Vitamin D seems to be a genuinely potent nutrient that a lot of doctors are recommending, including my family practitioner. The vitamin appears to be associated with lower rates of cancer and diabetes (to name just two large benefits). And the amount that you might want to consider taking is pretty high (compared to previous recommendations). Dr. Andrew Weil, for example, recently upped his recommendation of vitamin D supplementation from 1,000 to 2,000 IU per day:
Low levels of vitamin D in the population as a whole suggest that most people need to take a vitamin D supplement. This may be especially true for seniors, as the ability to synthesize vitamin D in the skin declines with age. Always take your vitamin D with a fat-containing meal to ensure absorption.
Don’t be concerned that 2,000 IU will give you too much. With exposure to sunlight in the summer, the body can generate between 10,000 IU and 20,000 IU of vitamin D per hour with no ill effects. In addition, no adverse effects have been seen with supplemental vitamin D intakes up to 10,000 IU daily.
If you decide to have your vitamin D levels tested, look for results in the normal range, from 30.0 to 74.0 nanograms of 25-hydroxy vitamin D per milliliter (ng/mL) of blood. If you are found to be deficient, your physician can advise you on the best way to raise your blood concentration into the normal range.
But exceeding 2,000 IU of vitamin D may not be a good idea. Contra Weil, I’ve read elsewhere that larger doses may be associated with the formation of kidney stones.