Facts You Probably Don't Know About Calcium & Vitamin D
Vitamin D - at even a minimum of 800-1000 IU/Day reduces cancer, osteoporosis, type 1 diabetes, and multiple sclerosis!
However, the “National Academy of Sciences–Institute of Medicine recommended adequate intake of Vitamin D3 should be revised upward to at least 3000 to 5000 IU/day. Adoption of the new adequate intake of Vitamin D3 would substantially reduce the incidence of cancer, and there are no consistently established adverse effects of vitamin D3 intake in the range of 3000-5,000 IU/day that would be sufficient to justify a lower adequate intake of Vitamin D3.” 
Vit D production decreases with age, so especially elderly people need higher levels.
I personally recommend that my patients try to get a total of at least 5000 IU per day, especially if they do not get much daily exposure to sunlight.
Vitamin D deficiency is now associated with higher risks of 22 forms of cancer, heart disease, multiple sclerosis, osteoporosis, flu and many other disorders!
An Intake of at least 2,000 IU/day of vitamin D3 would lead to 25% reduction in incidence of BREAST CANCER and 27% reduction in incidence of COLORECTAL CANCER in North America. 
Higher sun exposure in childhood and adolescence reduce the lifetime incidence of prostate cancer by about 50%.
Published in the American Journal of Clinical Nutrition in June, 2007, a four-year clinical trial followed 1,200 women who took high levels of vitamin D and matched them against a control group who did not take the vitamin. Those rich in vitamin D had up to 77 percent fewer cancers as compared to the control group. That's twice the impact on cancer risk attributed to smoking! 
The evidence that vitamin D has profound effects on our body's innate immunity is rapidly growing...
In a 2007 study, 104 women given vitamin D were three times less likely to report cold and flu symptoms than placebo controls. “A low dose (800 IU/day) not only reduced reported incidence, it abolished the seasonality of reported colds and flu." A higher dose (2000 IU/day), given during the last year of their trial, virtually eradicated all reports of colds or flu.
Pregnant women should consult their physicians about getting at least 2,000 international units (IU) of vitamin D daily - this is 10 times the current government recommendation, and much higher than you will find in prenatal vitamins!
1200 mg of Calcium per day also decreases the risk of colon cancer by 27%. This should be taken always with it's sister mineral in a 1:2 ratio, which is 600 mg Magnesium
Ideally, healthy adults should get between 1500mg to 2000mg of Calcium per day, with 600mg to 1000mg of Magnesium. After age 35 women can no longer deposit calcium into their bones using most regular supplements. A supplemental form of calcium which can build bone in women after age 35-- and even after menopause--is called microcrystalline hydroxyapitate. It is available from a few different companies, but the one I recommend is “Bone Up” by Jarrow Formulas. Six (6) capsules per day supply sufficient calcium, magnesium, some vitamin D, and many other cofactors for continued bone growth and maintenance.
More than 50% of women already being treated for osteoporosis are Vitamin D deficient. 25-50 % of the population over age 50 is Vitamin D deficient 
Vitamin D deficiency is associated with increased risk of…
- 22 types of cancer including breast, colon, and prostate
- Multiple sclerosis
- Rheumatoid Arthritis
- Type I Diabetes
- Chronic Pain Syndromes (90 percent of people wth chronic non-
specific pain have Vit D deficiency)
* Sometimes receiving about 10 Minutes of daily sun exposure can prevent Vit D deficiency *The time of year, the latitude at which we live, the amount of clothing we wear, our skin pigmentation,and the amount of sun screen we have on are all factors which affect how much Vitamin D we can produce from the sun...
Click here to read an excellent article explaining these factors in detail
Conditions Contributing to Vitamin D Deficiency (a partial list):
• Geography – northern latitudes have decreased amounts of sun radiation
• Weather/Season – overcast, rainy, or cold regions requiring less outdoor time & more clothes be worn
• Statin Drug users or patients on cholesterol lowering medications
• Malabsorption syndromes – especially interfering with fat digestion
• Normal ageing
• Institutionalized elderly patients with decreased sun exposure
• Lack of sun exposure and sunscreen use – the UV(B) burning rays that sunscreens block also block Vit D production in the skin
• People who largely spend their days indoors due to work, climate, habit
• Cancers: prostate, colon, breast
• Long-term: use of prednisone, anti-convulsant medications
• Use of medications with photosensitivity precautions
• Liver and kidney disease – including kidney stones and gall stones
• Congestive heart failure
• Peripheral arterial disease
• Systemic Lupus Erathematosus (S.L.E.)
"Approximately 3,000 research studies have been published in biomedical journals investigating the benefits of Vitamin D and its metabilites have on cancer, including 275 epidemiological studies, according to a PubMed search.
To date there have been 748 randomly controlled reasearch trials that assigned vitamin D supplements to study participants, according to a PubMed search in August 2008. Supplementation was found to be safe at levels up to 5,000 IU per day." 
 Haroon M, Fitzgerald O (2012) Vitamin D Deficiency and its Repletion: A Review of Current Knowledge and Consensus Recommendations. J Arthritis 1:105. doi:10.4172/2167-7921.1000105.
 (Cedric F. Garland Dr PH, Edward D. Gorham MPH, PhD, Sharif B. Mohr MPH, FrankC. Garland PhD. Vitamin D for Cancer Prevention: Global Perspective Annals of Epidemiology Volume 19, Issue 7, July 2009; 468-483.
 Joan M Lappe, Dianne Travers-Gustafson, K Michael Davies, Robert R Recker, and Robert P Heaney. Vitamin D and calcium supplementation reduces cancer risk: Results of a randomized trial. Am J Clin Nutr 2007;85:1586 –91.
 Sunyecz JA. The use of calcium and vitamin D in the management of osteoporosis. Therapeutics and Clinical Risk Management. 2008;4(4):827-836.