The one caution here in the US is to be certain your test is performed at a lab like Labcorp, that uses the gold standard Diasorin test for checking vitamin D levels. Due to information published by the New York Times about Quest labs, where they admitted to inaccurate results, I no longer recommend using them.In the United States, late winter 25-hydroxyvitamin D levels generally range from 15 to 18 ng/ml, so this vitamin deficiency affects a very large portion of the U.S. population. African Americans are even more prone to vitamin D deficiencies, as they produce less vitamin D3 than do whites in response to usual levels of sun exposure, and therefore have lower vitamin D serum concentrations year-round. This deficiency may help explain why African Americans also have the highest rates of prostate cancer in the world, according to the Harvard Center for Cancer Prevention.The OPTIMAL value that you’re looking for is 45-52 ng/ml (115-128 nmol/l), but previous research has suggested that maintaining a slightly higher level of 55 ng/ml (nanograms per milliliter) is optimal for cancer prevention.For those who already have cancer, meanwhile, vitamin D can help to treat the disease and you’ll want to keep your levels around 65-90 ng/ml for this purpose.Sun exposure is, hands-down, the best way to get your vitamin D. But if you find you’re not spending enough time outdoors in the sun, you can instead use a safe tanning bed or an oral vitamin D supplement as the last choice approach to normalize your levels.The disadvantage of swallowing vitamin D is that you’ll need to have your blood levels tested to be sure your vitamin D levels are in the correct range, but remember not just any test -- or any lab -- will do. I’ve discussed exactly what you need to know to get the right vitamin D test, with accurate results, here. Please also set aside some time to watch my one-hour vitamin D lecture, as it is loaded with all the details you need to use this vital nutrient to protect your health. More Natural Tips to Prevent Prostate CancerOptimizing your vitamin D levels is an important part of prostate cancer prevention, but it is far from the only method. Another sensible strategy is to increase your intake of vitamin K2 (found in fermented foods such as natto), which may reduce your risk of prostate cancer by 35 percent. You can also follow these helpful tips for prostate cancer prevention and all-natural alternative treatments given to me by former guest commentator Dr. Larry Clapp, author of Prostate Health in 90 Days Without Drugs or Surgery.