Vitamin D was discovered in the 1920s, and put an end to the painful childhood bone disease rickets. More recent research has found this nutrient to be crucial in many areas of health. Deficiencies have been found to play a role in depression, cancer prevention, the development of diabetes and auto-immune diseases such as Multiple Sclerosis and Rheumatoid Arthritis.
Vitamin D deficiencies were rare when people worked outside, in the fields, rather than in offices, and when it was the norm for children to play outside all day, rather than inside in front of a screen. The bottom line is, when man evolved, we didn’t wear much clothing, foraged for many hours each day outside for food, and lived close to the equator ie we lived in sunny climes and exposed our skin to the sun.
Vitamin D is actually many different chemicals – beginning as a form of cholesterol in the skin, which requires sunshine to be transformed into Vitamin D3. The D3 is then converted in the liver to active D3, which is 5 times more potent, and then again in the kidneys to a form of D3 10 times more potent.
Because of skin cancer, we tend not to expose ourselves to those valuable rays, covering up and applying sunscreen liberally whenever we’re outside. While it is true that the UVB rays can damage skin cells and lead to increased levels of skin cancer, it has become clear through scientific studies that we need vitamin D to our health.
What can Vitamin D do for you?
It can reduce the chances of a child becoming diabetic , when given in the first year of life, and improve insulin resistance in women  – an important factor in type II diabetes
It can reduce the likelihood of depression in women when taken over winter 
It has been shown to reduce the risk of cancer in post-menopausal women by 60% 
What dose do we need?
A new report shows everyone needs a minimum of 4,000iu daily, and most likely 10,000iu daily to get blood levels of vitamin D to the optimum cancer- preventative levels.
Vitamin D is an accessible, cheap nutrient that can make a huge difference to our health.
Check your Vitamin D level at www.grassrootshealth.net
 Hypponen E, Laara E, Jarvelin M-R, Virtanen SM. Intake of vitamin D and risk of type 1 diabetes: a birth-cohort study. Lancet 2001;358:1500–3
 von Hurst PR, Stonehouse W, Coad J. Vitamin D supplementation reduces insulin resistance in South Asian women living in New Zealand who are insulin resistant and vitamin D deficient - a randomised, placebo-controlled trial. Br J Nutr. 2010 Feb;103(4):549-55.
 Shipowick CD, Moore CB, Corbett C, Bindler R. Vitamin D and depressive symptoms in women during the winter: a pilot study. Appl Nurs Res. 2009 Aug;22(3):221-5
 Lappe JM, Travers-Gustafson D, Davies KM, Recker RR, Heaney RP. Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. Am J Clin Nutr. 2007 Jun;85(6):1586-91