Vitamin D is different from a lot of other essential nutrients in that our bodies can manufacture it if exposed to sunlight. Vitamin D is needed to regulate the absorption of calcium and phosphorus in our bones and to help the cells in our body communicate.
To date, five forms of vitamin D have been identified. The two forms most important to humans are D2 (ergocalciferol) and D3 (cholecalciferol). The best ways to obtain vitamin D are from sun exposure, food, and dietary supplements. Vitamin D is biologically inert and has to undergo two hydroxylation reactions to become active in the body. Calcitriol (1, 25-Dihydroxycholecalciferol) is the active form of vitamin D in the body and readily promotes the absorption of calcium and phosphorus from food in the gut and allows for reabsorption of calcium in the kidneys. This allows for an increase in the flow of calcium in the bloodstream and is essential for normal mineralization of bone.
In northern latitudes, vitamin D deficiency is very common and, according to a study published in the American Journal of Clinical Nutrition, is considered an epidemic in the United States. Vitamin D2 and D3 are used as nutritional supplements. Many believe that the two are equally effective in our bloodstream. New research suggests that D3 is more effective.
What are other benefits of vitamin D?
- The U.S. Department of Health and Human Services says vitamin D is essential for the “formation, growth, and repair of bones and for normal calcium absorption and immune function.” Studies suggest that “higher levels of vitamin D in the blood are associated with reduced risks of colorectal cancer, however, the research results overall have been inconsistent.”
- Aids the immune system against disorders like the common cold, according to scientists from the University of Colorado Denver School of Medicine, Massachusetts General Hospital, and Children’s Hospital, Boston.
- It may reduce the risk of developing multiple sclerosis, according to Dennis Bourdette, chair of the department of neurology at Oregon Health and Science University. Multiple sclerosis is much less common the nearer you get to the tropics, where there is much more sunlight.
- Plays a key role in helping the brain to work well later in life, according to a study of 3,000 European men between the ages of 40 and 79.
- Can reduce the severity and frequency of asthma symptoms, according to researchers from Harvard Medical School who monitored 616 children in Costa Rica.
- Is believed to play an important role in maintaining a healthy body weight, according to research at the Medical College of Georgia.
- Has been shown to reduce the risk of developing rheumatoid arthritis in women.
- High doses of vitamin D can help people recover from tuberculosis more rapidly, reported researchers in the Proceeding of the National Academy of Sciences in September 2012.
- In a study carried out by the Cancer Treatment Centers of America, vitamin D deficiency was prevalent in cancer patients, regardless of nutritional status. Various studies have shown that people with adequate levels of vitamin D have a significantly lower risk of developing cancer compared to those whose levels are low.
According to the Institute of Medicine of the National Academies, the group responsible for the creation of the Dietary Reference Intakes, people should take in the following amounts of vitamin D if they are not getting direct sunlight exposure to the skin.
- Ages 1 – 70: 600 IU/day (15 ug/day)
- Ages 71+: 800 IU/day (20 ug/day)
- Pregnant/lactating 600 IU/day (15 ug/day)
If children do not receive at least 400 IU per day through vitamin D-fortified milk and food, it is recommended that they take a 400 IU vitamin supplement daily.
Not many foods contain vitamin D, though it’s found in fish such as salmon, tuna and mackerel, as well as fish liver oils. It is also found in beef liver, egg yolks, and cheese. Most of the food-sourced vitamin D in the western diet comes from foods that have been fortified through the artificial adding of vitamin D. The fortification of milk started in the 1930s to combat rickets, which was a major health problem.
Maine Vitamin D/diabetes study
Vitamin D is a hot topic. Recent research has shown that obesity can cause vitamin D deficiency, which can speed up the aging of bones. One of the largest research studies ever to be done in Maine, starting later this year, will examine whether vitamin D can help prevent diabetes. Thanks to Dr. Cliff Rosen’s participation on a national committee about the topic, Maine became one of 20 sites chosen for the nationwide study.
The Maine Medical Center Research Institute’s Vitamin D and diabetes study is looking for 600 to 700 people possibly at risk of developing type 2 diabetes who would like to be part of the National Institutes of Health research study. The trial will take more than a year to complete and participants will be screened every six months to see if they went from being at risk of diabetes to having the disease.
For information about participating in the Vitamin D and diabetes study, call 661-7624 or visit d2study.org. The MMC Research Institute is currently accepting applications.
Georgia Clark-Albert is a registered dietitian nutritionist and certified diabetes educator at Penobscot Community Health Care in Bangor. She provides nutrition consultant services through Mainely Nutrition in Athens. Read more of her columns and post questions at bangordailynews.com or email her at GeorgiaMaineMSRDCDE@gmail.com.