Some people, especially those with darker skin living outside the tropics during winter months, find it impossible to maintain the recommended blood levels just by eating good food. While overdosing can be dangerous, that would take a pretty extreme amount of supplementation for most people.
That's right. Just being out in the sun for several hours per day will do wonders for you.
Naturally, you'll want to start engaging in activities that increase your heart rate to the level necessary to remain healthy over the many decades of your life.
My understanding is that _several_ hours per day can mean a very significant chance of skin cancer down the road especially for lighter skinned people in subtropical or tropical regions.
Active ingredients in most sunscreens are carcinogenic upon exposure to sunlight. Careful about studies which say the sun causes cancer in light-skinned people without accounting for their increased use of (non-mineral-based) sunscreen.
Consider which industry profits from and funds such studies.
I was tested recently and my doctor said I had dangerously low Vitamin D. It was so low they were going to proscribe high dose supplements. I eat very healthy, mostly salads and a bit of dairy and fish here and there. I bet a lot of people didn't get enough sunlight during covid. Also people with darker skin need more sun exposure to get enough. (Among Black people in snowy climates something like 70% of the population have a Vitamin D deficiency)
If you take over-the counter supplements and follow the instructions you're unlikely to overdose.