Buzz
Our skin has the ability to convert 7-dehydrocholesterol into vitamin D with the help of sunlight. If you aren’t getting much sun, no worries, you can still obtain vitamin D from your diet. But you might be curious—how much sunshine is really necessary?
Dminder (free on iOS and Android) is a helpful app that calculates the right amount of sunlight exposure for you. The process is a bit more complex than just a specific number of minutes in the sun because it’s not any sunlight that helps produce vitamin D, but rather the UVB rays that cause sunburns. You only receive sufficient UVB exposure when conditions align: the sun needs to shine directly above you. For those living near the equator (or certain parts of the southern US), this typically happens during midday. For the rest of us, summer midday provides the optimal vitamin D time.
Your required UVB exposure is also influenced by various factors such as:
Your altitude
Your skin tone and ability to tan
Your age
The clothing you wear
And, naturally, how much vitamin D you consume through your diet.
Most people are likely doing fine with their vitamin D levels, so if you haven't been concerned about it, there's no need to worry. However, if you're interested, you can input a recent vitamin D test result (optional) and track how much vitamin D you typically consume in your diet. (Dminder doesn’t estimate vitamin D from food, but several food tracking apps can assist you in calculating this.)
The app also uses your location and the time of day to calculate how much D you can receive from sunlight. In my area, on a cloudy day, it will take about 20 minutes in jeans and a t-shirt to replenish my vitamin D stores. But if I stay outside for longer than 10 minutes, I'll risk burning, so the app helpfully reminds me to come inside. Perhaps I could instead have a piece of salmon (425 IU in a three-ounce portion) to get my dose.
