Blood sugar regulator. Many studies have shown that vitamin D—sometimes used in combination with calcium to increase calcium absorption—improves insulin function and lowers blood sugar. In a new study of 96 healthy people, researchers found that a modest daily amount of vitamin D (420 IU) decreased fasting blood sugar and insulin resistance. Other recent research found that vitamin D supplements reduced blood sugar levels by 10 percent after two to four months, and also decreased blood sugar in women with gestational diabetes.
Dose: Studies have used various amounts of vitamin D, but at least 2,000 IU daily is a good target for adults. Consider adding 500 mg of calcium citrate.