How Much Vitamin D Do You Get From The Summer Sun?

By Teresa Wagner, RD, LD
August 17, 2021

	ng/dL
Deficient	< 15
Insufficient	15-30
Minimum Target	30
*Therapeutic	40-70
Upper Limit	100
Excessive	> 100

            *The Vitamin D Council recommends a level of 50-80ng/dL year-round. (1)

What causes vitamin D deficiency?

How much vitamin D does sun exposure give?

With all these variables in place it can be difficult to say how much sun a person needs in order to make adequate amounts.  A young, light-skinned, lean person will make vitamin D more readily than an older, dark-skinned, overweight person. Light-skinned people can usually tolerate 10-20 minutes basking in the sun while dark-skinned folks could handle 90-120 minutes. 

The other variable is your attire! To give you an idea of some numbers and ranges, using the timing we just mentioned above, here are some estimates for getting adequate D from the sun on a clear, sunny Minnesota day (45° latitude) between May and September, 10:00am-2:00pm, no sunscreen with the goal of around 2000 IU per day (3):

• 70% skin exposure (swimsuit only) 1400-2800 IU
• 46% skin exposure (shorts and t-shirt) 800-1600IU
• 5-12% skin exposure (hands and face) 100-200 IU

Please don’t try to make up for less skin exposure with more time in the sun. At this amount of time, a person is not likely to become burned. The goal is exposure to UVB rays, so if your skin turns pink that’s a sign of too much sun for that area of skin and can lead to skin cancer with overexposure. 

Could you get too much vitamin D?

While the possibility of Vitamin D toxicity is relatively low from sun exposure, we can have levels too high if we continuously supplement. 

The best way to protect yourself from vitamin D toxicity is to have your blood levels tested and supplement according to those numbers. Early spring is the best time of year for vitamin D testing due to several months of low/no sun exposure.

Another way to protect yourself from vitamin D toxicity is to eat foods with the other fat-soluble vitamins (real food for the win yet again!). The body does a wonderful job of protecting itself when the right nutrients are on board.

The fat-soluble vitamins A, D, E and K are great at keeping each other in check. Foods rich in these vitamins tend to be in higher fat foods, like beef liver, natto, salmon, herring, nuts, seeds and avocado. Leafy greens, orange and red colored vegetables and fruits, and some mushrooms are sources as well.

Why is Vitamin D Important?

• Immune Function – Vitamin D triggers an anti-microbial response that fights off pathogenic foreign invaders, aka things that can make you sick.
• Strong Bones and Teeth – Vitamin D works in tandem with calcium and vitamin K2. Vitamin D plays a crucial role in the absorption of calcium into the intestines and blood.  Vitamin K2 then takes the calcium from there and deposits it into the bones and teeth. (4)
• Prevention of Heart Disease – If vitamins D and K2 are low, excess calcium may not be absorbed into the bones and can end up accumulating in your arteries leading to blockages. (4)
• Mood – Vitamin D activates genes that regulate the release of our feel-good chemicals, serotonin and dopamine.  The vitamin D receptors in the brain are located in the same regions associated with depression. (5)
• Cancer Prevention - adequate amounts of vitamin D could be associated with a lower risk of colon, breast, prostate and ovarian cancers. (6)