You must do what you feel is best.
I wish you good health and good luck!
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From what I've read, from mainstream, legitimate medical sources, there is no question that Vitamin D insufficiency can be detrimental to the health. I will close by quoting a few of them:
Vitamin D Deficiency: A Worldwide Problem with Health Consequences
American Journal of Clinical Nutrition 2008 Apr;87(4):1080S-6S.
"Vitamin D deficiency is now recognized as a pandemic. ....Vitamin D deficiency causes rickets in children and will precipitate and exacerbate osteopenia, osteoporosis, and fractures in adults. Vitamin D deficiency has been associated with increased risk of common cancers, autoimmune diseases, hypertension, and infectious diseases. A circulating level of 25-hydroxyvitamin D of >75 nmol/L, or 30 ng/mL, is required to maximize vitamin D's beneficial effects for health."
from WebMD:
http://www.webmd.com/food-recipes/vitamin-d-deficiency
"Symptoms of bone
pain and muscle weakness can mean you have a vitamin D deficiency. However, for many people, the symptoms are subtle. Yet even without symptoms, too little vitamin D can pose health risks. Low blood levels of the vitamin have been associated with the following: Increased risk of death from cardiovascular disease, Cognitive impairment in older adults, Severe
asthma in children, Cancer.
Research suggests that vitamin D could play a role in the prevention and treatment of a number of different conditions, including type1 and
type 2 diabetes,
hypertension, glucose intolerance, and
multiple sclerosis."
Here is an exhaustive list by the Mayo Clinic showing evidence of some of the effects of low Vitamin D:
http://www.mayoclinic.com/health/vitamin-d/NS_patient-vitamind/DSECTION=evidence
From Dr. Marcelle Pick at Women to Women, an influential medical practice in Maine:
http://www.womentowomen.com/healthynutrition/vitamind.aspx
"I just returned from a conference where everyone was discussing vitamin D. It’s been a hot topic in both conventional and alternative medicine lately because vitamin D deficiency is widespread and seems to be related to so many health concerns:
osteoporosis,
depression,
heart disease and stroke, cancer,
diabetes, parathyroid problems, immune function — even
weight loss.
Many of today’s conventional clinicians received little to no training in medical school for this problem."
"If you think you may be suffering from vitamin D deficiency, get a blood test and ask for the results. I like to see an optimal value of 50–70 ng/mL.
A conventional doctor might think anywhere from 20–50 ng/mL is normal, but that recommendation will soon change as the newest research becomes incorporated into the standard of conventional care."