Vitamin D helps with calcium absorption and the function of bone cells, and we can synthesize much of what we need in our skin, assuming we get a little sun exposure. But during the winter months in the northern half of the United States and in Canada, the sun is too low in the sky to provide enough ultraviolet rays, so we need to look to food sources and supplements, says Lappe.
The Institute of Medicine recommends that adults with minimal sun exposure get 600 international units (IU) of vitamin D per day, increasing to 800 IU for those age 70 and up.
There are only a few good food sources of vitamin D:
- Fatty Fish Three ounces of salmon or swordfish can provide about 500 IU, with lower amounts in sardines and canned tuna.
- Vitamin D-Fortified Beverages Cow’s milk, plant-based milks, and juice have about 100 IU per serving but check the label for exact amounts. Some breakfast cereals and yogurts are also fortified.
- Egg Yolks, Beef Liver, Pork, and Cheese These foods provide small amounts of vitamin D (20 to 40 IU per serving) but can contribute to your total intake over the day.
If you’re worried that you don’t get enough vitamin D from sun exposure and foods, you can talk with your doctor about taking a supplement.