Vitamin D: What is it good for and how do we get it?

Vitamin D3 is synthesized in skin by Sunshineexposure to direct sunlight (ultraviolet B radiation) and obtained in the diet mostly in fish liver oils and salt water fish. In some developed countries, milk and other foods are fortified with vitamin D. Most people don’t realise that it affects every system of the body and a deficiency can contribute to many illnesses, including diabetes and heart disease. The best way to increase your Vitamin D level is by exposing your body (torso, limbs or both) to the sun for fifteen minutes, at least three times a week. This should happen at safer times of the day like early morning and late afternoon, when the sun isn’t too hot, to minimise your chances of getting burnt. However, many people are unable to do this in the cooler months and need to take supplements in the form of tablets or Vitamin D drops to boost their levels.

What is Vitamin D and what does it do?

  • Vitamin D is a prohormone with several active metabolites that act as hormones. Vitamin D is metabolised by the liver and then converted by the kidneys to active vitamin D.

Actions of Vitamin D and Its Metabolites

Organ

Action

Bone

Promotes bone formation by maintaining  appropriate calcium and phosphate concentrations

Immune system

Stimulates immunogenic and antitumour activity. Decreases risk of autoimmune disorders

Intestines

Enhances calcium and phosphate transport

Kidneys

Enhances calcium reabsorption by the tubules

Parathyroid glands

Inhibits parathyroid hormone secretion

Pancreas

Stimulates insulin production

What are the different ways you could become Vitamin D deficient?

A brighter future - Ruth Jotua, 24, mum-of-two

1. Inadequate exposure or intake: Inadequate direct sunlight exposure (or sunscreen use) and inadequate intake usually occur simultaneously to result in clinical deficiency. Latitude, season, time of day, air pollution, cloud cover may contribute to lack of exposure (Cannell et al, 2008).

2.  Reduced absorption: Malabsorption can deprive the body of dietary vitamin D. Causes of fat malabsorption are: pancreatic enzyme deficiency, Crohn’s disease, cystic fibrosis, sprue, liver disease, small bowel disease, surgical removal of bladder. Symptoms: greasy stools, diarrhea.

3.  Abnormal metabolism: Vitamin D deficiency may result from defects in the production of 25(OH)D or 1,25(OH)2D occurs with a chronic renal disease.

4. High concentrations of melanin in the skin slows down the production of Vitamin D and aging greatly reduces the production of skin and impairs the ability of the skin to make Vitamin D (Cannell et al, 2008). Therefore dark-skinned people need longer UV exposure times (Cannell et al, 2008).

5. Obesity is also a major risk factor for vitamin D deficiency as larger amounts of body fat further increase requirements (Cannel et al, 2008).

Picture of an Obese Teenager (146kg/322lb) wit...

What are the Potential Impacts of a Vitamin D Deficiency?

  • Inadequate exposure to sunlight predisposes to vitamin D deficiency. Deficiency impairs bone mineralization, causing rickets in children and osteomalacia in adults and possibly contributing to osteoporosis.
  • Severe deficiencies are very common in newborn infants and pregnant women especially African-Americans.
  • According to Cannell et al (2008) vitamin D deficiency is associated with cancer, cardiovascular disease, hypertension, stroke, diabetes, multiple sclerosis, rheumatoid arthritis, inflammatory bowel disease, periodontal disease, macular degeneration, mental illness, chronic pain, and a propensity to fall.

  • Vitamin D deficiency may predispose to glucose intolerance, altered insulin secretion and type 2 diabetes. Its’ replenishment improves glycaemia and insulin secretion in type 2 diabetes. Vitamin D is also thought to have a direct effect on pancreatic beta-cell function (Palomer et al, 2008).
  • A cross-sectional population study of South Asian women found that chronic pain was three times more likely to occur among those with the lowest 25(OH)D levels (Cannel et al, 2008).
  • In the largest recent open study 83% of 299 patients with idiopathic chronic low back pain were found to be severely vitamin D deficient (Cannel et al, 2008).
  • A recent meta-analysis of 18 randomised controlled trials indicated that even in small doses vitamin D reduces total mortality (Cannell et al, 2008).

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Significant Interactions

  • Cardiac drugs, erythromycins,  psychotropics, and grapefruit juice may adversely interfere with Vitamin D intake.
  • Anticonvulsants, corticosteroids, cimetidine, theophylline, and orlistat may lower 25(OH)D levels
  • A number of studies found oestrogen and progesterone raised vitamin D levels.

Requirements

  • Oral vitamin D treatment is more difficult than treatment with UVB light because the amount of vitamin D varies with body weight and fat, age, skin colour, season, latitude and sunning habits (Cannell et al, 2008).
  • Recommended direct sunlight exposure is 5 to 15 min (suberythemal dose) to arms and legs, or face, arms and hands, at least 3 times a week (Merck Manual, 2008).

So if you haven’t checked your Vitamin D levels before, it might be a good idea to do so. You may, like many Australians, be deficient in Vitamin D which could negatively impact on your health and well being. As a naturopath I am able to assess how your levels could be contributing to certain conditions and offer you the correct nutriitional support and advice to address these issues. I am also able to supply you with Practitioner Only Vitamin D drops to boost your levels, rather than the large over the counter tablets, making it easier to take and digest. So if you need any support or advice don’t hesitate to contact me Monique on 0432 540 996 or check out my On-Line Consultation Page.

 

References

Cannell, J, Hollis, B, Zasloff M, Heaney, R. (2008). “Diagnosis and treatment of vitamin D deficiency” Expert Opinion Pharmacotherapy 9(1): 107-18

www.merckmanual.com  Merck Manual Vitamin D Deficiency, 2008.

Palomer, X, Gonzalez-Clemente. (2008). “Role of Vitamin D in the pathogenisis of type 2 diabetes mellitus”. Diabetes

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