This section looks at the potential health benefits of vitamin D, from assisting good bone health to possible cancer prevention.
1) Vitamin D for healthy bones
Vitamin D plays a substantial role in the regulation of calcium and maintenance of phosphorus levels in the blood, two factors that are extremely important for maintaining healthy bones. We need vitamin D to absorb calcium in the intestines and to reclaim calcium that would otherwise be excreted through the kidneys.
Vitamin D deficiency in children can cause rickets, a disease characterized by a severely bow-legged appearance triggered by impaired mineralization and softening of the bones.
In adults, vitamin D deficiency manifests as osteomalacia or osteoporosis. Osteomalacia results in poor bone density, muscular weakness and often causes small pseudo fractures of the spine, femur and humerus. Osteoporosis is the most common bone disease among post-menopausal women and older men.
2) Reduced risk of flu
Children given 1,200 IU of vitamin D per day for 4 months during the winter reduced their risk of influenza A infection by over 40%.2
3) Reduced risk of diabetes
Several observational studies have shown an inverse relationship between blood concentrations of vitamin D in the body and risk of type 2 diabetes. In type 2 diabetics, insufficient vitamin D levels may have an adverse effect on insulin secretion and glucose tolerance.3 In one particular study, infants who received 2,000 IU/day of vitamin D had an 88% lower risk of developing type 1 diabetes by the age of 32.
4) Healthy infants
Children with normal blood pressure who were given 2,000 IU/day had significantly lower arterial wall stiffness after 16 weeks compared with children who were given only 400 IU/day.
Low vitamin D status has also been associated with a higher risk and severity of atopic childhood diseases and allergic diseases, including asthma, atopic dermatitis and eczema. Vitamin D may enhance the anti-inflammatory effects of glucocorticoids, making it potentially useful as a supportive therapy for people with steroid-resistant asthma.5,8
5) Healthy pregnancy
Pregnant women who are deficient in vitamin D seem to be at greater risk of developing preeclampsia and needing a cesarean section. Poor vitamin D status is also associated with gestational diabetes mellitus and bacterial vaginosis in pregnant women. It is also important to note that vitamin D levels that were too high during pregnancy were associated with an increase in food allergy of the child during the first two years of life.
6) Cancer prevention
Vitamin D is extremely important for regulating cell growth and for cell-to-cell communication. Some studies have suggested that calcitriol (the hormonally active form of vitamin D) can reduce cancer progression by slowing the growth and development of new blood vessels in cancerous tissue, increasing cancer cell death and by reducing cell proliferation and metastases. Vitamin D has an influence on more than 200 human genes, which can be impaired when D status is suboptimal.3
Vitamin D deficiency has also been associated with an increased risk of cardiovascular disease, hypertension, multiple sclerosis, autism, Alzheimer's disease, rheumatoid arthritis, asthma severity and swine flu, however more reliable studies are needed before these associations can be proven.