For people aged 71+, they recommended 800 IU/day. Research suggests that low levels of vitamin D are common in older adults who don’t take supplements, but are uncommon in those who do take supplemental vitamin D. I think either 800 IU/day. I call this the “healthy aging” dose of daily vitamin D.
Fish is a great source of vitamin D. Shutterstock. "If you're eating a balanced diet — people who don't get any sun exposure — it should be perfectly fine to take a supplement of 1000 to 2000 IUs a day. However, many people can get the vitamin D that they need if they get the major dietary sources of vitamin D, such as dark fatty fish