Vitamin D has many benefits to health. Musculoskeletal problems are more common in those with vitamin D deficiency/insufficiency. This includes osteoporosis, an increased risk of fractures, an increase risk of falls and reduced muscle function.
Osteoporosis affects a large percentage of nursing home residents. Osteoporosis is a bone disease associated with low bone mass and an increased risk of fracture. Ten million Americans are afflicted with osteoporosis while 34 million are afflicted with osteopenia. It is estimated that 70 to 85 percent of individuals who live in a nursing home have osteoporosis.
Osteoporosis is associated with inadequate calcium intake, but vitamin D helps with calcium absorption. Long-term vitamin D deficiency increases the risk of osteoporosis2. Vitamin D may prevent osteoporosis in older adults who are non-ambulatory, those on chronic steroids and for post-menopausal women.
Vitamin D supplementation has the potential to increase bone density. In one study there was an increase in the density of lumbar spine and the femoral neck bone with vitamin D supplementation of 50,000 international units twice a week for five weeks in those who were vitamin D deficient.
Vitamin D and calcium together reduce fractures in institutionalized older adults, but vitamin D alone is not effective in reducing the risk of falls or fractures. Those over the age of 65 with low vitamin D levels are at increased risk for hip fractures and reduced muscle mass and strength.
Vitamin D has the potential to reduce the risk of falls. It potentially does this through the improvement of muscle function. Low levels of vitamin D in the blood are linked to the poorest muscle function and higher levels are linked to better muscle function. Those with a low baseline level of serum 25-hydroxyvitamin D concentration (between 10-20 ng/ml) are likely to benefit the most in regards to muscle strength when supplemented with vitamin D.
When vitamin D supplementation is consumed in doses of 700 to 1000 international units per day the risk of falls are reduced. When 500,000 units of cholecalciferol were given once annually the risk of falls was actually increased.
A link between vitamin D and cancer has been established. Vitamin D may help in the prevention of colon, breast and prostate cancer. Precancerous lesions of the intestine and breast are linked to a deficiency of the vitamin D receptor in animals.
Many cancers have been linked to poor vitamin D status. Colorectal cancer risk is increased in those with poor vitamin D status. One analysis showed that those who consume 1000 international units per day of vitamin D have a reduced risk of colorectal cancer. Another analysis showed that vitamin D intake is inversely related to the risk of colorectal cancer. Despite the positive data on vitamin D, the research is inconsistent and the National Cancer Institute does not advise for or against the use of vitamin D supplements to lower the risk of colorectal or any other type of cancer.
Some studies show serum 25-hydroxyvitamin D concentration is associated with a reduced risk of breast cancer but findings do not reach statistical significance. More research is needed to determine the role of vitamin D on breast cancer risk.
There is some evidence that vitamin D may be harmful. One large prospective study suggested that vitamin D does not decrease the risk of prostate cancer and higher circulating vitamin D levels may be associated with an elevated risk of aggressive disease. Other research suggests that those with the highest level of vitamin D may be at an increased risk for pancreatic cancer.
Despite some research suggesting that vitamin D reduces the risk of some cancers, current evidence does not recommend large doses of vitamin D in the prevention of cancer. A large analysis of over 16,000 people suggested that total cancer mortality is not related to baseline vitamin D status. Overall research does not support role of vitamin D in the prevention of cancer. More research is needed to determine the exact link between cancer and vitamin D.
Vitamin D has effects on the immune system. Vitamin D may reduce the risk of autoimmune diseases in animals. Diseases that may be affected by vitamin D status include: diabetes mellitus type 1, multiple sclerosis and inflammatory bowel disease.
Vitamin D supplementation in early infancy reduces the risk of type 1 diabetes. One study suggested that those with a serum 25-hydroxyvitamin D concentration below 20 ng/mL had about a twofold increased rate for the future development of multiple sclerosis. Currently only animal, in vitro and epidemiological studies suggest a link between diabetes/multiple sclerosis and vitamin D. Before a firm conclusion can be reached, randomized controlled trails need to occur.
Higher levels of vitamin D are associated with a lower risk of Crohn’s disease. The impaired regulation of vitamin D is related to the development of autoimmune processes (including inflammatory bowel disease) in animals. The administration of vitamin D may improve these symptoms.
Vitamin D may help fight both bacterial and viral infections. Vitamin D levels are linked to tuberculosis. Vitamin D deficiency may be more common in those with tuberculosis. Vitamin D may have a role in the treatment of tuberculosis, but more research is needed before this link is definitely established.
Vitamin D levels may have a beneficial effect on respiratory tract viral infections, but this relationship is not strongly established. Multiple studies have not found a link between vitamin D status and the prevention of viral respiratory infections. A more recent analysis suggested that vitamin D supplementation may reduce the risk of viral upper respiratory tract infections and tuberculosis.
Vitamin D and the Heart
Many genes in the cardiovascular system are regulated by vitamin D. Vitamin D deficiency has been linked to heart attack, stroke, high blood pressure, diabetes, peripheral vascular disease and heart failure. There is a paucity of studies that look at vitamin D and cardiovascular disease. Observational research suggests that there is a link between cardiovascular disease and vitamin D status. More research is needed to determine the role of vitamin D supplementation in cardiovascular disease.
The renin-angiotensin system is regulated in part with the help of vitamin D. There is an inverse relationship between incident hypertension and serum 25-hydroxyvitamin D concentration. More research is needed to confirm a causative relationship between vitamin D levels and blood pressure.
In a review study, five out of seven studies showed an inverse relationship between the serum 25-hydroxyvitamin D level and cardiovascular disease. The prevalence of coronary heart disease is higher in those with a low serum 25-hydroxyvitamin D concentration than those with higher levels. Supplementation with vitamin D did not result in any beneficial effect on risk factors for cardiovascular disease and no benefit was appreciated after increasing the serum 25-hydroxyvitamin D concentration from 23 ng/mL to over 40 ng/mL.
Vitamin D and Other Diseases
Diabetes is linked to vitamin D. The link between vitamin D and diabetes mellitus type 1 was discussed above. Low vitamin D levels are associated with type 2 diabetes. Higher levels of vitamin D intake are associated with a lower risk of type 2 diabetes. Despite these correlations, interventional studies with vitamin D have not demonstrated that vitamin D supplementation reduces the risk of diabetes.
Vitamin D is important for brain development, so it may be linked to psychopathology. Low levels of serum 25-hydroxyvitamin D have been shown to be present in those with Alzheimer’s disease and depression. These studies do not demonstrate that low levels of vitamin D are the cause of these conditions.
Low levels of vitamin D may increase the risk of death. Even though there is an association between vitamin D and all cause mortality, it is unclear if this increased risk of death is strictly related to the vitamin D deficiency or simply overall poor health status. Some studies suggest that cancer patients have a reduced risk of mortality with a higher vitamin D level, but other studies showed no association between cancer death rates and serum 25-hydroxyvitamin D concentration.
A recent analysis showed that higher vitamin D levels. are associated with reduced all-cause mortality, but no association between vitamin D levels and stroke or ischemic heart disease was established. Those with severe chronic renal failure are at increased risk for death with low levels of serum 25-hydroxyvitamin D concentration and treatment with vitamin D improves survival.