VITAMIN D : WHAT DO WE NEED VITAMIN D FOR?


VITAMIN D
Vitamin D is different from other essential vitamins because our own bodies can manufacture it with sunlight exposure. The main function of vitamin D is to regulate the absorption of calcium and phosphorus in our bones and aid in cell to cell communication throughout the body.
Frequent exposure of the skin to sunlight promotes sufficient vitamin D synthesis without the need for supplements, however, adults who have darker skin pigmentation or frequently wear sun protection during outdoor activities are often vitamin D deficient.
Five forms of vitamin D have been discovered, vitamin D1, D2, D3, D4, D5. The two forms that seem to matter to humans the most are vitamins D2 (ergocalciferol) and D3(cholecalciferol).


SOURCE

Vitamin D for humans is obtained from sun exposure, food and supplements. It is biologically inert and has to undergo two chemical reactions to become active in the body. The active form of vitamin D in the body is called Calcitriol (1,25-Dihydroxycholecalciferol).

Calcitriol promotes the absorption of calcium and phosphorus from food in the gut and reabsorption of calcium in the kidneys – this increases the flow of calcium in the bloodstream. This is essential for the normal mineralization of bone.

SUNLIGHT AND VITAMIN D REQUIREMENTS
The following factors may reduce your vitamin D synthesis:
If you live far from the equator, your sunlight exposure will be less during many months of the year.
• Cloud cover
• Smog
• Sunscreens
WHAT DO WE NEED VITAMIN D FOR?
• It is crucial for the absorption and metabolism of calcium and phosphorous, which have various functions, especially the maintenance of healthy bones.
• Aids the immune system - vitamin D may be an important way to arm the immune system against disorders like the common cold, say scientists from the University of Colorado Denver School of Medicine, Massachusetts General Hospital and Children’s Hospital Boston.
• MS risk - it may reduce the risk of developing multiple sclerosis. Multiple sclerosis is much less common the nearer you get to the tropics, where there is much more sunlight, according to Dennis Bourdette, chairman of the Department of Neurology and director of the Multiple Sclerosis and NeuroimmunologyCenter at Oregon Health and Science University, USA.
• Maintaining cognitive functions - vitamin D may play a key role in helping the brain keep working well in later life, according to a study of 3000 European men between the ages of 40 and 79.
• Healthy body weight - vitamin D probably plays an important role in maintaining a healthy body weight, according to research carried out at the Medical College of Georgia, USA.
• Asthma symptoms and frequency - it can reduce the severity and frequency of asthmasymptoms, and also the likelihood of hospitalizations due to asthma, researchers from HarvardMedicalSchool found after monitoring 616 children in Costa Rica.
• Rheumatoid arthritis - it has been shown to reduce the risk of developing rheumatoid arthritis in women.
• Protects from radiation damage - a form of vitamin D could be one of our body’s main protections against damage from low levels of radiation, say radiological experts from the New York City Department of Health and Mental Hygiene.
• Vitamin D and cancer risk - various studies have shown that people with adequate levels of Vitamin D are at lower risk for cancer.
REQUIREMENTS
If your body cannot produce enough vitamin D because of insufficient sunlight exposure you will need to obtain it from supplements and dietary sources. In the absence of sun exposure 1000 IU of cholecalciferol is required daily for both children and adults. People with dark skin pigmentation and the elderly are more likely to have vitamin D deficiencies.
• Vitamin D levels in females in winter - women with arthritis, diabetes and some other chronic conditions are much more susceptible to reductions in vitamin D levels during the winter months.
• 1-70 years of age: 600 IU/day (15 µg/day)
• 71+ years of age: 800 IU/day (20 µg/day)
• Pregnant/lactating: 600 IU/day (15 µg/day)
• The American Academy of Pediatrics recommends5 that exclusively or partially breastfed babies should receive supplements of 400 UI per day shortly after birth, and when they are weaned they should consume a minimum of 1,000 mL/day of vitamin D fortified formula or whole milk. Non-breastfed infants consuming less than 1,000 mL/day of vitamin D-fortified formula or milk should receive a vitamin D supplement of 400 IU per day.
• The Academy also recommends that older children and adolescents who do not get 400 IU per day through vitamin D fortified milk and foods should take a 400 IU vitamin supplement each day.
• The Vitamin D Council recommends higher supplementation than most, at 1,000 IU per day for infants and children and 5,000 IU per day for adults.
VITAMIN D AND NUTRITION

Over the last few hundred years human lifestyles have changed. The industrial revolution resulted in more indoor work and less exposure to sunlight.
Many societies around the world wore more clothing over the centuries, further reducing skin exposure to sunlight. These changes have brought with them a significant reduction in the natural production of vitamin D and subsequent diseases.
Countries responded to these changes by fortifying some foods with vitamins D2 and D3, examples include breakfast cereals, bread, pastries, oil spreads, margarine, milk and other dairy products.

ALARMING RATES OF VITAMIN D DEFICIENCY

According to a study published recently, “sensible sun exposure (usually 5-10 minutes of exposure of the arms and legs or the hands, arms, and face, 2 or 3 times per week) and increased dietary and supplemental vitamin D intakes are reasonable approaches to guarantee vitamin D sufficiency.” more