Today's "Independent" reports on a review of all published work on Vit D and cancer (breast, ovarian, colon) over the last 40 years. Conclusion: 1,000 IU daily cuts risk in half. From a PD perspective, however, a sidebar is even more interesting-

Heart disease
Vitamin D works by lowering insulin resistance, which is one of the major factors leading to heart disease.
<Longterm use of Ldopa increases insulin resistance and leads to hyperglycemic problems. The potassium problems that Laura and I are wrestling with are made worse by this as our bodies pump out more insulin and trigger these attacks.>

Lung disease
Lung tissue undergoes repair and "remodelling" in life and, since vitamin D influences the growth of a variety of cell types, it may play a role in this lung repair process.

Cancers (breast, colon, ovary, prostate)
Vitamin D is believed to play an important role in regulating the production of cells, a control that is missing in cancer. It has a protective effect against certain cancers by preventing overproduction of cells.

Diabetes
In type 1 diabetes the immune system destroys its own cells. Vitamin D is believed to act as an immunosuppressant. Researchers believe it may prevent an overly aggressive response from the immune system.
<A primary defense against neuroinflammation.>

High blood pressure
Vitamin D is used by the parathyroid glands that sit on the thyroid gland in the neck. These secrete a hormone that regulates the body's calcium levels. Calcium, in turn, helps to regulate blood pressure, although the mechanism is not yet completely understood.
<Calcium also is needed to make muscles and neurons to work>

Schizophrenia
The chance of developing schizophrenia could be linked to how sunny it was in the months before birth. A lack of sunlight can lead to vitamin D deficiency, which scientists believe could alter the growth of a child's brain in the womb.
<Like the various disorders being discussed in another thread, schizophrenia has some discomforting things in common with PD.>

Multiple sclerosis
Lack of vitamin D leads to limited production of 1.25-dihydroxyvitamin D3, the hormonal form of vitamin D3 which regulates the immune system, creating a risk for MS.
<Same comment as above.>

Rickets and osteoporosis
The vitamin strengthens bones, protecting against childhood rickets and osteoporosis in the elderly.
<I was born with rickets and research suggests that I may handle Vit D with less efficiency because of that early shortage.>