Getting enough Vitamin D each day is vital for good health.
We find it in oily fish, fortified milk, even egg yolks - Vitamin D, often called the sunshine vitamin.
But 1 out of 3 Americans aren't getting enough of the supplement in their diet and this can lead to health problems.
When you're low on vitamin D, there are no warning signs.
Patient Tigisty Girmay says, "I think it was just shock, cuz I wasn't expecting it. I feel like I'm overall like a healthy person."
Tigisty Girmay is now taking vitamin D supplements.
Most other vitamins and minerals we can get through diet, Vitamin D is the exception.
Doctors recommend people ages 1 - 70 get 600 international units a day.
One of the best sources is sunlight but....
Right now the general recommendation is not to go out in sunlight and use that as your primary source of vitamin D - largely because of the risk of skin cancer.
When vitamin D levels get too low it can weaken our bones and may increase the risk for other conditions.
Heart disease, high blood pressure, increase risk of dementia, also higher risks of cancer.
The best evidence is against colorectal cancer.
Other studies suggest that vitamin D may also play a role in the risk of developing multiple sclerosis, type 2 diabetes, and catching a cold or the flu.
But taking too high of a dose is also harmful. So try to stick to the recommended daily allowance.
Dr. Bergquist found Girmay's low levels with a simple blood test.