of anti-cancer effects on local tissues that convert 25-hydroxy vitamin D into calcitriol for their own purposes, such as breast cells, prostate cells and colon cells. As such, circulating levels of 25 hydroxyvitamin D serves as the raw material from which many tissues synthesize calcitriol for their own internal use. Studies reveal that higher amounts of circulating 25-hydroxy vitamin D in the blood enables local tissues, such as breast, prostate and colon cells, to synthesize greater amounts of calcitriol for their own needs.

Epidemiological (observational) studies suggest that lower blood levels of 25-hydroxy vitamin D are associated with a higher risk of developing breast, colon, ovarian, and prostate cancer. This is an important finding as one in nine women are expected to develop breast cancer in their lifetime, one in eight men are expected to develop prostate cancer in their lifetime, and one in 16 women and one in 15 men, will develop colon or rectal cancer in their lifetime. Colon caner is the second leading cause of cancer death (after lung cancer) when statistics for men and women are combined. Thus, breast, prostate and colorectal cancers are the three most prevalent cancers, after lung cancer. Of all lung cancer cases, 87% occur in smokers, providing evidence that avoiding smoking is the principle way to prevent this disease. For breast, prostate and colon cancer, evidence suggests that a variety of dietary and lifestyle behaviors account for the majority of the risk factors. Most recently, Vitamin D has been recognized, as one of several important nutrients, for its potential ability to prevent these cancers.

Interestingly, studies show that rates of breast, prostate and colon cancers increase as you travel further from the equator (either north of south) and that populations residing further from the equator also have lower year round average blood levels of vitamin D. This is related to the fact that our bodies make vitamin D in response to direct exposure to sunlight (but not through a window). When sunlight hits our skin it triggers the conversion of 7-dehydrocholesterol into vitamin D (cholecalciferol) within our skin. From there, the vitamin D made in our skin (cholecalciferol) enters the blood stream and travels to the liver, where it is converted to 25-hydroxy vitamin D, which is five times more potent than cholecalciferol in terms of its vitamin D activity. Thus, populations living closer to the equator, who enjoy more year round sunlight intensity and exposure, manufacturer more cholecalciferol in their skin and demonstrate higher year round average blood levels of 25-hydroxy vitamin D. As a general statement, populations in North America that live at or above the 42nd latitud have significantly higher rates of breast, colon and prostate cancer than populations living below the 42nd degree latitude. The 42nd degree latitude essentially divides the U.S. into two equal halves, north and south (running through the middle of California, and the tops of Arizona, New Mexico, Texas, Tennessee and the Carolinas). Some exceptions to this observation exist, in that people living in large cities in the South of the U.S. also have higher rates of these cancers per capita. C.F. Garland and F.C. Garland, who first published this data in the 1980’s, explain this finding by indicating that the air pollution in large cities and tall buildings block much of the sunlight, and that city-dwellers tend not to wear short-sleeve shirts and shorts as often as country folk, and tend not to be outdoors during the sunniest hours of the day. As such, individuals in large cities in the South do not have blood levels of vitamin D that are high enough to protect them from breast, colon and prostate cancer as do individuals living in the more rural parts of the South. The Drs. Garland were the first researchers to build the case that optimal vitamin D status can protect us from cancer. Since then many researchers have provided additional evidence to show the various influences, through which vitamin D helps prevent cancerous changes from occurring in the cells of our body.

Overall, studies indicate that blood levels of 85-120 nmol/L are associated with a high degree of protection with respect to risk of breast, prostate and colon cancer, and may significantly reduce the risk of developing multiple sclerosis via its immune modifying influences.

Experimental studies reveal that calcitriol exhibits a number of anti-cancer effects. Essentially prostate cells, breast cells, colon cell, and other cells that contain vitamin D receptors, extract 25-hydroxy vitamin D from the bloodstream and convert it into calcitriol once inside the cell. Calcitriol, in turn, slows down the rate of replication of these cells, an effect associated with decreased cancer development. The presence of calcitriol has also been shown to slow the rate of replication of human prostate, breast and colon cancer cells, under experimental conditions. Calcitriol also promotes newly formed cells to mature to their full adult potential, which also decreases the chance of these cells being transformed into a cancer cell by some external influence. Calcitriol also exerts a favorable effect on immune function, which is also thought to account for some of its anti-cancer influences. Calcitriol has also been shown to transform the appearance of human cancer cells (e.g. prostate cancer cells) back to healthy, non-malignant looking cells, and inhibit their replication, an effect that is lost once the calcitriol is no longer administered. In his review of the scientific evidence pertaining to vitamin D and cancer, M. Holick states that the local cellular production of calcitriol may be essential for the regulation of cellular health, thereby decreasing the risk of developing some cancers. Further evidence for this contention stems from the observation that African Americans, who are chronically Vitamin D deficient (largely due to heavy melanin concentrations blocking UV-light penetration of the skin, and thereby significantly reducing the synthesis of Vitamin D under the skin upon exposure to sunlight), have a higher incidence and more aggressive forms of many cancers, including breast and prostate cancers. One study showed that men who are exposed to more sunlight tend to delay the onset of prostate cancer by more than 5 years.

The Wide Spread Problem Of Vitamin D Deficiency and Insufficiency

Several studies have shown that a large percentage of adults of all ages have inadequate vitamin D in their blood to prevent osteoporosis, as well as prostate, breast and colon cancers. Research conducted at Boston’s Massachusetts General Hospital found that 57% of people hospitalized for a variety of reasons were vitamin D deficient. Of those 37% had consumed the recommended daily amount of vitamin D, which presently stands at 200 IU per day for adults under the age of 50, and 400 IU per day for adults 51-70, and 600 IU for adults over 70. These recommended levels are not only too low to guard against vitamin deficiency and insufficiency it appears, but studies show that higher levels of intake are required to reduce the risk of cancer. The studies by CF Garland and fellow researchers (Ann NY Acad Sci, 1999) reveal that an intake level of 800 IU of vitamin D and 1,000-1,200 mg of calcium per day are required to prevent colon cancer, and that 800 IU per day of vitamin D is the intake level that is associated with a significant decrease in the incidence of breast and prostate cancer, as well as enhanced survival rates for these cancers.

A Canadian study showed that 34% of men and women ages 27-89 had insufficient levels of vitamin D in their blood, based upon blood collections that were taken throughout the year. A study of more than 3,100 veterans ages 50-75 who underwent screening colonoscopies for the detection of colon cancer, revealed that subjects who consumed more than 645 IU per day of vitamin D were 40% less likely to have precancerous colon polyps than those who ingested little of no vitamin D. Researchers at Dartmouth Medical School demonstrated the synergistic effect of vitamin D and calcium as they work together to reduce the risk of colon cancer. In study of 800 adults participating in a polyp prevention study, only people with a higher-than-average vitamin D blood levels benefited from calcium supplements in regards to lower incidence of polyps. Likewise, vitamin D levels were protective against polyp development among subjects using calcium supplements. Experimental studies demonstrate that calcium and vitamin D work together to slow the replication rate of colon cells, which reduces the risk that cancerous genetic mutations will occur.

The evidence, though very much under appreciated by members of the public and health professionals, strongly suggests that optimal intake of vitamin D and optimal blood levels of vitamin D (25-hydroxy vitamin D) exert very strong influences on the prevention of osteoporosis, breast, colon and prostate cancer, and evidence is accumulating to show that vitamin D is also important in the prevention of ovarian cancer and multiple sclerosis.

From an evolutionary standpoint, exposure to direct sunlight is the principle way in which we are set up to derive our Vitamin D stores. To maximize vitamin D synthesis within the skin all that is required is 15-20 minutes of direct sunlight exposure to your face, arms and legs, three times per week. However, experts warn than that even this amount of cumulative sun exposure increases risk of skin cancer over our lifetime and that it is best to derive vitamin D from the consumption of fish, vitamin D-fortified dairy products and supplements. The point is that many people don’t get 15-30 minutes of direct sunlight exposure each day, especially those of us living above the 40th parallel within North America, where sunlight intensity between October and May is insufficient for our bodies to make vitamin D inside our skin.

Very few foods contain Vitamin D in their native form. It is best to eat fatty fish such as salmon and mackerel 3-4 times per week to help satisfy the body’s Vitamin D requirement. Of course, there is suppose to be 100 IU of Vitamin D in every eight ounces of fortified milk, but studies undertaken by M. Holick and others showed that nearly two-thirds of the whole milk samples tested in one study had less than 80%, and several skim milk samples had 0%-50% of the amount of vitamin D appearing on the label. This problem will continue as vitamin D levels in milk are affected by season, the breed of cow, then animal’s diet, its exposure to sunlight, and procedures used in fortification. Although the 1997 recommendations by the Institute of Medicine suggest that middle-aged adults (50-70 yrs) should consume 400 IU of Vitamin D per day and older subjects should consume 600 IU of Vitamin D per day, evidence is strong to indicate that in the absence of exposure to sunlight, the adequate intake for Vitamin D should be at least 800–1,000 IU per day by age 45-50. M. Holick points out that Vitamin D intake is completely safe up to 2,000 IU per day for ages 1 year and above and that the risk of Vitamin D toxicity is greatly exaggerated by many health policy makers.

Low Fat Food Sources Of Vitamin D:

Ensure That Your Vitamin D Status Is Optimal By Supplementing Your Diet With 800-1,000 IU After The Age Of 45

The only way to know your actual Vitamin D status is via a blood test to measure circulating levels of 25-hydroxyvitamin D, which should be performed annually. A good target to shoot for is 85–120 nmolL. Vitamin D toxicity has never occurred with blood levels of 25-hydroxyvitamin D below 250 nmol/LL. Thus, a wide margin of safety is in place to guard against risk of toxicity in the event that you choose to implement Vitamin D supplementation at 1,000 IU per day after the age of 45, as I am suggesting.

The totality of evidence suggests that many North Americans are Vitamin D deficient or more commonly insufficient, and would benefit from additional Vitamin D supplementation. Most multiple vitamins contain 400 IU of Vitamin D, an amount that is reported to raise Vitamin D blood levels (25-hydroxyvitamin D) by approximately 45 ng/mL. However, even higher amounts of total supplemental Vitamin D (800 – 1,000 IU per day) should be implemented after the age of 45 or 50, as the body’s ability to convert 25-hydroxy vitamin D to calcitriol slows down to a significant degree. Studies prove that having higher blood levels of the less potent 25-hydroxy vitamin D (in the range of 85-120 nmol/L) can compensate for the reduced synthesis and availability of calcitriol in the bloodstream after ages 45-50, and can significantly reduce your risk of osteoporosis. Furthermore, this amount of 25-hydroxy vitamin D in your blood is also strongly associated with a reduction in risk of breast, colon, prostate and ovarian cancers, as well as multiple sclerosis. In a study released in 2004, K.L Munger and fellow researchers showed that participants in the Nurses’ Health Study who ingested 400 IU of Vitamin D from supplements each day (most notable from a multivitamin product) showed a 40% reduction in risk of multiple sclerosis compared to women who did not use supplements containing vitamin D. This group of 95,253 female registered nurses, residing in the United States, have been followed by researches since 1980. Vitamin D has been shown to exert favourable influences on immune cells that are consistent with preventing events related to multiple sclerosis, which have been confirmed in animal and human investigations. Over and above vitamin D supplementation, note that sardines, mackerel, herring and salmon are excellent food sources of vitamin D as well.

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The Global Integrative Medicine Academy was created to satisfy a need, expressed by many health professionals, to establish credentials as experts in Nutritional Medicine. But, health professionals also needed to be able to complete the programme with a minimum impact on their career, family, and lifestyle. That is why the Advanced Nutritional Medicine and Sports Nutrition Certification Program was created.