Spring! The Sun is back for more than 12 hours daily! The sun crossed the equator at 0529 CDT. Vitamin D? Not so fast. This is Iowa and we are still too far north.
Your skin can make Vitamin D when exposed to strong enough sunlight. Strong enough sunlight happens when the sun is high enough in the sky that its UV rays are not blocked by the atmosphere. This happens at mid-day all year round in the tropics.
Iowa needs to wait another couple of weeks for our first moments of Vitamin D from the sun. Mid-day is around 1:10 to 1:25 pm CDT, depending on location. Southern Iowa will get enough sunlight several days before northern Iowa. Late June we will have 4-5 hours of opportunity.
Unfortunately, Vitamin D, Sunburn and Skin Cancer are often a package deal. You can encourage them all, or block them all with Sun-block.
Your safest move is to protect yourself from sunburn and skin cancer, and take your vitamin D3 tablets or gel-caps. A 25-hydroxy Vitamin D blood test will show if you have achieved the ideal range of 40-80 ng/ml.
You need to take control, but this is one area where naturally can have a significant downside.
Jay Ginther, MD