The fourth vitamin to be discovered, vitamin D is a group of secosteroid compounds that include ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). The term “vitamin” is generally reserved for vital substances the body cannot synthesize on its own.
If the body is given cholesterol and sunshine, it can synthesize its own vitamin D, so technically Vitamin D is not an essential dietary vitamin.Serious deficiencies in vitamin D can lead to rickets, and it was research into this childhood disease, that led to the vitamin’s 1922 discovery by Edward Mellanby.
Vitamin D and Bones
Vitamin D has long been known to play an important role in bone health, and several recent studies provided additional confirmation. One study showed that girls who consumed the most vitamin D had the lowest risk for stress fractures.
It’s not just children who are at risk: 44% of postmenopausal women treated for distal radius fracture were vitamin D deficient or insufficient. And a meta-analysis showed that high doses of vitamin D lower the risk for fracture by 14% to 30% in people age 65 years or older.
Links to Diabetes
Low levels of vitamin D have been linked to several types of diabetes. It’s unclear, however, whether low levels of vitamin D caused the diabetes or vice versa. A larger study in active-duty military personnel in the United States, found that those with low levels of vitamin D were more likely to develop insulin-requiring diabetes within 1 year. And women who have low vitamin D levels during their first trimester of pregnancy were more likely to develop gestational diabetes
Vitamin D and Cardiovascular Disease
Numerous epidemiologic studies, including the largest one to date, suggest that a low vitamin D level increases the risk for cardiovascular disease.
Women with low levels of vitamin D during pregnancy may have children that are more prone to excess body fat at age 6 years. Furthermore, children ages 6 to 18 years who are overweight are more likely to have low vitamin D levels. Adequate levels of vitamin D are associated with less weight gain among women age 65 and older.
Vitamin D has been tied to several higher neurologic functions. Studies have linked autism to low vitamin D during pregnancy, a connection that was strengthened by a map showing that autism rates were highest among children living in states with the lowest levels of ultraviolet B radiation.
People with Alzheimer’s disease tend to have low levels of vitamin D, and better cognitive test results are linked to higher vitamin D levels. Vitamin D3 may help clear the brain of amyloid-β. And low vitamin D levels in pregnant women have been associated with poor language development in their offspring.
Stroke and Multiple Sclerosis
Data from the Honolulu Heart Program show that people with low dietary vitamin D at baseline were about 25% more likely to sustain thromboembolic stroke, but not hemorrhagic stroke, during the ensuing 34 years.
The last year has seen a flurry of studies linking vitamin D to multiple sclerosis (MS), and all of them tie low levels of vitamin D to the disease. Three of these studies were published in a single issue of the journal Neurology. Another study linked low levels of vitamin D plus exposure to the Epstein-Barr virus to the development of MS.
Low vitamin D levels predict a near-term conversion of clinically isolated syndromes to definite MS. And the risk of developing MS has been linked to lower sun exposure in early life.
About half of women with metastatic breast cancer suffer intense musculoskeletal pain, but high-dose vitamin D2 supplements appear to help. A single oral dose of 300,000 IU of vitamin D appears to help with dysmenorrhea. And a low level of vitamin D in black Americans increases the risk for knee osteoarthritis pain.
A recent study showed that women with sufficient vitamin D levels at baseline are 62% less likely to develop Crohn’s disease over the 22 year study than those with vitamin D insufficiency. Additionally, women living at southern latitudes in the United States are 52% less likely to have inflammatory bowel disease than those living in the north.
Vitamin D deficiency is almost universal among patients with chronic kidney disease (CKD). Two recent studies independently concluded that high-dose cholecalciferol (vitamin D3) supplementation safely prevents and corrects this in patients undergoing dialysis.
But Wait, There’s More
Within the past year, studies have shown that vitamin D may reduce risk for dental caries (aka cavities). Low vitamin D may be a result of depression,may increase the risk for perforated eardrums, and is linked to food allergies.
How Much Is Enough?
There’s little consensus about what blood levels of vitamin D are adequate, and even less on how much supplementation is enough. The US Recommended Dietary Allowance is 600 IU for people ages 1 to 70 years and 800 IU for those who are older.
Some authorities recommend that people who are deficient should receive supplements of 1,000 to 5,000 IU daily, but others have recommended single-bolus doses of up to 500,000 IU.
If you have questions about your Vitamin D level or supplementation, please contact the office.
Gently adapted from Medscape news.