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Vitamin D the Key to Good Health E-mail
Written by Lynn Glenn   

Vitamin D is recognized to play a major roll in contributing togirl_sun_bathing overall health. Vitamin D was once linked only to bone diseases. Today however, Vitamin D has shown to contribute to good health in the adaptive and innate immune systems, the secretion and regulation of insulin by the pancreas, the heart and blood pressure regulation, muscle strength and brain activity. In addition, Vitamin D is believed to be beneficial towards reducing the risk of cancer and has been shown to prevent many other diseases and conditions.

Vitamin D deficiency is associated with muscle strength decrease, high risk for falls, and increased risk fo colorerctal cancer, colon cancer, prostate cancer, breast cancer and many other major cancers. In addition, Vitamin D deficiency can impact 36 organ tissues in the body whose cells respond biologically to Vitamin D. The list includes bone marrow, breast, colon, intestine, kidney, lung, prostate, retina, skin, stomach and the uterus.

Vitamin D Highlights

  • Vitamin D is a fat-soluble vitamin. Vitamin D is a fat-soluble vitamin that is naturally present in very few foods. Vitamin D is added to some foods and also available as a dietary supplement.relaxing-beach-375325
  • Vitamin D is the only vitamin that the body can manufacture itself.  Vitamin D is the only vitamin that the body can manufacture itself. The only requirement is sunshine, specifically ultraviolet B rays. Vitamin D is absorbed by the sun's ultraviolet rays and triggers Vitamin D synthesis. About 10 to 15 minutes of exposure two to three times a week during nonpeak sun hours is considered adequate.
  • Vitamin D supplements. Vitamin D supplements are often taken because of limited food choices. The current daily recommended dose of Vitamin D for adults 50 and older is 400 to 600 international units (IU). But many researchers believe that a higher amount is warranted because of the many health benefits. The National Osteoporosis Foundation[1] recommends a daily intake of 800 to 1,000 IU per day for adults over age 50.
  • Vitamin D is prohormone. Vitamin D is considered a prohormone because Vitamin D has no hormone activity itself, but is converted to the active hormone 1,25-D through a tightly regulated synthesis mechanism.

Vitamin D and the Role Vitamin D Plays in Human Health

  • Vitamin D regulates the calcium and phosphorus levels. Vitamin D regulates the calcium and phosphorus levels in the blood by promoting their absorption from food in the intestines, and by promoting re-absorption of calcium in the kidneys.
  • Vitamin D is needed for bone growth. Vitamin D is alsobone needed for bone growth and bone remodeling by osteoblasts and osteoclasts. Without sufficient Vitamin D, bones can become thin, brittle, or misshapen. However, at very high levels it will promote the resorption of bone.
  • Vitamin D inhibits parathyroid hormone secretion from the parathyroid gland. Parathyroid hormone (PTH) enhances the absorption of calcium in the intestine by increasing the production of activated Vitamin D. Vitamin D activation occurs in the kidney. PTH up-regulates 25-hydroxyvitamin D3 1-alpha-hydroxylase, the enzyme responsible for 1-alpha hydroxylation of 25-hydroxy Vitamin D, converting Vitamin D to its active form (1,25-dihydroxy Vitamin D). This activated form of Vitamin D increases the absorption of calcium (as Ca2+ ions) by the intestine via calbindin.[2]
  • Vitamin D affects the immune system. Vitamin D affects the immune system by promoting phagocytosis, anti-tumor activity, and immunomodulatory functions.
  • Vitamin D maintenance role on the organ systems. Vitamin D plays an important role in the maintenance of several organ systems.[3] However, its major role is to increase the flow of calcium into the bloodstream, by promoting absorption of calcium and phosphorus from food in the intestines, and reabsorption of calcium in the kidneys; enabling normal mineralization of bone and preventing hypocalcemic tetany. It is also necessary for bone growth and bone remodeling by osteoblasts and osteoclasts. [4][5]
  • Vitamin D has other roles in human health. Vitamin D has other roles in health including modulation of neuromuscular and immune function and reduction of inflammation. Many genes encoding proteins that regulate cell proliferation, differentiation, and apoptosis are modulated in part by Vitamin D.
  • Vitamin D is essential for promoting calcium absorption. Vitamin D is essential for promoting calcium absorption and maintaining adequate serum calcium and phosphate concentrations to enable normal mineralization of bone and prevent hypocalcemic tetany. Vitamin D is also needed for bone growth and bone remodeling by osteoblasts and osteoclasts.
  • Vitamin D protects against osteoporosis. Vitamin D together with calcium helps protect older adults from osteoporosis. Sufficient Vitamin D is needed so bones don't become thin, brittle, or misshapen.
  • Vitamin D prevents rickets and osteomalacia. Vitamin D sufficiency prevents rickets in children and osteomalacia in adults.
  • Vitamin D and mortality. Information from the Nationalold_woman_birthday Health and Nutrition Examination Survey a group of researchers concluded that having low levels of Vitamin D (<17.8ng/mL) was independently associated with an increase in all-cause mortality, and mortality associated cancer, and cardiovascular disease.[6] The study evaluated whether low serum Vitamin D levels were associated all-cause mortality, cancer, and cardiovascular disease (CVD) mortality among 13,331 diverse American adults who were 20 years or older. Vitamin D levels of these participants were collected over a 6-year period (from 1988 through 1994), and individuals were passively followed for mortality through the year 2000.
  • Vitamin D appears to boost health from head to toe. Vitamin D appears to boost health from head to toe, according to the September issue of Mayo Clinic Health Letter.[7] But, so far, there's no consensus on what level of Vitamin D is optimal for good health.

Additional Vitamin D Findings

  • Vitamin D and Coronary disease prevention. Research indicates that Vitamin D may play a role in preventing or reversing coronary disease. As with cancer incidence, a qualitative inverse correlation was found between coronary disease incidence and serum Vitamin D levels of 32.0 versus 35.5 ng/mL. Cholesterol levels were found to be reduced in gardeners in the UK during the summer months. Heart attacks peak in winter and decline in summer in temperate but not tropical latitudes.[8]
  • Vitamin D and autoimmune/inflammatory diseases. Low levels of Vitamin D have been implicated in the risks of developing various autoimmune disorders, including multiple sclerosis (MS) and rheumatoid arthritis.[9][10][11][12][13]
  • Vitamin D and depression. Olderdepressed_man_sitting adults with low blood levels of Vitamin D and high blood levels of a hormone secreted by the parathyroid glands may have a higher risk of depression, according to a report in the Archives of General Psychiatry; a medical scientific journal.[12] About 13 percent of older individuals have symptoms of depression, and other researchers have speculated that Vitamin D may be linked to depression and other psychiatric illnesses. The Vitamin D depression study findings may be important to patients because both low blood Vitamin D levels and high parathyroid hormone levels can be treated with higher dietary intake of Vitamin D or calcium and increased sunlight exposure.
  • Vitamin D may lower cancer risk. Laboratory and animal evidence as well as epidemiologic data suggest that Vitamin D status could affect cancer risk.[14][15][16] Strong biological and mechanistic bases indicate that Vitamin D plays a role in the prevention of  colorerctal cancer, colon cancer, prostate cancer, breast cancer, and many other major cancers.[17[18][19][20][21] Emerging epidemiologic data suggest that Vitamin D has a protective effect against colon cancer, but the data are not as strong for a protective effect against prostate cancer and breast cancer, and are variable for cancers at other sites. Studies do not consistently show a protective effect or no effect, however.
  • Vitamin D may retard prostate cancer growth. Researchers found that  activated Vitamin D (calcitriol) inhibits the growth prostatic carcinoma cells and that Vitamin D may retard prostate cancer growth.[22]
  • Vitamin D and diabetes. Vitamin D supplements in early childhood may ward off the development of type 1 diabetes in later life, according to research published in the Archives of Disease in Childhood.[23]
  • Vitamin D and chronic pain. Mayo Clinic research shows a correlation between inadequate Vitamin D levels and the amount of narcotic medication taken by patients who have chronic pain. These patients often end up taking narcotic-type pain medication such as morphine, fentanyl or oxycodone. This study found that patients who required narcotic pain medication, and who also had inadequate levels of Vitamin D, were taking much higher doses of pain medication - nearly twice as much - as those who had adequate levels.[24][25]

How to Get More Vitamin D in Your Diet

Few foods are naturally rich in Vitamin D. Fish such assalmon salmon, tuna, sardines, mackerel and fish liver oils are among the best sources of Vitamin D. Other sources of Vitamin D include fortified milk, cod liver oil, some yogurt and breakfast cereals, and the sun. However, if you wear an SPF of eight or more, you will have a tough time converting the sunlight into Vitamin D.

Foods small amounts of Vitamin D are found in. Small amounts of Vitamin D are found in beef liver, cheese, and egg yolks. Vitamin D in these foods is primarily in the form of Vitamin D3 (cholecalciferol) and its metabolite 25(OH)D3. Some mushrooms provide Vitamin D2 (ergocalciferol) in variable amounts.

Most Vitamin D intake is in the form of fortified products. Most Vitamin D intake is in the form of fortified products including milk, soy milk and cereal grains or supplements. For example, almost all of the U.S. milk supply is fortified with 100 IU/cup of Vitamin D (25% of the Daily Value or 50% of the AI level for ages 14-50 years). Other dairy products made from milk, such as cheese and ice cream, are generally not fortified. Ready-to-eat breakfast cereals often contain added Vitamin D, as do some brands of orange juice, yogurt, and margarine.

Vitamin D Recommended Dietary Allowance.

Vitamin D recommended dietary allowance (RDA) is the average daily dietary intake level that is sufficient to meet the nutrient requirements of nearly all (97-98%) healthy individuals in each life-stage and gender group.[4] Unlike many other nutrients, there is insufficient evidence to establish an RDA for Vitamin D. Instead, an Adequate Intake (AI) -- a level of intake sufficient to maintain healthy blood levels of an active form of Vitamin D -- has been established. The AIs for Vitamin D for adults are the same in males and females, but increase with age. For instance:  Ages 19-50: 200 International Units (IU), Ages 51-69: 400 IU and  Age 70 and older: 600 IU. Most adults over age 50 need to take a daily supplement of Vitamin D if they don't think they are getting the daily recommended amount. Adults under age 50, including pregnant women, need 200 IU of Vitamin D daily. A person over age 50 needs 400 IU daily and it goes up to over 600 IU at age 70.[4]

Vitamin D Toxicity

Taking the correct amount is important because too much Vitamin D can be toxic.[3][4] Vitamin D is stored in the liver and in the fat tissue. When you take too much it cannot leave the body as easily as water soluble vitamins such as Vitamin C. The excess Vitamin D can lead to too much calcium in the blood, which can cause kidney stones and/or kidney failure.[5]

Bottom Line on Vitamin D

There is more and more evidence daily that Vitamin D is essential for good health, for not only day to day functioning but for the prevention of many diseases and conditions. Additionally, as we age, and because of poor diets and people limited their sun exposure many people are deficient in this important vitamin. If good health is important to you, you are encouraged to investigate your personal Vitamin D level with your doctor as part of a comprehensive approach to your total health.


  1. National Osteoporosis Foundation. Prevention Vitamin D
  2. Parathyroid hormone
  3. Vitamin D at Merck Manual of Diagnosis and Therapy Professional Edition
  4. Van den Berg H (January 1997). "Bioavailability of vitamin D". Eur J Clin Nutr 51 Suppl 1: S76-9. PMID 9023488." Dietary Supplement Fact Sheet: Vitamin D". National Institutes of Health. Archived from the original on 2007-09-10.
  5. Sept. 2009 Mayo Clinic Health Letter
  6. Freedman DM, Looker AC, Chang SC, Graubard BI (2007). "Prospective study of serum vitamin D and cancer mortality in the United States". J. Natl. Cancer Inst. 99 (21): 1594-602. doi:10.1093/jnci/djm204. PMID 17971526."
  7. Sam D. Stout; Sabrina C. Agarwal; Stout, Samuel D. (2003). Bone loss and osteoporosis: an anthropological perspective. New York: Kluwer Academic/Plenum Publishers. ISBN 0-306-47767-X.
  8. Lack of vitamin D may increase heart disease risk. American Heart Association rapid access journal report
  9. Journal of the American Medical Association
  10. Munger KL. , Levin, LI,Hollis BW , Howard, NS , Ascherio A (2006). "Serum 25-hydroxyvitamin D levels and risk of multiple sclerosis". Journal of the American Medical Association 296 (23): 2832-2838. doi:10.1001/jama.296.23.2832. PMID 17179460.
  11. "Science News / Molecular Link Between Vitamin D Deficiency And MS". Retrieved 2009-02-25.
  12. Archives of General Psychiatry
  13. Vieth R (01 May 1999). "Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety". Am J Clin Nutr 69 (5): 842-56. PMID 10232622.
  14. Gorham ED, Garland CF, Garland FC et al. (2007). "Optimal vitamin D status for colorectal cancer prevention: a quantitative meta analysis. Am J Prev Med. 32:210-216.
  15. Holick MF (01 Dec 2004). "Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease". American Journal of Clinical Nutrition Full Text 80 (6): 1678S-88S. PMID 15585788.
  16. Lack of Vitamin D linked to pain. WebMD
  17. Buyru N, Tezol A;,Yosunkaya-Fenerci E, Dalay, N. Vitamin D receptor gene polymorphisms in breast cancer. Experimental and Molecular Medicine. 2003; 35(6):550-555.
  18. Lin J, Manson JE, Lee IM, Cook NR, Buring JE, Zhang SM. Intakes of calcium and vitamin D and breast cancer risk in women. Archives of Internal Medicine.2007; 167(10):1050-9.
  19. Chen WY, Bertone-Johnson ER, Hunter DJ, Willett WC, Hankinson SE. Associations Between Polymorphisms in the Vitamin D Receptor and Breast Cancer Risk. Cancer Epidemiology, Biomarkers, & Prevention. 2005; 14(10):2335-2339.
  20. Gorham ED, Garland CF, Garland FC et al. (2007). "Optimal vitamin D status for colorectal cancer prevention: a quantitative meta analysis. Am J Prev Med. 32:210-216.
  21. Buyru N, Tezol A;,Yosunkaya-Fenerci E, Dalay, N. Vitamin D receptor gene polymorphisms in breast cancer. Experimental and Molecular Medicine. 2003; 35(6):550-555.
  22. Miller GJ, Stapleton GE, Hedlund TE, Moffat KA. Vitamin D receptor expression, 24-hydroxylase activity, and inhibition of growth by 1alpha,25-dihydroxyvitamin D3 in seven human prostatic carcinoma cell lines. Clin Cancer Res. 1995 Sep;1(9):997-1003.
  23. Archives of Disease in Childhood
  24. Straube S, Andrew Moore R, Derry S, McQuay HJ (January 2009). "Vitamin D and chronic pain". Pain 141 (1-2): 10-3. doi:10.1016/j.pain.2008.11.010. PMID 19084336.
  25. Chronic pain clients respond to vitamin D.

About Lynn Glenn

lynn_glenn_expert_black_sleevelessLynn Glenn is a 61 year old natural athlete from Southern California who started training at the ripe young age of 48. After catching the "bodybuilding bug", Lynn Glenn became interested in living a healthy lifestyle and started writing about hot topics in the areas of health, fitness, weightlifting, and nutrition. Lynn is a feature writer for several health and fitness websites including, and



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