While these studies don't directly mention vitamin D3, it's likely that the enhancements are due to the benefits of vitamin .

Here's what to know about vitamin D3 benefits, sources ... available over-the-counter are sold in dosages between 1000–5000 IU, but some are higher. “Ask for your provider’s recommendation ...

If you are 70 years and older, your daily dose should be closer to 800 IU, notes Gans. Most people can take a vitamin D supplement for its immunity and other health benefits, says Arsenault.