Vitamin D was once known as simply a bone builder. It's true that vitamin D works with calcium to help keep bones strong. We can't absorb calcium without vitamin D.

But new and emerging research suggests vitamin D may be far more versatile, offering an array of wellness benefits.

Some preliminary research suggests vitamin D helps regulate the immune system and helps support heart health, normal blood pressure, healthy blood sugar and healthy aging. And, ongoing research continues to explore the potential connection to certain diseases, including some cancers.

While more research is needed to fully understand the links, below is an online library of some of the recent research supporting vitamin D. Check out what today's science has to say about the solar power of the sunshine vitamin.

Click here for a list of select references on the benefits of vitamin D.

It's probably vitamin D's most established role in health - keeping your bones healthy and strong. Vitamin D helps your body absorb calcium, and after reviewing years of research, the government recently concluded that adequate calcium and vitamin D throughout life, as part of a well-balanced diet, may reduce the risk of osteoporosis - the debilitating disease that's a major public health threat for more than 44 million Americans.

Too little vitamin D has been linked to an increased risk of bone fractures. One University of Pittsburgh study found that women ages 50 to 79 with the lowest levels of vitamin D had a 71 percent increased risk for hip fractures compared with women with the highest levels of vitamin D. The case-control study compared 400 women with hip fractures to 400 women without who were matched for age, race or ethnicity and date of blood draw, measuring the vitamin D levels in the body and finding a significant difference between the two groups.

One analysis that reviewed 12 clinical trials evaluating vitamin D supplements and fracture prevention found that higher daily doses of vitamin D - in the range of 700-800 IU - reduced the risk of fractures in older adults by 23 to 26 percent. The Harvard researchers concluded that this higher supplement dose appeared to reduce the risk of hip and any nonvertebral fractures in older adults, however there was no significant benefit when a 400 IU daily supplement was tested.

Bischoff-Ferrari HA, Willett WC, Wong JB, Giovannucci E, Dietrich T, Dawson-Hughes B. Fracture prevention with vitamin D supplementation: a meta-analysis of randomized controlled trials. Journal of the American Medical Association. 2005;293:2257-2264.

Cauley JA, Lacroix AZ, Wu L, Horwitz M, Danielson ME, Bauer DC, Lee JS, Jackson RD, Robbins JA, Wu C, Stanczyk FZ, LeBoff MS, Wactawski-Wende J, Sarto G, Ockene J, Cummings SR. Serum 25-hydroxyvitamin D concentrations and risk for hip fractures. Annals of Internal Medicine. 2008;149:242-250.

Food and Drug Administration, HHS. Food labeling: health claims; calcium and osteoporosis, and calcium, vitamin D, and osteoporosis. Final rule. Federal Register. 2008;73:56477-56487.

U.S. Department of Health and Human Services. Bone health and osteoporosis: A report of the Surgeon General. Rockville, MD: U.S. Department of Health and Human Services, Office of the Surgeon General, 2004.

Some research suggests low vitamin D levels could impact your heart health - an important finding since heart disease remains the leading cause of death for both men and women in this country.

One recent study found that men with low blood levels of vitamin D had nearly two and a half times the risk of a heart attack when compared to men with adequate levels of vitamin D. The Harvard case-control study included more than 450 men, ages 40 to 75 who suffered from heart disease and 900 men without the disease (with similar age, smoking status and timing of vitamin D measures). The researchers followed the men for 10 years, and compared those who were deficient in vitamin D to men who were in at least the low end of the "normal" range - finding significant differences between the two groups.

Another study published in the American Heart Association journal, Circulation, found that low levels of vitamin D could increase the risk heart attack, heart failure or stroke by 62 percent for men and women. A team of Boston researchers studied 1739 men and women, with an average age of 59, tracking their vitamin D status and heart health over approximately five years. One hundred and twenty adults had a heart attack or stroke during that time period - and those falling in the lowest category of vitamin D levels, were at significantly higher risk for disease, even after the researchers considered other factors such as vitamin use and physical activity. The researchers noted that the effect was magnified in those participants with hypertension, finding that their risk for a cardiovascular event was more than twice those without hypertension and further noted that cardiovascular risk increased as vitamin D levels decreased.

Giovannucci E, Liu Y, Hollis BW, Rimm EB. 25-hydroxyvitamin D and risk of myocardial infarction in men: a prospective study. Archives of Internal Medicine. 2008;168:1174-1180.

Wang TJ, Pencina MJ, Booth SL, Jacques PF, Ingelsson E, Lanier K, Benjamin EJ, D'Agostino RB, Wolf M, Vasan RS. Vitamin D deficiency and risk of cardiovascular disease. Circulation. 2008;117:503-511.

Nearly one-third of American adults suffer from high blood pressure - a condition that puts them at serious risk for cardiovascular disease, stroke and even kidney failure. Some research suggests milk and vitamin D could help support healthy blood pressure levels.

A recent cross-sectional study published in the American Journal of Clinical Nutrition investigated the relationship between vitamin D levels and systolic blood pressure. The researchers found that adults with optimal vitamin D levels in the body had a 20 percent lower chance of typical age-related increases in systolic blood pressure, compared to those with lower vitamin D levels. The researchers noted that very few (8 percent) African-Americans achieved optimal vitamin D levels, supporting the need for further investigation in the African-American populations.

A study in The Journal of Clinical Endocrinology and Metabolism evaluated the short-term effect of vitamin D and calcium supplementation compared to calcium supplementation alone on blood pressure. One hundred forty eight older women (70 and older) received either 1200 mg calcium and 800 IU of vitamin D or 1200 mg of calcium per day for eight weeks. The researchers found that only the participants who received the calcium and vitamin D supplementation had a significant reduction, reducing systolic blood pressure by nine percent.

Plus, vitamin D-rich lowfat milk is an important part of the clinically-proven healthy eating plan known as DASH (Dietary Approaches to Stop Hypertension). Some research suggests milk's vitamin D contribution may be at least partly responsible for the blood pressure benefit.

In one study, women who drank more fat free milk and had higher intakes of calcium and vitamin D from foods, and not supplements, tended to have a lower risk for developing hypertension or high blood pressure. Harvard researchers investigated the association of milk and milk products, vitamin D and calcium intake with the incidence of hypertension - considering the diets of nearly 30,000 middle-aged and older women. They found that women who consumed more low-fat milk and milk products and had diets higher in calcium and vitamin D from foods were better protected against high blood pressure. When examining the benefits of milk specifically, women who drank two or more servings of fat free milk each day reduced their risk for high blood pressure by up to 10 percent compared to those who drank fat free milk less than once a month. The same was not found for higher fat milk and milk products or calcium and vitamin D supplements.

Judd SE, Nanes MS, Ziegler TR, Wilson PW, Tangpricha V. Optimal vitamin D status attenuates the age-associated increase in systolic blood pressure in white Americans: results from the third National Health and Nutrition Examination Survey. American Journal of Clinical Nutrition. 2008;87:136-141.

Pfeifer M, Begerow B, Minne HW, Nachtigall D, Hansen C. Effects of a short-term vitamin D(3) and calcium supplementation on blood pressure and parathyroid hormone levels in elderly women. Journal of Clinical Endocrinology and Metabolism. 2001;86:1633-1637.

Wang L, Manson JE, Buring JE, Lee IM, Sesso HD. Dietary intake of dairy products, calcium, and vitamin D and the risk of hypertension in middle-aged and older women. Hypertension. 2008;51:1-7.

Scientists have identified an important role for vitamin D in normal brain development and function. While more research is needed, experts suggest this "smart" vitamin could affect healthy mood and even cognition (our ability to think), especially for older Americans at risk for cognitive decline. The early research suggests vitamin D could affect proteins in our brain directly related to memory and learning.

One study suggests that for the estimated 11 million Americans who feel down during the winter (technically referred to as Seasonal Affect Disorder), low levels of vitamin D in the body may be at least one factor involved in the condition. In fact, a study found that boosting vitamin D levels (600 IU to 4,000 IU daily) improved winter well-being scores for older adults. In a two-part study of 37 and 66 men and women (average age about 50 years old), Canadian researchers compared the effects of different doses of vitamin D supplements on wellbeing response (as measured by a wellbeing questionnaire) finding benefits for what they term "low" (600 IU) and "high" (4,000IU) dose supplementation.

Another recent cross-sectional study published in the Journal of Geriatric Psychiatry and Neurology investigated the effects of vitamin D on cognition in older adults. The British researchers studied nearly 2,000 adults over age 65 and found that the adults with the lowest vitamin D levels in the bloodstream were more than twice as likely to be cognitively impaired (lower levels of attention, orientation in time, space and memory) as those with optimum levels.

Llewellyn DJ, Langa K, Lang I. Serum 25-Hydroxyvitamin D concentration and cognitive impairment. Journal of Geriatric Psychology and Neurology. 2008;Dec 10 [Epub ahead of print].

Vieth R, Kimball S, Hu A, Walfish PG. Randomized comparison of the effects of the vitamin D3 adequate intake versus 100 mcg (4000 IU) per day on biochemical responses and the wellbeing of patients. Nutrition Journal. 2004;3:8.

It may not be able to turn back time, but vitamin D could be a part of healthy aging - good news for the 76 million baby boomers in this country.

In one 6-year review of 18 clinical trials including 57,000 adults published in the Archives of Internal Medicine, researchers evaluated the risk of dying from any cause in subjects participating in clinical trials examining the impact of vitamin D supplementation on any health condition. The investigators found that those who supplemented their vitamin D intake (an average of about 500 IU daily) had a 7 percent lower risk of dying, on average, compared to those who did not. The researchers conclude that "intake of ordinary doses of vitamin D supplements seems to be associated with decreases in total mortality rates."

A 2008 cross-sectional study from the same journal, followed more than 13,000 adults over a nine-year period to test the association of low vitamin D levels with the risk of dying from all causes. The researchers found that those, with the lowest vitamin D levels had a 26 percent extra risk of dying after nine years, compared to those with the highest levels, after controlling for seasonal, heart disease and other demographic factors.

Some research also suggests vitamin D could affect inflammation and body stress linked to the aging process. In a genetic study of more than 2,100 female twin pairs ages 19-79, British and American researchers found that higher vitamin D levels were linked to improved genetic measures of lifelong aging and chronic stress. Using a genetic marker called leukocyte telomere length (LTL), they found those with the highest vitamin D levels had longer LTL, indicating lower levels of inflammation and body stress. The telomere difference between those with the highest and lowest vitamin D levels was equivalent to 5 years of aging.

Previous research has found that shortened LTL is linked to risk for heart disease and could be an indication of chronic inflammation - a key determinant in the biology of aging. While there are several lifestyle factors that affect telomere length (obesity, smoking and lack of physical activity), the researchers noted that boosting vitamin D levels is a simple change to affect this important marker.

Autier P, Gandini S. Vitamin D supplementation and total mortality. Archives of Internal Medicine. 2007;167:1730-1737.

Melamed ML, Michos ED, Post W, Astor B. 25-hydroxyvitamin D levels and the risk of mortality in the general population. Archives of Internal Medicine. 2008;168:1629-1637

Richards JB, Valdes AM, Gardner JP, Paximadas D, Kimura M, Nessa A, Lu X, Surdulescu GL, Swaminathan R, Spector TD, Aviv A. Higher serum vitamin D concentrations are associated with longer leukocyte telomere length in women. American Journal of Clinical Nutrition. 2007;86:1420-1425.

Experts have long known that vitamin D deficiency can lead to rickets in growing children - a softening of growing bones, which can lead to stunted growth, and potentially fractures and deformity.

A recent resurgence of this debilitating disease, along with new information on the potential health benefits of vitamin D, prompted the American Academy of Pediatrics to double its recommendations and reaffirm the importance of this bone-building vitamin for children of all ages. The Academy now recommends children and adolescents aim for 400 IU of vitamin D each day to prevent rickets and reap the potential preventive health benefits.

Some researchers estimate that up to 55 percent of adolescents may be deficient putting them at increased risk for osteoporosis and debilitating bone diseases, according to one recent analysis of children living in the northeastern United States.

Wagner CL, Greer FR; American Academy of Pediatrics Section on Breastfeeding; American Academy of Pediatrics Committee on Nutrition. Prevention of rickets and vitamin D deficiency in infants, children, and adolescents. Pediatrics. 2008;122:1142-1152.

Weisberg P, Scanlon KS, Li R, Cogswell ME. Nutritional rickets among children in the United States: review of cases reported between 1986 and 2003. American Journal of Clinical Nutrition. 2004;80:1697S-1705S.

Weng FI, Shults J, Leonard MB, Stallings VA, Zemel BS. Risk factors for low serum 25-hyroxyvitamin-D concentrations in otherwise health children and adolescents. American Journal of Clinical Nutrition. 2007;86:150-158.

Some research suggests vitamin D may support healthy gums and strong teeth.

One clinical study of 145 adults (originally designed to determine risk of hip bone loss) found that supplementation with vitamin D and calcium was linked to reduced tooth loss in men and women ages 65 and older over a 3-year period. The elderly adults were given a supplement of 1,000mg of calcium with 400 to 600 IU of vitamin D daily and during the 3-year period, 27 percent subjects taking a placebo lost one or more teeth compared to just 13 percent of those taking supplements.

Another study from the American Journal of Clinical Nutrition looked at data from more than 11,000 adults and found that among women and men aged 50 and older, those with the lowest vitamin D levels had 23 to 27 percent more tooth loss than had those in the highest range. The researchers suggest vitamin D may affect inflammation and gum health, which could lead to tooth loss - independent of bone density.

Dietrich T, Joshipura KJ, Dawson-Hughes B, Bischoff-Ferrari HA. Association between serum concentrations of 25-hydroxyvitamin D3 and periodontal disease in the US population. American Journal of Clinical Nutrition. 2004;80:108-113.

Krall EA, Wehler C, Garcia RI, Harris SS, Dawson-Hughes B. Calcium and vitamin D supplements reduce tooth loss in the elderly. American Journal of Medicine. 2001;111:452-456.

Vitamin D plays an important role in regulating the immune system, helping the body's normal process of fighting illness and infection. There's even some evidence that vitamin D insufficiency may be linked to the seasonal flu and respiratory infections - the "common cold."

One recent cross-sectional study published in the Archives of Internal Medicine examined the association between vitamin D levels and recent upper respiratory tract infection in more than 18,000 Americans ages 12 and older. The researchers found that those with the lowest vitamin D levels in the body were 36 percent more likely to have had a respiratory infection compared to those with the highest levels.

Some researchers suggest the lack of vitamin D may be at least one reason for the seasonal flu - since exposure to sunlight and therefore vitamin D levels in the body tend to go down in the winter. Vitamin D helps support a healthy immune system through its involvement in your body's innate immunity - the general ability to fight off and prevent germs from gaining entry into the body and causing infection.

Cannell JJ, Vieth R, Umhau JC, Holick MF, Grant WB, Madronich S, Garland CF, Giovannucci E. Epidemic influenza and vitamin D. Epidemiology and Infection. 2006;134:1129-1140.

Ginde AA, Mansbach JM, Camargo CA Jr. Association between serum 25-hydroxyvitamin d level and upper respiratory tract infection in the third national health and nutrition examination survey. Archives of Internal Medicine. 2009;169:384-390.

National Institutes of Health Office of Dietary Supplements: Dietary Supplement Fact Sheet on Vitamin D. http://ods.od.nih.gov/factsheets/vitamind.asp

Researchers have known for decades that vitamin D plays a role in normal muscle function. Now, there's new evidence to suggest vitamin D deficiency could negatively affect performance, muscle power and pain.

Not only does vitamin D work with calcium to keep bones strong and help teens perform their best, one recent study published in the Journal of Clinical Endocrinology and Metabolism found that teenage girls (ages 12 to 14) with higher vitamin D levels may be able to jump higher and faster than their peers with lower levels, after considering differences in body weights.

The UK researchers collected vitamin D levels for 99 girls, ages 12 to 14. To test the girls' muscle function, the girls were instructed to jump as high as possible while researchers used a device designed to measure power and performance called jumping mechanography. After controlling for differences in the girls' body weight, the girls with the highest vitamin D levels had the highest jump speeds, jump height, power and force.

Muscle weakness is also a recognized symptom of vitamin D deficiency in children and a number of studies have also suggested a link between low levels of vitamin D and reduced muscle strength in adults. One study of nearly 300 patients in Switzerland linked reduced muscle strength in older men and women to lower vitamin D levels. Twelve percent of the women and 18 percent of the men studies had low vitamin D values - and by measuring leg extension power, they concluded that muscle strength was modestly, but significantly linked to vitamin D levels in the body. The researchers suggest that increasing vitamin D may help improve muscle strength, thereby also reducing fracture risk through fall prevention.

Additionally, vitamin D inadequacy has been linked to higher incidence of chronic pain - possibly linked to impaired neuromuscular function. In a recent retrospective Mayo Clinic study of 267 patients with chronic pain, those with the highest vitamin D levels reported the lowest use of pain-controlling drugs, compared to the lowest vitamin D levels. The researchers suggest this may be a sign that vitamin D deficiency may be an under-recognized source of pain and muscle weakness. More than one quarter of the adults had inadequate vitamin D levels and the pain-controlling drug users with inadequate vitamin D levels reported worse physical functioning and health perception compared to those with adequate vitamin D levels.

Another British study linked low vitamin D levels to chronic widespread pain for women, after investigating the connection for nearly 10,000 British adults with data collected from the 45-year British survey. Compared to the women with the lowest levels of vitamin D, women with the highest vitamin D levels were the least likely to experience ongoing pain symptoms (as measured by questionnaire), though more research is needed to fully understand the link - the same findings were not replicated for the men in the study.

Atherton K, Berry DJ, Parsons T, Macfarlane GJ, Power C, Hypponen E. Vitamin D and chronic widespread pain in a white middle-aged British population: evidence from a cross-sectional population survey. Annals of Rheumatic Disease. 2008 Aug 12. [Epub ahead of print]

Bischoff HA, Stahelin HB, Urscheler N, Ehrsam R, Vonthein R, Perrig-Chiello P, Tyndall A, Theiler R. Muscle strength in the elderly: its relation to vitamin D metabolites. Archives of Physical Medicine and Rehabilitation. 1999;80:54-58.

Turner MK, Hooten WM, Schmidt JE, Kerkvliet JL, Townsend CO, Bruce BK. Prevalence and clinical correlates of vitamin D inadequacy among patients with chronic pain. Pain Medicine 2008;9:979-984.

Ward KA, Das G, Berry JL, Roberts SA, Rawer R, Adams JE, Mughal Z. Vitamin D status and muscle function in post-menarchal adolescent girls. Journal of Clinical Endocrinology and Metabolism. 2009; 94:559-563.

Ongoing research is investigating the link between vitamin D and type 1 and type 2 diabetes. In fact, some scientists hypothesize that America's shortfall in vitamin D may be one of the reasons behind the current epidemic of type 2 diabetes - the more common form of diabetes.

One large, 20-year study published in Diabetes Care found that a high intake of supplemental vitamin D (more than 800 IU daily) along with more than 1,200mg of calcium daily, compared to a low intake (less than 400 IU of vitamin D and 600mg of calcium daily) reduced the risk of type 2 diabetes by one-third for otherwise healthy women. As a part of the Nurses' Health Study, researchers identified nearly 5,000 cases of type 2 diabetes over a 20-year period and concluded that their research suggests "a potential beneficial role for both vitamin D and calcium intake in reducing the risk of type 2 diabetes."

Additionally, in a thorough analysis of more than 50 previously published studies, Tufts University researchers found chronically low levels of vitamin D were linked to as high as 46 percent greater risk of type 2 diabetes, compared to higher vitamin D levels. Yet boosting vitamin D alone would likely have little effect in healthy adults. Instead, the researchers suggested that a combination of vitamin D and calcium, like that found in milk, would have the greatest potential to help prevent diabetes, especially among those at highest risk for the disease.

Examining the intake of milk and milk products specifically, the researchers found there was nearly a 15 percent lower risk for type 2 diabetes among individuals with the highest dairy intake (3-5 servings per day) compared to those getting less than 1 1/2 servings each day. Most of the studies assessed were observational and the limited number of intervention trials makes definitive conclusions difficult, yet the Tufts researchers suggest calcium and vitamin D may affect the body's ability to produce or utilize insulin, the hormone the body makes to process sugar that is impaired in those with diabetes and pre-diabetes.

Research suggests vitamin D may also affect type 1 diabetes risk. In a long-term study including all pregnant women, due to give birth in select Finnish cities, more than 10,000 children were given 2,000 IU of vitamin D daily and were followed for the next 31 years. After controlling for other factors affecting child health, researchers found that children who regularly took their vitamin D supplements were 78 percent less likely to develop type 1 diabetes, compared to children who did not get enough vitamin D, according to the 2001 study published in the Lancet.

Hyppönen E, Läärä E, Reunanen A, Järvelin MR, Virtanen SM. Intake of vitamin D and risk of type 1 diabetes: a birth-cohort study. Lancet. 2001;358:1500-1503.

Pittas AG, Dawson-Hughes B, Li T, Van Dam RM, Willett WC, Manson JE, Hu FB. Vitamin D and calcium intake in relation to type 2 diabetes in women. Diabetes Care. 2006;29:650-656.

Pittas AG, Lau J, Hu FB, Dawson-Hughes B. REVIEW: The role of vitamin D and calcium in type 2 diabetes. A systematic review and meta-analysis. Journal of Clinical Endocrinology and Metabolism. 2007;92:2017-2029.

There are more than 80 different types of autoimmune diseases - conditions where the body's immune system mistakenly attacks the body instead of protecting it against disease and infection - and some ongoing investigations are suggesting vitamin D could affect certain conditions, specifically, multiple sclerosis and rheumatoid arthritis.

One recent study published in the Journal of the American Medical Association found that higher levels of vitamin D in the body were associated with a lower risk of multiple sclerosis (MS) - one of the most common neurological diseases affecting two million people worldwide. Using data from more than 7 million military personnel, the researchers identified 257 cases of MS from 1992 through 2004 and then matched the cases to 514 people without the disease with similar age, sex, ethnicity and timing of vitamin D measures, finding the risk of MS significantly decreased with increasing vitamin D levels for Caucasians, though the same could not be seen for the black and Hispanic adults, who generally had lower vitamin D levels. The researchers concluded that high levels of vitamin D in the body "are associated with lower risk of multiple sclerosis."

Another study published in the journal Neurology found that women who met the 400 IU daily recommendation for vitamin D through foods and supplements had a 33 percent lower chance of developing MS, compared to those falling short on vitamin D. Using large sets of data (more than 180,000 women from the Nurses' Health Study I and II), the researchers assessed the diets of the 173 women who developed MS linking total vitamin D intake to lower risk.

Assessing data from nearly 30,000 middle-aged women (ages 55-69) followed over an 11-year period, researchers also found a 33 percent lower likelihood of rheumatoid arthritis for women with the highest vitamin D levels from food and supplements (more than 220 IU per day), compared to those missing the mark on vitamin D intake, according to the study published in the journal Arthritis and Rheumatism.

Merlino LA, Curtis J, Mikuls TR, Cerhan JR, Criswell LA, Saag KG; Iowa Women's Health Study. Vitamin D intake is inversely associated with rheumatoid arthritis: results from the Iowa Women's Health Study. Arthritis and Rheumatism. 2004;50:72-77.

Munger KL. Levin LI, Hollis BW, Howard NS, Ascherio A. Serum 25-hyroxyvitamin D levels and risk of multiple sclerosis. Journal of the American Medical Association. 2006;296:2832-2838.

Munger KL, Zhang SM, O'Reilly E, Hernán MA, Olek MJ, Willett WC, Ascherio A. Vitamin D intake and incidence of multiple sclerosis. Neurology. 2004;62:60-65.

With an estimated 10.5 million Americans living with cancer, researchers are on a quest for new means to prevent or delay the occurrence of this deadly disease. While the research is still preliminary, ongoing research is investigating a potential link between vitamin D and certain cancers, including colon and breast cancer. Preliminary mechanism studies suggest vitamin D may play a role in blocking certain cancer cells from multiplying and dividing in the body.

One recent study published in the American Journal of Clinical Nutrition found that increasing intake of vitamin D, along with calcium, may reduce the risk for cancer in women by 60 percent. The four-year clinical trial included more than one thousand women over the age of 55 in one of three supplement groups: 1) calcium (1400-1500mg) plus vitamin D (1100 IU vitamin D) 2) calcium only (1400-1500 mg) or 3) a placebo. The researchers found that the risk of developing cancer was 60 percent lower for those who took calcium and vitamin D and 47 percent lower for those taking calcium alone, compared to the placebo.

Fifty women developed nonskin cancer through the course of the four-year study, including breast, colon, lung and other cancers. When researchers excluded the 13 cancers diagnosed during first year of the study, determining these cancers were likely present at the study onset, the protective effect of calcium and vitamin D was even greater, with a 77 percent lower risk for cancer for those taking calcium plus vitamin D compared to the placebo.

Another study published in the journal Cancer Epidemiology Biomarkers and Prevention found that boosting vitamin D levels early in life (ages 10 to 19) through sun exposure, milk intake and cod liver oil consumption was associated with protection against breast cancer later in life. In the study, drinking at least 10 glasses of milk each week was linked to a reduced risk for breast cancer later in life, which the researchers attributed to the importance of vitamin D. In the case-control study, the scientists identified 972 women with newly diagnosed invasive breast cancer and compared their habits to 1,135 women without cancer diagnoses.

Knight JA, Lesosky M, Barnett H, Raboud JM, Vieth R. Vitamin D and reduced risk of breast cancer: a population-based case-control study. Cancer Epidemiology Biomarkers and Prevention. 2007;16:422-429.

Lappe JM, Travers-Gustafson D, Davies KM, Recker RR, Heaney RP. Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. American Journal of Clinical Nutrition. 2007;85:1586-1591.