A study conducted by Cedric Garland and other prominent vitamin D researchers determined that women with vitamin D levels above 52 ng/ml have half the risk of developing breast cancer as those with 13 ng/ml! [footnote 7] Garland (et al) estimates that 58,000 new cases of breast cancer in the United States could be prevented per year by raising vitamin D levels to 52 ng/ml. Imagine what the global impact could be!
A simple blood test is all that's needed to find out your vitamin D level. Five years ago, a range of 20–100 ng/ml was considered normal. Just recently, this range was raised to 32–100 ng/ml. Make sure to ask your healthcare provider what your actual vitamin D level is. Too often women are told that their levels are normal, which is not the same as optimal.
If you're deficient, the best way to boost your vitamin D quickly is to supplement with vitamin D3. Initially, you may need to take 5,000 IUs per day. After establishing a healthy level, I recommend supplementing with1,000 to 2,000 IUs per day—it's hard to get all you need from food. Some healthy fish provides 300 to 700 IUs, but milk only provides 100 IUs per glass.
The best source of vitamin D